A rigid tank is heated for 9 minutes with a 800W electrical heater. During this time 70kJ of energy is lost due to heat transfer to the environment. The tank is 11L in volume and contains 8kg of liquid refrigerant R134a whose internal energy can be expressed as:
u=1.23xT (kJ/kg.K), where T is the temperature in Kelvins. Find the temperature of the refrigerant at the end of the heating process.