4) 2 kg of Refrigerant 134-a is contained in a constant volume tank as a saturated vapor. When it is heated, the refrigerant pressure and temperature become 400 kPa and 50C, respectively. Determine the change of entropy of the refrigerant during this process. If the heat transfer is coming from a thermal energy reservoir at 100C, what is the change in entropy of the thermal energy reservoir, and sum of the changes in entropy of refrigerant and the thermal energy reservoir?