Cascade variable-frequency air source heat pump hot water system and operation control method

Abstract

The invention relates to a cascade variable-frequency air source heat pump hot water system and an operation control method. The cascade variable-frequency air source heat pump hot water system is characterized by comprising a low-pressure-stage compressor, a heat storage heat exchanger, a first three-way valve, an evaporation-condenser, a high-pressure-stage gas-liquid separator, a high-pressure-stage compressor, a three-pipe heat exchanger, a three-way proportional regulating valve, a circulating water return temperature sensor, a circulating water outlet temperature sensor, a high-pressure-stage electronic expansion valve, a low-pressure-stage electronic expansion valve, a bypass electronic expansion valve, an outdoor environment temperature sensor, an outdoor unit fan, an outdoor unit heat exchanger, an outdoor unit heat exchanger tube temperature sensor, a second three-way valve and a low-pressure-stage gas-liquid separator. It is implemented that the cascade heat pump low-pressure stage system still operates in a forward heating mode during defrosting operation and can continuously provide heat for a heat using end, and heat supply is stable.

Description

technical field [0001] The invention relates to a cascade frequency conversion air source heat pump hot water system and an operation control method. Background technique [0002] Compared with the single-stage compression air source heat pump, the cascade air source heat pump hot water system can be used at a lower outdoor ambient temperature, and can also provide a higher hot water temperature, but there is also an important problem that in When the outdoor ambient temperature is low, frost will form on the surface of the heat exchanger of the outdoor unit. As the frost layer thickens, the performance of the heat pump system will gradually decrease. Therefore, it is necessary to defrost the heat exchanger of the outdoor unit. [0003] At present, the most commonly used defrosting method for cascade heat pumps is that the low-pressure heat pump system runs in reverse, the high-pressure heat pump system stops running, and the low-pressure heat pump system obtains heat from t...

AI Technical Summary

Problems solved by technology

The main problem of this defrosting method is that not only can’t provide heat for the hot end during the defrosting process, but it needs to absorb heat from it.

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