CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2007

  • question_answer
      A Carnot engine with sinks temperature at \[17{}^\circ C\] has 50% efficiency. By how much should its source temperature be changed to increase its efficiency to 60%?

    A)  225 K                                   

    B)  \[128{}^\circ C\]             

    C)         580 K                   

    D)         145 K

    E)  \[145{}^\circ C\]

    Correct Answer: D

    Solution :

    \[\eta =1-\frac{{{T}_{2}}}{{{T}_{1}}}\] Initially, \[\frac{50}{100}=1-\frac{(273+17)}{{{T}_{1}}}\] Or           \[\frac{290}{{{T}_{1}}}=\frac{1}{2}\] \[\Rightarrow \]               \[{{T}_{1}}=580\,K\] Finally,   \[\frac{60}{100}=1-\frac{(273+17)}{T_{1}^{}}\] Or           \[\frac{290}{T_{1}^{}}=\frac{2}{5}\] \[\Rightarrow \]               \[T_{1}^{}=725\,K\] Hence, change in source temperature \[=(725-580)K=145K\]


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