Post on 04-Jan-2016
description
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ME421 Heat Exchanger Design
Drain Water Heat Recovery System
Project Presentation
Group #5
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OUTLINE
Problem Definition Available Solutions Proposed Solution Application Data Solution Procedure Results and Discussions Conclusion
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PROBLEM DEFINITION
Heat wasted during shower
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AVAILABLE SOLUTIONS
Gravity Film Heat Exchanger(GFX)
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PROPOSED SOLUTION
Gasketed Plate Heat Exchanger: High Area/Volume Ratio Low Cost compared to GFX Easy to clean Flexible Design
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APPLICATION DATAParameter Magnitude Unit (SI)
Hot Inlet Temperature 37 °C
Hot Outlet Temperature 23 °C
Cold Inlet Temperature 11 °C
Cold Outlet Temperature 25 °C
Cold Water Mass Flow Rate 0.2 kg/s
Hot Water Mass Flow Rate 0.2 kg/s
Hot Side Fouling Factor 0.00005 m.K/W
Cold Side Fouling Factor 0.0000086 m.K/W
Maximum Allowable Pressure Drop 16 bar
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SOLUTION PROCEDURE
Initial Assumptions:
Steady state and steady flow processes Negligible potential and kinetic energy change Equal inlet & outlet mass flow rates Single pass counter flow arrangement Safety factor Plate dimensions based on MIT 522 [1] Lv, Lh, b, t, Dp, β, Φ
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SOLUTION PROCEDURE (Cont’d)
Procedure:
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 ΔPlimit and Δpcalculated
Pump power calculations
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RESULTS and DISCUSSIONS
Nt ranging between 3 and 11
Pre
ssur
e D
rop
(Pa)
Pressure Drop vs Number of Plates (Nt)
2 3 4 5 6 7 8 9 10 11 127.2 10
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7.3 104
7.4 104
7.5 104
7.6 104
7.7 104
7.8 104
7.9 104
8 104
p t.c
p t.h
Nt
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RESULTS and DISCUSSIONS (Cont’d)
20 27.5 35 42.5 50 57.5 65 72.5 806 10
3
7.75 103
9.5 103
1.125 104
1.3 104
1.475 104
1.65 104
1.825 104
2 104
Qc W( )
Qf W( )
β values : 30 ° ,45 ° ,50 ° ,60 ° ,65°
Hea
t R
ecov
ery
(W)
Heat Recovery vs Chevron Angle (β)
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RESULTS and DISCUSSIONS (Cont’d)Pum
p P
ow
er
(W)
Nt ranging between 3 and 11
Pump Power vs Number of Plates (Nt)
Pum
p P
ow
er
(W)
2 3 4 5 6 7 8 9 10 11 1224.5
24.833
25.167
25.5
25.833
26.167
26.5
Wp
Nt
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RESULTS and DISCUSSIONS (Cont’d)
β values : 30 ° ,45 ° ,50 ° ,60 ° ,65°
Pre
ssure
Dro
p (
Pa)
Pressure Drop vs Chevron Angle (β)
20 30 40 50 607.3 10
4
7.35 104
7.4 104
7.45 104
7.5 104
p t.c
p t.h
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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 1.17x104 W
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CONCLUSION
Preheated .