Question

In an air standard diesel cycle compression starts at 100kpa and 300k. the compression ratio is 16 to 1. The maximum cycle temperature is 2031K. Determine the thermal efficiency.

Answer 1

Answer:

$\eta$=0.60

Explanation:

Given :Take $\gamma$=1.4 for air

      $P_1=100 KPa ,T_1=300K$

  $\frac{V_1}{V_2}$=r ⇒ r=16

As we know that  

   $T_2=T_1(r^{\gamma-1})$

So $T_2=300\times 16^{\gamma-1}$

  $T_2$=909.42K

Now find the cut off ration $\rho$

      $\rho=\frac{V_3}{V_2}$  

         $\frac{V_3}{V_2}=\frac{T_3}{T_2}$

$\rho=\frac{2031}{909.42}$

 $\rho=2.23$

So efficiency of diesel engine

$\eta =1-\dfrac{\rho^\gamma-1}{\gamma\times r^{\gamma-1}(\rho-1)}$

Now by putting the all values

$\eta =1-\dfrac{2.23^{1.4}-1}{1.4\times 16^{1.4-1}(2.23-1)}$

So $\eta$=0.60

So the efficiency of diesel engine=0.60