Defrost mode for HVAC heat pump systems
US7228692B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 11, 2004 |
| Grant date | Jun 12, 2007 |
| Priority date | — |
| Expiry date | Sep 26, 2024 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF25B2700/21151
- WIPO fieldThermal processes and apparatus
- WIPO sectorMechanical engineering
Abstract
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 …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.