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Railways NTPC (Technical Ability) Refrigeration and Air-Conditioning Question Bank Refrigeration and Air-Conditioning

  • question_answer
    A building in a cold climate is to be heated by a Carnot heat pump. The minimum outside temperature is \[-\,23{}^\circ C.\] If the building is to he kept at \[27{}^\circ C\] and heat requirement is at the rate of 30 kW, what is the minimum power required for heat pump?

    A) 180 k W           

    B) 30 k W

    C) 6 k W               

    D) 5 k W

    Correct Answer: A

    Solution :

    \[{{T}_{1}}=273+27=300\,\,K,\] \[{{T}_{2}}=273-23=250\,K\] \[{{(COP)}_{HP}}=\frac{{{T}_{1}}}{{{T}_{1}}-{{T}_{2}}}=\frac{300}{300-250}=\frac{300}{50}=6=\frac{W}{Q}\] \[W\,\,=\,\,30\,\,\times \,\,6\,\,=\,\,180\,\,k\,W\]


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