A rigid tank of volume 0.5m3 is connected to a piston-cylinder by a valve as shown below.

Both vessels contain pure water; they are immersed in a constant temperature bath at 200and 600kPa. Consider the tank and the piston cylinder assembly as the system and the constant temperature bath as the surroundings.  Initially the valve is closed and both units are in equilibrium with the surroundings (the bath).  The rigid tank contains saturated water with a quality of95% (i.e., 95% of the mass of water is vapor).  The piston cylinder assembly initially has a volume of 0.1 m3

Solution:

Using the steam stable to write the following values of water at constant volume container initially at 200.

Express mass of water inside the piston cylinder assembly

After the valve is opened, final temperature and pressure is equilibrium with the surrounding. Thus final specific internal energy of piston-cylinder assembly is equal to that of initial state

Expressing energy balance to find Q,

2. Considering filling compressed argon from a high pressure supply line as shown below. Before filling cylinder is empty. The valve is then open, exposing the tank 50 bar line at room temperature until the pressure of the cylinder reaches 50 bar. The valve is then closed. For argon take Cp = (5/2)R and the molecular weight to be 40 kg/kmol. You may use the ideal gas model. 

use the ideal gas model. 

Solution:

Inline pressure = P = 50 Bar

Cylinder pressure = P= 50 Bar

By using the ideal gas equation

PV = nRt

Argon is monoatomic ideal gas;

We have ; H= U+PV

Considering the volume of cylinder = unit

PV= nRT

T= 12.02K

a) What is the temperature right after the valve is closed?

T = 12.02K

b) If the cylinder sits in storage for a long time, how much heat is transferred (in k J/kg)?

Heat transferred = Q= m

Q= 9993.43KJ/kg

c) What is the pressure of the cylinder when it is shipped (after it was stored for a long time)?

Pressure after long time in cylinder is same because the heat lessees are negligible. But it should be slightly less than 50bar.

3. A boiler operates at steady states. The entering water is saturated liquid at P= 5bar and has a floe rate of 10,000kg/hr. The existing steam is also at P = 5 bar and T = 400^oC. The pipe entering the boiler is 8 cm in diameter, and the pipe leaving the boiler is 30 cm in diameter. What is the rate at which heat is added in the boiler?

Solution

Given; 

4. A rigid tank has a volume of 0.01m³. It initially contains saturated water at a temperature f 200 and a quality of 0.4. The top of the tank contains a pressure regulating valve which maintains the vapor at constant pressure. This system undergoes a process where it is heated until all the liquid vaporizes. How much heat in (kJ) is required? You may assume there is no pressure drop in the exit line.

Solution 

Volume = 0.01m³

Initially saturated water ⁼ 200

Quality Y = 0.4

So, with steam table ar T= 200  saturation

After heating to all liquid vaporize with same pressure

And mg = 0.01 = 10kg 

So, mt= 25kg

Q= mt(1045.59)