A researcher claims that he has developed an engine, which while working between source and sink temperatures of 377°C and 27° C rejects only 50 % of absorbed heat. What will his engine be? 

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ESE Mechanical 2014 Official Paper - 1
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  1. An impossible engine
  2. A Stirling engine
  3. A reversible engine
  4. A practical engine

Answer (Detailed Solution Below)

Option 4 : A practical engine
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ST 1: UPSC ESE (IES) Civil - Building Materials
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Detailed Solution

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Explanation:

Given:

T2 = 27° C = 300 K, T1 = 377° C = 650 K, Q2 = 0.5Q1

The efficiency of given engine 

The efficiency of given engine 

∴ Efficiency of given engine= 0.5 = 50 %

Now,

Efficiency of the reversible engine operating in the same temperature range

As  which is practical

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