Q9/ 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. Now, heat is transferred to 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 the enthalpy of the refrigerant-134a.

A cylinder-piston device provided with stops, so that the water supports the weight of the piston, and the force of the atmosphere,It contains water, initially at 300 kPa and 0.5 m3 / kg. The water is heated to a saturated steam condition and the plunger rests on the stops. With the plunger on the stops, the water is heated up to the pressure of 600 kPa. In the P-V and T-V diagrams, with respect to the saturation lines, the process curves go through the initial and final states of the water. On both T-V and P-V diagrams draw the isotherms that pass through both states, and show their values in ° C, in the isotherms. (see img 1)