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76 Cha p te r F o u r
temperature lift of ΔT = 45°C; the COP is now 3.5964, W = 2.657
pump
MW, and the sink load Q = 9.557 MW; see Figure 4.36.
sink
However, the heat sink is oversized in this case (Figure 4.36), so
the heat source temperature has to be shifted upward. An increase of
* = 87.28˚C;
2.28°C (see Figure 4.37) yields the following values: T
source
ΔT = 42.72°C; a maximum source load (also taken as the selected
pump
source load) of 5.152 MW; a maximum sink load equal to the selected
sink load of Q = 7.016 MW; COP = 3.7637; and W = 1.864 MW. Better
sink
results can be obtained by optimizing the two temperatures
simultaneously while using the overall utility cost as a criterion.
140
Q SINK
120
100 The sink is oversized
T* [°C] 80
Q SOURCE
60
40
20
0 5 10 15 20 25
ΔH [MW]
FIGURE 4.36 Heat-pump sizing example: Attempt 2.
140
Q SINK
120
100
T* [°C] 80
Q
SOURCE
60
40
20
0 5 10 15 20 25
ΔH [MW]
FIGURE 4.37 Heat-pump sizing example: Attempt 3.
