1. ME421 Heat Exchanger Design
Drain Water Heat Recovery System
Project Presentation

2. OUTLINE Problem Definition Available Solutions Application Data
Solution Procedure
Results and Discussions
Conclusion

3. Heat wasted during shower
PROBLEM DEFINITION
Heat wasted during shower

4. AVAILABLE SOLUTIONS
Gravity Film Heat Exchanger

5. APPLICATION DATA Parameter Magnitude Unit (SI) Hot Inlet Temperature37 °C
Hot Outlet Temperature 23
Cold Inlet Temperature 11
Cold Outlet Temperature 25
Cold Water Mass Flow Rate
0.2
kg/s
Hot Water Mass Flow Rate
Hot Side Fouling Factor
m.K/W
Cold Side Fouling Factor

6. SOLUTION PROCEDURE Initial Assumptions:
Steady state and steady flow processes
Plate dimensions based on MIT 522 [1]
Negligible potential and kinetic energy change
Equal inlet & outlet mass flow rates
Single pass counter flow arrangement
Safety factor

7. SOLUTION PROCEDURE (Cont’d)
Iteration method to find Nt
U Ae Nt G Re Nu h U
Rechecking of Nt using calculated U
Pressure drop and pump power calculations
Comparison of ΔPallowable and ΔPcalculated

8. RESULTS and DISCUSSIONS
Cleaned and Fouled Heat Transfer Rates
Chevron Angle ranging between 30° - 70°

9. RESULTS and DISCUSSIONS (Cont’d)
Parameter
Magnitude
Number of Plates 7
Effective Heat Transfer Area
1.463 m2
Fouled Heat Transfer Coefficient
933 W/m2.K
Required Pump Work
24.5 W
Heat Transfer Rate
1.17x104 W
Net Heat Recovery

10. WELL DONE