Shell and Tube Heat Exchanger

1. Shell and Tube Heat Exchanger Frank Faulkenberg Jimmy Huser John Snodgrass Eric Bush David Giles ME 414: Thermal Fluids

2. Design a heat exchanger to meet the customer requirements for heat transfer and maximum dimensions, while optimizing the weight and pressure losses in both the tube and shell sides. Problem Statement

3. Project Definition • Chemical Specifications: • Temperature must be reduced from 40°C to 25°C • Mass flow rate is 120,000 kg/hr • Material properties closely approximate that of water • Cooling Water Specifications: • Treated city water at 20°C • Mass flow rate is not fixed • Exit temperature is function of design

4. Customer Requirements • Must cool the chemical from 40 C to 25 C • Heat exchanger length can not exceed 7m • Heat exchanger shell diameter can not exceed 2m • Minimize heat exchanger shell and tube weight hence the cost • Minimize heat exchanger pressure drop

5. Matlab Used to run code that takes the input variables that affect exchanger performance and returns numerical values for the performance of the exchanger Minitab Used to statistically analyze the results from Matlab to narrow down the input variables to those that have the greatest affect of exchanger performance. Analysis

6. First Trial • Total heat exchanger weight = 4384.68 kg • Desired Heat Transfer Rate = 2088969 W • Calculated Heat Transfer Rate = 2084742 W • Difference = 4227.48 W • Desired-to-Calculated Ratio = 1.00 • Shell Side Delta-P = 9875.34 Pa • Tube Side Delta-P = 134.48 Pa

7. Analyzing data • Good • Light in weight • Good pressure drops • Achieved desired-to-calculated ratio

8. Analyzing data • Bad • Further inspection shows that this design is impossible. • Shell side outlet cannot be greater than the tube side outlet for a parallel heat exchanger. • For parallel flow, a shell mass flow rate of ~400000 kg/hr must be used to satisfy this condition

10. Second Trial • Parallel flow • No baffles • About 4 meters in length

11. Analyzing Data Good: • Yielded very low weight • Very low pressure drops • Desired heat transfer Bad: • Impossible design in reality • Structurally unsound, tubes would sag

12. Critical Parameter Flow Down • 14 parameters • 7 factor DOE • 4 factor DOE

13. Tube length Tube diameter (OD) Shell diameter (ID) Mass Flow Rate of cooling water Pipe layout Baffle Spacing Shell material Tube material Shell thickness Tube thickness Flow configuration (counter, parallel) Pipe layout angle Number of Tubes Tube Pitch Initial Parameters

14. Tube length Tube diameter (OD) Shell diameter (ID) Mass Flow Rate of cooling water Pipe layout Baffle Spacing Shell material 1st DOE

15. 7 factor MEPs

16. Tube length Tube diameter (OD) Shell diameter (ID) Mass Flow Rate of cooling water 2nd DOE

17. 4 factor MEPs

18. 4 factor MEPs

19. 4 factor MEPs

20. 4 factor MEPs

21. 4-factor Interaction Plots

22. Pareto Charts

23. Final Design

24. Expected Performance • Total heat exchanger weight 4868 kg • Desired Heat Transfer Rate 2088969 W • Calculated Heat Transfer Rate 2095309 W • Difference -6340 W • Desired-to-Calculated Ratio 1.00 • Shell Side Delta-P 9228 Pa • Tube Side Delta-P 556 Pa

25. References [1] Jones, Luke. “Minitab tutorial.” [2] Toksoy, John. “Heat Exchanger Project – fall 2006.” [3] Toksoy, John. “TFD-HE4 Log Mean Temperature Difference.” fall 2006