Refrigerant-12 is employed as the working medium in a heat pump. The evaporator temperature (outdoor temperature) is 50C and the condenser temperature (the indoor temperature) is 300C. The efficiency of the compressor is 85%. The heating requirement is 60,000 kcal /h. Determine the co-efficient of performance of the heat pump. If direct electric resistance heating is employed for the purpose what would be the relative gain of the heat pump. Assume that the drive for the heat pump compressor is a electric motor of 70% efficiency.
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Properties of R - 12 are given below:
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Temp.
0C
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(P),
kgf/cm2
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hf,
kcal / kg
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hg,
kcal / kg
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sf ,
kcal /kg K
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sg,
kcal /kgoK
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5
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3.7
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9.72
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45.3
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0.0379
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0.1658
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30
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7.6
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15.43
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47.675
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0.0573
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0.1637
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Properties of superheated R - 12:
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p,
kgf / cm2
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hg,
kcal / kg
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sg,
kcal / kg K
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7.6
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48.98
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0.1658
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