Refrigerant-134a at -12°C, in which 2.55kg of the refrigerant is in the liquid phase. An electric switch is turned on, and a 110-V source supplies current to a resistance heater inside the cylinder for a period of 20 minutes until the volume is doubled.

1. Determine the quality and the specific internal energy of the refrigerant at the initial state.

2. Determine the quality of the refrigerant and the pressure at the final state.

3. Sketch the process on a T-v diagram with respect to saturation lines.

4. Determine the work done during the process. Hence, or otherwise, determine the current that passes through the resistance heater