Question

An air standard dual-combustion cycle has a mean effective pressure of 10 bar. The minimum pressure and temperature are 1 bar and 17 ?C, respectively, and the compression ratio is 16/1. Calculate the maximum cycle temperature when the cycle efficiency is 60%. The maximum cycle pressure is 60 bar.

Answer 1

$P_1=1bar$

$V_1/V_2=16$

$P_3=60 bar$

$C_v=0.718$

$C_p=1.005$

$T_2=T_1\times(V_1/V_2)^{r-1}$

$T_2=879K$

$P_2=P_1\times(V_1/V_2)^r$

$P_2=48.5 bar$

$T_2=T_2 \times P_3/P_2$

$=879\times60/48.5$

$T_3=1087K$

Now,

$V_4/V_3=T_4/T_3$

$V_4/V_3\times T_3 =T_4$

$T_4=1087\times (V_4/V_3)$ ——————(*)

$T_5=0.3298\times T_4 \times (V_4/V_3)^{1.4-1}$

$T_5=0.020126\times T_41.4$

$=1-\frac{C_v(T_5-T_2)}{C_v(T_5-T_2)+C_p(T_4-T_3)}$

by the equation putting values;

$T_4=1959k$

when the cycle efficiency is 60%