Heat Exchanger Design

Reduce Monthly Natural Gas Consumption HVACDepartment of Mechanical Engineering, IUPUIME 414 Thermal-Fluid Systems DesignFall 2010, Professor John Toksoy

Mohammad Shams, Seyed Alireza Tabatabaei, Roozbeh Hojatpanah, Siavash Farahmand, Shahriar Ahmadi GhoohakiY StatementReduce monthly natural gas consumption by 20% for the months of Dec thru MarSet back temperatureInsulation improvements

The Funneling EffectCritical Input Variables30+ Inputs8 - 104 - 83 - 6Found Critical XsControlling Critical Xs10 - 15All Xs1st Hit ListScreened ListMEASUREANALYZEIMPROVECONTROLProcess MapsFailure Modes and Effects AnalysisMulti-Vari StudiesDesign of Experiments (DOE)Control PlansC&E MatrixDoes the Setup Measure Energy Consumption AccuratelyFor each of the 24 hr data setCalculate the heater on timeCalculate heating degree daysPlot HDD vs. heater on timeDoes it show a linear behavior

AnalysisHeater on Time vs HDD

AnalysisHeater on Time vs HDD

AnalysisHeater on Time vs HDD

AnalysisError Percent of Heater on Time vs HDD

Therms Analysis

Measurement ErrorError due to long signal wiresFilter designImpact on mean value

Initial CapabilityInitial capabilityWhat is the current energy usage as baseline where savings will be calculated fromDegree day comparisonPast 5 to 10 years gas and electric bills (kWhr used not $$$)Calculate heat loss from the house using the excel analysis toolMake the tool more general to include individual roomsRun transient heat transfer analysis using the Matlab tool and compare to measured data

Energy Cost Estimation

ResultsThe cost for one day at these temperatures is: $0.33The optimal day time temperature is: 51 Degrees FThe total running time per day is: 97 Minutes

Jan 22ndResults

The cost for one day at these temperatures is: $0.13The optimal day time temperature is: 59 Degrees FThe total running time per day is: 38 MinutesJan 28th

ResultsThe cost for one day at these temperatures is: $0.18The optimal day time temperature is: 47 Degrees FThe total running time per day is: 53 MinutesJan 29th

Results

The cost for one day at these temperatures is: $0.24The optimal day time temperature is: 48 Degrees FThe total running time per day is: 71 MinutesFeb 3rdResultsThe cost for one day at these temperatures is: $0.28The optimal day time temperature is: 50 Degrees FThe total running time per day is: 83 Minutes

Feb 4thResultsThe cost for one day at these temperatures is: $0.27The optimal day time temperature is: 50 Degrees FThe total running time per day is: 79 Minutes

Feb 5th

ResultsThe cost for one day at these temperatures is: $0.22The optimal day time temperature is: 49 Degrees FThe total running time per day is: 64 Minutes

Feb 6thHeat Exchanger DesignDepartment of Mechanical Engineering, IUPUIME 414 Thermal-Fluid Systems DesignFall 2010, Professor John ToksoyMohammad Shams, Seyed Alireza Tabatabaei, Roozbeh Hojatpanah, Siavash Farahmand, Shahriar Ahmadi GhoohakiDesign ParametersProcess FluidWaterInlet 45COutlet 25CCity WaterInlet 20COptimal Length Less Than 7 metersEffective VariablesEffective VariablesTube ThicknessShell ThicknessShell MaterialM-dot TubeM-dot TubeShell I/DShell I/DTube LengthTube LengthCounter / ParallelTube O/DTube O/DTube MaterialDue to previous iterations these nine were the variables that had the greatest effect on Weight, Length, Q, and PsGenerated Matlab File

Initial Inputs Generating

Plots of Main Effect

Pareto Charts for OptimizationShell side pressure drop- Shell I/D had the greatest effectHeat Exchanger overall weight- Shell I/D and Tube LengthTube pressure drop- Mass flow rate through the tubes, Shell I/D and Tube Length

Shell side pressure drop- Shell I/D had the greatest effectHeat Exchanger overall weight- Shell I/D and Tube LengthTube pressure drop- Mass flow rate through the tubes, Shell I/D and Tube Length

Pareto Charts for Optimization

Optimization Plot

Optimization ResultsTube Side Heat Transfer ParametersNumber of Tubes, N4169Number of Passes1Tubes OD0.0063 mTubes ID0.0054 mTube Length, L4.4000 mTube Pitch, PT0.0079 mHeat Transfer Coefficient, h4158.44 W/m2.C Shell Side Heat Transfer ParametersShell ID0.5398 mShell Cross Sectional Area0.2289 m2Shell Flow Area0.1059 m2Shell Equivalent Diameter0.0046 mMass Velocity, G1028.84 kg/m2.s Heat Transfer Coefficient, h4419.42 W/m2.COverall Heat Transfer CoefficientU (Tube outside Area)1739.11 W/m2.CHeat Transfer RateDesired Heat Transfer Rate5106273.07 WCalculated Heat Transfer Rate5133356.91 WDifference-27083.84 WDesired - To - Calculated Ratio 0.99 HE Pressure DropShell Side P85606.84 Pa Tube Side P8115.88 Pa Heat Exchanger WeightTotal Weight1362.78 kgAdjusted Optimized ResultsTube Side Heat Transfer ParametersNumber of Tubes, N3881Number of Passes1Tubes OD0.0062 mTubes ID0.0053 mTube Length, L4.2759 mTube Pitch, PT0.0077 mHeat Transfer Coefficient, h4087.62 W/m2*CShell Side Heat Transfer ParametersShell ID0.5462 mShell Cross Sectional Area0.2343 m2Shell Flow Area0.1084 m2Shell Equivalent Diameter0.0045 mMass Velocity, G1006.65 kg/m2*sHeat Transfer Coefficient, h4383.64 W/m2*COverall Heat Transfer CoefficientU (Tube outside Area)1715.16 W/m2*CHeat Transfer RateDesired Heat Transfer Rate5106273.07 WCalculated Heat Transfer Rate5163877.58 WDifference-57604.51 WDesired - To - Calculated Ratio0.99HE Pressure DropShell Side P85674.36 PaTube Side P7956.80 PaHeat Exchanger WeightTotal Weight1360.46 kgQuestions?