A piston cylinder device contains 0.85 kg of refrigerant 134a

Homework 5

Due: Wednesday, 8-October-2014

1. A rigid tank has a volume of 1.8 m3 and contains steam at 220°C. One-third of the tank volume is

in the liquid phase, while the rest is in the vapor phase. Determine: (a) the pressure of the steam,

(b) the quality of the saturated mixture, and (c) the density of the mixture.

2. A piston-cylinder device contains 0.85 kg of refrigerant-134a at -10°C. The piston, that is free to

move, has a mass of 12 kg and a diameter of 25 cm. The local atmospheric pressure is 88 kPa. At

some point, heat is transferred to the refrigerant-134a until the temperature is 15°C. Determine:

(a) the final pressure, (b) the change in the volume of the cylinder, and (c) the change in enthalpy

of the refrigerant-134a.

3. Carbon dioxide gas enters a pipe at 3 MPa and 500 K at a rate of 2 kg/s. CO2 is cooled at constant

pressure as it flows in the pipe and the temperature of CO2 drops to 450 K at the exit. Determine

the volumetric flow rate and the density of carbon dioxide at the inlet and the volumetric flow

rate at the exit of the pipe using (a) the ideal gas equation of state and (b) the generalized

compressibility chart. Also, determine (c) the error involved in the first case.

4. Liquid propane is commonly used as a fuel for heating homes, powering vehicles such as

forklifts, and filling portable picnic tanks. Consider a propane tank that initially contains 5 L of

liquid propane at the ambient temperature of 20°C. If a hole develops in the connecting tube of

the propane tank and the propane starts to leak out, determine the temperature of propane when

the pressure in the tank drops to the ambient pressure of 1 atm. Also, determine the total amount

of heat transferred from the environment to the tank in order to vaporize all of the propane in the

tank.