Question

A pressure gage at the inlet to a gas compressor indicates that the gage pressure is 35.0 kPa. Atmospheric pressure is 1.01 bar. The absolute pressure at the exit is 6 times the absolute pressure at the inlet. What is the absolute pressure of the gas at the inlet and what is the gage pressure of the gas at the exit?

Answer 1

Answer:

136 kPa is the absolute pressure of the gas at the inlet.

715 kPa is the gage pressure of the gas at the exit.

Explanation:

Pressure of the gas at inlet = $P_i$

Pressure of the gas at outlet = $P_e=6\times P_i$

The gage pressure =$P_g=35.0 kPa$

Atmospheric pressure of the gas = P = 1.01 bar

Absolute pressure = gauge pressure + Atmospheric pressure

$P_i = P_g+P$

$P_i=35.0 kPa+1.01 bar=35.0kPa+1.01\times 100 kPa=136 kPa$

(1 bar = 100 kPa)

136 kPa is the absolute pressure of the gas at the inlet.

Pressure of the gas at outlet = $P_e=6\times P_i$

$P_e=6\times 136 kPa=816 kPa$

The gage pressure of the gas at the exit: $P_g'$

$P_e=P_g'+P$

$816 kPa=P_g'+1.01\times 100 kPa$

$P_g'=715 kPa$

715 kPa is the gage pressure of the gas at the exit.