In an air standard Diesel cycle, p is the fuel-cut off ratio and y is the adiabatic index and r is the compression ratio. What is the air standard efficiency of the cycle?

A

$$ \eta =1 - \left[\frac{1}{\gamma r^{\gamma}}-\frac{(p^{\gamma}-1)}{(p-1)}\right]$$

B

$$ \eta =1 - \left[\frac{1}{\gamma r^{\gamma - 1}}-\frac{(p^{\gamma-1}-1)}{(p-1)}\right]$$

C

$$ \eta =  1 - \left[\frac{1}{\gamma r^{\gamma - 1}}-\frac{(p^{\gamma}-1)}{(p-1)}\right]$$

D

$$ \eta = 1 - \left[\frac{1}{\gamma r^{\gamma}}-\frac{(p^{\gamma-1}-1)}{(p-1)}\right]$$