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Railways NTPC (Technical Ability) Thermodynamics Question Bank Thermodynamics

  • question_answer
    An ideal heat pump and an ideal refrigerator, which are reversible in operation, operate between same upper and lower temperature limits. If the coefficient of performance of the refrigerator is 4.5, then what  is the coefficient of performance of the heat pump

    A) 3.5                               

    B) 5.5              

    C) 2.5                               

    D) 6.5

    Correct Answer: B

    Solution :

    \[{{(COP)}_{\text{Ref}}}=\frac{{{T}_{2}}}{{{T}_{1}}-{{T}_{2}}}=4.5\] \[{{(COP)}_{pump}}\,1+{{(COP)}_{ref}}=1+4.5=5.5\]


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