Question

The thermal efficiency of the hypothetical cycle shown in the figure is

• A. 0.35
• B. 0.23
• C. 0.59
• D. 0.47

Answer 1

The correct option is B 0.23


Heat addition happens in process(2)-(3) because the entropy is increasing.

$Ar(1-2)=\frac{1}{2}(300+500)(3-1)=800kJ/kg$

$Ar(2-3)=\frac{1}{2}(500+600)(5-1)=2200kJ/kg$

$Ar(5-1)=\frac{1}{2}(300+600)(5-3)=900kJ/kg$

$\text{So,}{Q}_s=2200kJ/kg$

$W_{net}=2200-800-900=500kJ/kg$

$\eta =\frac{W_{net}}{Q_s}=0.23$