Effect of outdoor conditions on characteristics of energy-storage air source heat pump water heater unit

In order to understand the effect of parameters of outdoor air on characteristics of energy-storage air source heat pump water heater unit, the prototype was developed and some experimental tests on performance of unit in different operation modes were conducted. The results showed that the mean EER and energy-saving impact reduces with the decrease of temperature of outdoor air in the mode of energy storage. However, the time of energy storage is extended with the decrease of temperature of outdoor air. In the mode of heat storage and cooling storage, the unit can recover half of the cooling of evaporator and the enlargement of capacity of tank of cooling storage can increase the cooling amount. In the mode of supplying hot water, there exists a break of hot water supply because the high flowrate of circulation water causes intensive disturbance in the tank of heat storage. Moreover, the time of break is prolonged with the decrease of temperature of outdoor air.