A mass of air confined to a rigid insulated tank of 01 m3 vo

A mass of air confined to a rigid, insulated tank of 0.1 m3 volume, is heated by a small resistor having a rating of 100 W. To maintain the contents of the tank at constant temperature, air is permitted to escape through a capillary tube at a controlled rate. At a certain time, the conditions in the tank are: pressure, 5 bar, and temperature, 300 K. Determine the rate of mass flow from the tank at this time?

Solution

Given: V=0.1 m³, Q = 100 W, P₂ = 5 bar, T₂ = T₁ = 300 K

R = 287 kJ/kg K

P₁ = R*T₁/(V)

So, P₁ = 8.61 bar

R\' = 8.314 kJ/kgK

Change in entropy ds = R\' *(ln (P₁/P₂)) = 4518.546 J/kgK

Q = m*(T*ds)

So, m = 7.377*10-5 kg/s = 0.265572 kg/hr