IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
UP-0744339
(2007-05-04)
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등록번호 |
US-7707842
(2010-06-03)
|
발명자
/ 주소 |
- Concha, Julio
- Chen, Yu
- Park, Young Kyu
- Sienel, Tobias H.
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출원인 / 주소 |
|
대리인 / 주소 |
|
인용정보 |
피인용 횟수 :
1 인용 특허 :
5 |
초록
▼
A heat pump, and in particular a heat pump for heating a hot water supply is provided with an improved defrost mode. The defrost mode is actuated to remove frost from an outdoor evaporator that may accumulate during cold weather operation. An algorithm for operation of the defrost mode is developed
A heat pump, and in particular a heat pump for heating a hot water supply is provided with an improved defrost mode. The defrost mode is actuated to remove frost from an outdoor evaporator that may accumulate during cold weather operation. An algorithm for operation of the defrost mode is developed experimentally by seeking to maximize the heat transfer provided by the refrigerant. A heating system condition is experimentally related to the heat transfer capacity. One then maximizes the average heat transfer capacity to determine the optimum initiation point for the defrost mode. Further, protections are included into the defrost mode. When the heat pump is utilized to heat hot water, methods are provided to prevent the water that remains in the heat exchanger from becoming unduly heated. In one method, the water pump may be periodically operated to move the water. In a second method, a control ensures the discharge pressure of the refrigerant leaving the compressor is reduced, and that the water pump is not stopped until that reduced temperature falls below a predetermined maximum. The temperature reduction is achieved through a dual control loop wherein a temperature that is too high results in a new desired discharge pressure. The control achieves the new desired pressure by controlling the expansion device. In another protection feature, as a control determines that the defrost mode is nearing its end, an evaporator fan is run to remove melted water from the evaporator coils, and also to ensure the refrigerant leaving the evaporator does not reach unduly high pressure or temperatures.
대표청구항
▼
What is claimed is: 1. A heat pump cycle comprising: a compressor for compressing a refrigerant; a heat exchanger downstream of said compressor; a main expansion device downstream of said heat exchanger; an evaporator downstream of said main expansion device, and a refrigerant flowing from said com
What is claimed is: 1. A heat pump cycle comprising: a compressor for compressing a refrigerant; a heat exchanger downstream of said compressor; a main expansion device downstream of said heat exchanger; an evaporator downstream of said main expansion device, and a refrigerant flowing from said compressor to said heat exchanger, to said expansion device, to said evaporator, and returning to said compressor; a hot water supply to be heated in said heat exchanger, and a water pump for moving water through said heat exchanger; and a control for said cycle, said control being operable to control components and initiate a defrost mode at which refrigerant from a discharge side of said compressor is cycled into said evaporator at a relatively hot temperature to defrost said evaporator, said control being operable to stop said water pump during defrost mode, and operates to minimize the likelihood of water in said heat exchanger being unduly heated during defrost mode, said water pump being intermittently actuated during defrost made to minimize said likelihood. 2. The cycle as set forth in claim 1, wherein said water pump is stopped during defrost mode, but said water pump does not stop until said control has determined that a discharge temperature of said refrigerant has dropped below a predetermined maximum to minimize said likelihood. 3. The cycle as set forth in claim 2, wherein an actual discharge temperature is compared to said predetermined maximum, and if said actual discharge temperature exceeds the predetermined maximum, a new target pressure is determined, and said control controlling said expansion device to achieve said new target pressure. 4. A heat pump cycle comprising: a compressor for compressing a refrigerant; a first heat exchanger downstream of said compressor; a main expansion device downstream of said first heat exchanger; an evaporator downstream of said main expansion device and a fan to deliver air over said evaporator, and the refrigerant flowing from said compressor to said first heat exchanger, to said expansion device, to said evaporator, and returning to said compressor; a water pump to circulate a flow of water to be heated through said evaporator; a control for said cycle, said control being operable to control components and initiate a defrost mode at which a hot refrigerant is cycled into said evaporator at a relatively hot temperature to defrost said evaporator, said control being operable to stop said water pump during defrost mode, and operates to minimize the likelihood of water in said heat exchanger being unduly heated during defrost mode; said control also stopping said fan during defrost mode, and monitoring a system condition to identify a point at which said fan should begin blowing air over said evaporator, said point being selected to be prior to an end of said defrost mode; and said water pump is stopped during defrost mode, but said water pump does not stop until said control has determined that a discharge temperature of said refrigerant has dropped below a predetermined maximum to minimize said likelihood. 5. The heat pump cycle as set forth in claim 4, wherein an actual discharge temperature is compared to said predetermined maximum, and if said actual discharge temperature exceeds the predetermined maximum, a target pressure is determined, and said control controlling said expansion device to achieve said target pressure. 6. The heat pump cycle as set forth in claim 4, wherein said hot refrigerant is tapped from a discharge side of said compressor. 7. The heat pump cycle as set forth in claim 4, wherein said monitored system condition being compared to a pre-determined limit, and said fan being started when said limit is crossed by said monitored system condition. 8. The heat pump cycle as set forth in claim 7, wherein said pre-determined limit is selected to be indicative of an approaching end of the defrost mode. 9. The heat pump cycle as set forth in claim 4, wherein said heat pump includes a hot water supply passing a water to be heated through said first heat exchanger.
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