Thermal Analysis of flow through Serpentine Tube in Tube Heat ExchangerGayakwad Shiwaji R.1, Jadhav S. Z.2, Dumbre S R31(Mechanical Engineering, SPCOE, Otur, India)2(Mechanical Engineering, SPCOE, Otur, India)Three(Mechanical Engineering, SPCOE, Otur, India)Summary: The serpentine tube in tube association could be very efficient for varied functions reminiscent of warmth exchanger and chemical reactors thermal energy plant and so forth. This serpentine tube in tube association can present lodging a big passive kind warmth exchanger. Throughout warmth switch, space in small house with excessive warmth switch coefficients attributable to these preparations.
This examine offers with the Assessment of warmth switch for flowing fluid through tubes utilizing experimentally and Computational Fluid Dynamics. The experimental and computation outcomes are in contrast with numerically and the temperature contours, the effectiveness and nusselt quantity of warmth exchangers are calculated and plotted. For the development of serpentine tube, copper is selecting. Water is flowing through the inside tube and likewise on the outer shell of the serpentine tube in tube warmth exchanger.
On this exact examine, an effort is made to guage the impact of counter flow solely.IntroductionThe warmth switch occurs by three ideas: 1) Conduction 2) Convection Three) Radiation and so forth. Heat switch through a warmth exchanger attributable to radiation isn’t thought of and it’s negligible examine with conduction and convection. The warmth switch take lace attributable to conduction by fluid is flowing through a close-by strong wall. By go for a least thickness of wall of a really conductive materials the conductive warmth switch is maximized. However convection performs a serious function in switch of warmth through a warmth exchanger.Within the warmth exchanger enactment augmentation of warmth switch is healthier method. The goal of power saving and to make a compact design for mechanical and chemical industries and course of crops and so forth. The necessary function of designing a warmth exchanger is enchancment in warmth switch. The enhancement method in warmth exchanger is mostly divided in two sorts.1. Passive method 2.Lively techniqueIn the passive method the development in warmth switch charge doesn’t require any exterior power or supply. By the adapting the geometrical change in exchanger, by altering look of floor or flow modification, by dietary supplements or additional gadgets which will increase the warmth switch charge in warmth exchanger. For instance: Components for gases, displaced enhancement gadgets, prolonged surfaces, swirl flow gadgets, Coiled tubes, handled surfaces, tough surfaces, and components for liquids.Within the lively method the development in warmth switch charge is require some exterior power or supply. For instance Jet impingement, Fluid vibration, Floor vibrations, Electrostatic fields (DC or AC), Mechanical aids.Serpentine Tube in Tube Heat Exchanger :Enlargement in warmth switch attributable to serpentine pipe is acknowledged by many investigators, nice accessible experimental or theoretical examine of a serpentine tube warmth exchanger bearing in thoughts fluid-to-fluid warmth switch are obtainable. Heat switch appearances intimate a serpentine tube for a number of boundary circumstances are measured. The warmth exchanger is examined as conjugate warmth switch and temperature needy properties of warmth transport media.Downside Assertion: To check and examined the serpentine tube in tube warmth exchanger, which preparations with the examine of warmth switch area and estimate amount of warmth switch between two fluids. Copper is used as tube materials, and decide the quantity of warmth switch for the particular supplies contemplating a number of properties. Altered techniques shall be used for varied outcomes for thermal parameter for checking the extent of warmth switch reminiscent of experimental methodology and numerical methodology by CFD Assessment and so forth.Calculate all thermal parameters through experimentally for specifically design compact warmth exchanger and discover the utmost warmth switch charge by making correct inlet and outlet temperature and flow charge through exchanger. On different hand calculate thermal parameters additionally by numerically. The temperature vary from 25-700C thought of with out section change course of and warmth switch is wise warmth. So these items are to be thought of.Experimental SetupThe trial arrange is proven in fig. 1 and arrange is correctly set for counter flow association and likewise for parallel flow association. Fig. 1 Experimental rigSet the majority flow charge of each chilly water and scorching water to an acceptable computing instrument. Utilizing a digital thermometer, measure the inlet and exit temperature of cold and warm water and remarks are famous and outcomes are estimated. The graphs are deliberate to allow to the attained outcomes. Dimensional parameters of serpentine tube in tube warmth exchanger is proven in Desk 1 as follows,Desk 1 Dimensional parameters of serpentine tube in tube warmth exchangerSr No. Dimensional Parameter Dimension (mm)1 Inside diameter of tube 12.72 Outer diameter of tube 12.83 Inside diameter of shell 38.14 Outer diameter of shell 38.45 Size (L) 460Fig. 2 Schematic diagram of serpentine tube in tube warmth exchangerThe experiment is to be carried out on the completely different collection of flow charge and outcomes are collected. Fig. 2 illustrates the presentation of the serpentine tube in tube warmth exchanger. The experiment is to be carried out on deciding on correct values, and likewise the Assessment is to be taken regarding the method of warmth switch.Mathematical AnalysisAnalytical Calculations: As flow geometry contain completely different correlation be used to attain warmth switch coefficients and calculations of Nusselt quantity is carried out utilizing this relationship given by Keys Xin and Roger for curved pipe association Correlation is given by Roger is as follows,Nu=Zero.Zero23Re0.84 Pr0.Four€‚Zero.1 (1)For Re > 2000In curved pipes, the warmth switch coefficient contained in the tube in the presence of warmth switch, the assorted empirical correlations proposed in the quite a few literatures is chosen probably the most extensively used being that by Xin and Ebadian. An empirical correlation is creating by Xin and Ebadian for the typical totally developed flow, utilizing this, estimate the warmth switch coefficient inside a curved tube. The correlation as follows,For Laminar flow,Nu=(2.153+Zero.318De0.643)Pr0.177 (2)20 < De < 2000, 07 < Pr < 175, Zero.0267 < ґ < Zero.088For turbulent flow,Nu=Zero.00619Re0.92Pr0.Four(1+Three.455 ґ) (Three) 5—103 < Re < 105, Zero.7 < Pr < 5, Zero.0267< ґ < Zero.0884Within the calculation the warmth switch coefficient at ho primarily based, the empirical correlation is given by Keys is utilized in Incropera and Dewitt as follows,Nu=Three.66+Zero.0668 DLRe Pr1+Zero.04 DL Re Pr23 (Four)The Effectiveness of warmth exchanger is calculated as,µ= QQmax= Ch(Th1-Th2)Cmin(Th1-Tc1)= Cc(Tc2-Tc1)Cmin(Th1-Tc1) (5)Numerical CalculationsSteady state implicit strain primarily based solver utilizing Ansys15 atmosphere is being allowed for the numerical resolution. For regular state streams for mass and momentum are defined by the most important partial differential equations. Utilizing second order up wind scheme, the discretization is full. Imply Flow Equations are offered in Cartesian tensor notation as follows, Continuity equation,€‚€‚xiVi=Zero (6)Momentum Equation,€‚€‚xi ViVj= €‚P€‚xi+ €‚€‚xjј €‚Vi€‚xj+ €‚Vj€‚xi- vivj (7)Power Equation,€‚€‚xi ViT= €‚€‚xj јPr €‚T€‚xj- Vi t (eight)The geometric mannequin of the serpentine tube was constructed utilizing workbench in ANSYS 15 atmosphere. Three-dimensional computational area modeled is proven in fig. Three. And this geometry is mesh by utilizing hexagonal mesh is as proven in fig. Four. Initially a fairly coarser mesh is made. The entire area of serpentine tube consists of ‰€7.eight lakes parts and straight tube consists of ‰€5.6 lakes parts. For checking the validity of the standard of the mesh in the outcomes are achieved by grid unbiased take a look at. Additional adaptation didn’t alter the outcomes by greater than Zero.87% which is occupied because the relevant mesh high quality for computation.A boundary situation reminiscent of fixed wall temperature is executed on the wall of the tube. Fluid is able to turn out to be chilly because it flows through the tube by isolating a wall temperature of 300 Okay. Strain outlet boundary circumstances are utilized on the outlet of each cold and warm fluid. Conservation calculations had been dedicated for the management quantity to capitulate water flow in the tube for velocity and temperature fields.There’s two inlet situation and two outlet situation as a result of right here two tubes are used. Copper is separated two fluid flows. The inside fluid is taken as scorching liquid flow and outer fluid as chilly liquid flow. Boundary Circumstances: Boundary situation is used allowing to the requisite of the mannequin as mass flow inlet and strain outlet is nicely outlined at inlet and outlet situation of the cold and hot fluid. The partitions are independently recognized with similar to boundary circumstances. No slip situation is deliberated for each single wall. Zero warmth flux situation is established at respective wall with the exception of the inside tube wall. The above desk demonstrations all boundary situation. 332422515176400Fig. Three 3D computational area modeledFig. Four Mesh modeledTable 2 Boundary conditionsHot Inlet Scorching Outlet Chilly Inlet Chilly OutletBoundary Situation Sort Mass Flow Inlet Strain Outlet Mass Flow Inlet Strain OutletMass Flow Inlet (kg/s) Zero.01-Zero.03 – Zero.05 -Temperature (ok) 333 – 300 -Turbulent Kinetic Power (m2/s2) Zero.01 – Zero.01 -Turbulent Dissipation Fee (m2/s2) Zero.1 – Zero.1 -Desk-Four Properties of the CopperDescription Density Particular warmth capability Thermal conductivityValue 8978 kg/m3 381 J/kg-Okay 387.6 W/m-KResult and DiscussionsFig. 5 illustrates the impact of Reynolds quantity on Nusselt quantity. Whereas calculating Nusselt quantity a unique scientist offers correlations to deliberate varied parameters. Therefore, 5 completely different curves for every correlation had been plotted. From above graphs for identical Reynolds quantity, it may be seen that a worth of the Nusselt quantity given by Xin and Ebadian for a curved tube association and is larger than straight tube association. In accordance with Roger, for calculation of nusselt quantity they think about the curvature rations and its outcomes are elevated warmth switch attributable to secondary turbulence happens at curvature. Thus, the values given by Roger are thought of for comparability.The schematic diagram of experimental setup is proven in Fig.-2. The setup is a nicely instrumented single section warmth trade system with a scorching water stream flowing contained in the tube aspect is cooled by a chilly water stream flowing in the shell aspect. The primary elements of the system are tube in tube warmth exchanger, centrifugal pump, storage tank, and heater. The warmth exchangers embody a copper tube and an insulated shell. The size of the warmth exchangers are illustrated in desk – 1. The water in storage tank is heated utilizing an electrical heater. Reaching to a prescribed temperature, pump is began to flow into the recent water in the system.Fig. 5 Reynolds quantity vs Nusselt numberFig. 6 Mass flow charge Vs Effectiveness for Zero.05 kg/s chilly fluid flowfig.- 7 characterize variation of mass flow charge over total warmth switch coefficient for counter flow warmth exchanger.Fig. 7 Mass flow charge vs Uo counter flowAs the mass flow charge of scorching water will increase the typical warmth switch charge will increase step by step for every corresponding mass flow charge of chilly water when it’s stored fixed for set of 5 readings. From fig.- eight The place characterize variation of mass flow charge over size through serpentine tube and straight tube in counter flow warmth exchanger respectively.Fig. eight Variation of complete strain in serpentine tube and straight tubeFig. 9 and 10 illustrate temperature distributions in a serpentine tube and straight tube with a counter. This exhibits temperature is lowering extra at curved part than a straight one. Fig. 11 Temperature distributions in serpentine tube with counter flowFig. 12 Temperature distributions in straight tube with counter flowCONCLUSIONSAn depth of secondary flow developed goes on growing inside curvature ratio primarily based on the experiments. This enhance in turbulence causes main mixing of fluid contained in the tube which will increase warmth switch coefficient. Heat switch is attained on the out flow of strain drop over a size larger in the serpentine tube in tube warmth exchanger than the straight tube in tube warmth exchanger tolerable limits as per beforehand analysis in a parallel subject.The examine supplied that there’s an extreme alteration in the warmth switch enactments of the serpentine tube configuration over straight tube configurations. From the numerical knowledge, Nusselt numbers at completely different factors alongside the tube size are decided. The mannequin was carried out for fluid to fluid warmth switch options and at a unique inlet temperature, Nusselt quantity for the serpentine tubes is established to be altering from Three-100. 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