Water (heat capacity = 4.174 kJ/kg: ° C) at a rate of 10 kg/min is heated from 20 ° C to 60 oil that has a specific heat of 1.9 kJ/kg: ° C. The oil enters the shell side of the heat exchanger at 120 ° C and leaves at 70 ° C. The overall heat transfer coefficient is 350 W/m2 · ° C. (a) Use the log mean temperature difference method to calculate the heat exchanger area if a counter flow double pipe heat exchanger is used. (b) Use the effectiveness-NTU method to calculate the heat exchanger area if a counter flow double pipe t heat exchanger is used. (c) Use the log mean temperature difference method to calculate the heat exchanger area if a 2-4 shell and tube heat exchanger is used. by

Steam at 140 ° C flows in a pipe having an inner radius of 50 mm and an outer radius of 55 mm. The convective heat transfer coefficient between the steam and the inner pipe wall is 2500 W / (m² ° C). The outer surface of the pipe exposed to ambient air is 20 ° C with a convective heat transfer coefficient of 10 W / (m² ° C). Assuming steady state, calculate the rate of heat transfer per meter of pipe from steam to air. Assume that the thermal conductivity of stainless steel is 15 W / (m ° C.). Steps of work according to example 4.16 Singh. a. Find the overall heat transfer coefficient = Answer W / m² ° C. b. Heat transfer rate per meter of pipe = Answer W / m.

In a heat exchanger, the heat transfer depends on the choice of the control volume

3.36 Both C's in a parallel-flow heat exchanger are equal to 156 W/K, U 327 W/m²K and A = 2 m². The hot fluid enters at 140°C and leaves at 90°C. The cold fluid enters at 40°C. If both C's are halved, what will be the exit temperature of the hot fluid?