A fluid at 8 bar and 200 degree C flows into a rigid tank of

A fluid at 8 bar and 200 degree C flows into a rigid tank of a 1m^3 volume through a 10 cm diameter pipe at an average velocity of 3 m/s. The tank is initially empty. After 30s, the temperature in the tank is recorded as 200 degree C. Calculate the pressure if the fluid is stream Calculate the pressure if the fluid is air.

Solution

Pipe cross-section area A = pi/4 * d^2 = 3.14/4 * 0.1^2 = 0.00785 m^2

a)

For steam at 8 bar, 200 C, we get specific volume v = 0.261 m3/kg

Mass flow rate m = A*V / v

= 0.00785*3 / 0.261

= 0.09 kg/s

Mass flown in 30 s = 30*0.09 = 2.7 kg

Tank capacity = 1 m3

New specific volume v = 1 / 2.7 = 0.369 m3/kg

From steam properties at 200 C and v = 0.369 m3/kg, we get P = 5.71 bar

b)

For air at 8 bar, 200 C, we get specific volume v = 0.17 m3/kg

Mass flow rate m = A*V / v

= 0.00785*3 / 0.17

= 0.139 kg/s

Mass flown in 30 s = 30*0.139 = 4.156 kg

Tank capacity = 1 m3

New specific volume v = 1 / 4.156 = 0.24 m3/kg

From air properties at 200 C and v = 0.24 m3/kg, we get P = 5.66 bar