A piston-cylinder device contains 12 kg of saturated vapor R-134a at 2.4 bar (State 1). A 110V electric source supplies current to a resistor within the cylinder for 6 minutes and heat transfer of 300kJ occurs to the system. During these energy interactions, the pressure is maintained constat and the refrigerant is heated to 70 degrees C (State 2).
a) Calculate the current (A) supplied to the resistor.
b) Show the expansion process for R-134a on a P-v diagram. Label states, show property values, and indicate appropriate lines of constant temperature.