Juice cocktail (1000 kg) needs to be pasteurized by heating it up from 20 C to 85 C and then hot filling it into the glass bottles. The Heating process is carried out in a counter-current heat exchanger using hot water entering the heat exchanger at 98 C and leaving the heat exchanger at 90 C. If the hot water flow rate is at 2 kg/s calculate (a) the flow rate of juice and (b) the amount of time needed to pasteurize the entire batch of juice cocktail (1000 kg). The specific heat of juice is 3.8 kJ/kg C and that of water is 4.2 kJ/kg C.

Question: Calculate the length of heat exchanger needed for this operation (as described in problem 2) if the inside radius of the inner stainless steel pipe is 4 cm with a thickness of 5 mm. The convective heat transfer coefficient on the juice side is 75 W/ m2 °C, thermal conductivity of stainless steel is 20 W/m C and convective heat transfer coefficient on the hot water side is 350 W/m2 C (10). You are required to use all three heat transfer coefficient values while solving the problem.