Page 187 - Defrosting for Air Source Heat Pump

Frosting evenness coefficient 181

28
24
Circuit 1
Temperature of tube surface ( o C) 16 8 172 s
20
Circuit 2
Circuit 3

12

o
3.73 C
174 s
4
175 s
0
80 100 120 140 160 180 200 220
Time (s)
Fig. 6.29 Measured tube surface temperatures at the exits of the three refrigerant circuits during
defrosting in Case 3.

28

24 Fin in Circuit 1
Temperature of fin surface ( o C) 16 8 Fin in Circuit 3 2.90 C 202 s
20
Fin in Circuit 2

12
o

4
170 s 203 s
207 s
0
80 100 120 140 160 180 200 220 240
Time (s)
Fig. 6.30 Measured fin surface temperatures at the center of the three refrigerant circuits during
defrosting in Case 1.

And thus, the negative effects of downward-flowing melted frost on defrosting
performance were eliminated fundamentally. Finally, as shown in Figs. 6.27–6.29,
the temperature curves of the three circuits left 0°C at the same time, at 100 s
into defrosting, and increased nearly at the same time, with the same trends as that