Page 186 - Defrosting for Air Source Heat Pump

180 Defrosting for Air Source Heat Pump

28
Circuit 1 Circuit 2 Circuit 3
24
Temperature of tube surface ( o C) 16 8 193 s
20

12

o
197 s
0 4 1.87 C 125 s 193 s
80 100 120 140 160 180 200 220
Time (s)
Fig. 6.27 Measured tube surface temperatures at the exits of the three refrigerant circuits during
defrosting in Case 1.

28
Circuit 1 Circuit 2 Circuit 3
24
Temperature of tube surface ( o C) 16 8 183 s
20

12

4
o
2.73 C
187 s
122 s 186 s
0
80 100 120 140 160 180 200 220
Time (s)
Fig. 6.28 Measured tube surface temperatures at the exits of the three refrigerant circuits during
defrosting in Case 2.

Figs. 6.27–6.29 show the measured tube surface temperatures at the exits of the
three refrigerant circuits during defrosting in the three cases. Due to the water-
collecting trays installed between circuits, the melted frost was locally drained before
it flowed downward into the down circuits along the surface of the outdoor coil.