Heat Exchanger Design ME 414- FLUID SYSTEMS DESIGN PROFESSOR: JOHN TOKSOY SPRING 2009 TEAM Tyler Laughlin • Denis Shkurapet • Ethan Sneed • Matt Tolentino • Tyler Turk • Objective To design a heat exchanger than meets the following criteria: Cools liquid from 45 C to 25 C Must be less than 7 meters in length Shell diameter is less than 2 meters Minimize weight of the tube and shell Minimize pressure drop Heat transfer ratio of 1 Design Parameters # of tubes passed Tube outer diameter Tube inner diameter Material Baffles Shell thickness Shell Material Strength factors Fluid allocation Type of flow (parallel or counter) Analysis Use Minitab and Matlab Minitab Use to obtain the main effects plots, Pareto charts, and the response optimizer. Matlab Use to run analysis of the DOE files and to give us the outputs of total weight, calculated heat transfer, cost, and pressure drops. DOE allows us to determine the most important variables in this design. Results Variable Initial value Final Value Explanations Shell fluid Water Water Tube fluid Chemical (water prop) Chemical (water prop) M-dot shell 3.45 kg/s 3.9117 kg/s Mdot tube 61.11 kg/s 61.11 kg/s T shell in 20°C 20°C Given Input T tube in 45°C 45°C Given Input T tube out 25°C 25°C Given Input Rf tube in .00018 m²K/W .00018 m²K/W Reference value for water Rf tube shell side .00018 m²K/W .00018 m²K/W Flow config Parallel Parallel # tube pass 1 1 Reference value for water DOE - Optimizer suggested using parallel The program only allows one pass # shell pass 1 1 For minimal weight Given Input Given Input DOE - Optimizer suggested value Given value -tube selected for cleaning Results Baffles No baffles No baffles Shell ID 0.3366 0.3366 Shell Th 1.00E-03 1.00E-03 Shell Mat'l Stainless Steel 304 Stainless Steel 304 Tube Mat'l Stainless Steel 304 Stainless Steel 304 Nusselt Shell Dittus Boelter Dittus Boelter Nusselt Tube Gnielinski Gnielinski Pressure Corr Shell Default from textbook Default from textbook Pressure Corr Tube Default from textbook Default from textbook Tube OD 6.35e-3 m 6.35E-03 Tube Th .711e-3 m 4.57E-04 2.00 1.85 90 90 Tube Length Tube Layout Angle To reduce weight/pressure drop DOE - Optimizer suggested no change DOE - Optimizer suggested no change Corrosion Resistant/ease of cleaning Corrosion Resistant/ease of cleaning Most basic correlation accounts for entrance effects Only option that was applicable Only option that was applicable DOE - Optimizer suggested no change DOE- Optimizer suggested value DOE- Optimizer suggested value DOE - Optimizer suggested no change Results Outputs Initial value Final Value Difference Units T shell out 353.59°C 318.76°C 34.83 °C # of tubes U (Heat Transfer Coeff.) 1313 1313 0 828.48 W/m2.C 876.97 W/m2.C -48.49 R value 1.00 0.98 0.02 Weight_He 411.21 350.88 kg 60.33 kg DP Shell 267.89 Pa 335.11 Pa -82.99 Pa DP Tube 45310.96 Pa 29832.58 Pa 15478.38 Pa W/m2.C Analysis: 1st DOE ME 414 Main Effects Plot: DP Tube ME 414 Main Effects Plot: Weight_HE F low M dot F low Tube Length M dot Tube Length 1000000 700 500000 500 0 300 P arallel C ounter 2.5875 Tube th 4.3125 1.5 S hew ll ID C ounter 2.5875 Tube th S hell Th 4.3125 1.5 2.5 S hew ll ID S hell Th 1000000 Mean 700 Mean P arallel 2.5 500 500000 0 300 0.000533 0.001250 0.25245 0.42075 0.0007500 0.000533 0.0012875 700 1000000 500 500000 300 0.00476 0.001250 0.42075 0.0007500 0.0012875 0 0.00793 0.00476 0.00793 ME 414 Main Effects Plot: DP Shell F low 1000 0.25245 Tube O D Tube O D ME 414 Main Effects Plot: Q Calc M dot Tube Length F low 10000000 M dot Tube Length 7500000 500 5000000 0 P arallel 2.5875 4.3125 1.5 S hew ll ID 2.5 P arallel C ounter S hell Th 500 2.5875 Tube th 10000000 Mean Mean C ounter Tube th 1000 4.3125 1.5 S hew ll ID 2.5 S hell Th 7500000 5000000 0 0.000533 0.001250 0.25245 0.42075 0.0007500 0.0012875 0.000533 Tube O D 1000 0.001250 Tube O D 10000000 7500000 500 5000000 0 0.00476 0.00793 0.00476 0.00793 0.25245 0.42075 0.0007500 0.0012875 Analysis: Pareto Charts 1st DOE Pareto Chart of the Standardized Effects Pareto Chart of the Standardized Effects (response is Weight, Alpha = 0.05) (response is DP Shell, Alpha = 0.05) 2 2.0 F actor A B C D A B B A AC AB Term Term C N ame F low M dot Tube Length Tube th D AB AD F actor A B C N ame F low M dot Tube Length F actor B C N ame M dot T ube Length C BC BD AC ABD 0 200000 400000 600000 800000 1000000 Standardized Effect 1200000 0 1400000 1600000 50 Pareto Chart of the Standardized Effects 100 Standardized Effect 150 200 Pareto Chart of the Standardized Effects (response is DP Tube, Alpha = 0.05) (response is Q Calc, Alpha = 0.05) 1.98 1.98 C Term Term Tube Length B Flow BC 0 2 4 6 8 Standardized Effect 10 12 14 0 10 20 30 40 Standardized Effect 50 60 Analysis: 1st Optimization Minitab solved for a local solution. The starting values were changed multiple times until Minitab found a new, more optimal solution. Analysis: 2nd DOE ME 414 Main Effects Plot Optimization 2: Q Calc F low M dot ME 414 Main Effects Plot Optimization 2: DP Tube Tube Length F low 10000000 150000 7500000 100000 P arallel C ounter Tube Thick 2.5875 4.3125 1.5 2.5 S hell ID P arallel S hell Thick C ounter 2.5875 4.3125 Tube Thick 1.5 2.5 S hell ID S hell Thick 150000 10000000 Mean Mean Tube Length 50000 5000000 7500000 5000000 0.0003430 0.0005713 Tube O D 0.25245 0.42075 0.0007500 100000 50000 0.0012875 0.0003430 10000000 7500000 100000 5000000 50000 0.00793 0.00476 ME 414 Main Effects Plot Optimization 2: DP Shell F low 1000 0.0005713 0.25245 0.42075 0.0007500 0.0012875 Tube O D 150000 0.00476 M dot 0.00793 ME 414 Main Effects Plot: Weight_HE F low Tube Length M dot Tube Length 700 500 500 300 0 P arallel C ounter 2.5875 Tube Thick 1000 4.3125 S hell ID 1.5 P arallel 2.5 C ounter 2.5875 Tube th S hell Thick 4.3125 1.5 S hew ll ID 2.5 S hell Th 700 Mean Mean M dot 500 500 300 0 0.0003430 0.0005713 0.25245 0.42075 0.0007500 0.0012875 0.000533 0.001250 Tube O D Tube O D 1000 700 500 500 300 0 0.00476 0.00793 0.00476 0.00793 0.25245 0.42075 0.0007500 0.0012875 Analysis: 2nd Optimization Starting values of the optimization were varied with no improvement in performance. Conclusions: Damn near perfect! Heat Transfer Coeff : R-value: Number of tubes: Shell Pressure Loss: Tube Pressure Loss: Weight of Heat Exchanger: 876.97 W/m2.C 0.98 1313 335.11 Pa 29832.58 Pa 350.88 kg Conclusions: Recommendations Could be further optimized if Tube Thickness was decreased Resulting in: Lower weight - decrease of 51.93 kg Lower Tube pressure loss - decrease of 6703.1 Pa No significant loss of R-value A smaller tube is not commercially available Possibly achieve greater performance at a greater price Questions