11

ME421 Heat Exchanger ME421 Heat Exchanger DesignDesign

Drain Water Heat Recovery Drain Water Heat Recovery SystemSystem

Project PresentationProject Presentation

Group #5Group #5

22

OUTLINEOUTLINE

Problem DefinitionProblem Definition Available SolutionsAvailable Solutions Proposed SolutionProposed Solution Application DataApplication Data Solution ProcedureSolution Procedure Results and DiscussionsResults and Discussions ConclusionConclusion

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PROBLEM DEFINITIONPROBLEM DEFINITION

Heat wasted during showerHeat wasted during shower

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AVAILABLE SOLUTIONSAVAILABLE SOLUTIONS

Gravity Film Heat Exchanger(GFX)Gravity Film Heat Exchanger(GFX)

55

PROPOSED SOLUTIONPROPOSED SOLUTION

Gasketed Plate Heat Exchanger:Gasketed Plate Heat Exchanger: High Area/Volume RatioHigh Area/Volume Ratio Low Cost compared to GFXLow Cost compared to GFX Easy to cleanEasy to clean Flexible DesignFlexible Design

66

APPLICATION DATAAPPLICATION DATAParameterParameter MagnitudeMagnitude Unit (SI)Unit (SI)

Hot Inlet Temperature Hot Inlet Temperature 3737 °C°C

Hot Outlet TemperatureHot Outlet Temperature 2323 °C°C

Cold Inlet TemperatureCold Inlet Temperature 1111 °C°C

Cold Outlet TemperatureCold Outlet Temperature 2525 °C°C

Cold Water Mass Flow RateCold Water Mass Flow Rate 0.20.2 kg/skg/s

Hot Water Mass Flow RateHot Water Mass Flow Rate 0.20.2 kg/skg/s

Hot Side Fouling FactorHot Side Fouling Factor 0.000050.00005 m.K/Wm.K/W

Cold Side Fouling FactorCold Side Fouling Factor 0.00000860.0000086 m.K/Wm.K/W

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SOLUTION PROCEDURESOLUTION PROCEDURE

Initial Assumptions:Initial Assumptions:

Steady state and steady flow processesSteady state and steady flow processes Plate dimensions based on MIT 522 Plate dimensions based on MIT 522

[1] [1]

LLvv, L, Lhh, b, t, D, b, t, Dpp, , ββ, , ΦΦ

Negligible potential and kinetic energy changeNegligible potential and kinetic energy change Equal inlet & outlet mass flow ratesEqual inlet & outlet mass flow rates Single pass counter flow arrangementSingle pass counter flow arrangement Safety factorSafety factor

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SOLUTION PROCEDURE SOLUTION PROCEDURE (Cont’d)(Cont’d)

Procedure:Procedure: Iteration method to find NIteration method to find Ntt

U AU Aee N Ntt G Re Nu h U G Re Nu h U Rechecking of NRechecking of Ntt using calculated U using calculated U Pressure drop and pump power calculationsPressure drop and pump power calculations Comparison of Comparison of ΔΔPPlimitlimit and and ΔΔPPcalculatedcalculated

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RESULTS and DISCUSSIONSRESULTS 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

4

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

1010

RESULTS and DISCUSSIONS RESULTS and DISCUSSIONS (Cont’d)(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)

1111

RESULTS and DISCUSSIONS RESULTS and DISCUSSIONS (Cont’d)(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)

Pump Power vs Number of Plates (Nt)

Pum

p P

ower

(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

1212

RESULTS and DISCUSSIONS RESULTS and DISCUSSIONS (Cont’d)(Cont’d)

β values : 30 ° ,45 ° ,50 ° ,60 ° ,65°

Pre

ssu

re D

rop (

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

1313

RESULTS and DISCUSSIONS RESULTS and DISCUSSIONS (Cont’d)(Cont’d)

ParameterParameter MagnitudeMagnitude

Number of PlatesNumber of Plates 77

Effective Heat Transfer AreaEffective Heat Transfer Area 1.463 m1.463 m22

Fouled Heat Transfer CoefficientFouled Heat Transfer Coefficient 933 W/m933 W/m22.K.K

Required Pump WorkRequired Pump Work 24.5 W24.5 W

Heat Transfer RateHeat Transfer Rate 1.171.17xx101044 W W

Net Heat RecoveryNet Heat Recovery 1.171.17xx101044 W W

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CONCLUSIONCONCLUSION

Preheated Preheated ..