ME 414- FLUID SYSTEMS DESIGN PROFESSOR: JOHN TOKSOY SPRING 2009 TEAM Tyler Laughlin Denis Shkurapet Ethan Sneed Matt Tolentino Tyler Turk Heat Exchanger Design

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 VariableInitial valueFinal ValueExplanations Shell fluidWater Given Input Tube fluidChemical (water prop) Given Input M-dot shell3.45 kg/s kg/s DOE - Optimizer suggested value Mdot tube61.11 kg/s Given value -tube selected for cleaning T shell in20°C Given Input T tube in45°C Given Input T tube out25°C Given Input Rf tube in m²K/W Reference value for water Rf tube shell side m²K/W Reference value for water Flow configParallel DOE - Optimizer suggested using parallel # tube pass11 The program only allows one pass # shell pass11For minimal weight

Results BafflesNo baffles To reduce weight/pressure drop Shell ID DOE - Optimizer suggested no change Shell Th1.00E-03 DOE - Optimizer suggested no change Shell Mat'lStainless Steel 304 Corrosion Resistant/ease of cleaning Tube Mat'lStainless Steel 304 Corrosion Resistant/ease of cleaning Nusselt ShellDittus Boelter Most basic correlation Nusselt TubeGnielinski accounts for entrance effects Pressure Corr ShellDefault from textbook Only option that was applicable Pressure Corr TubeDefault from textbook Only option that was applicable Tube OD6.35e-3 m6.35E-03 DOE - Optimizer suggested no change Tube Th.711e-3 m4.57E-04 DOE- Optimizer suggested value Tube Length DOE- Optimizer suggested value Tube Layout Angle90 DOE - Optimizer suggested no change

Results OutputsInitial valueFinal ValueDifferenceUnits T shell out353.59°C318.76°C34.83°C # of tubes U (Heat Transfer Coeff.) W/m2.C W/m2.C-48.49W/m2.C R value Weight_He kg60.33kg DP Shell Pa Pa-82.99Pa DP Tube Pa Pa Pa

Analysis: 1 st DOE

Analysis: Pareto Charts 1 st DOE 7 Factor Analysis for DP_Tube

Analysis: 1 st Optimization Minitab solved for a local solution.The starting values were changed multiple times until Minitab found a new, more optimal solution.

Analysis: 2 nd DOE

Analysis: 2 nd Optimization Starting values of the optimization were varied with no improvement in performance.

Conclusions: Damn near perfect! Heat Transfer Coeff : W/m2.C R-value:0.98 Number of tubes:1313 Shell Pressure Loss: Pa Tube Pressure Loss: Pa Weight of Heat Exchanger: kg

Conclusions: Recommendations Could be further optimized if Tube Thickness was decreased Resulting in:  Lower weight - decrease of kg  Lower Tube pressure loss - decrease of Pa  No significant loss of R-value A smaller tube is not commercially available Possibly achieve greater performance at a greater price

Questions