Optimization Of Heat Sink Research Articles

Topology optimization for spider web heat sinks for electronic cooling

• The topology optimization method is firstly employed for bionic heat sinks. • The performance of the heat sinks are studied by numerically and experimentally. • Different optimization goals for temperature uniformity can lead to different results. • The optimal heat sinks is superior to the conventional heat sinks in terms of the performance. • The CFD results agree well with the experimental results. In this paper, topology optimization method is applied to bionic domain, and in order to improve the thermal performance of heat sinks, two topological heat sinks are obtained under two objectives. One objective is minimize the temperature difference and pressure drop, and another is minimize the average temperature and pressure drop. The topological heat sink designed by topology optimization with the minimum temperature difference and the pressure drop as a goal is named as M2, while that designed with the minimum average temperature and the pressure drop as a goal is called M3. The flow and thermal performance of these two topological flow channel heat sinks are investigated numerically. The results show that for Re = 2056.8, the temperature difference of the topological heat sink M2 is reduced by 57.35% compared to conventional spider web heat sink M1, while that of the topological heat sink M3 is reduced by 10.64% compared to M1. In addition, the thermal resistance of the topological heat sinks are smaller than the conventional spider web heat sink. Through analysis, it can be known that M2 has the best comprehensive heat dissipation capacity. In order to verify the correctness of the numerical simulation, M2 is manufactured, and the heat transfer performance of M2 is investigated experimentally. The experimental results of the optimal heat sink agree well with the calculated results.

Dynamic performance and multi-objective optimization of fin-concrete heat sinks

• A novel parametric dynamic thermal network of a fin-concrete ceiling is developed. • The optimal solutions set is used to design the finned plate layout. • Dynamic performance of heat sink is stabilized with high-density finned plate. In a passive nuclear plant, the main control room must provide self-support functions for 72 h after an accident occurs. In this isolation mode, the heat generated by indoor occupants and equipment should be removed by using concrete walls that are 610 mm thick, and the finned ceiling made of concrete should maintain thermal habitability. However, the finned ceiling design has not been studied in normal buildings, and the cooling storage effect of plate-shaped fins is usually ignored during the design phase. In this study, a novel parametric resistance–capacitance thermal network is proposed to simulate the thermal performance of different fin-plate layout forms in the case of an accident. An experiment was conducted on a 1200 mm × 1200 mm × 610 mm fin-concrete module for 72 h to validate the model under constant air temperature conditions. Based on the model, multi-objective optimization was conducted to obtain optimal solution sets by using a radial basis function approximation model. The results show that the optimal performance indicators can be classified into unsteady and quasi-steady states, in which the dominant factors for heat transfer include the heat transfer area and the thickness of the finned plate, respectively. Further, the optimal solution sets for different convection and heating conditions obtained through an optimization process are used to design a fin layout based on actual temperature control demands and cooling storage.

Multi-objective topology optimization of pin-fin heat exchangers using spectral and finite-element methods

Forced convective pin-fin heat exchangers, due to the high wet surface area per volume and the hindered thermal boundary layers, feature low thermal resistances. However, the considerable coolant pressure drop, particularly for densely packed fin arrays, imposes operational costs for pumping power supply. This paper develops a multi-objective topology optimization approach to optimize sink geometries in order to minimize thermal resistance and pressure loss, concurrently. In accordance to the pin-fin geometrical characteristics, a dedicated pseudo-3D conjugate heat transfer model is utilized, by assuming periodic flow and fin design pattern, to reasonably reduce the high cost of full-3D model optimization. For the solution of flow part, a pseudo-spectral scheme is used, which is intrinsically periodic and features a high spectral accuracy, and the finite element method for the non-periodic conjugate heat transfer model. Exact partial derivatives of the discrete solutions are obtained analytically by hand-differentiation. This task is rather convenient for the flow part, due to the simplicity of the pseudo-spectral implementation; however, the MATLAB symbolic toolbox is selectively utilized for the finite element code to ensure an error-free implementation. Finally, the sensitivities are computed directly or via a discrete adjoint method, for the flow and heat models, respectively. To examine the present approach, two approaches are used for optimization of a practical cooling task: constrained and unconstrained multi-objective formulations, where in all cases more emphasis is placed on thermal resistance minimization. A series of optimized heat sink geometries via constrained or unconstrained multi-objective optimizations are obtained to examine practical utility of the present approach. The optimized topologies demonstrated superior cooling performances at lower costs of pressure losses compared to conventional (circular) in-line and staggered fins, and confirmed the supremacy of topology over pure sizing optimization.

Constructal design of two-phase stacked microchannel heat exchangers for cooling at high heat flux

Constructal design of high heat flux two-stacked horizontal microchannel heat sinks are presented for cooling of electronic devices. Using ANSYS Computational Fluid Dynamics (CFD) code for subcooled nucleate boiling, fixed volume constraints were invoked for the heat sinks and microchannels to achieve optimal flow velocities and pressure drops at global minimum thermal resistances of the microchannel heat sinks; this is in line with constructal design principle. Validation of the CFD code was done by comparing its results with those of experimental data in the open literature. The closeness of the two results showed the CFD code to be accurate in predicting subcooled flow boiling for cooling of microelectronic devices. Heat fluxes of 1100 and 1200 W/cm2 (1.1 × 107 W/m2 and 1.2 × 107 W/m2) were used in the simulations and optimizations. The thermal resistance, pumping power and Bejan number were based on microchannels that an optimal heat sink of 1 cm width could accommodate. The thermal resistances and base temperatures for optimal microchannel heat sinks at these high heat fluxes (the focus of the study) are low; the pumping power requirements are also low, which show that they are useable in the cooling of electronic devices and other similar applications. Also, this is an indication that optimal two-stacked microchannel heat sinks operating in subcooled flow boiling could be considered as a viable alternative in the cooling of electronics. Optimal two-stacked microchannel heat sink operating at 1200 W/cm2 and in counterflow and parallel flow arrangements, was used for the critical heat flux study and the results show that both have good CHF performance, although counterflow arrangement was better.

Systematic micro heat sink optimization based on hydrofoil shape pin fins

Multi-objective optimization of the hydrofoil shaped pin fins for micro heat sinks was studied. Optimization tool utilized a multi objective genetic algorithm (MOGA) and a numerical model that was validated against previously obtained experimental single-phase heat transfer results on a hydrofoil shape micro scale pin fin. The numerical model was built using StarCCM + software. Several turbulence models were examined against single-phase experimental data and the Lag-EB k-epsilon turbulence model was chosen for validation. Optimization tool varied the shape of the hydrofoil pin fin through flexible parametrization utilizing an ellipse and polynomials. An algorithm coupling pin fin parametrization code, validated the 3D CFD solutions and a MOGA interface was implemented. Subsequently, multi-objective optimization was performed to maximize the heat transfer coefficient while minimizing pressure drop. A broad range of novel geometries were obtained with a tradeoff between thermal and hydraulic performance for low Reynolds number. Novel pin fin shape, bird design, is proposed as a result of the study. Additional 3D steady state conjugate CFD simulations including the bird design pin fin were performed using already verified setup, and it was shown that the enhancement in the average heat transfer coefficient dominates over the pressure drop increase at higher Reynolds numbers.

Design and optimization of a liquid cooled heat sink for a motor inverter in electric vehicles

The rapid development of power electronic devices has made them have higher power density, which puts forward higher requirements for cooling technology. The contribution of this paper is the integrated design of the liquid cooled heat sink for a 30 kW motor inverter considering the distribution of power devices. In order to find an optimal heat sink configuration, the cooling performance of three different configurations of heat sinks was investigated. And the distribution characteristics of the temperature and fluid velocity field were compared and analyzed. The heat sink with serpentine channel configuration was selected due to its best temperature uniformity and cooling characteristic. In addition, the effects of geometric parameters (fin thickness) and flow parameters (flow rate) on cooling performance were further studied. On this basis, the geometrical configuration of the heat sink was optimized. The experimental results of the optimized heat sink are in good agreement with the numerical simulation results. The motor inverter achieves high power density of 9.677 kW/kg.

Analytical Modeling and Optimization of a Heat Sink Design for Passive Cooling of Solar PV Panel

High temperature is the primary challenge in the development of solar photovoltaic (PV) systems in an arid climate. A rise in temperature diminishes the performance of the PV systems and shortens their lifespan. The goal of this manuscript is to develop an analytical model to predict the temperature of PV panels under a passive cooling system for an arid environment. Taking into consideration the link between solar panel temperature and its conversion efficiency, Kirchhoff’s and Ohm’s laws for a complex circuit were applied to calculate the heat flux in the solar panel system, and hence obtain the temperatures of each layer in the system. Closed-form analytical expressions for temperature, output power, and conversion efficiency of the solar panel were deduced and presented as functions of solar irradiance, ambient temperature, emissivity, wind velocity, tilt angle, and dimensions of fins. Comparison between the results presented in the literature and those predicted by the developed analytical model validated the presented model. Moreover, the length of the fins required for safe thermal operation of solar panels in harsh desert environment were also obtained from analysis. Furthermore, the effect of using such a cooling system on the temperature and efficiency of the solar panels was verified by using the developed model under real conditions in Dammam city during summer and winter seasons. The results showed that the optimized heat sink could raise the solar panel power by 8.7% during summer and by 6.5% during winter.

Optimization of a microchannel heat sink using entropy minimization and genetic aggregation algorithm

A copper heat sink with rectangular U-shaped microchannels for cooling high power laser diode arrays was numerically optimised. The control volume method based commercial software was applied for solving heat transfer and fluid flow in the considered device. The optimisation procedure included over 130 various geometrical configurations with five independent geometric parameters. The Entropy Generation Minimization criterion was applied to find the optimal geometric structure. Some relations between geometrical parameters of the microchannel heat sink were analysed through statistical studies and two most important ones, i.e., the relative height (α) and width (β) of a single microchannel, were selected. Using the genetic aggregation, the entropy generation characteristics were determined as a function of α and β as well as mass flow rate of cooling medium (Ġ). The most optimal from the second law of thermodynamics point of view configuration was the one with αopt = 0.86, βopt = 0.347 and Ġ = 0.00183 kg/s. Comparing with the initial geometry, over 35% reduction of irreversibility losses for the optimal heat sink had been achieved, i.e., heat sink thermodynamic efficiency increases from 90.05% to 91.8%, while maximum temperature of cooled semiconductor element was reduced from 333.3 K to 324.2 K.

Thermal analysis and parametric optimization of plate fin heat sinks under forced air convection

Heat dissipation is becoming more and more challenging with the preface of new electronic components having staggering heat generation levels. Present day solutions should have optimized outcomes with reference to the heat sink scenarios. The experimental and theoretical results for plate type heat sink based on mathematical models have been presented in the first part of the paper. Then the parametric optimization (topology optimization) of plate type heat sink using Levenberg-Marquardt technique employed in the COMSOL Multiphysics? software is discussed. Thermal resistance of heat sink is taken as objective function against the variable length in a predefined range. Single as well as multi-parametric optimization of plate type heat sink is reported in the context of pressure drop and air velocity (Reynolds number) inside the tunnel. The results reported are compared with the numerical modeled data and experimental investigation establish the conformity of results for applied usage. Mutual reimbursements of greater heat dissipation with minimum flow rates are confidently achievable through balanced, heat sink geometry as evident by the presented simulation outcome. About 12% enhancement in pressure drop and up to 51% improvement in thermal resistance is reported for the optimized plate fin heat sink as per data manifested.

Performance enhancement of a natural-gas-fired high-temperature thermoelectric generation system: Design, experiment and modelling optimization

High-temperature thermoelectric generation (TEG) system that driven by combustion is an efficient way for simultaneously providing heat and electric power, but its application prospect is restricted by very low ratio of electric power to heat supply. In this work, an annular high-temperature TEG system is extended by adding medium-temperature TEG modules, and correspondingly a novel two-stage annular multi-hole burner with baffle construction is specially designed to replace original single-stage annular multi-hole burner. The optimal geometric dimensions of the new burner are obtained by conducting a simplified 2D model in ANSYS. Experiment results show that, due to the new burner design, the inner-wall temperature of the high-temperature TEG module is averagely increased by 73 K, bringing an electric power rise of 14.8%; in comparison with the single-stage high-temperature TEG system, the total electric power generation of the high- and medium-temperature coupled TEG system is greatly improved by 73.8%. To further improve the electric performance of the high-temperature TEG module, a well-developed multi-physics field coupled model which containing 2D combustion reactions in the new burner and 1D multi-physical thermoelectric (TE) effects is established to reveal the optimal length and number of TE element, and to assess the optimization of cold-side heat sink.

Deep learning for both broadband prediction of the radiated emission from heatsinks and heatsink optimization

Heatsinks have quasi-antenna behavior in many cases and cause interference both at the system level and at the PCB design level. Therefore, determination or prediction of both resonance frequencies and maximum radiated emission are crucial at any design step. In this paper, as a novelty, in 2–8 GHz band, a model based on deep learning is developed to predict resonance frequencies in parallel plate-fin type heatsinks. Parameters taken into account are the number of fins, the width, length, and height of the heatsinks. 3888 heatsinks with different sizes are modeled to prepare data set and the Grey Wolf Optimizer algorithm (GWO) is utilized to optimize the heatsink parameters. Consequently, while this model obtains outputs for certain inputs, the optimization algorithm procures certain inputs for these outputs. Furthermore, the predicted and optimized results are compared with the simulation and measurement results. The proposed model successfully works according to the measurement and the proposed model results since R2 values are 0.96, 0.98, 0.97, and 0.99 for f1,f2,REmax1, and REmax2, respectively. The results are good agreement and R-squared values of resonances (f1,f2) and the maximum radiated emissions (REmax1,REmax2) are quite acceptable considering the sophisticate of the proposed model.

Laminar Thermally Developing Flow in Elliptical Minichannels with Isoflux Wall

Laminar convective heat transfer for the thermally developing flow in elliptical minichannels is numerically investigated under constant heat flux with high thermal conductivity materials (H1) and low thermal conductivity materials (H2) boundary conditions. The effects of the Peclet number and the aspect ratio on both the local Nusselt number and the thermal entrance length are presented graphically. The Peclet number is a key parameter for heat transfer in the developing flow. The local Nusselt number is a decreasing function of the Peclet number, especially for the Peclet number less than 500, where a sharp decline can be observed. As the aspect ratio decreases, the Nusselt number increases for the H1 boundary condition but diminishes for the H2 boundary condition. Generalized correlations for the thermal entrance length and the local Nusselt number are proposed for the design and optimization of elliptical minichannel heat sinks.

Secondary heat transfer enhancement design of variable cross-section microchannels based on entransy analysis

Convective heat transfer enhancement is a trade-off between heat transfer enhancement and pumping power reduction. Entransy theory, evaluating the heat transfer efficiency from the viewpoint of irreversibility, is an ideal way to evaluate convective heat transfer performance. In this paper, the entransy dissipation is re-recognized from the viewpoints of heat transfer and fluid flow to explain the contradiction between heat transfer entransy dissipation (HTED) and fluid flow entransy dissipation (FFED). The concept of local entransy is introduced to analyze the heat transfer enhancement mechanism of variable cross-section microchannels (VC-Ms). Based on the analysis, a secondary design was used to further enhance heat transfer performance. The results found that the secondary design of VC-Ms showed lower entransy dissipation and higher convective heat transfer efficiency, which provided data supporting the optimization and active design of the microchannel heat sink.

Optimization of a Wavy Microchannel Heat Sink with Grooves

In this study, a wavy microchannel heat sink with grooves using water as the working fluid is proposed for application to cooling microprocessors. The geometry of the heat sink was optimized to improve heat transfer and pressure loss simultaneously. To achieve optimization goals, the average friction factor and thermal resistance were used as the objective functions. Three dimensionless parameters were selected as design variables: the distance between staggered grooves, groove width, and groove depth. A modified Latin hypercube sampling (LHS) method that combines the advantages of conventional LHS and a three-level full factorial method is also proposed. Response surface approximation was used to construct surrogate models, and Pareto-optimal solutions were obtained with a multi-objective genetic algorithm. The modified LHS was proven to have better performance than the conventional LHS and full factorial methods in the present optimization problem. A representative optimal design showed that both the thermal resistance and friction factor improved by 1.55% and 3.00%, compared to a reference design, respectively.

Hybrid microchannel/multi-jet two-phase heat sink: A benchmark and geometry optimization study of commercial product

In this paper, an experimental study of two-phase cooling heat sink using the dielectric working fluid Novec/HFE-7000 is performed. The liquid flow is directed into microchannel fins through multiple impinging jets. A copper microchannel heat sink with a fin height of 3mm, fin thickness of 0.1 mm and channel width of 0.1 mm was used for removing heat flux from the heated surface. A copper block was used to mimic computer chip with a surface area of 1” x 1” (6.45 cm2). The experiment was performed at heat flux from 5 W/cm2 to 80 W/cm2, subcooling of 5 °C, 15 °C, 25 °C, and flow rates 1, 1.25 and 1.75 lpm. The results in the two-phase regime for high heat fluxes are compared with analytical correlations. Reduced subcooling can results in enhancement of heat transfer coefficient by 25 % but will increase the pressure drop through the heat sink. Heat transfer coefficient increases with flow rate in the single-phase region and in the convective boiling region. In nucleate boiling region, heat transfer coefficient increases with heat flux rather than flow rate. Geometry optimization of heat sink was carried out considering effects of fin height on thermal and hydraulic performance. It is found that thermal resistance variation with fin height shows a parabolic trend and an improvement of 46 % in thermal performance can be obtained. A new correlation was also developed to predict results of experimental data with mean absolute error of 7 %. The inclusion of Reynolds number and hydraulic diameter was found to considerably reduce error when compared to values obtained with the previously available correlation, in which only the subcooling and heat flux were the parameters for modelling the heat transfer.

Topology optimization of microchannel heat sinks using a homogenization approach

Topology optimization for heat sink devices typically relies on penalization methods to ensure the final designs are composed of strictly solid or open regions. In this work, we formulate a homogenization approach wherein the partial densities are physically represented as porous microstructures. This formulation allows design of thermal management components that have sub-grid features and leverages additive manufacturing techniques that can produce such partially porous regions within the build volume. Topology optimization of a liquid-cooled microchannel heat sink is presented for a hotspot over a uniform background heat input. The partial densities are represented as arrays of pin fins with varying gap sizes to achieve sub-grid-resolution features. To this end, the pin fins are modeled as a porous medium with volume-averaged effective properties. Height-averaged two-dimensional flow and non-equilibrium thermal models for porous media are developed for transport in the pin fin array. Through multi-objective optimization, the hydraulic and the thermal performance of the topologically optimized designs is investigated. The pin fin thickness is chosen based on the minimum reliable printing feature size of state-of-the-art direct metal laser sintering machines, and the gap sizes between the pin fins are optimized. The resulting topologies have porous-membrane-like designs where the liquid is transported through a fractal network of open, low-hydraulic-resistance manifold pathways and then forced across tightly spaced arrays of pin fins for effective heat transfer. The effects of the grid resolution and the initial design guess on the resulting topologies and performances are reported. The topologically optimized designs are revealed to offer significant performance improvements relative to the benchmark, a straight microchannel heat sink with features optimized under the same multi-objective cost function. The work demonstrates that representing partial densities as porous microstructures results in nearly resolution-independent performance at sufficiently-small grid sizes through the use of sub-grid features.

Heat Sink Design for WBG Power Modules Based on Fourier Series and Evolutionary Multi-Objective Multi-Physics Optimization

Optimal heat dissipation in power modules can significantly increase their power density. Removing the generated heat is critical for capturing the benefits of advanced semiconductor materials and improving the reliability of the device operation. This study proposes a design optimization method for liquid-cooled heat sinks that use a Fourier analysis--based tool and an evolutionary optimization algorithm to optimize the heat sink geometry for specified objectives. The optimized heat sink geometry was compared with state-of-the-art solutions in the literature based on finite element analysis of different designs. The proposed methodology can develop complex geometries that outperform conventional heat sink geometries. Optimized heat sink design from the proposed method was fabricated and tested in an experimental setup under representative operating conditions. The experimental setup was also modeled in the finite element model that was used for the proposed heat sink optimization method. The experimental results show that developed finite element models can predict the thermal and flow performance of the complex design with high fidelity, and the results validate the proposed design approach.

Thermal reliability-based design optimization using Kriging model of PCM based pin fin heat sink

This paper deals with the thermal reliability optimization of a pin fin heat sink (HS) filled with phase change material (PCM) in order to study the heat transfer performance for cooling of electronic devices. Aluminium is taken to carry out the pin fin heat sink with a constant volume fraction of 9% by choosing 72 pin fins. Paraffin wax is used as PCM inside the heat sink to retain the heat produced by the electronic device. A reliability-based design optimization (RBDO) is addressed to determine the optimum thermal configuration of the pin fin heat sink that satisfies the desired reliability. The presented methodology is summarized by the combination of the 3D finite element simulation (FES), the Kriging substitution model and the optimization procedure. The surrogate model is built and validated using two metrics such as error predictions and cross validation (CV). A comparison of the number of training points shows that the Kriging predictor with 100 Latin hypercube sampling (LHS) points provides a better approximation of the original model. Thermal optimization results show that the time taken by the latent heating phase of the optimal design is higher than that obtained by the baseline model. With the reliability optimization, the maximum temperature of the optimal design was reduced by 30%.

Analysis of Thermal Performance Metrics—Application to CPU Cooling in HPC Servers

Optimization of heatsinks has a critical importance for the energy-efficient cooling of high-performance computing (HPC) servers to meet reliability, performance, and cost targets. This article provides a detailed application of the effectiveness as a performance metric to provide a qualitative comparison of the CPU heatsink solutions. First, the use of effectiveness as a metric to provide an absolute performance of heatsinks on a simple scale of 0–1 is highlighted. Then, the effectiveness and thermal resistances are compared to explore the limits of air cooling and the relative merits of liquid cooling. Second, a response surface method (RSM) for the heatsink optimization is presented. Furthermore, a response surface optimization (RSO) based on the design of experiments (DOE) is performed on the numerical models of the heatsink and cold plates using FloTHERM computational fluid dynamics (CFD) software. The simulation results obtained at 45 °C inlet are used to provide an objective comparison among the optimum heatsink and cold plates. The simulations show that heatsinks have the effectiveness of 0.65–0.75 and a cooling capability of 150–250 W. The cold plates have an effectiveness of 0.25–0.30 and a cooling capability of 325–425 W. Furthermore, the simulation results are compared with benchmark validation studies. Counterintuitively, the higher effectiveness obtained for the air-cooled heatsinks indicates limited scope for further improvement, whereas the cold plates (with lower effectiveness) provide great scope for further improvements to meet future cooling challenges.

The Optimal Design of Heat Sinks: A Review

Heat sinks are used in industrial equipment to dissipate the excess heat from their heat-generating parts to the ambient. In the last few years, efforts on manufacturing electronic or mechanical devices with less weight, space, and lower cost were spent. Heat dissipation from the heat sink is stalling a big problem which many researchers are trying to solve. The aim of this study is to brief the previous investigation attempted enhancing the heat sinks thermal performance and to provide help to understand the cooling ability of their specific geometries. The various enhancement techniques used for optimizing the hydrothermal design of a pin fin, flat fin, micro-channel, and topology optimized heat sinks were summarized. The way in which the heat sinks’ thermal performance is affected by orientation, shapes, perforation, slot, interruption, and space between fins and their arrangement under free and forced convection condition also reviewed.