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United States Patent
5927088
Shaw
July 27, 1999
Title
Boosted air source heat pump
Abstract
A boosted air source heat pump system is presented having a primary compressor, a booster compressor and an economizer. On activation of the heat pump system, the primary compressor is operated. When the primary compressor cannot meet the demand, the booster compressor is activated, but only upon receipt of a signal enabling the operation of the booster compressor. The booster compressor is preferably a variable speed booster, and its speed is controlled to be at or between an absolute minimum speed and an absolute maximum speed. The booster may be on the low side or the high side of the primary compressor. The operation of the economizer may be modulated to meet the demand on the system.
Inventors:
Shaw; David N.
(New Britain,
CT
)
Appl. No.:
069351
Filed:
April 29, 1998
Current U.S. Class:
62/175
62/196.2
62/510
Field of Search:
62/196.2,175,510
U.S. Patent Documents
2243541
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3500962
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Grant
3775995
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Conley et al.
3785169
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3859815
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Kasahara
4197719
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Shaw
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Shaw
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0 106 414
Apr., 1984
EP
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Jun., 1996
EP
06213170
Feb., 1994
JP
Other References
Theory of Mechanical Refrigeration, N.R. Sparks, McGraw Hill, 1938 (pp. 111-127). .
J.L. Threlkeld, Thermal Environmental Engineering, Prentice-Hall, Inc. .COPYRGT.1970, 1962 (pp. 63-69). .
Survey And Comparison Of Interstage Cooling Systems For Two Stage Compression, Data Sheet, No. 20, May 1979. .
E.G. Pita, Refrigeration Principles and Systems, Business News Publishing Company, 1991 (pp. 243-245). .
B.D. Wood, Applications Of Thermodynamics, Waveland Press, Inc., .COPYRGT.1982 (pp. 218-222). .
S.M. Elenka and Q.W. Minich, Standard Refrigeration and Air Conditioning Questions & Answers, McGraw Hill, .COPYRGT.1983, 1973, 1961 (pp. 28-31, 50-53. .
I. Cerepnalkowski, Modern Refrigerating Machines, Elsevier Science Publishers, B.V., .COPYRGT.1991 (pp. 47,48). .
A Technical Handbook From SWEP, 1993 (1 page plus cover and back sheets)..~
Primary Examiner:
Wayner; William
Attorney, Agent or Firm:
Cantor Colburn LLP
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a continuation of U.S. application Ser. No. 08/806,696 filed Feb. 26, 1997 now abandoned, which, in turn, is a continuation-in-part of U.S. application Ser. No. 08/607,707, filed Feb. 27, 1996.
Claims
What is claimed is:
1. A heat pump including:
a primary compressor;
a booster compressor;
first and second heat exchange means;
flow conduit means connecting said first and second heat exchange means and said primary compressor for circulating a refrigerant fluid in a closed loop;
economizer means connected in said flow conduit means between said first and second heat exchangers;
bleed means connected from said flow conduit means to said economizer means to deliver a portion of the refrigerant fluid to said economizer means for vaporization in heat exchange with the remaining portion of refrigerant fluid passing through said economizer means;
conduit means connected from said economizer means to said flow conduit means upstream of the intake of said primary compressor;
first sensor means for sensing a parameter commensurate with the temperature of ambient outdoor air;
second sensor means for sensing a parameter of booster compressor operation commensurate with power input to said booster compressor;
thermostat means for sensing the temperature of a fluid to be heated or cooled; and
control means responsive to inputs from said first sensor means, said second sensor means and said thermostat means for controlling operation of said primary compressor and said booster compressor, said control means functioning initially to operate said primary compressor in response to a first input signal from said thermostat means while maintaining said booster compressor inoperative, and thereafter functioning to operate said booster compressor and said primary compressor upon receipt of a second signal from said thermostat means and receipt of a booster enabling signal commensurate with the temperature of ambient outdoor air;
said flow conduit means being connected to bypass said booster compressor and deliver fluid from one of said heat exchangers to said primary compressor when said booster compressor is inoperative, and said flow conduit means being connected to deliver fluid from said one heat exchanger to said booster compressor and from said booster compressor to said primary compressor when operation of said booster compressor is initiated.
2. The heat pump of claim 1 wherein:
said parameter of booster compressor operation is chosen from the group comprising:
pressure of the refrigerant fluid between the discharge from said booster compressor and the intake to said primary compressor, the rotational speed of said booster compressor, and the kilowatt input to said booster compressor.
3. The heat pump of claim 1 wherein:
said first heat exchanger means is an evaporator located in said flow conduit means downstream of said economizer means and upstream of said booster compressor and said primary compressor; and
said second heat exchange means is a condenser located in said flow conduit downstream of said primary compressor and upstream of said economizer.
4. The heat pump of claim 1 wherein:
said control means is effective to control operation of said booster compressor in accordance with a set point of said parameter of booster compressor operation sensed by said second sensor means; and
said control means is responsive to said first sensor means to vary the level of said set point of said parameter of booster compressor operation as a function of outdoor ambient temperature.
5. The heat pump of claim 1 wherein:
said first heat exchanger means is an evaporator serving as an outdoor coil located in said flow conduit means downstream of said economizer means and upstream of said booster compressor, said evaporator receiving a flow of outdoor ambient air; and
said second heat exchanger means is a condenser serving as an indoor coil located in said flow conduit downstream of said primary compressor and upstream of said economizer, said condenser receiving a flow of air to be conditioned; and further including
third sensor means for sensing the temperature of air from said condenser; and
flow control means for controlling the flow of air over said condenser in response to said third sensor means.
6. The heat pump of claim 1 wherein:
one of said first and second heat exchange means is an evaporator; and
the other of said first and second heat exchange means is a condenser.
7. The heat pump of claim 6, including:
third sensor means for sensing the temperature of air from said condenser; and
flow control means for controlling the flow of air over said condenser in response to said third sensor means.
8. The heat pump of claim 1, including:
valve means moveable from a first position to a second position to control the direction of flow of refrigerant fluid in said closed loop;
said valve means in a first position directing the flow of refrigerant fluid from said primary compressor to one of said heat exchange means functioning as a condenser, and from said condenser to said economizer and then to the other of said heat exchange means functioning as an evaporator; and
said valve means in a second position directing the flow of refrigerant fluid from said primary compressor to said other of said heat exchange means functioning as a condenser, and from said condenser to said economizer and then to said one of said heat exchange means functioning as an evaporator.
9. The heat pump of claim 1 wherein:
said primary compressor is a one speed compressor; and
said booster compressor is a variable speed or multispeed compressor.
10. The heat pump of claim 1 wherein:
said primary compressor is a one speed compressor; and
said booster compressor is a variable speed or multispeed compressor.
11. A heat pump including:
a primary compressor;
a booster compressor;
first and second heat exchange means;
flow conduit means connecting said first and second heat exchange means and said primary compressor for circulating a refrigerant fluid in a closed loop;
economizer means connected in said flow conduit means between said first and second heat exchangers;
bleed means connected from said flow conduit means to said economizer means to deliver a portion of the refrigerant fluid to said economizer means for vaporization in heat exchange with the remaining portion of refrigerant fluid passing through said economizer means;
conduit means connected from said economizer means to said flow conduit means upstream of the intake of said primary compressor;
first sensor means for sensing a parameter commensurate with the temperature of ambient outdoor air;
second sensor means for sensing the pressure of refrigerant fluid at a point in said flow conduit means between said booster compressor and said primary compressor;
thermostat means for sensing the temperature of a fluid to be heated or cooled; and
control means responsive to inputs from said first sensor means, said second sensor means and said thermostat means for controlling operation of said primary compressor and said booster compressor, said control means functioning initially to operate said primary compressor in response to a first input signal from said thermostat means while maintaining said booster compressor inoperative, and thereafter functioning to operate said booster compressor and said primary compressor upon receipt of a second signal from said thermostat means and receipt of a booster enabling signal from said second sensor means;
said flow conduit means being connected to bypass said booster compressor and deliver fluid from one of said heat exchangers to said primary compressor when said booster compressor is inoperative, and said flow conduit means being connected to deliver fluid from said one heat exchanger to said booster compressor and from said booster compressor to said primary compressor when operation of said booster compressor is initiated.
12. The heat pump of claim 11 wherein:
said first heat exchanger means is an evaporator located in said flow conduit means downstream of said economizer means and upstream of said booster compressor and said primary compressor; and
said second heat exchange means is a condenser located in said flow conduit downstream of said primary compressor and upstream of said economizer.
13. The heat pump of claim 11 wherein:
said control means is effective to control operation of said booster compressor in accordance with a set point of said second sensor means; and
said control means is responsive to said first sensor means to vary the level of said set point as a function of outdoor ambient temperature.
14. The heat pump of claim 11 wherein:
said first heat exchanger means is an evaporator serving as an outdoor coil located in said flow conduit means downstream of said economizer means and upstream of said booster compressor, said evaporator receiving a flow of outdoor ambient air; and
said second heat exchanger means is a condenser serving as an indoor coil located in said flow conduit downstream of said primary compressor and upstream of said economizer, said condenser receiving a flow of air to be conditioned; and further including
third sensor means for sensing the temperature of air from said condenser; and
flow control means for controlling the flow of air over said condenser in response to said third sensor means.
15. The heat pump of claim 11 wherein:
one of said first and second heat exchange means is an evaporator; and
the other of said first and second heat exchange means is a condenser.
16. The heat pump of claim 15, including:
third sensor means for sensing the temperature of air from said condenser; and
flow control means for controlling the flow of air over said condenser in response to said third sensor means.
17. The heat pump of claim 11, including:
valve means moveable from a first position to a second position to control the direction of flow of refrigerant fluid in said closed loop;
said valve means in a first position directing the flow of refrigerant fluid from said primary compressor to one of said heat exchange means functioning as a condenser, and from said condenser to said economizer and then to the other of said heat exchange means functioning as an evaporator; and
said valve means in a second position directing the flow of refrigerant fluid from said primary compressor to said other of said heat exchange means functioning as a condenser, and from said condenser to said economizer and then to said one of said heat exchange means functioning as an evaporator.
18. The heat pump of claim 11 wherein:
said primary compressor is a one speed compressor; and
said booster compressor is a variable speed or multispeed compressor.
19. A heat pump including:
a primary compressor;
a booster compressor;
first and second heat exchangers;
a conduit loop connecting said first and second heat exchangers, and said primary compressor for circulating a refrigerant therein;
an economizer connected in said conduit loop between said first and second heat exchangers;
a first economizer conduit connecting said economizer and said conduit loop to deliver a portion of the refrigerant from said conduit loop to said economizer for vaporization with the remaining portion of the refrigerant passing through said economizer;
a second economizer conduit connecting said economizer to said conduit loop upstream of the intake of said primary compressor;
a first sensor for sensing a parameter commensurate with the temperature of ambient outdoor air;
a second sensor for sensing a parameter of booster compressor operation commensurate with power input to said booster compressor;
a thermostat for sensing the temperature of a medium to be heated or cooled; and
a controller responsive to inputs from said first sensor, said second sensor and said thermostat for controlling operation of said primary compressor and said booster compressor, said controller functioning initially to operate said primary compressor in response to a first input signal from said thermostat while maintaining said booster compressor inoperative, and thereafter functioning to operate said booster compressor and said primary compressor upon receipt of a second signal from said thermostat and receipt of a booster enabling signal commensurate with the temperature of ambient outdoor air;
said conduit loop being connected to bypass said booster compressor and deliver the refrigerant from one of said first and second heat exchangers to said primary compressor when said booster compressor is inoperative, and said conduit loop being connected to deliver the refrigerant from said one heat exchanger to said booster compressor and from said booster compressor to said primary compressor when operation of said booster compressor is initiated.
20. The heat pump of claim 19 wherein:
said parameter of booster compressor operation is chosen from the group comprising:
pressure of the refrigerant between the discharge from said booster compressor and the intake to said primary compressor, the rotational speed of said booster compressor, and the kilowatt input to said booster compressor.
21. The heat pump of claim 19 wherein:
said first heat exchanger is an evaporator located in said conduit loop downstream of said economizer and upstream of said booster compressor and said primary compressor; and
said second heat exchanger is a condenser located in said conduit loop downstream of said primary compressor and upstream of said economizer.
22. The heat pump of claim 19 wherein:
said controller is effective to control operation of said booster compressor in accordance with a set point of said parameter of booster compressor operation sensed by said second sensor; and
said controller is responsive to said first sensor to vary the level of said set point of said parameter of booster compressor operation as a function of outdoor ambient temperature.
23. The heat pump of claim 19 wherein:
said first heat exchanger is an evaporator serving as an outdoor coil located in said conduit loop downstream of said economizer and upstream of said booster compressor, said evaporator receiving a flow of outdoor ambient air; and
said second heat exchanger is a condenser serving as an indoor coil located in said conduit loop downstream of said primary compressor and upstream of said economizer, said evaporator receiving a flow of air to be conditioned; and further including
a third sensor for sensing the temperature of air from said condenser; and
a flow controller for controlling the flow of air over said condenser in response to said third sensor.
24. The heat pump of claim 19 wherein:
one of said first and second heat exchangers is an evaporator; and
the other of said first and second heat exchangers is a condenser.
25. The heat pump of claim 24 including:
a third sensor for sensing the temperature of air from said condenser; and
a flow controller for controlling the flow of air over said condenser in response to said third sensor.
26. The heat pump of claim 19 including:
a valve moveable from a first position to a second position to control the direction of flow of the refrigerant in said conduit loop;
said valve in a first position directing the flow of the refrigerant from said primary compressor to one of said heat exchangers functioning as a condenser, and from said condenser to said economizer and then to the other of said heat exchangers functioning as an evaporator; and
said valve in a second position directing the flow of the refrigerant from said primary compressor to said other of said heat exchangers functioning as a condenser, and from said condenser to said economizer and then to said one of said heat exchangers functioning as an evaporator.
27. The heat pump of claim 19 wherein said medium is air or fluid.
28. The heat pump of claim 19 wherein:
said primary compressor is a one speed compressor; and
said booster compressor is a variable speed or multispeed compressor.
29. A heat pump including:
a primary compressor;
a booster compressor;
first and second heat exchangers;
a flow conduit connecting said first and second heat exchange means and said primary compressor for circulating a refrigerant fluid in a closed loop, said booster compressor being upstream of said primary compressor in said loop;
an economizer connected in said flow conduit between said first and second heat exchangers;
a bleed connected from said flow conduit to said economizer to deliver a portion of the refrigerant fluid to said economizer for vaporization in heat exchange with the remaining portion of refrigerant fluid passing through said economizer;
an economizer vapor conduit connected from said economizer to said flow conduit upstream of the intake of said primary compressor;
an economizer flow controller in said bleed to control the flow of fluid from said bleed through said economizer and to said economizer vapor conduit;
a first sensor for sensing a parameter commensurate with the temperature of ambient outdoor air;
thermostat means for sensing the temperature of a fluid to be heated or cooled; and
controller responsive to inputs from said first sensor and said thermostat means for controlling operation of said primary compressor and said booster compressor and said economizer, said controller being effective initially to operate said primary compressor in response to a first input signal from said thermostat while inhibiting operation of said booster compressor and said economizer flow controller, and said controller thereafter being effective to operate said booster compressor and said primary compressor upon receipt of a second signal from said thermostat means and receipt of a booster enabling signal commensurate with the temperature of ambient outdoor air, and said controller thereafter being effective to operate said economizer by controlling the flow of fluid from said bleed line and through said economizer flow controller to said economizer and to said economizer vapor conduit;
said flow conduit being connected to bypass said booster compressor and deliver fluid from one of said heat exchangers to said primary compressor when said booster compressor is inoperative, and said flow conduit being connected to deliver fluid from said one heat exchanger to said booster compressor and from said booster compressor to said primary compressor when operation of said booster compressor is initiated.
30. The heat pump of claim 29 wherein:
said first heat exchanger is an evaporator located in said flow conduit downstream of said economizer and upstream of said booster compressor and said primary compressor; and
said second heat exchange is a condenser located in said flow conduit downstream of said primary compressor and upstream of said economizer.
31. The heat pump of claim 29 wherein:
said first heat exchanger is an evaporator serving as an outdoor coil located in said flow conduit downstream of said economizer and upstream of said booster compressor, said evaporator receiving a flow of outdoor ambient air; and
said second heat exchanger is a condenser serving as an indoor coil located in said flow conduit downstream of said primary compressor and upstream of said economizer, said condenser receiving a flow of air to be conditioned; and further including
a second sensor for sensing the temperature of air from said condenser; and
a flow controller for controlling the flow of air over said condenser in response to said second sensor.
32. The heat pump of claim 29 wherein:
one of said first and second heat exchangers is an evaporator; and
the other of said first and second heat exchangers is a condenser.
33. The heat pump of claim 32, including:
a second sensor for sensing the temperature of air from said condenser; and
a flow controller for controlling the flow of air over said condenser in response to said second sensor.
34. The heat pump of claim 29, including:
a valve moveable from a first position to a second position to control the direction of flow of refrigerant fluid in said closed loop;
said valve in a first position directing the flow of refrigerant fluid from said primary compressor to one of said heat exchangers functioning as a condenser, and from said condenser to said economizer and then to the other of said heat exchangers functioning as an evaporator; and
said valve in a second position directing the flow of refrigerant fluid from said primary compressor to said other of said heat exchangers functioning as a condenser, and from said condenser to said economizer and then to said one of said heat exchangers functioning as an evaporator.
35. The heat pump of claim 29 wherein:
said controller is connected to said booster compressor to inhibit operation of said booster compressor until outdoor ambient temperature drops to a first predetermined level and said controller is connected to said economizer flow controller to inhibit operation of said economizer flow controller until the outdoor ambient temperature reaches a second predetermined level below said first predetermined level.
36. The heat pump of claim 35 wherein:
said economizer flow controller is normally fully closed to prevent flow of fluid from said bleed to said economizer means; and
said economizer flow controller responds to a signal from said controller to move to a fully open position.
37. The heat pump of claim 35 wherein:
said economizer flow controller is normally fully closed to prevent flow of fluid from said bleed to said economizer; and
said economizer is modulated between the closed position thereof and a fully open position in response to signals from said controller.
38. The heat pump of claim 29 wherein:
said primary compressor is a one speed compressor; and
said booster compressor is a variable speed or multispeed compressor.
39. The heat pump of claim 29 wherein:
said primary compressor is a one speed compressor and said booster compressor is a two speed compressor; and
said controller is effective to permit operation of said primary compressor when the outdoor ambient temperature falls to a first predetermined level while inhibiting operation of said booster compressor and said economizer means; and
said controller is effective to continue operation of said primary compressor and to operate said booster compressor at the low speed thereof when outdoor ambient temperature falls to a second predetermined level below said first predetermined level while continuing to inhibit operation of said economizer means; and
said controller is effective to continue operation of said primary compressor and said booster compressor at low speed and to operate said economizer when outdoor ambient temperature falls to a third predetermined level below said second predetermined level; and
said controller is effective to continue operation of said primary compressor and to operate said booster compressor at the high speed thereof and to discontinue operation of said economizer when outdoor ambient temperature falls to a fourth predetermined level below said third predetermined level; and
said control means is effective to continue operation of said primary compressor and to continue operation of said booster compressor at the high speed thereof and to reinitiate operation of said economizer when the outdoor ambient temperature falls to a fifth predetermined level below said fourth predetermined level.
40. A heat pump including:
a primary compressor;
a booster compressor;
first and second heat exchangers;
a flow conduit connecting said first and second heat exchange means, and said primary compressor for circulating a refrigerant fluid in a closed loop, said booster compressor being upstream of said primary compressor in said loop;
an economizer connected in said flow conduit between said first and second heat exchangers;
a bleed connected from said flow conduit to said economizer to deliver a portion of the refrigerant fluid to said economizer for vaporization in heat exchange with the remaining portion of refrigerant fluid passing through said economizer;
an economizer vapor conduit connected from said economizer to said flow conduit upstream of the intake of said primary compressor;
an economizer flow controller in said bleed to control the flow of fluid from said bleed through said economizer and to said economizer vapor conduit;
a first sensor for sensing the temperature of ambient outdoor air;
a second sensor for sensing a parameter commensurate with power input to said booster compressor;
a thermostat for sensing the temperature of a fluid to be heated or cooled; and
a controller responsive to inputs from said first sensor and said thermostat for controlling operation of said primary compressor and said booster compressor and said economizer, said controller being effective initially to operate said primary compressor in response to a first input signal from said thermostat while inhibiting operation of said booster compressor and said economizer flow controller, and said controller thereafter being effective to operate said booster compressor and said primary compressor upon receipt of a second signal from said thermostat and receipt of a booster enabling signal commensurate with the temperature of ambient outdoor air, said control means thereafter being effective to operate said economizer means by operating said economizer flow controller to control the flow of fluid from said bleed line and through said economizer to said economizer vapor conduit;
said flow conduit being connected to bypass said booster compressor and deliver fluid from one of said heat exchangers to said primary compressor when said booster compressor is inoperative, and said flow conduit being connected to deliver fluid from said one heat exchanger to said booster compressor and from said booster compressor to said primary compressor when operation of said booster compressor is initiated.
41. The heat pump of claim 40 wherein:
said first heat exchanger is an evaporator located in said flow conduit downstream of said economizer and upstream of said booster compressor and said primary compressor; and
said second heat exchange means is a condenser located in said flow conduit downstream of said primary compressor and upstream of said economizer.
42. The heat pump of claim 40 wherein:
said controller is effective to control operation of said booster compressor in accordance with a set point of said second sensor; and
said controller is responsive to said first sensor to vary the level of said set point as a function of outdoor ambient temperature.
43. The heat pump of claim 40 wherein:
said first heat exchanger is an evaporator serving as an outdoor coil located in said flow conduit downstream of said economizer and upstream of said booster compressor, said evaporator receiving a flow of outdoor ambient air; and
said second heat exchanger is a condenser serving as an indoor coil located in said flow conduit downstream of said primary compressor and upstream of said economizer, said evaporator receiving a flow of air to be conditioned; and further including
a third sensor for sensing the temperature of air from said condenser; and
an air flow controller for controlling the flow of air over said condenser in response to said third sensor.
44. The heat pump of claim 40 wherein:
one of said first and second heat exchangers is an evaporator; and
the other of said first and second heat exchangers is a condenser.
45. The heat pump of claim 44, including:
a third sensor for sensing the temperature of air from said condenser; and
an air flow controller for controlling the flow of air over said condenser in response to said third sensor.
46. The heat pump of claim 40 including:
a valve moveable from a first position to a second position to control the direction of flow of refrigerant fluid in said closed loop;
said valve in a first position directing the flow of refrigerant fluid from said primary compressor to one of said heat exchangers functioning as a condenser, and from said condenser to said economizer and then to the other of said exchangers means functioning as an evaporator; and
said valve in a second position directing the flow of refrigerant fluid from said primary compressor to said other of said heat exchange means functioning as a condenser, and from said condenser to said economizer and then to said one of said exchangers means functioning as an evaporator.
47. The heat pump of claim 40 wherein:
said controller is connected to said booster compressor to inhibit operation of said booster compressor until outdoor ambient temperature drops to a first predetermined level, and said controller is connected to said economizer flow controller to inhibit operation of said economizer flow controller until the outdoor ambient temperature reaches a second predetermined level below said first predetermined level.
48. The heat pump of claim 47 wherein:
said economizer flow controller is normally fully closed to prevent flow of fluid from said bleed to said economizer; and
said economizer flow controller responds to a signal from said controller to move to a fully open position.
49. The heat pump of claim 47 wherein:
said economizer flow controller is normally fully closed to prevent flow of fluid from said bleed to said economizer; and
said economizer flow controller is modulated between the closed position thereof and a fully open position in response to signals from said controller.
50. The heat pump of claim 46 including:
a first modulating valve between said economizer and said one of said heat exchangers functioning as an evaporator to modulate the flow of refrigerant fluid from said economizer to said evaporator when said first modulating valve is in said first position thereof; and
a second modulating valve between said economizer and said one of said heat exchangers functioning as an evaporator to modulate the flow of refrigerant fluid to said evaporator when said second modulating valve is in said second position thereof.
51. The heat pump of claim 34 wherein:
said primary compressor is a one speed compressor and said booster compressor is a two speed compressor; and
said controller is effective to permit operation of said primary compressor when the outdoor ambient temperature falls to a first predetermined level while inhibiting operation of said booster compressor and said economizer means; and
said controller is effective to continue operation of said primary compressor and to operate said booster compressor at the low speed thereof when outdoor ambient temperature falls to a second predetermined level below said first predetermined level while continuing to inhibit operation of said economizer means; and
said controller is effective to continue operation of said primary compressor and said booster compressor at low speed and to operate said economizer when outdoor ambient temperature falls to a third predetermined level below said second predetermined level; and
said controller is effective to continue operation of said primary compressor and to operate said booster compressor at the high speed thereof and to discontinue operation of said economizer when outdoor ambient temperature falls to a fourth predetermined level below said third predetermined level; and
said controller is effective to continue operation of said primary compressor and to continue operation of said booster compressor at the high speed thereof and to reinitiate operation of said economizer when the outdoor ambient temperature falls to a fifth predetermined level below said fourth predetermined level.
52. The heat pump of claim 40 wherein:
said primary compressor is a single speed compressor, and said booster compressor is a one speed or two speed compressor.
53. A heat pump system including:
a primary compressor;
a booster compressor;
first and second heat exchangers;
a conduit loop connecting said first and second heat exchangers and said primary compressor for circulating a refrigerant therein, said booster compressor being upstream of said primary compressor in said conduit loop;
an economizer connected in said conduit loop between said first and second heat exchangers;
a first economizer conduit connecting said economizer and said conduit loop to deliver a portion of the refrigerant from said conduit loop to said economizer for vaporization, the remaining portion of the refrigerant passing through said economizer in said conduit loop;
a second economizer conduit connecting said economizer to said conduit loop upstream of the intake of said primary compressor to deliver refrigerant fluid vaporized in said economizer to said primary compressor;
a flow control element in said first economizer conduit to control the flow of fluid from said first economizer conduit to said economizer and to said second economizer conduit;
a first sensor for sensing a parameter commensurate with the temperature of ambient outdoor air;
a thermostat for sensing the temperature of a medium to be heated or cooled; and
a controller responsive to inputs from said first sensor and said thermostat for controlling operation of said primary compressor, said booster compressor, and said economizer, said controller being effective initially to operate said primary compressor in response to a first input signal from said thermostat while inhibiting operation of said booster compressor and said economizer, and said controller thereafter being effective to operate said booster compressor and said primary compressor upon receipt of a second signal from said thermostat and receipt of a booster enabling signal commensurate with the temperature of ambient outdoor air, and said controller thereafter being effective to operate said economizer upon receipt of a signal from said first sensor to operate said flow control element to control the flow of fluid from said first economizer conduit through said economizer and to said second economizer conduit;
said conduit loop being connected to bypass said booster compressor and deliver the refrigerant from one of said first and second heat exchangers to said primary compressor when said booster compressor is inoperative, and said conduit loop being connected to deliver the refrigerant from said one heat exchanger to said booster compressor and from said booster compressor to said primary compressor when operation of said booster compressor is initiated.
54. The heat pump of claim 53 wherein:
said first heat exchanger is an evaporator located in said conduit loop downstream of said economizer and upstream of said booster compressor and said primary compressor; and
said second heat exchanger is a condenser located in said conduit loop downstream of said primary compressor and upstream of said economizer.
55. The heat pump of claim 53 wherein:
said first heat exchanger is an evaporator serving as an outdoor coil located in said conduit loop downstream of said economizer and upstream of said booster compressor, said evaporator receiving a flow of outdoor ambient air; and
said second heat exchanger is a condenser serving as an indoor coil located in said conduit loop downstream of said primary compressor and upstream of said economizer, said evaporator receiving a flow of air to be conditioned; and further including
a second sensor for sensing the temperature of air from said condenser; and
a flow controller for controlling the flow of air over said condenser in response to said third sensor.
56. The heat pump of claim 53 wherein:
one of said first and second heat exchangers is an evaporator; and
the other of said first and second heat exchangers is a condenser.
57. The heat pump of claim 56 including:
a second sensor for sensing the temperature of air from said condenser; and
a flow controller for controlling the flow of air over said condenser in response to said second sensor.
58. The heat pump of claim 53 including:
a valve moveable from a first position to a second position to control the direction of flow of the refrigerant in said conduit loop;
said valve in a first position directing the flow of the refrigerant from said primary compressor to one of said heat exchangers functioning as a condenser, and from said condenser to said economizer and then to the other of said heat exchangers functioning as an evaporator; and
said valve in a second position directing the flow of the refrigerant from said primary compressor to said other of said heat exchangers functioning as a condenser, and from said condenser to said economizer and then to said one of said heat exchangers functioning as an evaporator.
59. The heat pump of claim 58 including:
a first modulating valve between said economizer and said one of said heat exchange means functioning as an evaporator to modulate the flow of refrigerant fluid from said economizer to said evaporator when said valve means is in said first position thereof; and
a second modulating valve between said economizer and said one of said heat exchange means functioning as an evaporator to modulate the flow of refrigerant fluid to said evaporator when said valve means is in said second position thereof.
60. The heat pump of claim 53 wherein said medium is air or fluid.
61. The heat pump of claim 53 wherein:
said controller is connected to said booster compressor to inhibit operation of said booster compressor until outdoor ambient temperature drops to a first predetermined level and said controller is connected to said economizer flow controller to inhibit operation of said economizer until the outdoor ambient temperature reaches a second predetermined level below said first predetermined level.
62. The heat pump of claim 61 wherein:
said economizer flow controller is normally fully closed to prevent flow of fluid from said bleed means to said economizer means; and
said economizer flow controller responds to a signal from said controller to move to a fully open position.
63. The heat pump of claim 61 wherein:
said economizer flow controller is normally fully closed to prevent flow of fluid from said bleed means to said economizer means; and
said economizer flow controller is modulated between the closed position thereof and a fully open position in response to signals from said controller.
64. The heat pump of claim 53 wherein:
said primary compressor is a one speed compressor; and
said booster compressor is a variable speed or multispeed compressor.
65. A heat pump including:
a primary compressor;
a booster compressor;
first and second heat exchangers;
a flow conduit connecting said first and second heat exchange means and said primary compressor for circulating a refrigerant fluid in a closed loop, said booster compressor being downstream of said primary compressor in said loop;
an economizer connected in said flow conduit between said first and second heat exchangers;
a bleed connected from said flow conduit to said economizer to deliver a portion of the refrigerant fluid to said economizer for vaporization in heat exchange with the remaining portion of refrigerant fluid passing through said economizer;
an economizer vapor conduit connected from said economizer to said flow conduit upstream of the intake of said primary compressor;
a first sensor for sensing a parameter commensurate with the temperature of ambient outdoor air;
a thermostat for sensing the temperature of a fluid to be heated or cooled;
a controller responsive to inputs from said first sensor means and said thermostat for controlling operation of said primary compressor and said booster compressor, said controller being effective initially to operate said primary compressor in response to a first input signal from said thermostat while inhibiting operation of said booster compressor, and said controller thereafter being effective to operate said booster compressor and said primary compressor upon receipt of a second signal from said thermostat and receipt of a booster enabling signal commensurate with the temperature of ambient outdoor air; and
isolation means in said flow conduit for isolating said booster compressor from the discharge pressure from said primary compressor when operation of said booster compressor is inhibited;
said flow conduit being connected to deliver refrigerant fluid from one of said heat exchangers to said primary compressor and to bypass said booster compressor and deliver refrigerant fluid to the other of said heat exchangers when said booster compressor is inoperative, and said flow conduit being connected to deliver fluid from said one heat exchanger to said primary compressor and from said primary compressor to said booster compressor when operation of said booster compressor is initiated.
66. The heat pump of claim 65 wherein:
said primary compressor is a multispeed compressor, and said booster compressor is a one speed compressor or a two speed compressor.
67. The heat pump of claim 65 wherein:
said first heat exchanger is an evaporator located in said flow conduit downstream of said economizer means and upstream of said booster compressor and said primary compressor; and
said second heat exchanger is a condenser located in said flow conduit downstream of said primary compressor and upstream of said economizer.
68. The heat pump of claim 65 wherein:
said controller is effective to control operation of said primary compressor in accordance with an outdoor ambient temperature sensed by said first sensor.
69. The heat pump of claim 65 wherein:
said first heat exchanger is an evaporator serving as an outdoor coil located in said flow conduit downstream of said economizer means and upstream of said booster compressor, said evaporator receiving a flow of outdoor ambient air; and
said second heat exchanger is a condenser serving as an indoor coil located in said flow conduit downstream of said primary compressor and upstream of said economizer, said evaporator receiving a flow of air to be conditioned; and further including
a second sensor for sensing the temperature of air from said condenser; and
a flow controller for controlling the flow of air over said condenser in response to said second sensor.
70. The heat pump of claim 65 wherein:
one of said first and second heat exchanges is an evaporator; and
the other of said first and second heat exchanges is a condenser.
71. The heat pump of claim 70, including:
second sensor means for sensing the temperature of air from said condenser; and
a flow controller for controlling the flow of air over said condenser in response to said second sensor means.
72. The heat pump of claim 65, including:
a control valve moveable from a first position to a second position to control the direction of flow of refrigerant fluid in said closed loop;
said control valve in a first position directing the flow of refrigerant fluid from said primary compressor to one of said heat exchangers functioning as a condenser, and from said condenser to said economizer and then to the other of said heat exchangers functioning as an evaporator; and
said control valve in a second position directing the flow of refrigerant fluid from said primary compressor to said other of said heat exchangers functioning as a condenser, and from said condenser to said economizer and then to said one of said heat exchangers functioning as an evaporator.
73. The heat pump of claim 65 wherein:
said controller is connected to said booster compressor to inhibit operation of said booster compressor until outdoor ambient temperature drops to a first predetermined level.
74. The heat pump of claim 65 wherein:
said controller is effective to vary the speed of said primary compressor as an inverse function of outdoor ambient temperature sensed by said first sensor when outdoor ambient temperature falls to a first predetermined level and outdoor ambient temperature is between said first predetermined level and a lower second predetermined level; and
said controller is effective to initiate operation of said booster compressor and operate said primary compressor at low speed when outdoor ambient temperature falls to a said second predetermined level; and
said controller is effective to continue operations of said booster compressor and to vary the speed of said primary compressor as an inverse function of outdoor ambient temperature sensed by said first sensor means when outdoor ambient temperature is lower than said second predetermined temperature.
75. The heat pump of claim 65 wherein:
said primary compressor is a variable speed compressor, and said booster compressor is a one speed compressor.
76. The heat pump of claim 65 wherein:
said primary compressor is a variable speed compressor, and said booster compressor is a two speed compressor.
77. The heat pump of claim 65 wherein said isolation means includes:
a two position valve in said flow conduit means;
said two position valve being effective in a first position thereof, when said booster compressor is inoperative, to block discharge flow from said primary compressor to said booster compressor; and
said two position valve being effective in a second position thereof to deliver discharge flow from said primary compressor to said booster compressor.
78. The heat pump of claim 77 wherein:
said two position valve is effective in the first position thereof to deliver economizer vapor to said primary compressor.
79. The heat pump of claim 77 wherein:
said two position valve is moved from said first position thereof to said second position thereof in response to initiation of operation of said booster compressor.
80. The heat pump of claim 29 wherein:
said primary compressor is a one speed compressor and said booster compressor is a two speed compressor; and
said controller is effective to permit operation of said primary compressor when the outdoor ambient temperature falls to a first predetermined level while inhibiting operation of said booster compressor and said economizer; and
said controller is effective to continue operation of said primary compressor and to operate said booster compressor at the low speed thereof when outdoor ambient temperature falls to a second predetermined level below said first predetermined level while continuing to inhibit operation of said economizer; and
said controller is effective to continue operation of said primary compressor and said booster compressor at low speed and to operate said economizer when outdoor ambient temperature falls to a third predetermined level below said second predetermined level; and
said controller is effective to continue operation of said primary compressor and to operate said booster compressor at the high speed thereof and to discontinue operation of said economizer when outdoor ambient temperature falls to a fourth predetermined level below said third predetermined level; and
said controller is effective to continue operation of said primary compressor and to continue operation of said booster compressor at the high speed thereof and to reinitiate operation of said economizer when the outdoor ambient temperature falls to a fifth predetermined level below said fourth predetermined level.
81. A heat pump including:
a primary compressor;
a booster compressor;
first and second heat exchange means;
flow conduit means connecting said first and second heat exchange means and said primary compressor for circulating a refrigerant fluid in a closed loop;
economizer means connected in said flow conduit means between said first and second heat exchangers;
bleed means connected from said flow conduit means to said economizer means to deliver a portion of the refrigerant fluid to said economizer means for vaporization in heat exchange with the remaining portion of refrigerant fluid passing through said economizer means;
conduit means connected from said economizer means to said flow conduit means upstream of the intake of said primary compressor;
first sensor means for sensing a parameter commensurate with the temperature of ambient outdoor air;
second sensor means for sensing a parameter of booster compressor operation commensurate with power input to said booster compressor;
thermostat means for sensing the temperature of a fluid to be heated or cooled;
control means responsive to inputs from said first sensor means, said second sensor means and said thermostat means for controlling operation of said primary compressor and said booster compressor, said control means functioning initially to operate said primary compressor in response to a first input signal from said thermostat means while maintaining said booster compressor inoperative, and thereafter functioning to operate said booster compressor and said primary compressor upon receipt of a second signal from said thermostat means and receipt of a booster enabling signal commensurate with the temperature of ambient outdoor air;
said flow conduit means being connected to bypass said booster compressor and deliver fluid from one of said heat exchangers to said primary compressor when said booster compressor is inoperative, and said flow conduit means being connected to deliver fluid from said one heat exchanger to said booster compressor and from said booster compressor to said primary compressor when operation of said booster compressor is initiated; and
means for varying the pumping capacity of at least one of said primary and booster compressors in response to a signal from said first sensor means.
82. The heat pump of claim 81 wherein:
said control means is effective to control operation of said booster compressor in accordance with a set point parameter of booster compressor operation sensed by said second sensor means; and
said control means is responsive to said first sensor means to vary the level of said set point of said parameter of booster compressor operation as a function of outdoor ambient temperature.
83. A heat pump including:
a primary compressor;
a booster compressor;
first and second heat exchangers;
a flow conduit connecting said first and second heat exchangers and said primary compressor for circulating a refrigerant fluid in a closed loop;
an economizer connected in said flow conduit between said first and second heat exchangers;
a bleed connected from said flow conduit to said economizer to deliver a portion of the refrigerant fluid to said economizer means for vaporization in heat exchange with the remaining portion of refrigerant fluid passing through said economizer;
an economizer conduit connected from said economizer means to said flow conduit means upstream of the intake of said primary compressor;
a first sensor for sensing a parameter commensurate with the temperature of ambient outdoor air;
a second sensor for sensing the pressure of refrigerant fluid at a point in said flow conduit means between said booster compressor and said primary compressor;
a thermostat for sensing the temperature of a fluid to be heated or cooled;
a controller responsive to inputs from said first sensor, said second sensor and said thermostat for controlling operation of said primary compressor and said booster compressor, said controller functioning initially to operate said primary compressor in response to a first input signal from said thermostat while maintaining said booster compressor inoperative, and thereafter functioning to operate said booster compressor and said primary compressor upon receipt of a second signal from said thermostat and receipt of a booster enabling signal from said second sensor;
said flow conduit being connected to bypass said booster compressor and deliver fluid from one of said heat exchangers to said primary compressor when said booster compressor is inoperative, and said flow conduit means being connected to deliver fluid from said one heat exchanger to said booster compressor and from said booster compressor to said primary compressor when operation of said booster compressor is initiated; and
means for varying the pumping capacity of at least one of said primary and booster compressors in response to a signal from said first sensor.
84. The heat pump of claim 83 wherein:
said controller is effective to control operation of said booster compressor in accordance with a set point of said second sensor; and
said controller is responsive to said first sensor to vary the level of said set point as a function of outdoor ambient temperature.
85. The heat pump of claim 83 wherein:
said primary compressor is a one speed compressor; and
said booster compressor is a variable speed or multispeed compressor.
86. A heat pump including:
a primary compressor;
a booster compressor;
first and second heat exchangers;
a conduit loop connecting said first and second heat exchangers and said primary compressor for circulating a refrigerant therein;
an economizer connected in said conduit loop between said first and second heat exchangers;
a first economizer conduit connecting said economizer and said conduit loop to deliver a portion of the refrigerant from said conduit loop to said economizer for vaporization with the remaining portion of the refrigerant passing through said economizer;
a second economizer conduit connecting said economizer to said conduit loop upstream of the intake of said primary compressor;
a first sensor for sensing a parameter commensurate with the temperature of ambient outdoor air;
a second sensor for sensing a parameter of booster compressor operation commensurate with power input to said booster compressor;
a thermostat for sensing the temperature of a medium to be heated or cooled;
a controller responsive to inputs from said first sensor, said second sensor and said thermostat for controlling operation of said primary compressor and said booster compressor, said controller functioning initially to operate said primary compressor in response to a first input signal from said thermostat while maintaining said booster compressor inoperative, and thereafter functioning to operate said booster compressor and said primary compressor upon receipt of a second signal from said thermostat and receipt of a booster enabling signal commensurate with the temperature of ambient outdoor air;
said conduit loop being connected to bypass said booster compressor and deliver the refrigerant from one of said first and second heat exchangers to said primary compressor when said booster compressor is inoperative, and said conduit loop being connected to deliver the refrigerant from said one heat exchanger to said booster compressor and from said booster compressor to said primary compressor when operation of said booster compressor is initiated; and
means for varying the pumping capacity of at least one of said primary and booster compressors in response to a signal from said first sensor.
87. The heat pump of claim 86 wherein:
said controller is effective to control operation of said booster compressor in accordance with a set point of said parameter of booster compressor operation sensed by said second sensor; and
said controller is responsive to said first sensor to vary the level of said set point of said parameter of booster compressor operation as a function of outdoor ambient temperature.
88. The heat pump of claim 86 wherein:
said primary compressor is a one speed compressor; and
said booster compressor is a variable speed or multispeed compressor.
89. A heat pump including:
a primary compressor;
a booster compressor;
first and second heat exchangers;
a flow conduit connecting said first and second heat exchange means and said primary compressor for circulating a refrigerant fluid in a closed loop, said booster compressor being upstream of said primary compressor in said loop;
an economizer connected in said flow conduit between said first and second heat exchangers;
a bleed connected from said flow conduit to said economizer to deliver a portion of the refrigerant fluid to said economizer for vaporization in heat exchange with the remaining portion of refrigerant fluid passing through said economizer;
an economizer vapor conduit connected from said economizer to said flow conduit upstream of the intake of said primary compressor;
an economizer flow controller in said bleed to control the flow of fluid from said bleed through said economizer and to said economizer vapor conduit;
a first sensor for sensing a parameter commensurate with the temperature of ambient outdoor air;
a thermostat for sensing the temperature of a fluid to be heated or cooled;
a controller responsive to inputs from said first sensor and said thermostat for controlling operation of said primary compressor and said booster compressor and said economizer, said controller being effective initially to operate said primary compressor in response to a first input signal from said thermostat while inhibiting operation of said booster compressor and said economizer flow controller, and said controller thereafter being effective to operate said booster compressor and said primary compressor upon receipt of a second signal from said thermostat and receipt of a booster enabling signal commensurate with the temperature of ambient outdoor air, and said controller thereafter being effective to operate said economizer by controlling the flow of fluid from said bleed line and through said economizer flow controller to said economizer and to said economizer vapor conduit;
said flow conduit being connected to bypass said booster compressor and deliver fluid from one of said heat exchangers to said primary compressor when said booster compressor is inoperative, and said flow conduit being connected to deliver fluid from said one heat exchanger to said booster compressor and from said booster compressor to said primary compressor when operation of said booster compressor is initiated; and
means for varying the pumping capacity of at least one of said primary and booster compressors in response to a signal from said first sensor means.
90. The heat pump of claim 89 wherein:
said primary compressor is a one speed compressor; and
said booster compressor is a variable speed or multispeed compressor.
91. The heat pump of claim 89 wherein:
said primary compressor is a one speed compressor and said booster compressor is a two speed compressor; and
said controller is effective to permit operation of said primary compressor when the outdoor ambient temperature falls to a first predetermined level while inhibiting operation of said booster compressor and said economizer means; and
said controller is effective to continue operation of said primary compressor and to operate said booster compressor at the low speed thereof when outdoor ambient temperature falls to a second predetermined level below said first predetermined level while continuing to inhibit operation of said economizer; and
said controller is effective to continue operation of said primary compressor and said booster compressor at low speed and to operate said economizer when outdoor ambient temperature falls to a third predetermined level below said second predetermined level; and
said controller is effective to continue operation of said primary compressor and to operate said booster compressor at the high speed thereof and to discontinue operation of said economizer when outdoor ambient temperature falls to a fourth predetermined level below said third predetermined level; and
said controller is effective to continue operation of said primary compressor and to continue operation of said booster compressor at the high speed thereof and to reinitiate operation of said economizer when the outdoor ambient temperature falls to a fifth predetermined level below said fourth predetermined level.
92. The heat pump of claim 89 wherein:
said first heat exchanger is an evaporator located in said flow conduit means downstream of said economizer and upstream of said booster compressor and said primary compressor; and
said second heat exchanger is a condenser located in said flow conduit downstream of said primary compressor and upstream of said economizer.
93. The heat pump of claim 89 wherein:
said first heat exchanger is an evaporator serving as an outdoor coil located in said flow conduit means downstream of said economizer and upstream of said booster compressor, said evaporator receiving a flow of outdoor ambient air; and
said second heat exchanger is a condenser serving as an indoor coil located in said flow conduit downstream of said primary compressor and upstream of said economizer, said evaporator receiving a flow of air to be conditioned; and further including
a second sensor for sensing the temperature of air from said condenser; and
an air flow controller for controlling the flow of air over said condenser in response to said third sensor means.
94. The heat pump of claim 89 wherein:
one of said first and second heat exchangers is an evaporator; and
the other of said first and second heat exchangers is a condenser.
95. The heat pump of claim 94, including:
a second sensor for sensing the temperature of air from said condenser; and
an air flow controller for controlling the flow of air over said condenser in response to said second sensor.
96. The heat pump of claim 89, including:
a valve moveable from a first position to a second position to control the direction of flow of refrigerant fluid in said closed loop;
said valve in a first position directing the flow of refrigerant fluid from said primary compressor to one of said heat exchangers functioning as a condenser, and from said condenser to said economizer and then to the other of said heat exchangers functioning as an evaporator; and
said valve in a second position directing the flow of refrigerant fluid from said primary compressor to said other of said heat exchangers functioning as a condenser, and from said condenser to said economizer and then to said one of said heat exchange functioning as an evaporator.
97. The heat pump of claim 89 wherein:
said controller is connected to said booster compressor to inhibit operation of said booster compressor until outdoor ambient temperature drops to a first predetermined level, and said controller is connected to said economizer flow controller to inhibit operation of said economizer flow controller until the outdoor ambient temperature reaches a second predetermined level below said first predetermined level.
98. The heat pump of claim 97 wherein:
said economizer flow controller is normally fully closed to prevent flow of fluid from said bleed to said economizer; and
said economizer flow controller responds to a signal from said controller to move to a fully open position.
99. The heat pump of claim 97 wherein:
said economizer flow controller is normally fully closed to prevent flow of fluid from said bleed to said economizer; and
said economizer is modulated between the closed position thereof and a fully open position in response to signals from said controller.
100. A heat pump including:
a primary compressor;
a booster compressor;
first and second heat exchange means;
flow conduit means connecting said first and second heat exchange means and said primary compressor for circulating a refrigerant fluid in a closed loop, said booster compressor being upstream of said primary compressor in said loop;
economizer means connected in said flow conduit means between said first and second heat exchangers;
bleed means connected from said flow conduit means to said economizer means to deliver a portion of the refrigerant fluid to said economizer means for vaporization in heat exchange with the remaining portion of refrigerant fluid passing through said economizer means;
economizer vapor conduit means connected from said economizer means to said flow conduit means upstream of the intake of said primary compressor;
economizer flow control means in said bleed means to control the flow of fluid from said bleed means through said economizer means and to said economizer vapor conduit means;
first sensor means for sensing the temperature of ambient outdoor air;
second sensor means for sensing a parameter commensurate with power input to said booster compressor;
thermostat means for sensing the temperature of a fluid to be heated or cooled;
control means responsive to inputs from said first sensor means and said thermostat means for controlling operation of said primary compressor and said booster compressor and said economizer means, said control means being effective initially to operate said primary compressor in response to a first input signal from said thermostat means while inhibiting operation of said booster compressor and said economizer flow control means, and said control means thereafter being effective to operate said booster compressor and said primary compressor upon receipt of a second signal from said thermostat means and receipt of a booster enabling signal commensurate with the temperature of ambient outdoor air, said control means thereafter being effective to operate said economizer means by operating said economizer flow control means to control the flow of fluid from said bleed line and through said economizer to said economizer vapor conduit means;
said flow conduit means being connected to bypass said booster compressor and deliver fluid from one of said heat exchangers to said primary compressor when said booster compressor is inoperative, and said flow conduit means being connected to deliver fluid from said one heat exchanger to said booster compressor and from said booster compressor to said primary compressor when operation of said booster compressor is initiated; and
means for varying the pumping capacity of at least one of said primary and booster compressors in response to a signal from said first sensor means.
101. The heat pump of claim 100 wherein:
said primary compressor is a single speed compressor, and said booster compressor is a one speed or two speed compressor.
102. The heat pump of claim 100 wherein:
said primary compressor is a one speed compressor and said booster compressor is a two speed compressor; and
said control means is effective to permit operation of said primary compressor when the outdoor ambient temperature falls to a first predetermined level while inhibiting operation of said booster compressor and said economizer means; and
said control means is effective to continue operation of said primary compressor and to operate said booster compressor at the low speed thereof when outdoor ambient temperature falls to a second predetermined level below said first predetermined level while continuing to inhibit operation of said economizer means; and
said control means is effective to continue operation of said primary compressor and said booster compressor at low speed and to operate said economizer when outdoor ambient temperature pulls to third predetermined level below said second predetermined level; and
said control means is effective to continue operation of said primary compressor and to operate said booster compressor at the high speed thereof and to discontinue operation of said economizer when outdoor ambient temperature falls to a fourth predetermined level below said third predetermined level; and
said control means is effective to continue operation of said primary compressor and to continue operation of said booster compressor at the high speed thereof and to reinitiate operation of said economizer when the outdoor ambient temperature falls to a fifth predetermined level below said fourth predetermined level.
103. The heat pump of claim 100 wherein:
said control means is effective to control operation of said booster compressor in accordance with a set point of said second sensor means; and
said control means is responsive to said first sensor means to vary the level of said set point as a function of outdoor ambient temperature.
104. The heat pump of claim 100 wherein:
said first heat exchanger means is an evaporator serving as an outdoor coil located in said flow conduit means downstream of said economizer means and upstream of said booster compressor, said evaporator receiving a flow of outdoor ambient air; and
said second heat exchanger means is a condenser serving as an indoor coil located in said flow conduit downstream of said primary compressor and upstream of said economizer, said evaporator receiving a flow of air to be conditioned; and further including
second sensor means for sensing the temperature of air from said condenser; and
flow control means for controlling the flow of air over said condenser in response to said second sensor means.
105. The heat pump of claim 100 including:
valve means moveable from a first position to a second position to control the direction of flow of refrigerant fluid in said closed loop;
said valve means in a first position directing the flow of refrigerant fluid from said primary compressor to one of said heat exchange means functioning as a condenser, and from said condenser to said economizer and then to the other of said heat exchange means functioning as an evaporator; and
said valve means in a second position directing the flow of refrigerant fluid from said primary compressor to said other of said heat exchange means functioning as a condenser, and from said condenser to said economizer and then to said one of said heat exchange means functioning as an evaporator.
106. The heat pump of claim 105 including:
modulating valve means between said economizer and said one of said heat exchange means functioning as an evaporator to modulate the flow of refrigerant fluid from said economizer to said evaporator when said valve means is in said first position thereof; and
modulating valve means between said economizer and said one of said heat exchange means functioning as an evaporator to modulate the flow of refrigerant fluid to said evaporator when said valve means is in said second position thereof.
107. The heat pump of claim 100 wherein:
said control means is connected to said booster compressor to inhibit operation of said booster compressor until outdoor ambient temperature drops to a first predetermined level, and said control means is connected to said economizer flow control means to inhibit operation of said economizer flow control means until the outdoor ambient temperature reaches a second predetermined level below said first predetermined level.
108. The heat pump of claim 107 wherein:
said economizer flow control means is normally fully closed to prevent flow of fluid from said bleed means to said economizer means; and
said economizer flow control means responds to a signal from said control means to move to a fully open position.
109. The heat pump of claim 107 wherein:
said economizer flow control means is normally fully closed to prevent flow of fluid from said bleed means to said economizer means; and
said economizer flow control means is modulated between the closed position thereof and a fully open position in response to signals from said control means.
110. The heat pump of claim 109 wherein:
said economizer flow controller is normally fully closed to prevent flow of fluid from said bleed means to said economizer means; and
said economizer flow controller responds to a signal from said controller to move to a fully open position.
111. The heat pump of claim 110 wherein:
said economizer flow controller is normally fully closed to prevent flow of fluid from said bleed means to said economizer means; and
said economizer flow controller is modulated between the closed position thereof and a fully open position in response to signals from said controller.
112. A heat pump system including:
a primary compressor;
a booster compressor;
first and second heat exchangers;
a conduit loop connecting said first and second heat exchangers and said primary compressor for circulating a refrigerant therein, said booster compressor being upstream of said primary compressor in said conduit loop;
an economizer connected in said conduit loop between said first and second heat exchangers;
a first economizer conduit connecting said economizer and said conduit loop to deliver a portion of the refrigerant from said conduit loop to said economizer for vaporization, the remaining portion of the refrigerant passing through said economizer in said conduit loop;
a second economizer conduit connecting said economizer to said conduit loop upstream of the intake of said primary compressor to deliver refrigerant fluid vaporized in said economizer to said primary compressor;
a flow control element in said first economizer conduit to control the flow of fluid from said first economizer conduit to said economizer and to said second economizer conduit;
a first sensor for sensing a parameter commensurate with the temperature of ambient outdoor air;
a thermostat for sensing the temperature of a medium to be heated or cooled;
a controller responsive to inputs from said first sensor and said thermostat for controlling operation of said primary compressor, said booster compressor, and said economizer, said controller being effective initially to operate said primary compressor in response to a first input signal from said thermostat while inhibiting operation of said booster compressor and said economizer, and said controller thereafter being effective to operate said booster compressor and said primary compressor upon receipt of a second signal from said thermostat and receipt of a booster enabling signal commensurate with the temperature of ambient outdoor air, and said controller thereafter being effective to operate said economizer upon receipt of a signal from said first sensor to operate said flow control element to control the flow of fluid from said first economizer conduit through said economizer and to said second economizer conduit;
said conduit loop being connected to bypass said booster compressor and deliver the refrigerant from one of said first and second heat exchangers to said primary compressor when said booster compressor is inoperative, and said conduit loop being connected to deliver the refrigerant from said one heat exchanger to said booster compressor and from said booster compressor to said primary compressor when operation of said booster compressor is initiated; and
means for varying the pumping capacity of at least one of said primary and booster compressors in response to a signal from said first sensor.
113. The heat pump of claim 112 wherein:
said primary compressor is a one speed compressor; and
said booster compressor is a variable speed or multispeed compressor.
114. The heat pump of claim 112 wherein:
said first heat exchanger is an evaporator located in said conduit loop downstream of said economizer and upstream of said booster compressor and said primary compressor; and
said second heat exchanger is a condenser located in said conduit loop downstream of said primary compressor and upstream of said economizer.
115. The heat pump of claim 112 wherein:
said first heat exchanger is an evaporator serving as an outdoor coil located in said conduit loop downstream of said economizer and upstream of said booster compressor, said evaporator receiving a flow of outdoor ambient air; and
said second heat exchanger is a condenser serving as an indoor coil located in said conduit loop downstream of said primary compressor and upstream of said economizer, said evaporator receiving a flow of air to be conditioned; and further including
a second sensor for sensing the temperature of air from said condenser; and
a flow controller for controlling the flow of air over said condenser in response to said third sensor.
116. The heat pump of claim 112 wherein:
one of said first and second heat exchangers is an evaporator; and
the other of said first and second heat exchangers is a condenser.
117. The heat pump of claim 112 including:
a valve moveable from a first position to a second position to control the direction of flow of the refrigerant in said conduit loop;
said valve in a first position directing the flow of the refrigerant from said primary compressor to one of said heat exchangers functioning as a condenser, and from said condenser to said economizer and then to the other of said heat exchangers functioning as an evaporator; and
said valve in a second position directing the flow of the refrigerant from said primary compressor to said other of said heat exchangers functioning as a condenser, and from said condenser to said economizer and then to said one of said heat exchangers functioning as an evaporator.
118. The heat pump of claim 117 including:
a first modulating valve between said economizer and said one of said heat exchange means functioning as an evaporator to modulate the flow of refrigerant fluid from said economizer to said evaporator when said valve is in said first position thereof; and
a second modulating valve between said economizer and said one of said heat exchange means functioning as an evaporator to modulate the flow of refrigerant fluid to said evaporator when said valve is in said second position thereof.
119. The heat pump of claim 112 wherein:
said controller is connected to said booster compressor to inhibit operation of said booster compressor until outdoor ambient temperature drops to a first predetermined level, and said controller is connected to said economizer flow controller to inhibit operation of said economizer until the outdoor ambient temperature reaches a second predetermined level below said first predetermined level.
120. A heat pump including:
a primary compressor;
a booster compressor;
first and second heat exchangers;
a flow conduit connecting said first and second heat exchangers, and said primary compressor for circulating a refrigerant fluid in a closed loop, said booster compressor being downstream of said primary compressor in said loop;
an economizer connected in said flow conduit means between said first and second heat exchangers;
a bleed connected from said flow conduit means to said economizer to deliver a portion of the refrigerant fluid to said economizer for vaporization in heat exchange with the remaining portion of refrigerant fluid passing through said economizer;
a economizer vapor conduit connected from said economizer to said flow means upstream of the intake of said primary compressor;
a first sensor for sensing a parameter commensurate with the temperature of ambient outdoor air;
a thermostat for sensing the temperature of a fluid to be heated or cooled;
a controller responsive to inputs from said first sensor and said thermostat for controlling operation of said primary compressor and said booster compressor, said controller being effective initially to operate said primary compressor in response to a first input signal from said thermostat while inhibiting operation of said booster compressor, and said controller thereafter being effective to operate said booster compressor and said primary compressor upon receipt of a second signal from said thermostat and receipt of a booster enabling signal commensurate with the temperature of ambient outdoor air;
isolation means in said flow conduit for isolating said booster compressor from the discharge pressure from said primary compressor when operation of said booster compressor is inhibited;
said flow conduit being connected to deliver refrigerant fluid from one of said heat exchangers to said primary compressor and to bypass said booster compressor and deliver refrigerant fluid to the other of said heat exchangers when said booster compressor is inoperative, and said flow conduit being connected to deliver fluid from said one heat exchanger to said primary compressor and from said primary compressor to said booster compressor when operation of said booster compressor is initiated; and
means for varying the pumping capacity of at least one of said primary and booster compressors in response to a signal from said first sensor means.
121. The heat pump of claim 120 wherein:
said primary compressor is a multispeed compressor, and said booster compressor is a one speed compressor or a two speed compressor.
122. The heat pump of claim 120 wherein:
said first heat exchanger is an evaporator located in said flow conduit downstream of said economizer means and upstream of said booster compressor and said primary compressor; and
said second heat exchanger is a condenser located in said flow conduit downstream of said primary compressor and upstream of said economizer.
123. The heat pump of claim 120 wherein:
said controller is effective to control operation of said primary compressor in accordance with an outdoor ambient temperature sensed by said first sensor.
124. The heat pump of claim 120 wherein:
said first heat exchanger is an evaporator serving as an outdoor coil located in said flow conduit means downstream of said economizer and upstream of said booster compressor, said evaporator receiving a flow of outdoor ambient air; and
said second heat exchanger is a condenser serving as an indoor coil located in said flow conduit downstream of said primary compressor and upstream of said economizer, said condenser receiving a flow of air to be conditioned; and further including
a second sensor for sensing the temperature of air from said condenser; and
a flow control for controlling the flow of air over said condenser in response to said third sensor.
125. The heat pump of claim 120 wherein:
one of said first and second heat exchangers is an evaporator; and
the other of said first and second heat exchangers is a condenser.
126. The heat pump of claim 125, including:
a second sensor for sensing the temperature of air from said condenser; and
a flow control for controlling the flow of air over said condenser in response to said second sensor.
127. The heat pump of claim 120, including:
a valve moveable from a first position to a second position to control the direction of flow of refrigerant fluid in said closed loop;
said valve in a first position directing the flow of refrigerant fluid from said primary compressor to one of said heat exchangers functioning as a condenser, and from said condenser to said economizer and then to the other of said heat exchangers functioning as an evaporator; and
said valve in a second position directing the flow of refrigerant fluid from said primary compressor to said other of said heat exchangers functioning as a condenser, and from said condenser to said economizer and then to said one of said heat exchangers functioning as an evaporator.
128. The heat pump of claim 120 wherein:
said controller is connected to said booster compressor to inhibit operation of said booster compressor until outdoor ambient temperature drops to a first predetermined level.
129. The heat pump of claim 120 wherein:
said controller is effective to vary the speed of said primary compressor as an inverse function of outdoor ambient temperature sensed by said first sensor when outdoor ambient temperature falls to a first predetermined level and outdoor ambient temperature is between said first predetermined level and a lower second predetermined level; and
said controller is effective to initiate operation of said booster compressor and operate said primary compressor at low speed when outdoor ambient temperature falls to a said second predetermined level; and
said controller is effective to continue operations of said booster compressor and to vary the speed of said primary compressor as an inverse function of outdoor ambient temperature sensed by said first sensor when outdoor ambient temperature is lower than said second predetermined temperature.
130. The heat pump of claim 120 wherein:
said primary compressor is a variable speed compressor, and said booster compressor is a one speed compressor.
131. The heat pump of claim 120 wherein:
said primary compressor is a variable speed compressor, and said booster compressor is a two speed compressor.
132. The heat pump of claim 120 wherein said isolation means includes:
a two position valve in said flow conduit;
said two position valve being effective in a first position thereof, when said booster compressor is inoperative, to block discharge flow from said primary compressor to said booster compressor; and
said two position valve being effective in a second position thereof to deliver discharge flow from said primary compressor to said booster compressor.
133. The heat pump of claim 132 wherein:
said two position valve is effective in the first position thereof to deliver economizer vapor to said primary compressor.
134. The heat pump of claim 132 wherein:
said two position valve is moved from said first position thereof to said second position thereof in response to initiation of operation of said booster compressor.
135. The heat pump of claim 89 wherein:
said primary compressor is a one speed compressor and said booster compressor is a two speed compressor; and
said controller is effective to permit operation of said primary compressor when the outdoor ambient temperature falls to a first predetermined level while inhibiting operation of said booster compressor and said economizer; and
said controller is effective to continue operation of said primary compressor and to operate said booster compressor at the low speed thereof when outdoor ambient temperature falls to a second predetermined level below said first predetermined level while continuing to inhibit operation of said economizer means; and
said controller is effective to continue operation of said primary compressor and said booster compressor at low speed and to operate said economizer when outdoor ambient temperature falls to a third predetermined level below said second predetermined level; and
said controller is effective to continue operation of said primary compressor and to operate said booster compressor at the high speed thereof and to discontinue operation of said economizer when outdoor ambient temperature falls to a fourth predetermined level below said third predetermined level; and
said controller is effective to continue operation of said primary compressor and to continue operation of said booster compressor at the high speed thereof and to reinitiate operation of said economizer when the outdoor ambient temperature falls to a fifth predetermined level below said fourth predetermined level.
Description
BACKGROUND OF THE INVENTION
This invention relates to air-source heat pumps. More particularly, this invention relates to a new and improved air source heat pump especially suitable for use in normally colder climates.
The air-source heat pump system is the most prevalent type of heat pump used in the world today. This is the case whether one is discussing room units, residential central type, ductless splits, or rooftop commercial systems.
Although the air-source concept in general has a high application potential worldwide, its popularity in the United States and elsewhere has been greatest in mild climate areas. This is because the compressor-derived heating capacity of conventional units declines rapidly as the outdoor ambient falls, due, in the most part, to the large increase in specific volume (i.e., decrease in density) of the outdoor coil generated refrigerant vapor as ambient (outdoor) temperature falls (see FIG.
2). This fall in compressor-derived heating capacity is obviously opposite to the heating requirement, which generally increases in proportion to the fall in outdoor ambient temperature. This problem is illustrated in FIG. 1, which shows a plot of heating requirements vs. outdoor ambient temperature and the heating performance of a 3 Ton Lennox HP 22-411 fixed speed scroll compressor heat pump system. As shown in FIG. 1, the heating requirements (line 2) increase as ambient temperature decreases, going from zero (0) BTU/hr at 65.degree. F. to 72,000 BTU/hr at 5.degree. F. outdoor ambient temperature. The compressor derived heating capacity is shown at line 4.
When a typical prior art heat pump operates below its balance point, (about 40.degree. F. in FIG. 1), supplemental heating is required. The most prevalent form of supplemental heat used is electric resistance. In other than mild climates, this use of supplemental electric resistance heat puts the air-source heat pump at an economic disadvantage to a consumer as compared with other forms of heating, because of the high cost of electric resistance heating. Electric utilities are also concerned because of the associated high peak power demand during cold weather.
One of the areas for improvement of air source heat pump systems lies in the efficient recovery of the low grade heat energy remaining in the condensed refrigerant liquid leaving the system condenser. If this remaining energy is recovered and then returned to the heating side of the system, rather than being further thermally degraded and sent to the system evaporator (as is now the case), very significant increases in overall compressor-derived heating capacity can be made.
The basic problem here is that after the refrigerant has been fully liquified in the condenser, there is still a large amount of energy left in the warm liquid. This remaining energy serves to evaporate a large portion of the liquid itself during the normal pressure reduction process that occurs across the system expansion device. Depending on the refrigerant utilized, and the temperatures existing between the evaporator and the condenser, as much as one-half, or even more, of this liquid can be evaporated during the normal pressure reduction process across the system expansion device. Obviously if liquid has already evaporated, it cannot be again evaporated in the system evaporator, and thus cannot absorb energy from the outside air. However, the net resulting vapor must pass through the system evaporator anyway, creating additional pressure drop along its way, and then must be fully compressed to the condensing level by the compressor. If the compressor must induct this useless vapor, it can only induct a smaller amount of useful vapor. However, compressor power must be expended to compress the total amount of vapor that has been inducted into the compressor. This is not a reasonable process for air-source heat pumps operating in other than the milder ambient temperatures.
Referring again to FIG. 1, the required heat input to an occupied space (line 2) increases in direct proportion to the fall in outdoor ambient temperature whereas the compressor derived heating capacity (line 4) declines rapidly. This is because the heat output of any heat pump is essentially proportional to the weight flow of refrigerant vapor entering the system condenser. FIG. 2 shows what happens to the specific volume of evaporator generated refrigerant vapor as the evaporating temperature falls. At a 50.degree. F. outdoor ambient supporting a 40.degree. F. evaporating temperature, the specific volume is about 0.46 cubic feet per pound of generated vapor whereas at 0.degree. F. outdoor ambient with an evaporating temperature of -25.degree. F., the specific volume is 1.6 cubic feet per pound of generated vapor. This is 3.5 times the volume of vapor per pound compared to the 50.degree. F. ambient level. Further to this, more than 4 times the amount of heat is required at
0.degree. F. as is required at 50.degree. F. This means that a dramatic increase of refrigerant vapor is required at 0.degree. F. ambient as compared to 50.degree. F. ambient in order to adequately match the heat energy requirement.
In addition, if the entire space heating requirement at 0.degree. F. outdoor ambient is to be supplied by compressor derived heating capacity, the air flow across the heating coil of the condenser must be such that the indoor delivered air temperature will be at least 110.degree. F. in order to provide adequate freedom from a sensation of cool drafts. This in turn will cause the system condensing temperature to rise to about 140.degree. F. considering a reasonably sized indoor coil surface. The end result of all this is to cause overall system operating compression ratios to rise to the point where it becomes unrealistic to even consider the use of present day technology for such an application.
The various factors presented above clearly show that present day air source heat pumps do not even come close to doing the job that is required for efficient heating in cold climates.
SUMMARY OF THE INVENTION
In order for air-source heat pumps to become a more effective contender for use in colder climates, significant changes must be made for the heat pump to realize its true potential. Fundamental Carnot thermodynamic principles unquestionably show that electric powered air source heat pumps indeed do have significant potential in cold climates. In fact, the theoretical Carnot C.O.P. (coefficient of performance) for a sink (room) temperature of 70.degree. F. and a source (outside air) temperature of -10.degree. F. is 6.62 (Carnot C.O.P.=(T.sub.2 .DELTA.S)/[T.sub.2 -T.sub.1).DELTA.S] where T.sub.2 is the delivered energy sink temperature (room temperature in absolute degrees) and T.sub.1 is the supplied energy source temperature (outside air temperature in absolute degrees) and .DELTA.S is change in entropy. It is feasible with the present invention to deliver an actual C.O.P. of at least 2.40 at this -10.degree. F. outdoor ambient condition. This represents a Carnot efficiency level of only 36% which certainly is within the bounds of rational achievability. In prior art systems, the actual delivered C.O.P. is only about 1.07 at this condition (70.degree. F. room temperature, -10.degree. F. outside air temperature) because most of the delivered energy comes from electric resistance heating coils, which (by definition) operate with a C.O.P. of 1.
A first embodiment of the present invention is directed to a refrigeration circuit which comprises at least one first stage compressor (sometimes referred to as a booster compressor), at least one second stage compressor (sometimes referred to as a primary compressor), a condenser, an economizer, an evaporator, and conduit means bearing a compressible refrigerant working fluid and connecting the first stage compressor, the second stage compressor, the condenser, the economizer, and the evaporator, in series and in that order, in a closed loop. The conduit means further comprises means for bleeding a portion of the condensed refrigerant from the closed loop downstream of the heating condenser and expanding it within the economizer for highly subcooling the liquid refrigerant within the closed loop being fed to the evaporator. The expanded refrigerant from the economizer is delivered to a point between the outlet of the first stage compressor and the inlet to the second stage compressors. Means are also provided for expanding the highly subcooled high pressure liquid refrigerant downstream of the economizer at the evaporator. The subcooling of the liquid refrigerant in the economizer significantly increases the capacity of the refrigerant to absorb heat in the evaporator. Motors are provided for driving the compressors, and the system includes means for first energizing the primary compressor motor and inhibiting booster operation unless the primary is both running and its inlet pressure has reached a satisfactory low value to enable booster operation. In accordance with this invention, the first stage booster compressor is preferably driven at a variable speed to effect a large variation in flow rate of the refrigerant passing therethrough, and the second stage primary compressor can be relatively fixed in volume flow handling capacity (i.e., a fixed speed compressor), or it can be a two speed or a variable speed machine. A control system includes a first transducer for sensing outdoor ambient temperature, a second transducer for sensing interstage pressure of the refrigerant circulating in the closed loop for controlling the speed of the first stage booster compressor such that control is achieved for booster speed until the interstage pressure reaches a predetermined value determined from outdoor ambient temperature, and a third transducer for sensing the temperature of the air leaving the condenser. The control system also responds to primary and secondary thermostats to operate the primary and booster compressors.
Any or all of the compressors may be positive displacement machines of any type. The first stage booster compressor may also be a variable speed centrifugal compressor for larger size systems.
In a second embodiment of this invention, the booster is a single speed compressor (although a two speed booster could also be used), and the operation of the economizer is modulated to add capacity to the system. In this second embodiment, as in the first embodiment the booster is on the low side of the primary compressor. In this second embodiment, the booster, of appropriately chosen size, is brought on line when the outdoor ambient temperature drops sufficiently to allow operation of the booster. The economizer is physically in the system, but operation of the economizer is inhibited initially. Subsequently, when additional system capacity is required, the economizer is operated to supply this additional required capacity. The economizer can be operated all at once, i.e., to its full capacity in an on/off mode to add the full additional capacity to the system in one step; or the economizer can be brought on line in a series of steps infinitely modulated to add incremental capacity to the system as required.
In a third embodiment of this invention, the primary compressor is on the low side of the system and the booster compressor is on the high side of the system. In this embodiment, the first pressure stage compressor is the primary compressor, and it is a variable speed compressor. The second pressure stage compressor is the booster compressor, and it is either a fixed speed or a two speed compressor. In this third embodiment the first pressure stage (primary) compressor operates whenever the system is in operation (i.e., for heating or for cooling). The second pressure stage (secondary) compressor (i.e., single speed) only operates on the heating cycle, and it is prevented from operating until the outdoor ambient temperature drops sufficiently low to warrant its use.. As with the second embodiment, economizer operation could also be modulated to meet system capacity requirements.
In the first and second embodiments, the primary compressor handles most or all of the cooling cycle. Accordingly, in those embodiments the cooling operation is essentially effected with a single or two speed machine. However, the third embodiment has the advantage that most or all of the cooling operation can also be effected with a variable speed compressor.
It is to be noted that in all embodiments, the first compressor to be operated is designated as the "primary" compressor, and the second compressor to be operated is designated as the "booster" compressor. This is true, regardless of whether the booster is on the low side of the system (first and second embodiments) or on the high side of the system (third embodiment).
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plot of heating requirements versus outdoor ambient temperatures for a typical heat pump system.
FIG. 2 is a plot showing the specific volume of evaporator generated vapor versus actual evaporating temperature in .degree.F.
FIG. 3 is a prior art heat pump system.
FIG. 4 is another prior art heat pump system.
FIG. 5 is a schematic diagram of a closed loop boosted air source heat pump system forming a preferred embodiment of the present invention.
FIG. 5A shows the system of FIG. 5 configured for operation as an air conditioning system.
FIG. 6 is a flow chart of the preferred control system for the boosted heat pump system of FIG. 5.
FIG. 7 is a plot illustrating aspects of the control system.
FIG. 8 is a schematic of an alternative boosted heat pump system in accordance with the present invention.
FIG. 9 is a view similar to FIG. 5 showing a schematic diagram of a closed loop boosted air source heat pump system in accordance with the second embodiment of this invention.
FIGS. 10 and 11 are plots illustrating aspects of operation of the second embodiment of FIG. 9.
FIG. 12 is a flow chart, similar to FIG. 6, of a control system for the second embodiment of FIG. 9.
FIG. 13 is a view similar to FIGS. 5 and 9 showing a schematic diagram of a closed loop boosted air source heat pump system in accordance with a third embodiment of this invention.
FIG. 14 is a partial view of FIG. 13 showing an alternative valving and isolation system for the third embodiment of FIG. 13.
FIGS. 15a and 15b show two positions of the isolation valve of FIG. 14 embodiment of this invention.
FIG. 16 shows a schematic of a single shell compression module in accordance with the third embodiment of FIG. 13.
FIG. 17 is a plot illustrating aspects of operation of the third embodiment of this invention.
FIG. 18 is a flow chart, similar to FIGS. 6 and 12 of a control system for the third embodiment of this invention.
PRIOR ART
Before describing the preferred embodiments of the present invention, the prior art systems of FIGS. 3 and 4 will be briefly described. FIG. 3 shows a typical prior art heat pump system 10 having an outdoor coil (evaporator) 12, a four way valve
14, a compressor 16, an indoor coil (condenser) 18, and an expansion valve 20. Conduit means 22 connects these components as shown in a closed loop system or cycle. A thermal fluid or refrigerant circulates through the closed loop system. Compressor
16 can be any type of positive displacement machine, and it is typically a reciprocating compressor. For heat pump operation, energy is picked up in outdoor coil 12, which functions as an evaporator, the thermal level and content are increased by compressor 16, and the energy is transferred by indoor coil 18, which is functioning as a condenser, to the medium to be heated. As is well known in the art, the system can also function as an air conditioning system, with the functions of evaporator 12
and condenser 18 being reversed.
FIG. 4 shows the prior art heat pump system of U.S. Pat. No. 4,332,144. This heat pump system employs an economizer 21 to improve the performance of the heat pump system. However, the heat pump system of FIG. 4 and U.S. Pat. No. 4,332,144
employs only a single compressor, with the economizer bleed line being connected to that single compressor to deliver the bleed fluid at the end of the compressor intake stroke. The present invention differs significantly in that it employs two compressors (primary and booster) in series, with the economizer bleed line being connected to a point between the two compressors for delivery to the intake to the primary compressor. Furthermore, the heat pump system of U.S. Pat. No. 4,332,144
requires modification of the compressor to admit the bleed fluid at the end of the intake stroke, whereas the heat pump system of the present invention can employ conventional compressors without any need for modification. While the invention of U.S. Pat. No. 4,332,144 was an improvement in heat pump systems, it is still not sufficiently economically practical for normally colder northern climates where ambient temperatures are often below 35.degree. F.
The prior art systems of FIGS. 3 and 4 are shown in U.S. Pat. No. 4,332,144, the entire contents of which are incorporated herein by reference.
U.S. Pat. No. 4,594,858 discloses a refrigeration system having two compressor stages in series and an economizer, with the bleed line of the economizer connected to a point between the two compressor stages. While there are structural similarities between the refrigeration system of U.S. Pat. No. 4,594,858 and the heat pump system of the present invention, the system of U.S. Pat. No. 4,594,858 is limited to a refrigeration system, and it cannot function as a heat pump. The system of U.S. Pat. No. 4,594,858 is dealing with a refrigeration case of essentially constant temperature, and that refrigerated space is itself in an environment of essentially constant temperature, e.g., an air conditioned supermarket. In the refrigeration system of U.S. Pat. No. 4,594,858, the specific volume (or density) of the refrigerant vapor is essentially constant. By way of contrast, and as pointed out above, the heat pump system of the present invention must function in an environment (i.e., the outside ambient air) where the temperature can vary from 100.degree. F. or higher to 0.degree. F. or lower. And, the present invention must deal with a specific volume of refrigerant vapor that varies over a wide range of 6:1 or more. In addition, the control system and the operation of the heat pump of the present invention are very different than the refrigeration system of U.S. Pat. No. 4,594,858.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIGS. 5 and 6, there is shown a closed loop heat pump system and control forming a preferred embodiment of the present invention. Referring first to FIG. 5, the closed loop system includes a first or booster stage compressor 22, a second or high stage primary compressor 24, an indoor coil or condenser 26 which delivers heated air to a space to be heated, an economizer 28, and an outdoor coil or evaporator 30 which, together with conduit means interconnecting these elements in a closed loop circuit, are basic components of the closed loop heat pump system. High stage or primary compressor 24 is normally operating whenever the heat pump system is delivering energy, but booster compressor 22 is operated only when the ambient temperature approaches or falls below the balance point for the primary compressor. Warm output vapor of the primary or second stage compressor 24 is fed to the inlet of indoor coil 26 via conduit segment 32 to warm air (indicated by the arrows) flowing over indoor coil 26 for delivery to the indoor space to be heated. A variable speed fan 27 normally causes the flow of air over indoor coil 20. The warm vapor is, of course, cooled and condensed in indoor coil 26. The outlet of indoor coil 26 delivers the condensed refrigerant to flow via conduit segment 34 and check valve 35 to the economizer 28. At point 36 in line 34, a bypass or bleed line 38 permits a portion of the liquid refrigerant to be bled from the primary closed loop circuit and to expand via an expansion valve 40 preceding economizer 28. The expansion of this bleed refrigerant within economizer 28 results in significant subcooling of the liquid refrigerant which flows in a closed conduit through economizer 28. This subcooled liquid refrigerant then passes directly to evaporator 30 via conduit segment 42. This highly subcooled liquid refrigerant expands via expansion valve 44 into and within the evaporator 30 to perform the function of absorbing energy from the outside air flowing over outdoor coil 30 (as indicated by the arrows) and vaporizing in evaporator 30. A fixed speed fan 31 delivers the air to flow over outdoor coil 30. The amount of energy absorbed within evaporator 30 is greatly increased because of the highly subcooled refrigerant delivered from economizer 28 to the evaporator. The refrigerant vapor from evaporator 30 then flows via conduit segment 46a, 46b and 46c and check valve 47 to point 52 and via conduit segment 48 to the suction or low side of primary compressor 24 to complete the closed loop circulation in effect when only the primary compressor 24 is operating.
Meanwhile, the refrigerant bled via line 38 which vaporizes within the economizer to perform the cooling effect in the economizer, passes via conduit segment 50 to point 52 in conduit 48 connected to the inlet of the primary compressor 24. It should be noted that while only one second or high stage compressor 24 is shown, there may be two or more high stage compressors, connected in parallel and suitably controlled (and/or two or more booster compressors connected in parallel and suitably controlled).
Each of compressors 22 and 24 has its own internal motor, indicated at 23 and 25, respectively, to drive directly each compressor, with at least the motor for booster compressor 22 being a variable speed motor and preferably providing at least a five to one flow range for the refrigerant passing through compressor 22. In the embodiment of FIG. 5, the motor for primary compressor 25 is of fixed speed. The heat pump system as illustrated allows highly efficient heating to take place utilizing evaporator 30 under all load conditions due to the constant use of an economizer cycle. While primary compressor 24 is described as a fixed speed machine, it may be a two speed machine, and it may also be a variable speed machine. At least a two speed primary compressor is preferred in order that the interstage pressure variation remains optimal. Also, the primary or high stage machine, which may be a reciprocating compressor, does not normally mechanically unload and thus always operates at its peak efficie