Engine A, compared to engine B, produces per cycle, five times the work but receives three times the heat input and exhausts twice the heat out. We have to determine the efficiency of each engine.
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Solution: Click For PDF Version Let the heat input, work output, and heat exhaust of the engine A be ,
 ,
and
 ,
respectively. Let the same thermodynamic quantities for the engine B
be denoted by
 ,
 ,
and
 .From the data of the problem we relate these quantities. We have
and
From energy conservation, we have
and
Solving these algebraic equations, we easily find
Therefore, the efficiency of the engine B is
That is the efficiency of the engine B is 33.3%. And,
That is the efficiency of the engine A is 56%.
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