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ME 414 Design Project

ME 414 Design Project. Heat Exchanger Design. Created and Designed by: Michael Stark Joshua Keith Billy Burdette Brandon Mullen Joseph Listerman. Project Goals. Design Heat Exchanger Create a light weight heat exchanger Heat exchange must be as efficient as possible

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ME 414 Design Project

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  1. ME 414 Design Project Heat Exchanger Design Created and Designed by: Michael Stark Joshua Keith Billy Burdette Brandon Mullen Joseph Listerman

  2. Project Goals • Design Heat Exchanger • Create a light weight heat exchanger • Heat exchange must be as efficient as possible • Cost must be kept low as possible • The size of the heat exchanger must be under design constraint

  3. Project Guidelines • During the process of a liquid chemical product, its temperature needs to be reduced by 20 degrees Celsius. • Mass flow rate is 220,000 kg/hr • Fluid enters the heat exchanger at 45 C and should leave at 25 C • Material properties of this chemical product can be approximated as water • Cooling of the chemical product will be achieved by using treated city water • City water is available at 20 C • Mass flow rate is adjustable and one of the design parameters to be selected • Exit temperature of city water from the heat exchanger is a function of the selected mass flow rate Professor Toksoy

  4. Project Optimization • Must cool the chemical from 45 C to 25 C • Heat exchanger length can not exceed 7 meters • Heat exchanger shell diameter can not exceed 2 meters • Minimize heat exchanger shell and tube weight hence the cost • Minimize heat exchanger pressure drop Professor Toksoy

  5. Heat Exchanger Design Inputs for MATLAB • Chemical to be cooled was set as Shell side liquid • Mass flow rate of cooling water = 220 kg/sec • Shell ID = .889 m • Shell thickness = 5 mm • Tube OD = 6.35 mm • Tube thickness = .457 mm • Tube Length = 2.88 m • Baffle space = .6 m • Helical Baffles • Counter flow • One shell pass and one tube pass • Aluminum was used for both shell and tube materials • Gnielinski equation used for tube side Nusselt correlation • Square tube pitch

  6. Nusselt Correlation

  7. D.O.E. Run 1

  8. D.O.E. Run 2

  9. Final D.O.E.

  10. Factorial Design Analysis – Heat Rate • Tube length has the largest affect on the heat rate. • Shell ID has the smallest relative affect on heat rate. • Shell ID had a negative affect on heat rate. • This was a result of more tubes decreasing the velocity in the tube. • The result is laminar flow inside the tube.

  11. Factorial Design Analysis - ∆P Tube • We can see that tube length has the largest affect on tube side pressure drop. • Shell ID has no affect on tube pressure drop. • We expected tube OD to have a larger affect on tube side pressure drop.

  12. Factorial Design Analysis - ∆P Shell • Shell ID had the largest affect on shell side pressure drop. • The affect of tube OD on the pressure drop was surprising. • We attribute this affect to the 60° triangular pitch tube arrangement. • As tube OD grows larger there is more pressure drop in the shell.

  13. Factorial Design Analysis – HE Weight • The shell inside diameter has the largest affect on weight. • The larger the shell diameter the more tubes we could fit inside, thus increasing weight. • Because tube length determines the length of the heat exchanger, it too has a large affect on heat exchanger weight.

  14. Design Optimization - 1 • The design optimized to our original design. • We expected our final tube diameter to be 6.35 mm with a mass flow rate of 220 kg/s. • Optimal Tube OD was 8.3mm • The tube length was longer than our original design called for, which was a result of maximizing the q calculated. • We set target values for the shell and tube side pressure drops. • We set a target range for total weight between 900-1100 kg.

  15. Design Optimization - 2 • The design optimized to our original design. • We expected our final tube diameter to be 6.35 mm with a mass flow rate of 220 kg/s. • Optimal Tube OD was 8.3mm, adjusted it to 9.525 mm to coincide with standard tube dimensions. • The tube length was longer than our original design called for, which was a result of maximizing the q calculated. • We set target values for the shell and tube side pressure drops. • We set a target range for total weight between 900-1100 kg.

  16. Heat Exchanger Design Output from MATLAB

  17. Matlab Program Improvements • Create program checks in order to eliminate unrealistic designs. • If multiple tube passes are used with parallel flow it is possible to calculate a LMTD_CF that is an imaginary number. • Provide the operator more detailed information regarding the Nusselt correlations.

  18. Cost Summary • Heat Exchanger Dry Weight • 730 Kg • Heat Exchanger & Fluid Weight • 2287 Kg • Cost • OnlineMetals.com • $37.00 per 8ft length of aluminum tubing • Total estimated aluminum tubing cost $337,000.00 • $11.00 per 8ft length of mild steel tubing • Total estimated mild steel tubing cost $100,000.00 • Instillation and Manufacturing

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