Optimization Of Heat Sink Research Articles

Thermally Developing Flow and Heat Transfer in Elliptical Minichannels with Constant Wall Temperature.

Laminar convective heat transfer of elliptical minichannels is investigated for hydrodynamically fully developed but thermal developing flow with no-slip condition. A three-dimensional numerical model is developed in different elliptical geometries with the aspect ratio varying from 0.2 to 1. The effect of Reynolds number (25 ≤ Re ≤ 2000) on the local Nusselt number is examined in detail. The results indicate that the local Nusselt number is a decreasing function of Reynolds number and it is sensitive to Reynolds number especially for Re less than 250. The effect of aspect ratio on local Nusselt number is small when compared with the effect of Reynolds number on local Nusselt number. The local Nusselt number is independent of cross-section geometry at the inlet. The maximum effect of aspect ratio on local Nusselt number arises at the transition section rather than the fully developed region. However, the non-dimensional thermal entrance length is a monotonic decreasing concave function of aspect ratio but a weak function of Reynolds number. Correlations for the local Nusselt number and the thermal developing length for elliptical channels are developed with good accuracy, which may provide guidance for design and optimization of elliptical minichannel heat sinks.

Optimization of heat sink for thyristor using particle swarm optimization

Abstract The objective of this work is to optimize the geometry of the heat sink, which improves the performance. The geometrical parameter chosen for optimization is fin gap. The heat sink is under the condition of natural convection. The optimization method used is particle swarm optimization (PSO). Entropy generation minimization is the objective function. The constraints are set according to the design requirements. The idea of entropy generation minimization is employed to combine the effects of thermal resistance and pressure drop within the heat sink. The optimization problem is solved with the help of MATLAB. The optimized fin gap obtained is b ​= ​6.5 ​mm. The value of entropy generation is 21.4365 ​W/K.

The Application of Evolutionary Algorithms in Multi-Objective Design and Optimization of Air Cooled Heatsinks

Abstract Genetic algorithms (GAs) are considered to be one of the main types of evolutionary algorithms (EAs) and are being increasingly used in various engineering design applications. To a large extent, plate-fin heatsinks are used in the thermal management of compact electronic equipment and data centers. The shape optimization of the heatsinks is not rigorously investigated during the design process of high power electronics. Any improvements in the effectiveness of the heatsinks impact the energy consumed by large-scale information communication technology (ICT) facilities including data centers and telecommunication systems and promote a more sustainable use of raw materials. This paper investigates the optimization of plate-fin heatsinks by modifying the fin layout in a forced crossflow using a multi-objective genetic algorithm (MOGA) combined with computational fluid dynamics (CFD) simulations. The main objective is to improve the heat dissipation rate by modifying geometric parameters, i.e., the number, arrangement, and orientation of fins. For a generic heatsink test case, the optimized performance is examined in terms of thermal resistance, turbulence intensity, pumping power, coefficient of performance, and Chilton–Colburn j-factors. Among all of the cases investigated, the input parameter optimization configurations which coupled and rotated fins in groups of ten proved to be the most successful. For one case, an 18% increase in the effectiveness of heat dissipation is reported. However, when weight reduction was considered by dividing by the unit mass, the designs in one of the investigated families which remove a number of fins from the heatsink outperformed the rest, achieving improvements of 65% over the baseline.

Performance Evaluation and parametric optimization of a Heat Sink for Cooling of Electronic Devices with Entropy Generation Minimization

Thermal management is essential for electronics products. Experimental and CFD analysis of a heat sink for thermal management are represented. After analysis, compared with the experimental and computation analysis. Also, Entropy generation model, fluid flow model and heat transfer model are described. Total entropy generation calculated Sgen and entropy generation minimization are done for best utilization of heat sink for cost, size and better power management. Optimized heat sink by two method one Parametric Optimization and other Multi-variable optimization for minimizing entropy generation. From the results behaviour of mass flow rates with temperature, velocity, pressure drops and other parameters are analysed. The maximum temperature is located at heated base surface of heat sink, below the channel outlet, due to the low velocity of the fluid flow and resulting high concentration of heat flux. The combined conduction–convection heat transfer in the heat sink produces very complex three-dimensional heat flow pattern with large, longitudinal, upstream directed heat recirculation zones in the highly conducting aluminium materials, where the fluid and solid are in direct contact. A detailed description of the average heat transfer coefficient, temperature, heat flux and Nusselt number was obtained. The goal of this research is to find the cooling of heat sink at minimum entropy generation for saving energy and sustainable development.

Optimization of Horizontal Rectangular Fin Heat Sink: a CFD with Response Surface Analysis and Parametric Study

In this article, a CFD analysis is performed on rectangular fin heat sink, which is used for electronic cooling applications. A steady-state heat transfer through natural convection is considered in this model. It focuses on thermal analysis of rectangular heat sink with aluminum as a material, by varying different parameters like temperature difference between fin base temperature (53–105 °C) and ambient temperature (20 °C), fin spacing (2–20 mm), fin height (25–100 mm), fin length (2–100 mm) and fin thickness (1–5 mm). The 3D elliptic governing equations of laminar flow and heat transfer are solved through the CFD tool ANSYS Fluent 15. Initially, a parametric study of fin is performed for obtaining orthogonal effect of input parameters on heat transfer coefficient (HTC) at fin base temperature 53 °C. Based on the parametric study, range of parameters is set for performing design of experiments (DOE) using ANSYS Design explorer 15. Response surface is generated between the geometrical fin parameters and HTC using DOE. Multi-objective genetic algorithm optimization is performed with the objective to maximize heat flux and HTC. Optimized values of geometrical parameters for maximum heat transfer are predicted using response surface.

Topology optimization of microchannel heat sinks using a two-layer model

This paper investigates the topology optimization of microchannel heat sinks. A two-layer heat sink model is developed allowing to do topology optimizations at close to two-dimensional computational cost. In the model, reduced two-dimensional fluid dynamics equations proposed in the literature based on a plane flow assumption are adopted. By assuming a fourth-order polynomial temperature profile of the heat sink thermal-fluid layer and a linear temperature profile in the substrate, two-dimensional heat transfer governing equations of the two layers are obtained which are thermally coupled through an out-of-plane heat flux term. Topology optimizations of a square heat sink are carried out using the two-layer model. Comparison with a three-dimensional conjugate heat transfer analysis of optimized designs in COMSOL Multiphysics validates the accuracy of the two-layer model. The re-evaluation of an optimized design by a one-layer model commonly seen in the literature shows the inadequacy of the one-layer model in predicting physical fields properly. In addition, the influence of physical and optimization parameters on the layout complexity of optimized designs is studied and related to the Peclet number. Optimizations under diffusion-dominated conditions are performed and typical optimized topologies for heat conduction structures are seen.

A theoretical simulation model for optimization of fins on the shell of a hermetic reciprocating compressor

The cost of a hermetic reciprocating compressor is quite dependent on the electric motor employed to drive it. Usually, the higher the motor efficiency, the higher the costs. Therefore, some compressors are designed to operate with low-efficiency electric motors. The main difficulty in such a case is to ensure that the motor operates at a temperature below the upper threshold. This paper presents a simulation model for optimization of fins on the shell of a hermetic reciprocating compressor which operates with a low-efficiency motor. The objective of the simulation is to obtain a set of fins with minimum volume that allows the compressor to operate under a critical operating condition without overheating the electric motor. The simulation model is implemented by coupling a lumped-parameter thermal simulation model of the reciprocating compressor with an optimization algorithm. The results of the thermal simulation are validated with experimental data. Different fin profiles are considered in the analysis. It is concluded that the optimum heat sink solution is conditioned to the minimum fin thickness or to the minimum fin diameter allowed, which are dependent on other compressor design constraints.

Fluid Flow and Entropy Generation Analysis of Al2O3-Water Nanofluid in Microchannel Plate Fin Heat Sinks.

The flow in channels of microdevices is usually in the developing regime. Three-dimensional laminar flow characteristics of a nanofluid in microchannel plate fin heat sinks are investigated numerically in this paper. Deionized water and Al2O3–water nanofluid are employed as the cooling fluid in our work. The effects of the Reynolds number (100 < Re < 1000), channel aspect ratio (0 < ε < 1), and nanoparticle volume fraction (0.5% < Φ < 5%) on pressure drop and entropy generation in microchannel plate fin heat sinks are examined in detail. Herein, the general expression of the entropy generation rate considering entrance effects is developed. The results revealed that the frictional entropy generation and pressure drop increase as nanoparticle volume fraction and Reynolds number increase, while decrease as the channel aspect ratio increases. When the nanoparticle volume fraction increases from 0 to 3% at Re = 500, the pressure drop of microchannel plate fin heat sinks with ε = 0.5 increases by 9%. It is demonstrated that the effect of the entrance region is crucial for evaluating the performance of microchannel plate fin heat sinks. The study may shed some light on the design and optimization of microchannel heat sinks.

Forced convective heat transfer optimization of plate-fin heat sink with insert-induced turbulence

The flow across the plate-fin heat sink under the influence of 2D planar space-filling square fractal grid-induced turbulence at Reynolds number ReDh of 2.0 × 104 is numerically characterized. Fractal thickness ratio tr, plate-fin inter-fin distance δ and grid-fin separation ℓ are numerically explored and optimized via Response Surface Optimization (RSO) with the objective of maximizing the Nusselt number Nu. Results reveal that, thanks to highly interactive, small and comparable turbulence length scale Lt, strong turbulence intensity Tu and high velocity adjacent to the fin surfaces, thermal dissipation of plate-fin heat sink enhances significantly. An optimum fractal grid and plate-fin geometrical combination having tr = 9.77, δ = 0.005 m and ℓ = 0.01 m is proposed. It delivers Nu of 3661.0 which is 6.1% and 16.3% greater than the reference case and least favorable configuration, respectively. Sensitivity analysis discovered that δ effectively dominates the thermal dissipation improvement while tr contributes the most on the pressure drop. Interestingly, fractal grid may not necessarily augmenting plate-fin forced convective heat transfer. Without proper-tuning the fluid flow structures within the fins may worsen the thermal dissipation instead of strengthening it. In short, the interaction between plate-fin heat sink and the fluid flow structures within the fins contributes greatly to heat transfer performance.

Optimal design of a natural convection heat sink for small thermoelectric cooling modules

Metal additive manufacturing technologies are increasingly being adopted for rapid prototyping and to build geometrically complex designs for thermal management. This paper develops and experimentally validates a numerical model to design a high performance, small-scale heat sink for use with a thermoelectric cooling cap. The design was constrained by a heat load of 2.15 W, and a target average base temperature of 45 °C as a compromise between avoiding burn injury and reducing heat dissipation requirements. Over successive numerical iterations, an optimal natural convection heat sink was developed with an estimated thermal resistance of 10.9 K·W−1 and base temperature of 44.4 °C. This design featured an internal cavity in a tapered pin array, and was able to achieve a steady state base temperature that was 11.7 °C cooler than a conventional design, with 51% less surface area and significantly less material.

Automated Heatsink Optimization for Air-Cooled Power Semiconductor Modules

Heatsink design is critical for power density and reliability enhancement of power semiconductor modules. In this letter, an automated design and optimization methodology for air-cooled heatsinks are proposed based on genetic algorithm and finite element analysis. While the genetic algorithm generates a population of candidates with complex heatsink cross-section geometry in each iteration, finite element analysis is used to evaluate the fitness function of individual heatsink, i.e., junction temperature of semiconductor devices. With the rule of “survival of the fittest,” the proposed methodology eventually converges to an optimum heatsink design with the lowest device junction temperature. The optimized heatsink is fabricated through three-dimensional printing technology for thermal performance evaluation. Simulation and experimental evaluations have been conducted based on a 50-kW three-phase air-cooled inverter with the fabricated heatsinks. The comparative evaluation results show that the optimized heatsink is superior over a customized solution by 27% less in size and 6% lower in junction temperature.

The Effectiveness of the Unit Cell Method in Numerically Modeling and Designing Liquid Cooled Heatsinks

This study compares two numerical strategies for modeling flow and heat transfer through mini- and microchannel heatsinks, the unit cell approximation, and the full 3D model, with the objective of validating the former approach. Conjugate heat transfer and laminar flow through a 2 × 2 cm2 copper–water heatsink are modeled using the finite element package COMSOL Multiphysics 5.0. Parametric studies showed that as the heatsink channels’ widths were reduced, and the total number of channels increased, temperature and pressure predictions from both models converged to similar values. Relative differences as low as 5.4% and 1.6% were attained at a channel width of 0.25 mm for maximum wall temperature and channel pressure drop, respectively. Due to its computational efficiency and tendency to conservatively overpredict temperatures relative to the full 3D method, the unit cell approximation is recommended for parametric design of heatsinks with channels’ widths smaller than 0.5 mm, although this condition only holds for the given heatsink design. The unit cell method is then used to design an optimal heatsink for server liquid cooling applications. The heatsink has been fabricated and tested experimentally, and its thermal performance is compared with numerical predictions. The unit cell method underestimated the maximum wall temperature relative to experimental results by 3.0–14.5% as the flowrate rose from 0.3 to 1.5 gal/min (1.1–5.7 l/min).

Numerical analysis and parametric optimization on flow and heat transfer of a microchannel with longitudinal vortex generators

In this paper, a three dimensional (3D) numerical model of a rectangular microchannel with longitudinal vortex generators (LVGs) is developed. The impacts of length, width, longitudinal spacing, and number of LVG pairs are discussed. To improve the flow and heat-transfer performance, the Taguchi method is employed for optimization. Three evaluation indexes—Nusselt number (Nu), Fanning friction factor (f), and overall efficiency (η)—are selected. The analysis of the influence degree of the geometric parameters of LVGs are carried out by intuitive analysis of the Taguchi method results, and the optimum combinations of geometric parameters are also determined. Also, the second-order dimensionless correlations involving multiple impact factors are obtained through response surface analysis. Results show that the number and longitudinal spacing of LVG pairs are the main impact factors for Nu. Regarding the flow resistance, the number and length of LVGs have a much stronger influence than other parameters. Two optimum combinations for Nu and overall efficiency are acquired, which achieve a 23.6% and 7.2% increase for Nu and overall efficiency, respectively, compared with the original model. The maximum differences between the correlations and test models are less than 15% for all of the evaluation indexes. The present investigation can be beneficial for the design and optimization of LVGs-enhanced microchannel heat sinks.

Experimental investigation on the effect of heat sink temperature on operational characteristics of a new-type loop heat pipe

Abstract With the development of the miniaturization and the high integration of electronic chip, the thermal management of the high power electronic becomes a major challenge. In this paper the influence of heat sink temperature on operational characteristics was comprehensively conducted and the 35% of charging ratio was selected through the experiment study. To evaluate the LHP system, temperatures, start-up time, thermal resistance, and evaporator heat transfer coefficient were selected as performance indicators. The result showed that, there existed an optimal heat sink temperature (18°C) to obtain the lowest evaporator bottom temperature (77°C), the shortest start-up time (1000s), the smallest thermal resistance (0.29k/W), and the highest evaporator heat transfer coefficient (3.1 × 104 W/(m2·k)). The temperature range to keep a high performance of LHP system was 14-20°C. The conclusion obtained through the experiment can provide the reference of design the cooling system when the LHP system applied into the electric cooling.

Pressure Drop of Microchannel Plate Fin Heat Sinks.

The entrance region constitutes a considerable fraction of the channel length in miniaturized devices. Laminar slip flow in microchannel plate fin heat sinks under hydrodynamically developing conditions is investigated semi-analytically and numerically in this paper. The semi-analytical model for the pressure drop of microchannel plate fin heat sinks is obtained by solving the momentum equation with the first-order velocity slip boundary conditions at the channel walls. The simple pressure drop model utilizes fundamental solutions from fluid dynamics to predict its constitutive components. The accuracy of the model is examined using computational fluid dynamics (CFD) simulations and the experimental and numerical data available in the literature. The model can be applied to either apparent liquid slip over hydrophobic and superhydrophobic surfaces or gas slip flow in microchannel heat sinks. The developed model has an accuracy of 92 percent for slip flow in microchannel plate fin heat sinks. The developed model may be used to predict the pressure drop of slip flow in microchannel plate fin heat sinks for minimizing the effort and expense of experiments, especially in the design and optimization of microchannel plate fin heat sinks.

Three-objective shape optimization and parametric study of a micro-channel heat sink with discrete non-uniform heat flux boundary conditions

A water-cooled multi-die heat sink with parallel rectangular micro-channels was designed to satisfy the operational requirements of a multi-die processor. A shape optimization strategy based on the RSM (response surface method) was used to minimize pressure drop and die maximum case temperatures. The effects of the thermal interface materials and heat spreader between the dies and heat sink were captured by the numerical simulation. The optimization was performed for constant values of coolant flow rate and inlet temperature, as well as the power, location, and surface area of the dies. The influence of channel hydraulic diameter, Reynolds number, thermal entrance length, and total heat transfer surface area on the hydraulic and thermal performance of the heat sink was determined using CFD (computational fluid dynamics) simulations at RSM design points. A sensitivity analysis was performed to evaluate the effect of the design parameters on the response parameters. The optimum designs were achieved by minimizing a weighted objective function defined based on response parameters using JAYA algorithm. The results of weighted sum method were compared with Pareto based three-objective optimization with a NSGA-II (non-dominated sorting GENETIC algorithm). Finally, a parametric study was performed to see the effect of the design parameters on the response parameters.

Development of a Thermally Aware-Compact Model With an Optimized Heat Sink for FinFETs

In this letter, we develop a compact thermal model that can predict changes in the threshold voltage and drain current because of the junction temperature, Δ $T_{J}$ , and its effect on a circuit performance by using circuit simulators. In addition, we propose a thermally aware layout methodology for FinFET-based digital circuits. Although heat sinks (called “via pillars”) are generally used for heat dissipation in FinFETs, these features increase the parasitic capacitance and power consumption. Therefore, we propose an optimized heat sink that is only on the critical node (showing high activity and drain–source voltage, $V_{DS}$ ) and uses high metal stacks up to metal 5. With the optimization of this heat sink, we observe that the $T_{J}$ of a 4-input NAND gate can be reduced about 3.2% while the oscillation frequency of an 11-stage ring oscillator can be increased about 12%, compared to conventional heat sinks.

Optimal shape design of a minichannel heat sink applying multi-objective optimization algorithm and three-dimensional numerical method

In the present study, an optimal laminar flow minichannel heat sink (MCHS) has been determined through three-dimensional simulations and the multi-objective optimization algorithm. The cross-sectional shape described by six variables is optimized by the multi-objective genetic algorithm (MOGA) and multi-objective particle swarm optimization (MOPSO). During the optimization, the thermal resistance θ and pumping power P are two conflicting objectives for evaluating the performances of the MCHS. After obtaining the non-inferior solutions, the technique for order preference by similarity to an ideal solution (TOPSIS) is applied as a decision-making method to determine the best compromise one. Results indicate that the TOPSIS can effectively reduce the P of the Pareto solutions without significantly increasing θ. Compared with the straight channel, the TOPSIS optimal solution could reduce θ by 7.47% or P by 31.54%. Meanwhile, the mechanism of performance improvement is analyzed by comparing the TOPSIS optimal solution and the straight channel with the same P. It is observed that the optimized channel shape changes the fluid distribution by increasing the heat transfer coefficient slightly and the heat transfer area by 12.22%, respectively.

Topology optimization and heat dissipation performance analysis of a micro-channel heat sink

Junction temperature in the electronic packaging process is one of the critical factors affecting the service life of electronic devices. A micro-channel heat sink is a common heat dissipating device used to reduce the thermal resistance between components and substrate. In order to maximize the heat dissipation while minimizing the pressure drop, this paper adopts a topology optimization method. A material interpolation method based on variable density principle is used together with a moving asymptote algorithm for the optimization. The physics is governed by the heat and mass transfer, coupled with the momentum conservation in the fluid. Four parameters are varied in order to investigate their influence on the optimization process. A three-dimensional geometry has been constructed to study the flow field and the results are compared to a reference case to verify the temperature uniformity and thermal performance of the model. It is demonstrated that the optimized design of the micro-channel heat sink is reliable and effective.

Thermal Optimization of Heat Sink for Inverter Applications

Power inverters enable efficient conversion of DC voltage and current to AC voltage and current and are intermediate device in renewable energy technology application especially solar, wind and thermoelectric energy. The key technologies behind power inverters switching operation are the semiconductor devices such as the IRF 3205 MOSFET chip. During operation the switches dissipate heat and if the dissipated heat is not properly managed, thermally induced failure may occur. The research work involves generation of a heat sink model and its optimization for a 24VDC/2.5K.V.A inverter. The thermal resistance, fval, of the optimized heat sink was found to be equal to 0.0345 °C/W which is less than the thermal resistance of the heat sink to ambient of the IRF 3205 MOSFET switch of 0.5063 °C/W. The thermal management of the power inverter package yields experimental and modeled package temperatures of 34.7°C and 36.5°C respectively. The optimized heat sink using the model created leads to reduction in size, weight and reliable operation of the power inverter.