Question

A mass of 0.2 kg of saturated refrigerant-134a is contained in a piston-cylinder device at 200 kPa. Initially, 75 percent of the mass is in the liquid phase. Now heat is transferred to the refrigerant at constant pressure until the cylinder contains vapor only. Show the process on a P-v diagram. Determine the volume occupied by the refrigerant initially.

Answer 1

To determine the initial volume of the refrigerant, we need to use the saturation properties of refrigerant-134a. Using the saturation pressure-temperature chart, we can find the corresponding saturation temperature at 200 kPa. Then we can find the specific volume of the liquid phase. Finally, the initial volume occupied by the refrigerant is given by (mass of liquid phase * specific volume of liquid phase).

Step-by-step explanation:

To determine the initial volume of the refrigerant, we need to use the saturation properties of refrigerant-134a. The initial pressure is given as 200 kPa and 75 percent of the mass is in the liquid phase.

Using the saturation pressure-temperature chart for refrigerant-134a, we can find the corresponding saturation temperature at 200 kPa. Let's assume it is Tinitial. Then we can find the specific volume of the liquid phase at Tinitial. Let's assume it is vliquid.

Now, using the mass of the refrigerant (0.2 kg) and the mass fraction of the liquid phase (75 percent), we can find the mass of the liquid phase. Let's assume it is mliquid. Finally, the initial volume occupied by the refrigerant is given by Vinitial = (mliquid * vliquid).