A piston-cylinder assembly with initial volume of 80 liters contains 4 kg of R-134a at a pressure of 160 kPa (state 1). Then, R-134a expands to a volume of 0.4916 m^3 at constant pressure (state 2). Finally, the pressure of R-134a becomes 100 kPa (state 3). During the process 2->3, volume increases as PV^1.01=constant. Determine the total heat transfer during the entire process.