Question

In a reciprocating compressor, air pressure at the entry is 1.01 bar. If the clearance ratio and the expanison co-efficient are 5% and 1.3 respectively, the discharge pressure for zero volumetric efficiency is

• A. 71.68 bar
• B. 52.87 bar
• C. 54.19 bar
• D. 1.01 bar

Answer 1

The correct option is B 52.87 bar

$\text{Suction pressure}{p}_1\text{=1.01 bar}$

$\text{Clearance ratio, C = 0.05}$

$\text{Expansion coefficient, n = 1.3}$


As we know,

$\text{volumetric efficiency,}{\eta }_v=1-C[{\left(\frac{p_2}{p_1}\right)}^{1/n}-1]$

$for{\eta }_v=0$

$0=1-0.05[{\left(\frac{p_2}{1.01}\right)}^{1/1.3}-1]$

$0.05[{\left(\frac{p_2}{1.01}\right)}^{1/1.3}-1]=1$

${\left(\frac{p_2}{1.01}\right)}^{1/1.3}=21$

$\Rightarrow {\text{Discharge pressure, p}}_2=52.869bar$