Avinash_PPT
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This document describes a conjugate heat transfer analysis of an electronics cooling system using OpenFOAM. It outlines the objectives to develop a CFD model for CHT analysis and validate it with experiments. The methodology section describes the governing equations solved for fluid and solid regions as well as the interface coupling. A simple circuit board cooling case is modeled and tested. Additionally, a server cooling case is proposed with details on geometry, meshing, boundary conditions and results showing temperature distributions.
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- 1. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Conjugate Heat Transfer for Electronic Cooling using OpenFOAM Avinash Valiba Gorde(CMS-1310) Internal Guide Dr. Sukratu Barve Dr. Mihir Arjunwadkar Centre for Modelling and Simulation External Guide Dr. Vikas Kumar Mr. Mohan Labade Centre for Development of Advanced Computing Pune,INDIA June 20, 2015
- 2. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Outline 1 Need of Project 2 Objectives 3 Methodology 4 CHT Case in OpenFOAM 5 Server Case 6 Preprocessing 7 Results 8 Conclusion 9 Future Scope 10 References
- 3. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Need of Project Considering following aspect, A very limited conjugate heat transfer case studies have been analyzed using OpenFOAM.
- 4. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Objectives To develop a CFD model for conjugate heat transfer analysis of an electronics cooling system Validation of CFD model with experimental results
- 5. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Methodology Conjugate Heat Transfer In CHT computational domain is divided into fluid and solid regions. The NaviereStokes equations and the energy equation in the fluid regions are solved first. Then the heat transfer equation in the solid regions is solved. Figure : Conjugate Heat Transfer
- 6. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Steady state heat transfer Steady state conditions the temperature within the system does not change with time. Steady State Equation for Solid − · (κ T) = Sh (1) Unsteady state heat transfer Unsteady state conditions the temperature within the system changes with time. Unsteady State Equation for Solid ρCp ∂T ∂t = · (κ T) + Sh (2)
- 7. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Solver chtMutiRegionSimpleFoam Solver It is steady state solver for conjugate heat transfer. It is combination of heatConductionFoam and buoyantFoam for conjugate heat transfer Governing Equation Used by OpenFoam chtMultiregionSimpleFoam Solver Continuity Equation ∂ρ ∂t + −→ · (ρ−→u ) = 0 (3)
- 8. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Momentum Equation The sum of all forces acting on a body is equal to the rate of change of momentum of it 1) Body forces = gravitational, centrifugal 2)Surface forces acting on the surface of the body e.g. pressure or viscous forces ∂ (ρu) ∂t + · (ρuu) = − p + · τ − ρg (4) Energy Equation ∂(ρE) ∂t + · (ρuE) = · (α e) − · [u (p − ρgr)] + Sh (5) α = µCp κ is the thermal diffusivity. Sh is the thermal source term. e is the specific internal energy. E is the specific total energy of the gas defined as: E = e + u2 2
- 9. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Equation in solid region ∂ (ρh) ∂t = · (α h) + Sh (6) α = µCp κ is the thermal diffusivity. Sh is the heat source term. h is the sensilbe enthalpy.
- 10. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Coupling at the solid-fluid interface Tw = ks δxs Ts kf δxf + ks δxs + (1 − k) Tf + Tref δxf = kf δxf Tf + ks δxs Ts kf δxf + ks δxs (7) Tf and Ts are the temperatures of the fluid and solid regions kf and ks are the heat conductivities of the fluid and solid Tref is a reference temperature δxf and δxs are the distances between the cell centers Figure : Interface Temp
- 11. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco CHT Case in OpenFOAM Geometry For Simple Circuit Board Cooling Figure : Simple cht case
- 12. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Meshing For Simple Circuit Board Cooling Figure : Simple cht case
- 13. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Implementation of Heat Source Heat source In src/fvOptions/lnInclude const dimensionSet ds = rho.dimensions()*fld.dimensions()/dimTime*dimVolume; ds = ρ * h/time * volume ds = kg/m3 * J/(kg * S) * m3 ds = W (watt) tmp <fvMatrix<Type > >tmtx(new fvMatrix < Type >(fld, ds)); h (200 0);
- 14. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Boundary Conditions Solid Region Initial Temperature=300K. Wall is zeroGradient. Heat Source 200 Watt (4 IC’s). Interface between solid(IC), fluid(AIR) Mixed B.C. Fluid Region Velocity v=0.3m/s. p = atmospheric. Initial Temperature (T) = 299K. Inlet=fixed Value Outlet=inletOutlet for Velocity & Temperature. Walls maintained at symmetry, zeroGradient. Interfaces between solid and fluid = Mixed B.C.
- 15. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Temperature contour at mid plane Figure : Temperature variation in solid along xaxis
- 16. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco 300 320 340 360 380 400 420 0 0.2 0.4 0.6 0.8 1 1.2 1.4 TemperatureinKelvin Distance along X-axis '100_watt.csv' u 8:2 '200_watt.csv' u 8:2 Figure : Temperature Distribution
- 17. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Server Case
- 18. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Server Case Geometry of Server This is Intel Server Board S2600GZ/GL having 2 SOCKETS, 24 RAMS, PCB, 2SMPS
- 19. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Generalized geometry of Server Figure : Generalized model of server
- 20. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Sink of Socket High Thermal conductivity, larger surface area Low thermal resistance Material Aluminium, Copper Air can be easily flow through it Figure : Sink of Socket
- 21. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Meshing For server create 3 blocks specifying coordinates of each point. Dimensions are L=0.46m Zaxis, W=0.41m Xaxis, H=0.09m Yaxis it is structured mesh Figure : blockMesh for Server
- 22. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco topoSet topoSet utility is use to create different domain inside the mesh block. Figure : blockMesh for Server
- 23. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Turbulance Model RNG κ − turbulence model Useful for rapidly strains flows, Heat and mass transfer Low Reynold number effect Standard κ − model for high reynolds number Turbulent Kinetic Energy (k) ∂ (ρk) ∂t + ∂ (ρkui ) ∂xi = ∂ ∂xj αk µeff + ∂k ∂xj + Gk + Gb − ρ − Ym + Sk (8) Dissipation rate ( ) ∂ (ρ ) ∂t + ∂ (ρ ui ) ∂xi = ∂ ∂xj αk µeff + ∂ ∂xj + C1 k (Gk + C3 Gb) − C2ρ 2 k − R + S (9) The coefficient updated each iteration C ∗ 1 = c1 − η 1 − η η0 1 + βη3 (10) η = k τij τij (11)
- 24. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Table : Constant values for turbulence model C1 C2 C3 Cµ η β σk σ 1.42 1.68 -0.33 0.085 4.38 0.012 0.7194 0.7194
- 25. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Boundary Conditions Solid Region Initial Temperature=299K. Walls zeroGradient. Heat Source :- 103 Watt (2 sockets), 4 Watt (on 1, 4, 9, 12, 13, 14, 16, 21, 24 ). Interface between solid(SOCKETs, RAMs), fluid(AIR) Mixed B.C. Fluid Region Velocity v=2.1m/s. p = atmospheric. Initial Temperature (T) = 299K. Inlet=fixed Value Outlet=inletOutlet for Velocity & Temperature. Walls maintained at symmetry, zeroGradient. Interfaces between solid and fluid = Mixed B.C.
- 26. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Solid Thermophysical Properties Table : Solid thermophysical properties Solid name κ(W/mK) Cp(J/kgK) rho(kg/m3) Material SOCKET 1 & 2 124 702 2325 Silicon SINK 1 & 2 220 903 2700 Aluminium RAM 124 702 2325 Silicon SMPS 1 & 2 53 450 8000 Steel BOX 1 & 2 53 450 8000 Steel FLAPPER 53 450 8000 Steel BOARD 0.02 1800 1500 FR4
- 27. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Table : Fluid(AIR) thermophysical properties Parameter value Cp (J/kg K) 1000 µ 1.8e−05 Pr 0.7
- 28. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Results Temperature Contours Figure : Temperature distrubution in Server
- 29. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Temperature along Heat Sink coordinates are (0.1 0.02 0.28) and (0.1 0.02 0.360) 298 300 302 304 306 308 310 312 314 316 318 320 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 TemperatureinKelvin distace along z-axis SinkTemp betn fins Figure : Temp. distrubution of fin along z-direction
- 30. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Temperature between fin passage coordinates are (0.06 0.02 0.332) & (0.19 0.02 0.0332) 298 300 302 304 306 308 310 312 314 316 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 Temp.inKelvin distace along x-axis HeatsinkTemp Figure : Temp. distrubution of fin along x-direction
- 31. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Temperature Variation of RAMs & SOCKETs coordinates are (0.095 0.0075 0) & (0.09 0.0075 0.46) 295 300 305 310 315 320 325 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 Temp.inKelvin distace along z-axis SOCKET & RAM Temp Figure : Temperature distribution along z-direction
- 32. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Comparision with experimental results Comparision of Sockets & Rams Temperature obtained from cfd model & experiment Table : Comparision of Socket & Ram Temp(K) Region OpenFOAM Result Experimental Result SOCKET 319.838 318 RAM 301.43 303
- 33. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Error in Results The % error in Sockets & Rams Temperature : %error = Resultexp − Resultcfd Resultcfd ∗ 100 (12) Sockets Temperature % error %error = 318 − 319.838 319.838 ∗ 100 = 0.57% (13) Rams Temperature % error %error = 303 − 301.43 301.43 ∗ 100 = 0.52% (14)
- 34. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Conclusion Results obtained from cfd model are good, as compared to experimental results. This CFD results gives three dimensional temperature distribution in server components such as RAMs, SOCKETs, BOARD The % error in Sockets temperature is 0.57 % and Rams temperature is 0.52 %
- 35. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Future Scope To implement Fan boundary condition for mass flow rate To implement micro thickness baffle for sink region
- 36. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco References ANSYS. Fluent 6.3 users guide. www.sharcnet.ca/Software/Fluent6/html/ug/node479.htm. Yunus A. Cengel. Heat Transfer A Practical Approach. McGraw-Hill, forth edition, 2003. Yongsheng Lian Chaolei Zang. Conjugate heat transfer analysis using simplified household refrigerator model. Technical report, Department of Mechanical Engineering University of Lousville USA, June 2014. Porterie B. Consalvi J.L., Pizzo Y. Numerical analysis of heating process in upward flame spread over thick pmma slab. Fire Safty J, V43(N5):351–362, 7/08. John D.Anderson. Computational Fluid Dynamics Basic with application. Mc GrawHill, 2000. Wilcox D.C. Turbulence Modeling for CFD. DCW Industries, 3 edition, 2006. D.E.Dwyer. Defining ventilation boundary condition for green house climate model. Master’s thesis, Delft University of Technology, August 2014. OpenFOAM Foundation. Openfoam programmer guide. www.openfoam.org. OpenFOAM Foundation. Openfoam user guide. www.openfoam.org.
- 37. Need of Project Objectives Methodology CHT Case in OpenFOAM Server Case Preprocessing Results Conclusion Future Sco Thank You !