150 kg of a refrigerant is contained in an adiabatic (no heat) cylinder-piston assembly, initially a saturated vapor at a pressure of 14.51 lbf/in2 and specific volume of 0.5 m3/kg. The refrigerant undergoes a polytropic process, defined by pν1.2 = C, where C is a constant, to a final pressure of 362.78 lbf/in2. Find the change in internal energy for the process in kJ, neglecting kinetic and potential energy effects