CPU Air Forced Convection Cooling Systems Design
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According to integration design concept of forced air convection cooling system aerodynamic design of small axial-flow 9238 fan for the CPU is implemented.File of 3D curves which are produced from Fortran procedure are imported into Pro/E to build solid modeling.The performance curve of fan prototype which is fabricated by CNC is measured in a standard wind tunnel.To reduce costs and shorten the design time,CFD is carried out to predict the performance of fan.According to outflow angle of fan series of radial heat sinks are developed.Based on the hexahedral block-grid strategy the numerical simulation is carried out on systems of fan and streamlined heat sink with Multiple Rotating Reference Frame and RNG k-e Model.Results show that resistance of the streamlined heat sink reduces by 15.9%when compared to the traditional heat sink.The numerical simulation proves to be true by the experiment.Series of heat sinks can reach the aim of high thermal exchange effect under the direction of the integration design concept.Keywords:
Forced convection
Passive cooling
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Micro heat sinks have a broad applicability in many fields such as aerospace applications, micro turbine cooling, micro reactors electronics cooling and micro biological applications. Among different types of micro heat sinks, those with micro pin-fins are becoming popular due to their enhanced heat removal performance. However, relevant experimental data is still scarce and few optimization studies are present in the literature. In order to effectively optimize their performance an extensive parametric study is necessary and should be based on a realistic model. Moreover, micro pin fin heat sinks should be optimized according to appropriate performance criteria depending on the application. The objective of this paper is to fill the research gap in micro pin fin heat sink optimization based on realistic configurations. In this paper, the parameters for micro pin optimization are the pin-fin height over diameter ratio (0.5<H/D<5) and the longitudinal and transverse pitch ratios (1.5<(SL, ST)/D<5), while Reynolds number and heat flux provided from the base of the micro heat sink are in the range of (1<Re<100) and (20<q(W/cm2)<500) respectively. In this research micro pin fin heat sinks are three dimensionally modeled on a one-to-one scale with the use of commercially available software COMSOL Multiphasics 3.5a. Full Navier-Stokes equations subjected to continuity and energy equations are solved for stationary conditions. To have increased computational efficiency, half of the heat sink is modeled with the use of a symmetry plane. In order to validate the use of numerical models parametric values from previous experimental data available in the literature are exactly taken and simulated. The numerical and experimental results show a good agreement. After this validation optimization study is performed using the three dimensional numerical models.
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Electronics cooling
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Topology optimization
Multiphysics
Forced convection
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Air cooling systems are currently the most popular and least expensive solutions to maintain a safe temperature in electronic devices. Heat sinks have been widely used in this area, allowing for an increase in the effective heat transfer surface area. The main objective of this study was to optimise the shape of the heat sink geometric model using the Adjoint Solver technique. The optimised shape in the context of minimal temperature value behind the heat sink is proposed. The effect of radiation and trapezoidal fin shape on the maximum temperature in the cooling system is also investigated. Simulation studies were performed in Ansys Fluent software using the Reynolds—averaged Navier–Stokes technique. As a result of the simulation, it turned out that not taking into account the radiation leads to an overestimation of temperatures in the system—even by 14 ∘C. It was found that as the angle and height of the fins increases, the temperature value behind the heat sink decreases and the heat source temperature increases. The best design in the context of minimal temperature value behind the heat sink from all analysed cases is obtained for heat sink with deformed fins according to iteration 14. The temperature reduction behind the heat sink by as much as 25 ∘C, with minor changes in heat source temperature, has been achieved.
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Passive cooling
Solver
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Heat sinks are widely used for cooling electronic devices and systems. Their thermal performance is usually determined by the material, shape, and size of the heat sink. With the assistance of computational fluid dynamics (CFD) and surrogate-based optimization, heat sinks can be designed and optimized to achieve a high level of performance. In this paper, the design and optimization of a plate-fin-type heat sink cooled by impingement jet is presented. The flow and thermal fields are simulated using the CFD simulation; the thermal resistance of the heat sink is then estimated. A Kriging surrogate model is developed to approximate the objective function (thermal resistance) as a function of design variables. Surrogate-based optimization is implemented by adaptively adding infill points based on an integrated strategy of the minimum value, the maximum mean square error approach, and the expected improvement approaches. The results show the influence of design variables on the thermal resistance and give the optimal heat sink with lowest thermal resistance for given jet impingement conditions.
Surrogate model
Fin
Shape Optimization
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According to field synergy principle and entropy generation minimization, the integration design concept is developed to improve thermal performance of forced air convection cooling system.Based on the hexahedra mesh the numerical simulation is carried out on systems of fan and streamlined heat sink with Multiple Rotating Reference Frame and RNG k-e Modle.Results show that resistance of the streamlined heat sink reduces by 15.9% when compared to the traditional heat sink.The numrical simulation proves to be true by the experiment.Series of heat sinks can reach the aim of high thermal exchange effect under the direction of the integration design concept.
Forced convection
Fin
Minification
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A compact, energy efficient heat sink design methodology is presented for shrouded, parallel plate fins in laminar flow. The analytic model accounts for the sensible temperature rise of the air flowing between fins, convective heat transfer to the flowing stream, and conduction in the fins. To evaluate the efficiency of the air cooling system, consideration is also given to the determination of the fan pumping power. This paper focuses on the optimization of the heat sink-fan combination for energy efficiency, subject to volumetric constraints. The design optimum is found by matching the most efficient operating point of the fan with the corresponding optimum fin geometry. A series of parametric studies was completed to identify the sensitivity of the cooling solution to parametric variations. This numerically validated model has been used to visualize the parametric impact of dealing with “real world” manufacturing limitation in the development of thermal packaging solutions for notebook computers and other electronic products.
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The housing of totally enclosed fan-cooled electrical machines is usually finned to maximize the heat dissipation over its surface. Complex models involving heat and fluid flow simultaneously are necessary to evaluate a single design. An optimization over a wide parameter range is, therefore, not possible. In this paper, a novel approach on how to model this particular conjugate heat transfer problem in 2-D without the help of lumped circuits is presented. The proposed method is applied to an optimization process controlled by an evolutionary algorithm. Comparative, more detailed simulations in computational fluid dynamic (CFD) verify the tendencies obtained in the optimization. In another case, the method is used to evaluate the allowable degree of engineering tolerance for a given design. Although the method does not provide results as accurate as CFD, it is very helpful to study a large parameter set and determine the CFD candidates.
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Natural convection cooling offers advantages such as low cost, high reliability, noiseless operation and positioning independent from other cooling circuits. Since the main disadvantage is a relatively low heat transfer, an analytic model is required to efficiently design natural convection heat sinks according to the applied design constraints. This paper describes a natural convection thermal model which can be applied to parallel plate heat sinks in order to find an optimum heat sink design. First, the theoretical model was applied to different commercially available heat sink profiles, from which the most suitable profile was chosen for an inverter prototype. As a reference, FEM simulations were performed. Thermal measurements were carried out to validate the model. Then, the achieved thermal performance was compared to the theoretical optimum design. It was found out that described model predicts the resulting heat sink temperatures with a practical accuracy compared to measurements. Therefore, the approach described in this paper is a mathematically simple and validated model for the design of natural convection heat sinks. Furthermore, with an optimum design the heat sink volume can be reduced by 45% compared to a commercially available heat sink profile.
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Passive cooling
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In this study, forced cooling of heat sinks mounted on CPUs was investigated. Heat sink effectiveness, effect of turbulence models, effect of radiation heat transfer and different heat sink geometries were numerically analyzed by commercially available computational fluid dynamics softwares Icepak and Fluent. The numerical results were compared with the experimental data and they were in good agreement. Conjugate heat transfer is simulated for all the electronic cards and packages by solving Navier-Stokes equations. Grid independent, well converged and well posed models were run and the results were compared. The best heat sink geometry is selected and it is modified in order to have lower maximum temperature distribution in the heat sink. This paper was also originally published as part of the Proceedings of the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems.
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Traditional aisle containment technology of data center are unable to cool server components with heat fluxes above 100 W/cm2 and above. As the demand of computational power is increasing day by day, there are rapid increase in data center density, which results in high CPU temperatures of computing servers. Cold plate based liquid cooling technology is one of the possible options for solving this kind of problem as it has advantages over air cooling technique due to high specific heat of fluid, which is mostly water. Computational Fluid Dynamics (CFD) technique can be used to optimize design of cold plate and its operating parameters. In the current study, a CFD model has been developed to analyze the heat transfer behavior of cold plates for conjugate heat transfer analysis using OpenFoam CFD tool box. An experimental study has been set up to conduct experiments and comparing the results of CFD simulations with experiments in order to validate the CFD model. A chtMultiRegionSimpleFoam solver has been used, which solves the conduction equation in solid region and momentum equation in fluid region. The results obtained by CFD simulation match well with experimental results.
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Data center
CFD in buildings
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