Page 68 - Defrosting for Air Source Heat Pump

Uneven defrosting on the outdoor coil in an ASHP 59

Table 3.4 Specifications of the tailor-made three-circuit outdoor coil
Item Parameter Value Unit

1 Height of the outdoor coil 500 mm
2 Width of the outdoor coil 590 mm
3 Thickness of the outdoor coil 44 mm
4 Fin height 152.4 mm
5 Fin width 44 mm
6 Fin thickness 0.115 mm
7 Fin pitch 2.1 mm
8 Fin type Plate –
9 Tube external diameter 10 mm
10 Tube thickness 0.5 mm
11 Tube spacing 20 mm
12 Circuit pitch 22 mm
13 Number of tube rows 2 –
14 Number of circuits 3 –
15 Number of water-collecting trays 3 –
16 Number of water-collecting cylinders 3 –
17 Number of wind boards 2
18 Material of tube Copper –
19 Material of fin Aluminum –
20 Material of wind board Wood
21 Material of water-collecting tray PVC –
22 Material of water-collecting cylinder PVC –
23 Volume of Cylinder A, B, and C 500 mL
24 Volume of Cylinder D 2000 mL

Table 3.5 Measurement/calculation errors of system parameters

Measurement/
Item Parameter calculation error Unit
1 Air dry-bulb temperature at upstream of 1 (K-type °C
the outdoor coil thermocouple)
2 Air wet-bulb temperature at upstream of 0.1 (PT100, class A) °C
the outdoor coil
3 Air temperature at downstream of the 0.2 (hygrosensor) °C
outdoor coil
4 Air relative humidity at downstream of the 1.0% (hygrosensor) –
outdoor coil
5 Air flow rate passing through the outdoor 3% (flow hood) –
coil
6 Temperatures of tube/coil and fin surfaces 1 (K-type °C
thermocouple)
7 Refrigerant pressure 0.3% (pressure –
transmitters)
Continued