Experimental research and operation optimization of an air-source heat pump water heater

In order to optimize design and operation strategy of air-source heat pump water heater, an experimental set-up and simulation model were constructed. Also, a methodology of optimizing operation, which takes into account thermostatic and timing control patterns, was presented and applied. Experimental results indicated that the average COP ranged from 2.82 to 5.51 under typical conditions. The recommended outside area ratio of condenser coil to evaporator is 0.14−0.31 when the evaporator outside area is between 6.0 and 6.5 m2 for this set-up. The optimal start-up time was between 12:00 and 14:00 if there was no electricity price difference between day and night, or it was near 22:00. The optimal setting water temperature should be adjusted according to the variation of seasonal ambient temperature. It was suggested that, based on this set-up, setting water temperature should be set higher than 46 °C in summer and 50 °C in other seasons.

► A methodology of optimizing operation was presented and applied.
► Experimental results of average COP ranged from 2.82 to 5.51 under typical conditions.
► The effect of evaporator and condenser coil outside area on average COP was discussed.
► The optimal start-up time was obtained.
► The optimal setting water temperature was obtained.