Orange juice (with a mean heat capacity of 3.8 kJ kg−1 K −1 ) enters a heat exchanger at 12℃ with a flow rate of 500 kg h−1 . It is heated by hot water flowing at 0.11 kg s−1 and the water temperature falls from 80 to 30℃. What is the final temperature of the orange juice? (Hint: use the specific heat of water at the average temperature of water from Table A.4.1 in the textbook; also note that the specific heat in kJ/kgK and kJ/kg℃ are the same)