Question

Find out the working capacity of an engine which is working between 110° to 25⁰c, if temperature of boyler is increased up to 140⁰c and sink temperature equal to its.

• A. $I - 20.2\%,\text{II} - 18\%$
• B. $I - 22.2\%,\text{II - 27.8\%}$
• C. $I - 28\%,\text{II} - 30\%$
• D. None of these

Answer 1

Answer: (B)

$I - 22.2\%,\text{II - 27.8\%}$

Answer 2

First condition

$T_{2} = 110^{o}C = 110 + 273K = 383K$ $\eta = ?$

$T_{1} = 25^{o}C = 25 + 273K = 298K$

$\eta = \frac{T_{2} - T_{1}}{T_{2}} = \frac{383 - 298}{383} = 0.222$ or $22.2\%$

Second condition

$T_{2} = 140^{o}C = 140 + 273K = 413K$ $\eta = ?$

$T_{1} = 25^{o}C = 25 + 273K = 298K$

$\eta = \frac{T_{2} - T_{1}}{T_{2}} = \frac{413 - 298}{413} = 0.278$ or $27.8\%$