A counterflow, double-pipe heat exchanger is designed to heat a cold-water flow from 20C to 80C by a hot-oil flow. The cold water has a mass flow rate of 0.80 kg/s, and the hot oil with a temperature of 150C enters into the heat exchanger at a mass flow rate of 1.2 kg/s. The overall heat transfer coefficient (U) of the heat exchanger is 500 W/m-K. Assume Cpwater = 4.2 kJ/kg-K and Cp,oil = 2.1 kJ/kg-K. Please determine the inner surface area for heat transfer in the double pipe to achieve the designed performance. 100 100 Effectiveness & % 80 60 40 20 0 lema min max Tube fluid 0 0.25 0.50 0.75 1.00 + Shell fluid 1 3 4 5 2 Number of transfer units NTU = A,UIC min Effectiveness &.% 80 60 40 20 0 0 50 0.25 0.75 1.00 Tube fluid Shell fluid 1 2 3 5 Number of transfer units NTU = AUCmin A counterflow, double-pipe heat exchanger is designed to heat a cold-water flow from 20C to 80C by a hot-oil flow. The cold water has a mass flow rate of 0.80 kg/s, and the hot oil with a temperature of 150C enters into the heat exchanger at a mass flow rate of 1.2 kg/s. The overall heat transfer coefficient (U) of the heat exchanger is 500 W/m-K. Assume Cpwater = 4.2 kJ/kg-K and Cp,oil = 2.1 kJ/kg-K. Please determine the inner surface area for heat transfer in the double pipe to achieve the designed performance. 100 100 Effectiveness & % 80 60 40 20 0 lema min max Tube fluid 0 0.25 0.50 0.75 1.00 + Shell fluid 1 3 4 5 2 Number of transfer units NTU A UIC min Effectiveness &.% 80 60 40 20 0 0 50 0.25 0.75 1.00 Tube fluid Shell fluid 1 2 3 5 Number of transfer units NTU = AUCmin