Chapter 15, Problem 22P

To determine

The efficiency of the engine.

Answer to Problem 22P

The efficiency of the engine is 73.7%.

Explanation of Solution

Given info:

The temperature of the liquid nitrogen is, $T_n=77\text{K}$ .

The room temperature to liquid nitrogen is, $T_r=293\text{K}$ .

Formula Used:

The expression to calculate the efficiency of the engine is,

  $\eta =1-\frac{T_n}{T_r}$

Calculation:

Substitute all the values in the above expression.

  $\begin{array}{c}\eta =1-\frac{77\text{K}}{293\text{K}}\\ =0.737\\ =73.7\%\end{array}$

Conclusion:

Thus, the efficiency of the engine is 73.7%.