Page 300 - Defrosting for Air Source Heat Pump

294 Defrosting for Air Source Heat Pump

Fig. 9.38 Total electricity inputs coming from outside the system during defrosting.

Fig. 9.39 Measured refrigerant volumetric flow rate during defrosting.

The measured temperatures of compressor suction and discharge and the temper-
atures of the tube surface at the entrance and exit of the outdoor coil during defrosting
are separately shown in Figs. 9.35 and 9.36. As analyzed in Fig. 9.35, the compressor
°
suction temperature will increase to its highest value, 2.6 C, at 170 s into defrosting,
°
and then decrease to its lowest value, 1.4 C, at 190 s into defrosting. It is demon-
strated that this period is special, and the most suitable DTT should be at this