1. ME414 Spring 2006 Design Project 2 Heat Exchanger Ugo Anyoarah Osinanna Okonkwo Vinay Prisad Daniel Reed

2. Introduction Introduction Introduction Project Definition Project Definition –Design Optimization Goals First Design Pass First Design Pass Second Design Pass Second Design Pass Other Factors Other Factors Design Results Design Results

3. Project Definition During the make of a liquid chemical product, its temperature needs to be reduced by 10 degrees Celsius. During the make of a liquid chemical product, its temperature needs to be reduced by 10 degrees Celsius. –Mass flow rate is 80,000 kg/hr –Fluid enters the heat exchanger at 35 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 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

4. Design Optimization Goals Must cool the chemical from 35 C to 25 C Must cool the chemical from 35 C to 25 C Heat exchanger length can not exceed 7 m Heat exchanger length can not exceed 7 m Heat exchanger shell diameter can not exceed 2 m Heat exchanger shell diameter can not exceed 2 m Minimize heat exchanger shell and tube weight hence the cost Minimize heat exchanger shell and tube weight hence the cost Minimize heat exchanger pressure drop Minimize heat exchanger pressure drop

5. First Design Pass Matlab Variables Matlab Variables –4 variables Tube_OD(6.350 – 25.4)e-3 meters Tube_OD(6.350 – 25.4)e-3 meters Shell_ID(.8 – 2) meters Shell_ID(.8 – 2) meters Tube_Len(4 – 7) meters Tube_Len(4 – 7) meters N_tube(40 – 100) N_tube(40 – 100) –7 levels Gives 7^4 = 2401 runs Gives 7^4 = 2401 runs

6. First Design Pass Matlab Variables Matlab Variables –Tube and Shell Material set to Aluminum Consistent expansion between shell & tubes. Consistent expansion between shell & tubes. Maximum heat transfer Maximum heat transfer Corrosion Resistance (chemical similar to H 2 0) Corrosion Resistance (chemical similar to H 2 0) –Tube pass set to two (2) Most space efficient Most space efficient – –Baffle Space set to 0.1048 m – –Baffle Cut set to 0.3750 m –City water flow rate set to –City water flow rate set to 38.8889 Kg / Sec

7. First Design Pass Matlab Results Matlab Results –Weight: 2069.17 – 22415.9 –DP Shell: 335149 – 6364756 –DP Tube: 17701.66 – 4.26e11 –Q Calc: 107043.7 – 919867.5 2401 runs = AAARRRGGGHHH!!!!! 2401 runs = AAARRRGGGHHH!!!!!

8. First Design Pass - MiniTab Results

9. First Design Pass Findings Findings –MiniTab will not do Pareto charts for systems with more than 2 levels. –Higher levels ( >4) are beneficial for identifying linear regions and critical areas.

10. Second Design Pass Used Excel to find variable combinations with Qcalc/Qdes = 1 +/-10% Used Excel to find variable combinations with Qcalc/Qdes = 1 +/-10% 12 combinations met criteria 12 combinations met criteria Used the max and min in 2 nd iteration of Matlab (2 level) Used the max and min in 2 nd iteration of Matlab (2 level)

11. Second Design Pass Matlab Variables Matlab Variables –4 variables Tube_OD(9.535 – 25.4)e-3 meters Tube_OD(9.535 – 25.4)e-3 meters Shell_ID(.8 – 1) meters Shell_ID(.8 – 1) meters Tube_Len(6.5 – 7) meters Tube_Len(6.5 – 7) meters N_tube(90 – 100) N_tube(90 – 100) –2 levels Gives 2^4 = 16 runs Gives 2^4 = 16 runs

12. Second Design Pass Matlab Results Matlab Results –Weight: 3444 – 5773 –DP Shell: 122279 – 3933472 –DP Tube: 24799 – 41293392 –Q Calc: 844667 – 919867 16 runs = MMM! (Much more manageable) 16 runs = MMM! (Much more manageable)

13. Second Design Pass - MiniTab Results

14. Second Design Pass - Optimizer

16. Second Design Pass Check W/ Matlab Check W/ Matlab –Number of Tubes N = 100.00 –Number of Passes = 2.00 –Tubes OD OD = 0.0191 m –Tubes ID ID = 0.0135 m –Tube Length L = 6.7500 m –Tube Pitch PT = 0.0238 m –Shell ID = 0.9000 m –Baffle Space = 0.1048 m –Number of Baffles = 63.0000 m –Desired Heat Transfer Rate = 928501.84 W –Calculated Heat Transfer Rate = 843364.57 W – Difference = 85137.28 W –Desired-to-Calculated Ratio = 1.10 –Shell Side Delta-P = 1517783.93 Pa –Tube Side Delta-P = 138509.45 Pa –Total HE Weight = 4550.87 kg

17. Second Design Pass Fouling Factor Fouling Factor –Increased tube number to account for fouling –116 tubes required for Q/q=1 –135 tubes for Q/q=0.91 DP Shell: Unchanged DP Shell: Unchanged DP Tube: 79943.83 Pa DP Tube: 79943.83 Pa Weight: 4607.82 Kg Weight: 4607.82 Kg

18. Other Factors Full Factorial desirable Full Factorial desirable –City Water Flow Rate –Baffle Spacing –Baffle Cut Height –Tube Pitch –Tube Layout Angle –Yields 12 factors Even 2 levels is long: 4096 data points Even 2 levels is long: 4096 data points

19. Design Results Length: 6.5m Length: 6.5m Shell ID: 1m Shell ID: 1m Tube OD: 19.1mm Tube OD: 19.1mm Tube Length: 6.75m Tube Length: 6.75m Number of Tubes: 135 Number of Tubes: 135