Question

A gas enters a compressor that provides a pressure ratio (exit pressure to inlet pressure) equal to 8. If a gage indicates the gas pressure at the inlet is 5.5 psig, what is the absolute pressure, in psia, of the gas at the exit? Atmospheric pressure is 14.5 lbf/in.2

Answer 1

`P_2_(abs)=160\ psia` (absolute).

Step-by-step explanation:

Given that

Pressure ratio r

r=8

`r=(P_2_(abs))/(P_1_(abs))`

`8=(P_2_(abs))/(P_1_(abs))` -----1

P₁(gauge) = 5.5 psig

We know that

Absolute pressure = Atmospheric pressure + Gauge pressure

Given that

Atmospheric pressure = 14.5 lbf/in²

P₁(abs) = 14.5 + 5.5 psia

P₁(abs) =20 psia

Now by putting the values in the above equation 1

`8=(P_2_(abs))/(20)`

`P_2_(abs)=8* 20\ psia`

`P_2_(abs)=160\ psia`

Therefore the exit gas pressure will be 160 psia (absolute).