Optimization Of Heat Sink Research Articles

Machine learning based surrogate models for microchannel heat sink optimization

Microchannel heat sinks are an efficient cooling method for semiconductor packages. However, to properly cool increasingly complex and thermally dense circuits, microchannel designs should be improved and expanded on. In this paper, microchannel designs with secondary channels and with ribs are investigated using computational fluid dynamics and are coupled with a multi-objective optimization algorithm to determine and propose optimal solutions based on observed thermal resistance and pumping power. A workflow that combines Latin hypercube sampling, machine learning-based surrogate modeling and multi-objective optimization is proposed. Random forests, gradient boosting algorithms and neural networks were considered during the search for the best surrogate. We demonstrated that tuned neural networks can make accurate predictions and be used to create an acceptable surrogate model. Optimized solutions show a negligible difference in overall performance when compared to the conventional optimization approach. Additionally, solutions are calculated in one-fifth of the original time. Generated designs attain temperatures that are lower by more than 10% under the same pressure limits as a convectional microchannel design. When limited by temperature, pressure drops are reduced by more than 25%. Finally, the influence of each design variable on the thermal resistance and pumping power was investigated by employing the SHapley Additive exPlanations technique. Overall, we have demonstrated that the proposed framework has merit and can be used as a viable methodology in microchannel heat sink design optimization.

Design optimization of plate-fin heat sink with forced convection for single-module thermoelectric generator

Thermoelectric generators (TEGs) often use plate-fin heat sinks as cold side heat exchangers under forced convection. The available net electrical power obtained from these TEGs corresponds to that generated (Seebeck effect) minus that consumed (cooling fan). Generation and self-consumption have different trends as a function of the air flow speed, so a maximum of the net electrical power is expected when varying the cooling flow rate. Here, a semi-analytical model was developed to predict the maximum net electrical power of a single TEG module with a plate-fin heat sink with non-bypassed forced convection. The model was successfully validated with experimental data. It was applied to determine the heat sink design (fin thickness and fin-to-fin distance) that optimized the net electrical power for given values of hot source temperature, TEG properties, and duct cross-section. Numerical results indicated that the optimal dimensions of the plate-fin heat sink depended, among others, on the TEG effective properties. For a given TEG, the net output power was less sensitive to changes in fin thickness than in fin spacing. The optimal heat sink designs predicted by the model for the cases studied had fin thicknesses of 0.32 and 0.44 mm with fin-to-fin distances of 1 mm.

Optimization and experimental verification of microchannel heat sink based on heat transfer and flow balance regulation

The heat transfer performance and flow performance of microchannel convective heat transfer processes are usually mutually constrained. However, we expect microchannel heat sinks to have both excellent heat transfer and good fluidity. In order to achieve a balance between heat transfer and fluidity, we established an optimization objective function of a complex network structure based on the linear programming method. This composite objective function included both the entransy dissipation rate model to express the heat transfer performance of the fractal microchannel heat sink and the pump power model to express its flow performance. Under the same initial values and constraints, we optimized the objective function. Finally, the comprehensive performance of the optimized structure (OPTS) and the randomly designed initial structure was compared through experiments. The experimental results show that the comprehensive performance of the OPTS was always better than the initial design structure (INDS) under any conditions, and the performance of the optimized structure with fewer fractal levels was better. Within the scope of the study, the average comprehensive performance of the OPTS was improved by a minimum of 14% and a maximum of 30% relative to the INDS. This validates the rationality of the optimization method proposed in this study. We have theoretically and experimentally solved the active optimization problem of how many levels of fractal structure should be designed in a constant space and what the channel size of each level is when the heat sink has optimal performance.

Thermal performance enhancement and optimization of double-layer microchannel heat sink with intermediate perforated rectangular fins

In the present work, three-dimensional numerical investigation has been carried out to comprehend the thermohydraulic performance of novel design of double-layer microchannel heat sinks (DL MCHS). Conventional DL MCHS is modified by incorporating intermediate rectangular fin with holes of four distinct shapes namely triangular, rectangular, circular and square having equal perimeter. Series of numerical simulations have been performed for the Reynolds number (Re) ranging from 100 to 400, and uniform heat flux varied from 500 to 2000 kW/m2. Single-phase liquid water with varying thermophysical properties is used as cooling medium. Predicted numerical results confirm that compared to conventional configuration; modified DL MCHS has significantly augmented the heat transfer rate causing average Nusselt number to be increased by ≈ 45–60%. But they also encounter higher pressure drop due to massive flow restrictions prevailing in such configurations. Nevertheless, overall thermal performance of the modified DL MCHS is better than the conventional design. Among all the considered cases, heat sinks with circular and triangular holes consistently show superior thermal performance compared to square and rectangular holes, but it is very marginal of the order of ≈ 2–5%. Analysis of coolant flow behavior reveals that intermediate fins with holes facilitate better fluid mixing and provides staggered flow passages in addition to thinner boundary layer which keeps on re-evolving. All these favourable flow behaviors led to improve the heat transfer rate in modified DL MCHS. Furthermore, optimization study of the heat sink with circular holes identify that a configuration with hole radius (Rh) = 0.286 mm and number of holes (Nh) = 15 is superior which exhibits maximum heat transfer rate ≈51–64% higher than conventional DL MCHS.

Topology Optimization Design of Micro-Channel Heat Sink by Considering the Coupling of Fluid-Solid and Heat Transfer

To investigate the effect of the target weight coefficient on the structure design of the micro-channel heat sink, an innovative method for the topology optimization design of micro-channel structures with different bifurcation angles is adopted. In this study, the improved interpolation function, density filtering, and hyperbolic tangent projection methods are adopted to obtain a clear topological structure of the micro-channel heat sink. The heat transfer of the micro-channel heat sink under different bifurcation angles is compared. At the same time, the influence of the two different objective functions, heat transfer, and flow energy consumption, is analyzed in the topology optimization of micro-channel heat sinks. The results show that when the bifurcation angle is 135°, both the heat transfer and the average outlet temperature of the micro-channel heat sink obtain the maximum value, and the heat transfer effect is the best. With the increase of the heat transfer weighting coefficient, the distribution of solid heat sources in the main channel increases, and the refinement of the branch channels also increases. On the other hand, although the heat transfer effect of the micro-channel heat sink is the best, the corresponding flow energy consumption is larger.

Multi-objective optimization of parallel microchannel heat sink with inlet/outlet U, I, Z type manifold configuration by RSM and NSGA-II

Designing an effective parallel microchannel heat sink (PMCHS) is necessary for addressing the cooling challenges of high heat-dissipating electronics. This paper presents a shape optimization of PMCHS to minimize the thermal resistance and pressure drop for each U, I, and Z-type inlet/outlet manifold configuration with vertical intake and coolant delivery. The performance of PMCHS influencing design parameters, such as channel width, fin width, and channel height, is designed using the response surface methodology (RSM). In the present communications adopting the Artificial Neural Network (ANN) coupled NSGA-II method, a three-dimensional numerical simulation is executed to minimize the pressure drop and thermal resistance. Numerical simulation is performed using the finite volume method; the computational domain is taken as the entire microchannel system including the inlet/outlet plenum area, ports and microchannels. The overall analysis demonstrated that the pareto optimal design point has better hydraulic and thermal performances than the predefined design. The optimized design showed benchmark thermal resistance of 0.0306 ˚C/W, 0.0315 ˚C/W, 0.0316 ˚C/W and pressure drop of 3.1 kPa, 3.2 kPa, 3.19 kPa for U, I, Z configurations respectively.

Multi-objective optimization of manifold microchannel heat sink with corrugated bottom impacted by nanofluid jet

The manifold microchannel heat sink (MMCHS) has been widely used for heat dissipation of high heat-flux electronic devices. To reduce the thermal resistance and flow resistance of MMCHS and obtain better heat dissipation performance, a novel manifold microchannel heat sink with corrugated bottom (CB-MMCHS) is proposed in this study. The flow and heat transfer characteristics of nanofluid jet impingement on CB-MMCHS are numerically studied under different structural parameters and nanofluid concentrations, respectively. The results show that the channel width ratio γ has the most significant effect on total thermal resistance Rt and pumping power Pp of CB-MMCHS among structural parameters, increasing nanofluid concentrations can enhance the heat transfer but also increases pumping power consumption. In order to obtain the optimal structural design, multi-objective optimization is performed with the objective of minimizing Rt and Pp. It is found that the optimized CB-MMCHS has lower thermal resistance and flow resistance compared with MMCHS. When Rt of optimized CB-MMCHS is 0.2794 K/W, Pp decreases to 0.1674 W, 43.81% lower than MMCHS; When Pp is 0.2979 W, Rt decreases to 0.2367 K/W, 14.86% lower than MMCHS. In addition, the compromise solution with minimum Rt is selected by introducing TOPSIS combined with entropy weight method.

Structure optimization and cooling performance of a heat sink with discontinuous arc protrusions impacted by nanofluid confined slot jet impingement

PurposeThe purpose of this paper is to improve the overall heat transfer performance and the temperature uniformity of the heat sink and to explore the effects of the jet Reynolds number and the nanoparticle volume fraction of the nanofluids on the flow and heat transfer performance.Design/methodology/approachA heat sink with discontinuous arc protrusions in the wall jet region is proposed for confined slot jet impingement. A sloping upper cover plate is added to improve the heat transfer effect in this area. An Al2O3–water nanofluid is selected as the working fluid of the jet for better heat transfer. The Standard k-e turbulence model is used for numerical calculation. The key structural parameters of the heat sink are optimized by the response surface method and a genetic algorithm. The effects of the jet Reynolds number (Re) and the nanofluid concentration (ϕ) on the flow and heat transfer performance of the optimized heat sink are investigated.FindingsThe average Nusselt number of the optimal heat sink is 8.2% higher and the friction resistance is 5.9% lower than that of the initial flat plate heat sink when ϕ = 0.02 and Re = 8,000. The discontinuous arc protrusions and the sloping upper cover plate substantially enhance the heat transfer in the later stage of jet development, improving the temperature uniformity of the heat sink. The maximum temperature difference of the optimal heat sink is 28.1% lower than that of the flat plate heat sink at the same nozzle height. As the jet Reynolds number and the nanofluid particle concentration increase, the Nusselt number of the optimized heat sink and the friction coefficients increase, resulting in a decrease in the evaluation coefficient. However, the overall temperature uniformity of the heat sink is improved under all conditions.Originality/valueThe novel heat sink structure provides a new way to enhance the heat transfer and temperature uniformity of confined slot jet impingement. The flow and heat transfer performance of the heat sink impinged by confined slot jet of nanofluids are obtained. The combination of response surface method and genetic algorithm can be applied to the multi-objective optimization of heat resistance and flow resistance of heat sink.

Pressure drop of R134a in mini channels with micro pin fins during flow boiling

Flow boiling in mini channel with micro pin fin arrays is a promising technology for thermal management in various fields such as microelectronics, energy utilization and national defence. Understanding its flow characteristics is the pave stone for further structure optimization of two-phase microchannel heat sinks. However, previous studies paid few attentions to the effect of different structural parameters on its flow performance, especially for the application with long channels for practical evaporators in aircraft environmental control systems. In this paper, an experimental system was set up to investigate the flow boiling pressure drops of refrigerant R134a in a 300 mm long channel with micro pin fin arrays. The flow characteristics of staggered diamond pin fin arrays with different channel widths of 1.0, 1.2 and 1.4 mm and fin angles of 30°, 60°and 90° were comprehensively investigated. The pin fins with a height of 0.5 mm were arranged in the rectangular channel through 3D printing. Two-phase pressure drops in the test section were then measured. The test range of vapor quality, mass flux, heat flux and saturation pressure were 0–1, 200–500 kg/m2s, 10.0–37.5 kW/m2 and 390–700 kPa respectively. Experimental results revealed that the smaller channel width and the greater diamond angle resulted in the greater two-phase pressure drops. The heat flux showed an insignificant influence on the two-phase pressure drops. The existing empirical correlations for pressure drops were evaluated and failed to predict the present experimental data. A new one with the consideration of pin fin structure parameters was then developed to improve the prediction accuracy with the maximum mean absolute deviation of 5.4 %. The proposed correlation can illuminate future study on flow boiling in mini channel with pin fin arrays and be beneficial for the practical design of two-phase microchannel heat sinks.

Parametric study for optimizing double-layer microchannel heat sink for solar panel thermal management

The most significant issue affecting the electric efficiency of solar panels is overheating. Concentration photovoltaic (CPV) modules work by converting approximately 80% of sunlight to heat; this may exceed the cell operating temperature limits. Therefore, thermal management is the best choice for keeping such panels working under specified conditions. Prior to producing an actual solar indoor unit, the current research primarily focuses on optimizing the heat sink dimensions that affect the cooling performance of the solar panel. Two parametric studies were employed to optimize the microchannel heat sink design. First, a two-dimensional numerical study was implemented to optimize the best channel height for more uniform flow inside a double-layer microchannel heat sink (DL-MCHS); the width of channels was kept as a constant value. Second, a three-dimensional conjugate heat transfer model for fluid flow in the optimized heat sink was used to optimize the inlet/outlet header length. To evaluate the overall CPV performance, a further numerical case study was carried out for the optimized designs at a wide range of inlet mass flow rates and steady-state heat flux. The findings indicated that a channel height of 0.5 mm and a header length of 20 mm were the best design points for the suggested heat sink. To assess the effectiveness of a solar/thermal module, the selected design points were applied to a 3D model. The maximum electricity efficiency measured was 17.45%, nearly 40% greater than the typical CPV/T system.

Local hotspot thermal management improved by ionic wind generator coupled with porous materials

Ionic wind is induced by corona discharge caused by extremely inhomogeneous electric field between two electrodes. Due to its compact size, energy saving, flexible design, and easy integration, ionic wind technique exhibits great potential to improve hotspot cooling, especially for compact electronic devices. However, the heat removal capability towards high power density is relatively low due to the limited heat transfer area and low air thermal conductivity. The principle and designs are still lacking for local hotspot cooling. Here, an ionic wind generator with a novel architecture coupled with porous medium is conceived to enhance cooling performance. It is demonstrated that when a porous medium block is coupled, heat transfer can be significantly boosted due to the modified heat and mass transfer in the porous block. It is also found that electrode configuration significantly influences the device performance. There is a trade-off between heat transfer area and airflow impediment in the device. The geometry and property parameters of the porous block are critical for the cooling performance, which is attributed to the modified flow field by changing porous structure. Based on this principle, another ionic wind generator improved by a coupled heat sink with porous fins is proposed, whose performance can be further enhanced by optimizing its design parameters. The optimized heat sink structure can maintain the max temperature of the cooling surface below 83.2 °C at a heat flux of 90 kW/m2. This study provides a promising way for air-side thermal management of hotspot. The findings are helpful for understanding EHD-induced airflow heat transfer in porous medium and shed new light on designing ionic wind generators with better performance.

Optimization of a boron nitride nanotubes nanofluid-cooled microchannel heat sink at different concentrations

The microchannel heat sink (MCHS) has become the most relevant micro-heat exchanger for a small area in need of an effective high heat removal system. However, heat dissipation from the microchips where the MCHS is utilized—the microprocessor and microcontroller—is getting higher with the sizes getting smaller. A more effective coolant is needed to address the increasing heat load from the microchip and nanofluid, nanosized particles dispersed in a base fluid, is among those explored. This paper reports a new potential use of non-metallic nanofluid, boron nitride nanotube (BNN), that is capable of improving the overall performance of a rectangular MCHS. A heuristic method, multi-objective genetic algorithm (MOGA), is employed to simultaneously minimize the thermal resistance and pressured drop of a boron nitride nanotubes (BNN) nanofluid-cooled MCHS to obtain optimized dimensions at various mass concentrations. The method is capable in achieving conflicting objectives, minimization of the thermal resistance and the pressure drop; an increase in the former decreases the latter and vice versa. In addition, experimental thermophysical properties of the BNN nanofluid are used to provide reliability to the optimization outcomes in identifying the best BNN concentration for cooling of a MCHS at 50 °C. The optimization results showed that as the thermal resistance decreases, the pressure drop decreases. For mass concentrations of 0.001, 0.003, 0.005, 0.01 and 0.03% the thermal resistance is the lowest, 0.0711 K/W at 0.01 mass.%. at 0.0115 W. The thermal resistance is lowered by 5.34% compared to water for the same operating conditions. These results indicate the great potential of BNN nanofluid as a coolant in the electronics cooling system. Optimization with the MOGA provides a fast analysis into the potentials of any coolants for MCHS applications as shown here, reliability being provided by experimentally obtained thermophysical properties.

Machine learning-based optimization of air-cooled heat sinks

Machine learning-based models using Artificial Neural Network (ANN) and greedy search algorithm are used to optimize air-cooled parallel plate-finned heat sinks (PPFHSs) subjected to laminar flow over an extensive range of design parameters. The thermal and hydraulic performances of PPFHSs are represented by heat transfer coefficient h and pressure dropΔP, respectively. Optimization objectives for PPFHS designs can vary from industry to industry depending on their design priorities. The present study proposes a novel and generalized optimization method that defines practical optimization objectives and provides an accurate optimization process to design effective PPFHSs for a wide range of industrial applications with different design requirements. Three optimization objectives are presented in this study: (i) the largesth/ΔP, (ii) the largest h within a specified maximum allowed flow rate, and (iii) the lowest weight that maximizes h for operation within the maximum allowed flow rate. While the shortcoming of the first objective is demonstrated, the other two objectives are found to be suitable for designing effective heat sinks (HSs) across different applications. Results suggest a promising trend from the third objective to develop HSs with ∼ 37–68% lower weight, 80–85% reducedΔP, and negligible penalty in h compared with optimized HSs obtained from the second objective. However, since the third objective leads to HSs with thinner fins, structural analysis should be performed to ensure reliable operation of the HSs.

Heat transfer efficiency optimization of a multi-nozzle micro-channel heat sink utilizing response surface methodology

Optimum heat transfer in modern micro-channel heat sinks (MCHSs) plays a considerable role in ameliorating the efficiency and power of these devices. The response surface methodology (RSM) is one of the recently developed techniques to study and optimize the thermal and hydraulic behaviors of the MCHSs. In the current investigation, a multi-nozzle MCHS with circular fins on both sidewalls of the micro-channels was elected to analyze. The RSM method predicted the Nusselt number ( Nu ) of the MCHS and pressure drop (ΔP) of the coolant (the responses of the model). The diameter, the longitudinal pitch, and the transverse pitch of the circular fins were considered as the independent variables. These variables were changed in the ranges of 0.02–0.06 mm (diameter), 0.1–0.4 mm (longitudinal pitch), and 0.1–0.2 mm (transverse pitch). The impact of changing the mentioned variables on Nu and ΔP of the coolant to achieve the higher cooling capacity was studied. At first, Nu and ΔP values were calculated by the numerical procedure and then predicted by the RSM. Comparing the values derived by the numerical and the RSM models, it was observed that the values predicted by the RSM were close to the ones calculated by the numerical simulation. The RSM model with the coefficient of determination of 97.51% and 98.74% for Nu and ΔP could predict these responses accurately.

A 380 V/50 kVar SiC-SVG Achieving a Power Density of 1.652 kVar/L With the Optimization of Heatsink and Output Filter Volume

With the rapid development of new energy vehicles, 5G facilities, electric aircraft, and new energy power generation, the high-power-density inverters are developed rapidly. A comprehensive optimization method combining heatsink and inductance filter was proposed in this article. Based on accurate thermal modeling and magnetic modeling, the method proposed chose an optimized switching frequency to minimize the volume of the inverters by compromising the design of the heatsink and inductor volume. Among them, a model of multichip forced air-cooling heatsink was proposed to reduce the size of the heatsink, and the comprehensive thermal resistance error of the proposed model is within 2%. The structure of the grid-connected filter and the inductor model is analyzed showing that the single inductor L-filter has a smaller size and more stability than the LCL-filter at a high switching frequency. The comprehensive optimization method proposed was implemented by 380-V/50-kVar SiC-static var generator (SVG) with the 50-kHz switching frequency, and its topology is a two-level inverter with a single inductor filter. This SiC-SVG reached a volume of 30.2 L (including all components required for mainstream products), which is 50% lower than insulated gate bipolar translator (IGBT)-SVGs. Its efficiency is 98.5% at full load, which is 1.5% higher than IGBT-SVGs. The experiments and temperature rising tests at full load proved the feasibility of the comprehensive optimization method.

Thermal performance enhancement of a new dual-PCM heat sink using two-objective optimization

Phase change materials (PCMs) can effectively improve the performance of electronic heat sinks especially when subjected to intermittent heat loads. PCMs however brings some shortcomings such as increased size of component, and slowed heat rejection during the discharging, which urged the inevitability in development of optimized design. This study presents the results of the two-objective shape optimization of a new dual-PCM heat sink. The cooling phenomenon is analysed with thorough and realistic consideration of heat loss through the fin tips to the ambient, as well as heat transfer between the PCM and the air above it. Natural convection of liquid PCM and its volume variation during phase change transition are taken into account. Two-objective optimizations are performed to maximize the heat sink operational time in the charging process and minimize the discharging time, for three critical temperatures of 50 °C, 65°C, and 80 °C. Response Surface Methodology (RSM) is utilized to attain this goal. The fin thickness, the fin height, the width of ducts and the base thickness are selected as design parameters. The optimum volumetric percentages of PCM are found to be 80.50%, 76.94% and 74.81% for set point temperatures (SPTs) of 50 °C, 65 °C, and 80 °C, respectively. The optimized designs for three SPTs deliver charging periods up to 7% longer and discharging periods up to 4.2% shorter than the reference geometry. Furthermore, total volume of the heat sink is decreased up to 23% due to current optimizations, signifying a favourable compact design.

Parametrized level set method for a coupled thermal–fluid problem using radial basis functions

This paper develops a parametric level set-based topology optimization method for the micro-channel heat sink design. In this study, the optimal objective functional is formulated as a bi-objective functional consisting of heat transfer maximization and pressure drop minimization based on the two- and three-dimensional steady-state Navier–Stokes and energy balance equations. The normal velocity of the interface propagation, which is derived from the steepest descent method and adjoint variable method, is used to drive the evolution of the level set function. Influence of the governing equations on the optimized heat sink structure and the distribution characteristics of adjoint variables are analysed through numerical experiments, which proved that governing equations can improve the heat dissipation capacity of the optimal structure. Based on Earth Mover’s Distance, the developed method is proved to have less dependence on initial structures compared with the density-based topology optimization method. Finally, through the experimental tests and numerical simulations, the effectiveness of the developed model is confirmed.

Optimization of an air-cooled heat sink for cooling of a solar photovoltaic panel: A computational study

Rapidly increasing global energy demand and resulting climate change effects have enhanced the integration of renewable systems such as solar photovoltaics into the built environment. For countries with hot climates, despite vast applications and numerous technological advancements, lower efficiencies of the solar panels due to high temperature is still a major disadvantage affecting the feasibility of using photovoltaic technology. This study analyses the cooling performance of air-cooled heat sinks for the climate of Dubai, UAE, using Computation Fluid Dynamics (CFD). A stepwise optimization study was conducted to investigate the effects of varying fin spacing, baseplate thickness, fin height and fin thickness on the heat dissipation rate. Further, the elemental properties of the heat sink were studied by altering its material to aluminium. The base-model heat sink could reduce PV cell temperature by 27 °C in an ambient temperature of 42 °C. The optimized fin spacing, baseplate thickness, fin height and fin thickness of 7, 0.0025 m, 0.12 m and 0.002 m further reduced the average panel temperatures by 3.5%, 4% and 9% respectively. The use of copper as an effective heat sink material was concluded compared to aluminium that conversely increased the average panel temperature by 2% despite the use of optimized heat sink structure.

Multi-objective optimization of microchannel heat sink with Cantor fractal structure based on Pareto genetic algorithm

Multi-objective optimization of microchannel heat sink with Cantor fractal structure based on Pareto genetic algorithm

New Optimal Heat Sink Design with Concave Fins for Cooling System in Light Emitting Diode Lamp

New Optimal Heat Sink Design with Concave Fins for Cooling System in Light Emitting Diode Lamp