SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 1 1.0INTRODUCTION The SOLTEQ HE104-PD Concentric Tube Heat Exchanger has been designed specifically todemonstratetheworkingprinciplesofindustrialheatexchangers.Theapparatus requires only a cold water supply, single phase electrical outlet and a bench top to enable a seriesofsimplemeasurementstobemadebystudents.Experimentscanbereadily conductedinashortperiodoftime,toaccuratelyshowthepracticalimportanceofthe following:- Temperature profiles Co- and counter-current flow Energy balances Log mean temperature difference Heat transfer coefficients The equipment consists of a concentric tube exchanger in the form of a 'U' mounted on a supportframe.Theexternalsurfaceoftheexchangerisinsulated.Threetemperature measuringdevicesareinstalledintheinsideandoutsidetubestomeasurethefluid temperatures accurately. To minimize losses in the system, the hot water is fed through the inner pipe, with the cooling water in the outer annulus. Controlvalvesareincorporatedineachofthetwostreamstoregulatetheflow.Theflow rates are measured using independent flowmeters installed in each line. Thehotwatersystemistotallyself-contained.Ahotstoragetankisequippedwithan immersiontypeheaterandanadjustabletemperaturecontrollerwhichcanmaintaina temperaturetowithinapproximately1C.Circulationtotheheatexchangerisprovided byapumpandhotwaterreturnstothestoragetanktobereheated.Thecoldwater required for the exchanger is taken from the laboratory mains supply. Areadilyidentifiablevalvearrangementallowssimplechangeoverbetweenco-and counter-current configurations. SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 2 2.0GENERAL DESCRIPTION (Refer to Figs. 1 and 2, pages 3 and 4). A supply of hot water at a temperature up to 65C is maintained in a storage tank (4) at the rearoftheapparatusbyanintegralheatingelement(3).Thetemperatureofthewaterin the tank is monitored by a sensor (25) adjacent to the integral heating element (3). Power to the heating element is regulated by a controller (12) connected to the sensor to maintain aconstanttemperature.Thecontrollerismountedonthefrontpanelwithalightemitting switch to show when power is being supplied to the heating element. The storage tank is fittedwithaloosecover(1)topreventingressofdustandreducelossofwaterthrough evaporation.Wateriscontinuouslyrecirculatedthroughthetankbyapump(7).The bypass valve (5) is set accordingly with the desired hot water flow rate to prolong the life of the pump. Hotwaterfortheexchangeristakenfromthepumpdischargeandpassesthroughthe1 mmthickofinnerpipewith13mmIDintheconcentrictubearrangement(14)before returning to the tank for reheating. Flow through this circuit is regulated by a control valve (22)andindicatedonaflowmeter(21).Temperaturesensors(18,20)areinstalledatthe inletandoutletoftheexchangerhotwatercircuittodisplaytherespectivewater temperatures.Atemperaturesensor(10)isinstalledinthetopbranchofthetubeto indicate the mid-point temperature in the hot water circuit. Cold water for the exchanger is supplied from an external source to the 1 mm thick of outer annulus with 20 mm ID in the concentric tube arrangement (14) via an inlet (23) and valve arrangement(19).Flowthroughthiscircuitisregulatedbyacontrolvalve(26)and indicatedonaflowmeter(27).Afterheatingintheexchangerwhere1360mmlengthof tube is in contact, the cold water leaves via an outlet (24). Temperatures through the cold watercircuitareindicatedonthreetemperaturesensors(8,17).Co-orcounter-flow configurations may be obtained by appropriate setting of the selector valves (19). Valves(9,11)atthetopoftheexchangerpermitairtobebledfromthesystemand facilitatedrainage.Adrainvalveunderneaththestoragetankpermitsthestoragetankto be drained. Eachtemperaturesensorintheexchangercircuitisinstalledinthemiddleoftheflow stream without touching the inner wall of the tube in order to obtain an accurate reading. Forco-currentflow,valvesV1andV3areopened,valvesV2andV4areclosed.For counter-current flow, valves V1 and V3 are closed, valves V2 and V4 are opened. SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 3 2.1 UNIT ASSEMBLY FIGURE 1: Rear view of the concentric tube heat exchanger SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 4 FIGURE 2: Front view of the concentric tube heat exchanger 1. Loose cover15.Temperature controller 2. Level switch16. Main switch 3. Heating element17.Temperature sensor 4. Storage tank18. Hot water inlet 5. Bypass valve19. Selector valve 6. Pump inlet20. Temperature sensor 7. Pump21. Flowmeter 8. Temperature sensor22. Control valve 9. Bleed Valve23. Cold water inlet 10.Temperature sensor24. Cold water outlet 11. Bleed Valve25. Temperature sensor 12. Flowrate indicator26. Control valve 13.Temperature indicator27. Flowmeter 14. Concentric tube SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 5 2.2 EXPERIMENTAL CAPABILITIES Determine heat transfer rate (heat flow), logarithmic mean temperature difference, and overall heat transfer coefficient. Determine surface heat transfer coefficient inside and outside the tube, and study the effect of fluid velocity on heat transfer coefficient. Perform energy balance on the working system. Compare performance in co-current (parallel) and in counter-current flow. Investigate the relationship between Nusselt (Nu) and Reynolds (Re) numbers. Determine temperature profile in co-current and counter-current flow. SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 6 3.0INSTALLATION REQUIREMENTS Theequipmentshouldbeinstalledonafirm,levelworksurfaceadjacenttoacoldwater supply and drain. A single phase electrical supply is also required. No other services are required. SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 7 4.0COMMISSIONING (Refer to Figs. 1 and 2, pages 3 and 4). 4.1 Check the drain valve underneath the water storage tank is fully closed (clockwise). 4.2Removethecover(1)fromthestoragetank(4)andfillthetankwithcleanwaterto within 40 mm (about 1.5 inch) from the top.NOTE: Heater will automatically off if the water level is below the level switch (2) in order to prolong the heater life. 4.3 Replace the cover on the storage tank. 4.4 Close the air bleed valves (11, 9) on the top of the heat exchanger. 4.5 Connect the cold water inlet (23) to a source of cold water using flexible tubing. 4.6 Connect the cold water outlet (24) to a suitable drain. 4.7 Close the hot water flow control valve (22). 4.8 Set the temperature controller (12) to zero on the front panel. 4.9 Switch on the pump and observe operation of the pump. 4.10 Raise the cover on the storage tank and observe circulation of water through the tank. 4.11Openthehotwaterflowcontrolvalve(22)andallowwatertoflowthroughthe exchanger until a steady flow of water is indicated on the hot water flowmeter (21). 4.12 Open the cold water flow control valve (26). Set the selector valves (19) to co-current position. Allow water to flow through the exchanger until a steady flow of water is indicated on the cold water flowmeter (27). 4.13 Close the hot and cold water flow control valves. 4.14 Attach a length of flexible tubing to each of the air bleed valves (11, 9) at the top of the exchanger. Open each bleed valve and allow water to flow until all air is expelled. 4.15 Close both bleed valves and remove the flexible tubing. 4.16 Set the temperature controller (12) to an elevated temperature e.g. 50.0C. Switch on theheaterandobservetheheaterswitchisilluminatedindicatingpoweroutputtothe heating element. Observe the heater in the storage tank and make sure it runs well. 4.17 Commissioning is now complete. SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 8 5.0INDEX TO EXPERIMENTS ExperimentPage No. ACO-CURRENT FLOW ARRANGEMENT9 BCOUNTER-CURRENT FLOW ARRANGEMENT12 CWATER TEMPERATURE VARIATION15 DFLOW RATE VARIATION17 SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 9 5.1EXPERIMENT A: CO-CURRENT FLOW ARRANGEMENT OBJECTIVE: To demonstrate the working principles of a concentric tube heat exchanger operating under co-currentflow conditions. EQUIPMENT SET-UP: Set desired hot waterinlet temperature onthe controller (12). Flow control valves draininlet Cold water flow direction control valves- Set for co-current flow (V1 &V3 on, V2 & V4 off) SUMMARY OF THEORY: Power emitted = QH H CpH(THin - THout)Power absorbed = QC C CpC(TCout TCin) Power lost = power emitted - power absorbed Efficiency =% 100 emitted powerabsorbed power Log mean temperature difference tm = 212 1lnttt t Overall heat transfer coefficient U = area tabsorbed powerm where, area= Surface area of contact = pi x ODinner pipe x Length = (3.142 x 0.015 x 1.36) m = 0.0641 m SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 10 Reynold number, Re = Nusselt number = 0.023 (Re^0.8) (Pr^0.33) Prandtl number, Pr = cp / k Surface heat transfer coefficient, h = Nu k / Theoretical Heat Coefficient,1 / U= 1 / h[cold side] + 1 / h[hot side]Where, = density, = dynamic viscosity, cp= specific heat, k= thermal conductivity d=diameter of pipe INITIAL VALUES OF VARIABLES TO BE USED: Controlled hot water temperature = 60CHot water flow rate QH = 2.0 L/minCold water flow rate QC = 1.5 L/min READINGS TO BE TAKEN: Record the hot and cold water temperatures at inlet, mid-point and outlet once conditions have stabilized. RESULTS: Readings TT1 ( tHin ) C TT2 ( tHmid ) C TT3 ( tHout ) C TT4 ( tCin ) C TT5 ( tCmid ) C TT6 ( tCout ) C Calcullations Power emitted W Power absorbed W Power lost W Efficiency % tm C U W/m2 C TemperatureT (C) Flow Rate Q (L/min) Reynold Number Re Nusselt Number Nu Surface Heat Transfer Coefficient h (W/mK) Theoritical U (W/mK) Experimental U (W/mK) Percentage error (%) Type of flow Hot Water Cold Water SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 11 Itwillbenecessarytorefertostandardtablesforvaluesofdensity(p)andspecificheat (Cp).Useappropriateconversionfactorstoensureconsistencyofunitswhenmaking calculations. Hot Co-current Flow Cold Students are recommended to do the following: 1.Compare the results obtained with those from a similar test under counter-current flow conditions.2.Discuss the effect of Re on h. 3.Compare the theoretical U and experimental U. SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 12 5.2 EXPERIMENT B: COUNTER-CURRENT FLOW ARRANGEMENT OBJECTIVE: To demonstrate the working principles of a concentric tube heat exchanger operating under counter-current flow conditions. EQUIPMENT SET-UP: Set desired hot waterinlet temperature onthe controller (12). Flow control valves draininlet Cold water flow direction control valves- Set for counter flow (V1 &V3 off, V2 & V4 on) SUMMARY OF THEORY: Power emitted = QH H CpH(THin - THout)Power absorbed = QC C CpC(TCout TCin) Power lost = power emitted - power absorbed System efficiency, =% 100 emitted powerabsorbed power Log mean temperature difference, tm = 212 1lnttt t Overall heat transfer coefficient, U = area tabsorbed powerm where, area= Surface area of contact = pi x ODinner pipe x Length = (3.142 x 0.015 x 1.36) m = 0.0641 m SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 13 Reynold number, Re = Nusselt number = 0.023 (Re^0.8) (Pr^0.33) Prandtl number, Pr = cp / k Surface heat transfer coefficient, h = Nu k / Theoretical Heat Coefficient,1 / U= 1 / h[cold side] + 1 / h[hot side]Where, = density, = dynamic viscosity, cp= specific heat, k= thermal conductivity d=diameter of pipe INITIAL VALUES OF VARIABLES TO BE USED: Controlled hot water temperature = 60CHot water flow rate QH = 2.0 L/minCold water flow rate QC= 1.5 L/min READINGS TO BE TAKEN: Record the hot and cold water temperatures at inlet, mid-point and outlet once conditions have stabilized. RESULTS: Readings TT1 ( tHin ) C TT2 ( tHmid ) C TT3 ( tHout ) C TT4 ( tCout ) C TT5 ( tCmid ) C TT6 ( tCin ) C Calcullations Power emitted W Power absorbed W Power lost W Efficiency % tm C U W/m2 C TemperatureT (C) Flow Rate Q (L/min) Reynold Number Re Nusselt Number Nu Surface Heat Transfer Coefficient h (W/mK) Theoritical U (W/mK) Experimental U (W/mK) Percentage error (%) Type of flow Hot Water Cold Water Itwillbenecessarytorefertostandardtablesforvaluesofdensity(p)andspecificheat (Cp).Utilizeappropriateconversionfactorstoensureconsistencyofunitswhenmaking calculations. SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 14 Hot Counter-current Flow Cold Students are recommended to do the following: 1.Comparetheresultsobtainedwiththosefromasimilartestunderco-currentflow conditions. 2.Discuss the effect of Re on h. 3.Compare theoretical U and experimental U. SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 15 5.3EXPERIMENT C: WATER TEMPERATURE VARIATION OBJECTIVE: Todemonstratetheeffectofhotwatertemperaturevariationontheperformance characteristics of a concentric tube heat exchanger. EQUIPMENT SET-UP: Thisexperimentcanbemadeusingeitherco-currentorcounter-currentflowoperation. This experiment sheet will assume counter-current flow. Select each required hot waterinlet temperature by setting thecontroller (12). Flow control valves draininlet Cold water flow direction control valves- Set for counter flow (V1 &V3 off, V2 & V4 on) SUMMARY OF THEORY: Theequationsforcalculatingtheperformancecharacteristics(poweremitted,power absorbed, power lost, efficiency, logarithmic mean temperature difference and overall heat transfercoefficient)arecontainedintheexperimentBsheet:Counter-currentFlow Arrangement- Concentric Tube Heat Exchanger HE104-PD INITIAL VALUES OF VARIABLES TO BE USED: Hot water flow rate QH = 2.0 L/minCold water flow rate QC = 2.0 L/min READINGS TO BE TAKEN: Record all water temperatures once conditions have stabilized for a range of hot water inlet temperatures as set on the controller. SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 16 RESULTS: Readings Temp set C TT1 ( tHin ) C TT2 ( tHmid ) C TT3 ( tHout ) C TT4 ( tCout ) C TT5 ( tCmid ) C TT6 ( tCin ) C 50 55 60 65 Calculations Temp set C Power emitted W Power absorbed W Power lostW Effic-iency % tm C U W/m2C 50 55 60 65 Itwillbenecessarytorefertostandardtablesforvaluesofdensity()andspecificheat (Cp).Useappropriateconversionfactorstoensureconsistencyofunitswhenmaking calculations. Hot Counter Flow Cold SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 17 5.4EXPERIMENT D: FLOW RATE VARIATION OBJECTIVE: Todemonstratetheeffectofflowratevariationontheperformancecharacteristicsofa concentric tube heat exchanger operating under counter-current flow conditions. EQUIPMENT SET-UP: Set desired hot water inlettemperature on the controllerusing decade switches (12). Flow control valves draininlet Cold water flow direction control valves- Set for counter-current flow (V1 &V3 off, V2 & V4 on) SUMMARY OF THEORY: Theequationsforcalculatingtheperformancecharacteristics(poweremitted,power absorbed,powerlost,efficiency/logarithmicmeantemperaturedifferenceandoverall heattransfercoefficient)arecontainedintheexperimentBsheet:Counter-currentFlow Arrangement - Concentric Tube Heat Exchanger HE104-PD Also, when QH H CpH > QC C CpC

then (T hot - T cold) = T willconverge at the hot inlet end. Alternatively, If QC C CpC > QH H CpH then T will converge atthe cold inlet end. SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 18 INITIAL VALUES OF VARIABLES TO BE USED: Controlled hot water temperature = 60CCold water flow rate QC = 2.0 L/min READINGS TO BE TAKEN: Record all water temperatures once conditions have stabilized for a range of hot water flow rates whilst maintaining a constant cold water flow rate.(Note:Ifpreferred,thisexperimentmayalternativelybemadebyvaryingthecoldwater flow rate whilst maintaining a constant hot water flow rate). RESULTS: Readings QH L / min TT1 ( tHin ) C TT2 ( tHmid ) C TT3 ( tHout ) C TT4 ( tCout ) C TT5 ( tCmid ) C TT6 ( tCin ) C 2.0 3.0 4.0 5.0 Calculations QH L / min Power emittedW Power absorbed WPower lostW Efficiency % tm C U W / m2 C 2.0 3.0 4.0 5.0 Itwillbenecessarytorefertostandardtablesforvaluesofdensity()andspecificheat (Cp).Useappropriateconversionfactorstoensureconsistencyofunitswhenmaking calculations. QH H CpH > QC C CpC QC C CpC > QH H CpH

Hot Counter-current Flow Cold SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 19 6.0REFERENCES 1.Holman, J.P.: Heat Transfer, McGraw-Hill Book Company, New York, 2001. 2.Perry, J.H.(Ed.): Chemical Engineers Handbook, 4th ed., McGraw-Hill Book Company, New York, 1963. SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 20 APPENDIX A Calculation Guide SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 21 Hot Water(inner pipe) Inner Diameter, : 13mm = 0.013m Outer Diameter,: 15mm = 0.015m Total Area,: 0.05555m Cold Water(outer pipe) Inner Diameter,: 20mm = 0.020m Outer Diameter,: 22mm = 0.022m Total Area,: 0.0641m Total Area for hot+cold side,= 0.0641+0.05555 = 0.11965m EXP A : CO-CURRENT FLOW ARRANGEMENT TH,in (C)TH,out (C)TH,ave (C)TC,in (C)TC,out (C)TC,ave (C) 60.35155.6528.738.733.7 QH(m3/s)H(kg/m3)CpH (kJ/kg.k)TH,in - TH,out (K) 3.15E-05985.144.1799.3 power emitted =1206.05W QC(m3/s)C(kg/m3)CpC (kJ/kg.k)TC,in - TC,out (K) 2.30E-05994.344.17410 power absorbed = 954.59W power lost = power emitted - power absorbed 251.46W =(Power Absorbed / Power Emitted) x 100% 79.15% LMTD, tm =(TH,in - TC,in) - (TH,out - TC,out) / ln[(TH,in - TC,in) / (TH,out - TC,out)] 20.45C U = power absorbed / (tm x area) 728.06W/m2 C For Hot Water : Water at 60C : density, =983.2kg/m dynamic viscosity, =0.467E-3Ns/m specific heat, cp= 4185J/kgK thermal conductivity, k=0.65W/mK SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 22 Flow rate, Q= 3.15E-5 m3/s (1.89 litre/min) A = / 4 = 0.013 / 4 = 1.33E-4

By continuity equation, Q=Av V=Q / A = 3.15E-5 / 1.33E-4 = 0.24m/s Reynolds number, Re = V/ = 983.2 0.24 0.013 / 0.467E-3 = 6568.7 > 4000 = turbulent flow Prandtl number, Pr = cp / k = 0.467E-3 4185 / 0.65 = 3 By turbulent flow, Nusselt number = 0.023 (Re^0.8) (Pr^0.33) Nusselt number, Nu = 0.023 (6568.7^0.8) (3^0.33) = 37.42 Surface heat transfer coefficient, h= Nu k / = 37.42 0.65 / 0.013 = 1871W/mK For Cold Water : Water at 30C : density, =995.65kg/m dynamic viscosity,=0.798E-3Ns/m specific heat, cp= 4179J/kgK thermal conductivity, k=0.62W/mK Flow rate, Q= 2.30E-5 m/s (1.38 litre/min) Cross Sectional Diameter,= ID for outer pipe(cold water) OD for inner pipe(hot water) = = 20mm 15mm = 5mm = 0.005m Cross Sectional Area, A= ((ID for outer pipe(cold water))2 ( OD for inner pipe(hot water))2)/ 4 = ((0.020)2 ( 0.015)2)/ 4 = 1.37E-4 SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 23 By continuity equation, Q=Av V=Q / A = 2.30E-5 / 1.37E-4 = 0.173m/s Reynolds number = V/ = 995.65 0.173 0.005 / 0.798E-3 = 1079 < 4000 = laminar flow For the laminar flow, Nusselt number for concentric tube heat exchanger can be found from table 11.3 pg. 638, Heat & Mass Transfer (Fundamentals & Applications), Mc Graw Hill 4th Edition,ODi/IDo = 0.015/0.22 = 0.75 extrapolated and found Nu = 5.3 Surface heat transfer coefficient, h = Nu k / = 5.3 0.62 / 0.005 = 657.2 W/mK Theoritical U, U = 1 / (1 / h [cold side] + 1 / [hot side]) =1 / (1 / 657.2) + (1 / 1871) ) =486.4 W/m2.K Experimental U = 728.06W/mK Percentage error = 100% = (486.4 728.06)/486.4 100% = 50% SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 24 EXP B : COUNTER-CURRENT FLOW ARRANGEMENT TH,in (C)TH,out (C)TH,ave (C)TC,out (C)TC,in (C)TC,ave (C) 60.450.955.6539.528.634.05 QH(m3/s)H(kg/m3)CpH (kJ/kg.k)TH,in - TH,out (K) 3.15E-05985.144.1799.5 power emitted =1231.98W QC(m3/s)C(kg/m3)CpC (kJ/kg.k)TC,in - TC,out (K) 2.30E-05994.224.17410.9 power absorbed = 1040.37W power lost = power emitted - power absorbed 191.61W =(Power Absorbed / Power Emitted) x 100% 84.45% LMTD, tm =(TH,in - TC,out) - (TH,out - TC,in) / ln[(TH,in - TC,out) / (TH,out - TC,in)] 21.59C U = power absorbed / (tm x area) 751.67 W/m2 C For Hot Water : Water at 60C : density, =983.2kg/m dynamic viscosity, =0.467E-3Ns/m specific heat, cp= 4185J/kgK thermal conductivity, k=0.65W/mK Flow rate, Q= 3.15E-5 m3/s (1.89 litre/min) A = / 4 = 0.013 / 4 = 1.33E-4

By continuity equation, Q=Av V=Q / A = 3.15E-5 / 1.33E-4 = 0.24m/s SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 25 Reynolds number, Re = V/ = 983.2 0.24 0.013 / 0.467E-3 = 6568.7 > 4000 = turbulent flow Prandtl number, Pr = cp / k = 0.467E-3 4185 / 0.65 = 3 By turbulent flow, Nusselt number = 0.023 (Re^0.8) (Pr^0.33) Nusselt number, Nu = 0.023 (6568.7^0.8) (3^0.33) = 37.42 Surface heat transfer coefficient, h= Nu k / = 37.42 0.65 / 0.013 = 1871W/mK For Cold Water : Water at 30C : density, =995.65kg/m dynamic viscosity,=0.798E-3Ns/m specific heat, cp= 4179J/kgK thermal conductivity, k=0.62W/mK Flow rate, Q= 2.30E-5 m/s (1.38 litre/min) Cross Sectional Diameter,= ID for outer pipe(cold water) OD for inner pipe(hot water) = = 20mm 15mm = 5mm = 0.005m Cross Sectional Area, A= / 4 = 0.005 / 4 = 1.96E-5 By continuity equation, Q=Av V=Q / A = 2.30E-5 / 1.96E-5 = 1.17m/s Reynolds number = V/ = 995.65 1.17 0.005 / 0.798E-3 = 7298.94 > 4000 = turbulent flow SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 26 Prandtl number, Pr = cp / k = 0.798E-3 4179 / 0.62 = 5.38 By turbulent flow, Nusselt number = 0.023 (Re^0.8) (Pr^0.33) Nusselt number, Nu = 0.023 (7298.94^0.8) (5.38^0.33) = 49.37 Surface heat transfer coefficient, h = Nu k / = 49.37 0.62 / 0.005 = 6121.88W/mK Theoritical U, 1 / U= 1 / h[cold side] + 1 / h[hot side] =1 / (6121.88 64) + 1 / (1871 55.55) =1.218E-5 U = 1 / (1.218E-5 119.55) = 686.76W/mK Experimental U = 751.67W/mK Percentage error = 100% = 100% = 9.45% SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 27 EXP C : WATER TEMPERATURE VARIATION TH=50C TH,in (C)TH,out (C)TH,ave (C)TC,out (C)TC,in (C)TC,ave (C) 50.343.346.834.52931.75 QH(m3/s)H(kg/m3)CpH (kJ/kg.k)TH,in - TH,out (K) 3.15E-05989.564.1747 power emitted =910.76W QC(m3/s)C(kg/m3)CpC (kJ/kg.k)TC,in - TC,out (K) 3.10E-05994.984.1745.5 power absorbed = 708.09W power lost = power emitted - power absorbed 202.66W =(Power Absorbed / Power Emitted) x 100% 77.75% LMTD, tm =(TH,in - TC,out) - (TH,out - TC,in) / ln[(TH,in - TC,out) / (TH,out - TC,in)] 15.04C U = power absorbed / (tm x area) 734.61W/m2 C SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 28 TH=55C TH,in (C)TH,out (C)TH,ave (C)TC,out (C)TC,in (C)TC,ave (C) 55.346.851.0535.92932.45 QH(m3/s)H(kg/m3)CpH (kJ/kg.k)TH,in - TH,out (K) 3.15E-05987.614.1768.5 power emitted =1104.27W QC(m3/s)C(kg/m3)CpC (kJ/kg.k)TC,in - TC,out (K) 3.10E-05994.814.1746.9 power absorbed = 888.18W power lost = power emitted - power absorbed 216.09W =(Power Absorbed / Power Emitted) x 100% 80.43% LMTD, tm =(TH,in - TC,out) - (TH,out - TC,in) / ln[(TH,in - TC,out) / (TH,out - TC,in)] 18.59C U = power absorbed / (tm x area) 745.42W/m2 C TH=60C TH,in (C)TH,out (C)TH,ave (C)TC,out (C)TC,in (C)TC,ave (C) 60.350.255.2537.429.133.25 QH(m3/s)H(kg/m3)CpH (kJ/kg.k)TH,in - TH,out (K) 3.15E-05985.334.17910.1 power emitted =1310.04W QC(m3/s)C(kg/m3)CpC (kJ/kg.k)TC,in - TC,out (K) 3.10E-05994.514.1748.3 power absorbed = 1068.07W power lost = power emitted - power absorbed 241.97W =(Power Absorbed / Power Emitted) x 100% 81.53% LMTD, tm =(TH,in - TC,out) - (TH,out - TC,in) / ln[(TH,in - TC,out) / (TH,out - TC,in)] 21.99C U = power absorbed / (tm x area) 757.81W/m2 C SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 29 TH=65C TH,in (C)TH,out (C)TH,ave (C)TC,out (C)TC,in (C)TC,ave (C) 65.353.159.239.229.134.15 QH(m3/s) H(kg/m3) CpH (kJ/kg.k) TH,in - TH,out (K) 3.15E-05983.424.18112.2 power emitted =1580.12W QC(m3/s)C(kg/m3)CpC (kJ/kg.k)TC,in - TC,out (K) 3.10E-05994.194.17410.1 power absorbed = 1299.19W power lost = power emitted - power absorbed 280.83W =(Power Absorbed / Power Emitted) x 100% 82.23% LMTD, tm =(TH,in - TC,out) - (TH,out - TC,in) / ln[(TH,in - TC,out) / (TH,out - TC,in)] 25.04C U = power absorbed / (tm x area) 809.64W/m2 C SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 30 EXP D: FLOW RATE VARIATION QH=2L/min TH,in (C)TH,out (C)TH,ave (C)TC,out (C)TC,in (C)TC,ave (C) 60.349.75537.328.733 QH(m3/s)H(kg/m3)CpH (kJ/kg.k)TH,in - TH,out (K) 3.15E-05985.464.17910.6 power emitted =1375.08W QC(m3/s)C(kg/m3)CpC (kJ/kg.k)TC,in - TC,out (K) 3.10E-05994.614.1748.6 power absorbed = 1106.79W power lost = power emitted - power absorbed 268.29W =(Power Absorbed / Power Emitted) x 100% 80.49% LMTD, tm =(TH,in - TC,out) - (TH,out - TC,in) / ln[(TH,in - TC,out) / (TH,out - TC,in)] 21.98C U = power absorbed / (tm x area) 785.39W/m2 C QH=3L/min TH,in (C)TH,out (C)TH,ave (C)TC,out (C)TC,in (C)TC,ave (C) 61.053.457.240.330.335.3 QH(m3/s)H(kg/m3)CpH (kJ/kg.k)TH,in - TH,out (K) 4.85E-05984.994.1798.7 power emitted =1736.86W QC(m3/s)C(kg/m3)CpC (kJ/kg.k)TC,in - TC,out (K) 3.10E-05994.324.17410.1 power absorbed = 1299.46W power lost = power emitted - power absorbed 437.41W =(Power Absorbed / Power Emitted) x 100% 74.82% LMTD, tm =(TH,in - TC,out) - (TH,out - TC,in) / ln[(TH,in - TC,out) / (TH,out - TC,in)] 22.19C U = power absorbed / (tm x area) 913.47W/m2 C SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 31 QH=4L/min TH,in (C)TH,out (C)TH,ave (C)TC,out (C)TC,in (C)TC,ave (C) 60.35356.6539.728.734.2 QH(m3/s)H(kg/m3)CpH (kJ/kg.k)TH,in - TH,out (K) 6.55E-05984.644.1807.3 power emitted =1967.97W QC(m3/s)C(kg/m3)CpC (kJ/kg.k)TC,in - TC,out (K) 3.10E-05994.174.17411 power absorbed = 1415.04W power lost = power emitted - power absorbed 552.93W =(Power Absorbed / Power Emitted) x 100% 71.90% LMTD, tm =(TH,in - TC,out) - (TH,out - TC,in) / ln[(TH,in - TC,out) / (TH,out - TC,in)] 22.40W/m2 C U = power absorbed / (tm x area) 985.55W QH=5L/min TH,in (C)TH,out (C)TH,ave (C)TC,out (C)TC,in (C)TC,ave (C) 60.453.957.1540.428.834.6 QH(m3/s)H(kg/m3)CpH (kJ/kg.k)TH,in - TH,out (K) 8.25E-05984.444.1806.5 power emitted =2206.65W QC(m3/s)C(kg/m3)CpC (kJ/kg.k)TC,in - TC,out (K) 3.10E-05994.014.17411.6 power absorbed = 1491.98W power lost = power emitted - power absorbed 714.67W =(Power Absorbed / Power Emitted) x 100% 67.61% LMTD, tm =(TH,in - TC,out) - (TH,out - TC,in) / ln[(TH,in - TC,out) / (TH,out - TC,in)] 22.45C U = power absorbed / (tm x area) 1036.62W/m2 C SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 32 P/S: 1. All the calculation for flow rate are based on the linearized value after the calibration of hot and cold water respectively. Experiment A:: 2.0 litre/min= 1.89 litre/min : 1.5 litre/min= 1.38 litre/min Experiment B:: 2.0 litre/min= 1.89 litre/min : 1.5 litre/min= 1.38 litre/min Experiment C:: 2 litre/min= 1.89 litre/min : 2 litre/min= 1.86 litre/min Experiment D:: 2 litre/min= 1.89 litre/min : 3 litre/min= 2.91 litre/min : 4 litre/min= 3.93 litre/min : 5 litre/min= 4.95 litre/min : 2 litre/min= 1.86 litre/min 2. All the calculation for temperature are based on specified temperature for properties references and easier calculation Experiment A:: 60C : 30C Experiment B:: 60C : 30C Experiment C:: 50C, 55C, 60C, 65C : 30C Experiment D:: 60C : 30C SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 33 APPENDIX B Physical Properties of Component SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 34 Table B1: Properties of water (saturated liquid) C Cp kJ/kg. Kkg/m3 21.114.179997.40 26.674.179995.80 30.004.176995.26 31.004.175995.10 32.004.174994.94 32.224.174994.90 34.004.174994.23 34.304.174994.14 34.654.174993.99 35.154.174993.83 35.654.174993.61 35.904.174993.53 36.204.174993.38 36.404.174993.35 37.254.174993.02 47.204.174989.42 48.894.174988.80 50.004.175988.18 51.504.176987.36 54.444.179985.70 54.654.179985.61 55.004.179985.46 55.054.179985.42 55.504.179985.22 56.504.180984.71 57.004.180984.48 57.254.180984.41 59.704.181983.16 60.004.179983.30 65.004.183980.60 65.554.183980.30 SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 35 APPENDIX C Calibration of Flowmeters SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 36 1.COLD WATER STREAM FLOWMETER CALIBRATION Meter Reading Experimental Value (L/min)(L/min) 2.02.14 3.03.14 3.94.15 4.95.30 5.96.10 Figure C1: Calibration Chart for Cold Water Stream Flowmeter Meter Reading Linearized Value (L/min)(L/min) 21.86 32.82 43.78 54.74 65.70 SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 37 2.HOT WATER STREAM FLOWMETER Meter Reading Experimental Value (L/min)(L/min) 2.02.17 3.13.16 4.14.11 5.15.10 6.16.20 Figure C2: Calibration Chart for Hot Water Stream Flowmeter Meter Reading Linearized Value (L/min)(L/min) 21.89 32.91 43.93 54.95 65.97 SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 38 APPENDIX D Typical Experimental Results SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 39 EXPERIMENT A: Table D1: Result Obtained From the Parallel Flow Arrangement Readings TT1 ( tHin ) C TT2 ( tHmid ) C TT3 ( tHout ) C TT4 ( tCin ) C TT5 ( tCmid ) C TT6 ( tCout ) C 60.355.55128.735.438.7 Calcullations Power emitted W Power absorbed W Power lost W Efficiency % tm C U W/m2 C 1206.05954.59251.4679.1520.45728.06 Table D2: Temperature T (C) Flow Rate Q (L/min) Reynold Number Re Nusselt NumberNu Surface Heat Transfer Coefficient h (W/mK) Theoritical U (W/mK) Experimental U (W/mK) Percentage error (%) Type of flow HotWater 601.896568.7037.421871 686.76 728.06 6.01 Turbulent Cold Water 301.387298.9449.376121.88Turbulent SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 40 EXPERIMENT B: Table D3: Result Obtained From the Counter Flow Arrangement Readings TT1 ( tHin ) C TT2 ( tHmid ) C TT3 ( tHout ) C TT4 ( tCout ) C TT5 ( tCmid ) C TT6 ( tCin ) C 60.456.350.939.534.328.6 Calcullations Power emitted W Power absorbed W Power lost W Efficiency % tm C U W/m2 C 1231.981040.37191.6184.4521.59751.67 Table D4: TemperatureT (C) Flow Rate Q (L/min) Reynold Number Re Nusselt Number Nu Surface Heat Transfer Coefficient h (W/mK) Theoritical U (W/mK) Experimental U (W/mK) Percentage error (%) Type of flow Hot Water 601.896568.7037.421871 686.76 751.67 9.45 Turbulent Cold Water 301.387298.9449.376121.88Turbulent SOLTEQ CONCENTRIC TUBE HEAT EXCHANGER UNIT (Model: HE 104-PD) 41 EXPERIMENT C: Table D5: Result Obtained From the Water Temperature Variation Readings Temp set C TT1 ( tHin ) C TT2 ( tHmid ) C TT3 ( tHout ) C TT4 ( tCout ) C TT5 ( tCmid ) C TT6 ( tCin ) C 5050.346.943.334.531.929.0 5555.351.346.835.932.729.0 6060.355.550.237.433.529.1 6565.359.653.139.234.229.1 Calculations Temp set C Power emitted W Power absorbed W Power lostW Efficiency % tm C U W/m2C 50910.76708.09202.6677.7515.04734.61 551104.27888.18216.0980.4318.59745.42 601310.041068.07241.9781.5321.99757.81 651580.121299.29280.8382.2325.04809.64 EXPERIMENT D: Table D6: Result Obtained From the Flow Rate Variation Readings QH L / min TT1 ( tHin ) C TT2 ( tHmid ) C TT3 ( tHout ) C TT4 ( tCout ) C TT5 ( tCmid ) C TT6 ( tCin ) C 2.060.355.449.737.333.228.7 3.060.356.551.638.834.128.7 4.060.357.453.039.734.728.7 5.060.457.853.940.435.228.8 Calculations QH L / min Power emittedW Power absorbed WPower lostW Efficiency % tm C U W / m2 C 2.01375.081106.79268.2980.4921.98785.39 3.01736.861299.46437.4174.8222.19913.47 4.01967.971415.04552.9371.9022.40985.55 5.02206.651491.98714.6767.6122.451036.62