Question

What is the source temperature of the Carnot engine required to get 70% efficiency?
Given sink temperature = ${27}^{o}C$

• A. ${1000}^{o}C$
• B. ${90}^{o}C$
• C. ${270}^{o}C$
• D. ${727}^{o}C$

Answer 1

Answer: (D)

${727}^{o}C$

Sink temperature $T_L={27}^{o}C=273+27=300$ K

Efficiency of Carnot engine is $70$ % i.e. $\eta =0.7$

Using $\eta =1-\frac{T_L}{T_H}$

$\therefore$ $0.7=1-\frac{300}{T_H}$ $⟹T_H=1000$ K

Or $T_H=1000-273={727}^{o}C$