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Effectiveness E, % 100 80 60 40 20 0.5 kg/s 90 deg C cô Cinemax. 0.25 Tube fluid 0.50 0.75 1.00 Shell fluid 10 deg C 1 kg/s 1 2 3 4 5 Number of transfer units NTU=A,U/C min Effectiveness , % 100 80 60 20 20.50 0.25 15 deg C Cmax Cmin 0.75 1.00 Tube fluid Shell fluid 1 1 2 3 4 5 Number of transfer units NTU=A,U/C min
Effectiveness E, % 100 80 60 40 20 n/max =0 Tube fluid 10 0.25- 0.50 0.75 1.00 Effectiveness , % 100 80 60 40 20 I 50 0.25 min/max 0.75 Shell fluid Shell fluid 1 2 3 4 5 1 2 3 4 5 Number of transfer units NTU=AU/C min Number of transfer units NTU=A,U/C min [20] a) Calculate the effectiveness of the parallel flow double pipe heat exchanger shown above. (Water thermal properties could be assumed as constant.) [20] b) What would have been the outlet temperatures of the cold and hot water streams if the exchanger would be twice as long? [20] c) Would you be able to increase the heat transfer rate between the fluids if you would reverse the cold water flow direction on the outer tube ? If yes, please quantify the heat transfer rate rise. If not, briefly explain your reasoning. 0 Tube fluid 41