Experimental Study of a Novel Direct-Expansion Variable Frequency Finned Solar/Air-Assisted Heat Pump Water Heater

Table 4

Effect of the ambient temperature on average COP and heating time.

Ambient temperature (°C)	Average COP			Heating time (min)
	Air	Solar	Dual	Air	Solar	Dual
20	2.23	3.35	2.65	382.2	336.6	328.8
30	3.40	4.15	3.48	260	276.3	262.2