Page 132 - Defrosting for Air Source Heat Pump

Investigation of effect on uneven defrosting performance 125

Fig. 5.6 Airside surface conditions of the outdoor coil at the start and end of defrosting in the
three cases (six photographs).

previously described in Section 5.2.1. As listed in Table 5.4, the frost accumulations,
or the total mass of the melted frost collected, were 921 g in Case 1, 948 g in Case 2,
and 957 g in Case 3, respectively. Their biggest difference, between Case 1 and Case
3, was just 36 g, or about 3.76%, which was small and acceptable in this section.
Meanwhile, as predicted, a lot of residual water was retained over the outdoor coil
downside surface when the defrosting operation terminated, especially in Case 2.
As shown in Fig. 5.6B2 and C2, the melted frost retained on the downside surface over