The ground-water heat-pump system (GWHP) provides a high efficient way for heating and cooling while consuming a little electrical energy. Due to the lack of scientific guidance for operating control strategy, the coefficient of performance (COP) of the system and units are still very low. In this paper, the running strategy of GWHP was studied. First, the groundwater thermal transfer calculation under slow heat transfixion and transient heat transfixion was established by calculating the heat transfer simulation software Flow Heat and using correction factor. Next, heating parameters were calculated based on the building heat load and the terminal equipment characteristic equation. Then, the energy consumption calculation model for units and pumps were established, based on which the optimization method and constraints were established. Finally, a field test on a GWHP system in Beijing was conducted and the model was applied. The new system operation optimization idea for taking every part of the GWHP into account that put forward in this paper has an important guiding significance to the actual operation of underground water source heat pump.
Totally 4 pumps are installed, of which 1 is a spare unit
Flow: 242 m3/h
Pump head: 27 m
Power: 37 kW
Submersible pump
Type: KQL200/285-37/4
3
Installed in Well 1, 2,and 4
Flow: 362 m3/h
Pump head: 24 m
Power: 37 kW
Tab.2
Type
Heat dissipation/kW
Number
Total heat dissipation/kW
ZK35
355.6
8
7637.5
ZK50
508.7
5
ZK60
606.4
2
ZK80
806.4
1
ZK25
230
1
Tab.3
Fig.3
Tp /°C
ΔTgw /°C
ηg /(m3·h-1)
Ts /°C
ΔTcw /°C
ηc /(m3·h-1)
Average value
14–19
4–8
60–150
44
1.5–4.5
210–230
Design value
15
5
194
45
5
243
Tab.4
Fig.4
Fig.5
Fig.6
Fig.7
Fig.8
Fig.9
Fig.10
Fig.11
Fig.12
Heat capacity/kW
Input power/kW
Temperatures of ground water loop/°C
Temperatures of circulation water loop/°C
inlet
outlet
inlet
outlet
1156.21
235.48
14.31
8.25
36.31
39.63
1165.75
237.91
14.38
8.44
37.31
40.63
1102.28
223.59
14.50
9.81
37.75
40.88
1137.81
227.56
14.50
8.31
36.81
40.06
1122.31
233.33
14.56
8.38
37.31
40.50
855.69
174.27
14.63
8.50
37.63
41.00
1267.50
247.08
14.88
8.38
36.06
39.69
1130.35
235.49
16.56
9.13
36.69
39.81
1110.51
227.56
17.31
8.94
36.81
39.56
1192.77
239.51
17.63
9.38
36.50
39.69
1171.89
236.27
18.13
9.50
35.75
38.50
1352.31
258.07
18.25
9.63
35.31
39.13
1158.10
238.78
18.31
9.81
34.75
37.88
Tab.5
Fig.13
Aij
i= 0
i= 1
i= 2
j= 0
0.9202
-0.01123
-0.003709
j= 1
-0.0062
-0.00073
-0.00054
j= 2
-0.00114
-0.00045
0.00035
Tab.6
System load rate distribution
Units load rate distribution
Φ≤0.33
PLR1 = 3Φ, PLR2 = PLR3 = 0
0.33<Φ≤0.67
PLR1 = PLR2 = 1.5Φ, PLR3 = 0
0.67<Φ≤1
PLR1 = PLR2 = PLR3 = Φ
Tab.7
Fig.14
Fig.15
Fig.16
Fig.17
Fig.18
Outdoor temperature/°C
Number of units in operation
COP of system
Circulation water flow rate /(m3·h-1)
Supply water temperature/°C
Ground water flow rate/(m3·h-1)
Reinjection water temperature/°C
Total input power/kW
-12
3
4.66
420
55.56
130
14.92
1016.96
-11
3
4.48
400
54.15
130
14.92
1017.20
-10
3
4.30
450
52.73
130
14.92
1016.83
-9
3
4.13
450
51.31
130
14.92
1015.06
-8
3
3.97
450
49.90
130
14.92
1011.90
-7
3
3.81
430
48.48
130
14.92
1007.35
-6
3
3.66
400
47.06
130
14.92
1001.39
-5
3
3.50
380
45.65
130
14.92
994.05
-4
3
3.35
360
44.23
130
14.92
1005.62
-3
3
4.82
340
42.81
130
14.92
596.61
-2
3
4.60
420
41.40
130
14.92
589.55
-1
2
4.37
400
39.98
130
14.92
646.87
0
2
4.15
405
38.56
130
14.92
624.25
1
2
3.93
315
37.15
130
14.92
610.34
2
2
3.71
340
35.73
130
14.92
602.36
3
2
5.24
270
34.31
130
14.92
348.81
4
2
4.90
270
32.90
125
15.12
340.97
5
2
4.54
270
31.48
120
16.00
332.57
6
2
4.18
270
30.06
80
15.00
323.62
7
1
5.05
270
28.65
80
15.00
265.68
8
1
4.52
270
27.23
80
15.00
257.18
9
1
5.97
270
25.81
80
15.00
146.74
10
1
5.08
270
24.40
80
15.00
141.17
11
1
6.54
270
22.98
80
15.00
66.77
12
1
4.90
270
21.56
80
15.00
63.75
Tab.8
Fig.19
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