Optimization Of Heat Sink Research Articles

An optimal design problem in determining non-uniform fin heights and widths for an impingement heat sink module

A three-dimensional optimal design problem is examined in this study using a general purpose commercial code (CFD-ACE+) and the Levenberg–Marquardt Method (LMM) to estimate the optimal shape of an impingement cooling heat sink using different design variables. In optimal heat sink design #1, the non-uniform fin widths are taken as the design variables, and in optimal heat sink design #2, the non-uniform fin widths and heights are chosen as the design variables. The objective of this study is to minimize the thermal resistance (Rth) of the fin array and to obtain the optimal dimensions of optimal heat sinks #1 and #2. The experimental results demonstrated that by utilizing the fabricated heat sinks and operating under the design condition Re = 5000, Rth can be decreased by 4.06% and Nu and COE can be increased by 4.23% and 4.20%, respectively, for optimal heat sink #1 compared to the original fin array. For optimal heat sink #2, Rth can be decreased by 10.53% and Nu and COE can be increased by 11.65% and 11.70%, respectively, compared to the original fin array. Consequently, the thermal performances of optimal impingement heat sinks can be greatly improved.

Optimization of a Refrigerant Base Nanofluid-Cooled Microchannel Heat Sink with Pumping Power Consideration

In this paper, the optimization of a nanofluid-cooled microchannel heat sink was reported. Al2O3-NH3 with three different volume fractions (1 %, 3 % and 5 %) was examined. An optimization scheme which is comprised of two objective functions (thermal resistance and pumping power) and the elitist non-dominated sorting genetic algorithm (NSGA-II) was employed to optimize the overall performance of the considered system. Under the same operating conditions, the ammonia-base nanofluid (Al2O3-NH3) exceeded other coolants (Al2O3-H2O and H2O) in terms of the required pumping power (0.144, 1.015 and 0.94 W for Al2O3-NH3, Al2O3-H2O and H2O, respectively). When the refrigerant base nanofluid is used as a cooling fluid, a lighter heat sink was produced. Finally, more studies should be dedicated to explore this nanofluid and the possibility of considering it for electronic systems cooling.

Role of Melt Convection on Optimization of PCM-Based Heat Sink Under Cyclic Heat Load

In this article, we study the thermal performance of phase-change material (PCM)-based heat sinks under cyclic heat load and subjected to melt convection. Plate fin type heat sinks made of aluminum and filled with PCM are considered in this study. The heat sink is heated from the bottom. For a prescribed value of heat flux, design of such a heat sink can be optimized with respect to its geometry, with the objective of minimizing the temperature rise during heating and ensuring complete solidification of PCM at the end of the cooling period for a given cycle. For given length and base plate thickness of a heat sink, a genetic algorithm (GA)-based optimization is carried out with respect to geometrical variables such as fin thickness, fin height, and the number of fins. The thermal performance of the heat sink for a given set of parameters is evaluated using an enthalpy-based heat transfer model, which provides the necessary data for the optimization algorithm. The effect of melt convection is studied by taking two cases, one without melt convection (conduction regime) and the other with convection. The results show that melt convection alters the results of geometrical optimization.

An impingement heat sink module design problem in determining optimal non-uniform fin widths

A three-dimensional inverse design problem is examined in this study for estimating the optimal non-uniform fin widths of an impingement heat sink module using a general purpose commercial code (CFD-ACE+) and the Levenberg–Marquardt Method (LMM). The optimal heat sink was designed based on the original 10 by 10 squared fin array with a fixed fin volume and height. The objective of this study is to minimize the thermal resistance (Rth) of the fin array and to obtain the optimal dimensions of non-uniform fin widths. The results obtained using the LMM to solve this three-dimensional fin design problem were initially justified numerically. Under the design operating condition Re=5000, Rth can be decreased by 12.98% and 4.81% compared to the original and to Yang and Peng’s optimal heat sinks, respectively. At the same time, the thermal performances of the optimal heat sink can be improved significantly. For instance, the Nusselt number (Nu) and the Coefficient of Enhancement (COE) can be increased by 14.92% and 15%, respectively, compared to the original heat sink, and these parameters can be increased by 5.06% and 3%, respectively, when compared to the optimal heat sink proposed by Yang and Peng. Finally, prototypes of the original and optimized heat sinks were fabricated and used to experimentally verify the validity of this work. The experimental results demonstrated that by utilizing the fabricated heat sinks and operating under the design condition Re=5000, Rth can be decreased by 12.49% and Nu and COE can be increased by 14.21% and 14%, respectively, compared to the original fin array. Consequently, the thermal performances of optimal impingement heat sinks can be greatly improved.

Thermal optimization of water heat sink for power converters with tight thermal constraints

The aim of this work is to show how it is possible to improve the reliability of a power converter by means of thermal–fluid dynamic numerical analysis. Power electronic converters such as those for High Energy Physics Experiments (HEPEs), must operate in hostile environment with tight thermal constraints and the reliability must be high because of the inaccessibility during the experiments and the high costs of the overall setup. Due to the high power density, the presence of closed environments and the requirement of non-thermal interaction with other subsystems, a liquid cooling system is mandatory. 3D FEM and/or FVM simulations can be used to analyze thermal fluid dynamic behavior of those systems and can be a useful support to design heat sinks optimized for specific applications. We show a comparison of different heat sink solutions to improve the thermal management of a 1.5kW DC/DC hybrid power module.

Numerical Optimization of Pin-Fin Heat Sink with Forced Cooling

Numerical Optimization of Pin-Fin Heat Sink with Forced Cooling

Development of heat sink device by using topology optimization

Small scale fluid flow systems have been studied for various applications, such as chemical reagent dosages and cooling devices of compact electronic components. This work proposes to present the complete cycle development of an optimized heat sink designed by using Topology Optimization Method (TOM) for best performance, including minimization of pressure drop in fluid flow and maximization of heat dissipation effects, aiming small scale applications. The TOM is applied to a domain, to obtain an optimized channel topology, according to a given multi-objective function that combines pressure drop minimization and heat transfer maximization. Stokes flow hypothesis is adopted. Moreover, both conduction and forced convection effects are included in the steady-state heat transfer model. The topology optimization procedure combines the Finite Element Method (to carry out the physical analysis) with Sequential Linear Programming (as the optimization algorithm). Two-dimensional topology optimization results of channel layouts obtained for a heat sink design are presented as example to illustrate the design methodology. 3D computational simulations and prototype manufacturing have been carried out to validate the proposed design methodology.

Optimization of Pin Fin Heat Sink by Application of CFD Simulations and Doe Methodology with Neural Network Approximation

A design optimization of a staggered pin fin heat sink made of a thermally conductive polymer is presented. The influence of several design parameters like the pin fin height, the diameter, or the number of pins on thermal efficiency of the natural convection heat sink is studied. A limited number of representative heat sink designs were selected by application of the design of experiments (DOE) methodology and their thermal efficiency was evaluated by application of the antecedently validated and verified numerical model. The obtained results were utilized for the development of a response surface and a typical polynomial model was replaced with a neural network approximation. The particle swarm optimization (PSO) algorithm was applied for the neural network training providing very accurate characterization of the heat sink type under consideration. The quasi-complete search of defined solution domain was then performed and the different heat sink designs were compared by means of thermal performance metrics, i.e., array, space claim and mass based heat transfer coefficients. The computational fluid dynamics (CFD) calculations were repeated for the most effective heat sink designs.

Simulation and Optimization of Cryogenic Heat Sink for Helium Gas Cooled Superconducting Power Devices

Superconducting power devices require cable terminations to be cooled within the operating cryogenic temperature range to reduce ambient heat influx. Shipboard power systems require the use of helium gas as coolant due to possible hazards by use of liquid cryogens. A model is being developed using finite element analysis to study the feasibility of a helium-gas-cooled heat sink for cable terminations. The results obtained using the COMSOL Multiphysics computing package are validated with an experimental setup. The coolant temperature and pressure drop correspond well with the theoretical results. Furthermore, the heat sink is geometrically optimized for given mass flow rate and input conditions to produce a better thermal and fluid performance in terms of temperature gain and pressure loss.

Performance analysis of a multi-functional heat pump system in cooling mode

A multi-functional heat pump system is proposed to effectively utilize waste heat and heat capacity in gray water for heating or cooling of residential buildings. Heat is also reclaimed from a plate heat exchanger installed at the discharge outlet of the compressor to provide sufficient hot water for residential use. To study the performance of this innovative system, laboratory testing has been performed with a prototype consisting of an outdoor heat pump, an indoor air handler, a gray water tank and a hot-water tank. This system is set in two environmental chambers that they mimic the outdoor and indoor environments, respectively. In this paper, the investigation of the proposed system is focused on the performance in cooling mode. The multi-functional heat pump system has been run under (i) space cooling mode and (ii) space cooling plus hot-water supply mode, with the same temperature conditions. The system performances in these two modes are compared and analyzed. The system is designed to allow four combinations of heat sinks with a water sink condenser and an air sink condenser. The four combinations are (1) air sink only, (2) water sink only, (3) air sink and water sink in parallel and (4) air sink and water sink in series, at the refrigerant cycle. Performance of the four combinations of heat sinks is experimentally investigated at a typical indoor air temperature of 26.7 °C and various outdoor air temperatures at 29.4 °C, 35 °C, and 40.5 °C. The results show that the heat sink combinations influence the cooling capacity and coefficient of performance (COP) of the system. The system performance and the optimal heat sink combination depend on the outdoor temperature. The impacts of outdoor temperature and gray water temperature on the performance of the system are discussed. The dynamic performance of the system for heating hot water from 30 °C to 48.9 °C is also studied. The proposed system has been shown providing significant energy savings in space cooling and hot-water supply. Moreover, the optimal source combination is critical in pursuing the maximum energy savings.

Thermal performance of elliptical pin fin heat sink under combined natural and forced convection

In this paper, the effects of design parameters have been experimentally investigated for the air side thermal performance under mixed (combined natural and forced) convection of the fully shrouded elliptical pin fin heat sinks and the values of optimum design parameters are sought. A theoretical model is used to predict the influence of various geometrical, thermal and flow parameters on the thermal resistance of the heat sink. An experimental measurement technique is utilized to indirectly measure the overall heat transfer coefficient of the heat sink in mixed convection with assisting flow. The thermal performance characteristics are obtained for various parameters with inline and staggered layout of the pin fin heat sinks resulting in optimum heat sink void fraction (α), and pin fin aspect ratio (ϒ). The comparative thermal performances of circular and elliptical profiled pin fin heat sinks are presented. Based on experimental data for the range of fin, air flow and heat sink parameters, with aspect ratio, 5.1⩽ϒ⩽9.18; heat sink void fraction, 0.534⩽α⩽0.884; approach velocity, 0.1⩽U∞⩽0.5; longitudinal fin pitch, 18⩽SL⩽36mm; transverse fin pitch, 9⩽ST⩽18mm; elliptical pin fin axis ratio ∊=0.66 and mixed convection parameter, 1⩽Grd/Red⩽100; generalized empirical correlations are developed for elliptical pin fin heat sink.

PLATE-FINNED HEAT SINK DESIGN

The thermal model of plate-finned heat sink is formed and described. The mathematical model of operability domain ellipsoid is created by approximating its borders. The optimization problem of heat sink mass is solved by Lagrange multipliers method. Hyperbolic model of the target function is used. The ratios for optimum mass of heat sink are found. The algorithm of heat sink design is developed. The initial approximation of standardized heat sink parameters is used. Thermal resistance is found by the numerical simulation in the systems engineering analysis. The mass and size parameters of finned and plate-finned heat sinks are compared. It is found, the optimization of finned and plate-finned heat sinks allows to reduce their weight by 2–3 times, and the volume is increased by 2 times. Optimized heat sinks have similar values of volumes; the mass of finned heat sink is less on 10 %. The using of plate-finned heat sink allows to increase the thickness of the fins on 50 % and to improve manufacturability of heat sinks elements.

Multi-objective optimization design of plate-fin heat sinks using a direction-based genetic algorithm

Heat-sink with air-cooling fan is the simplest and the most effective way to disperse generated heat of a high-tech device. A common approach to optimize heat sinks is based on the minimization of the entropy generation rate that takes the two major heat dissipation factors, heat transfer rate and air resistance, into consideration. However, a lower entropy generation rate often corresponds to a larger size of the designed heat sink. To have a balance design of heat sinks for heat dissipation, this paper considers the simultaneously minimization of the entropy generation rate and the material cost of the heat sinks. A multi-objective real-coded genetic algorithm using a novel direction-based crossover operator is developed for the formulated optimal heat sink design problem. With the proposed design framework, we compare and evaluate the performance of the plate-fins equipped with flow-through and impingement-flow air cooling systems. Extensive simulation results show that the balance design for heat sinks can achieve both the benefits of light weight and excellent heat dissipation.

Optimization of Serpentine Channel Heat Sink Based on Multi-objective Genetic Algorithm

In order to improve the efficiency of serpentine channel heat sink,optimization design must be done for it on the condition that outline dimensions of the heat sink(length,width and height) are chosen.The thermal resistance network model and pressure loss model are proposed based the discrete thermal resistance unit,which are parallel of N channels.Thermal resistance and pressure loss model are selected as objective functions,and structural parameters of heat sink are optimized in laminar flow range based on multi-objective genetic algorithm with fixed length,width and height.The variables include the number of channels,channel width and height and the velocity at the inlet.The Pareto optimal solutions are obtained after much iteration.Computational fluid dynamics simulation is performed to validate the correctness of thermal resistance model and pressure drop model.This method not only can provide some theoretical base for the optimization design of serpentine channel water-cooling heat sink,but also can be used in the engineering.

히트싱크의 자연대류 열유동 특성 분석

제품의 성능 및 신뢰성 향상을 위하여 효과적이고, 적정한 방열장치의 중요성이 지속적으로 부각되고 있다. 현재 가장 널리 쓰이는 방열장치는 알루미늄 압출식 평행핀 형상의 히트싱크(heat sink)로 이의 설계를 위해서는 방열량과 최대 허용온도 등에 대한 목표가 결정되어야 하며, 사용 환경 및 설치 방법에 따른 열전달 계수의 예측이 이루어져야 한다. 본 연구에서는 히트싱크의 베이스가 수직, 수평상태를 유지함에 따라 나타나는 핀 주변의 자연대류 유동 특성을 전산모사 해석을 통해 고찰하였다. 또한, 일반적인 자연대류형 히트싱크를 대상으로 수평 및 수직상태에서의 열적 성능 실험을 수행하였으며, 기존의 연구결과와 비교함으로써 설치방향이 히트싱크 방열성능에 미치는 영향에 대하여 분석하였다. 실험결과 수평상태의 경우는 수직인 경우에 비하여 약 10~15% 열전달 계수의 감소가 발생하였다.

Development and Characterization of Optimum Heat Sink for 30 W Chip on Board LED Down-Light

An optimum heat sink for a 30 W chip on board (COB) LED down-light is designed, fabricated, and characterized. By using the SolidWorks Flow simulator and thermal analysis software, the thermal characteristics of the optimum heat sink is analyzed. Four different types of heat sink are simulated and an optimum structure of the heat sink is found. The simulated temperature of the heat sink when operating the LED down-light is <TEX>$55.9^{\circ}C$</TEX>, which is only a difference of <TEX>$2^{\circ}C$</TEX> from the measured temperature. In order to reduce the temperature further, a copper spreader is introduced to the heat sink. The temperature of the heat sink with the copper spreader is <TEX>$3^{\circ}C$</TEX> lower than without the copper spreader.

LED 조명용 히트싱크 방열기 설계를 위한 냉각성능 평가

In comparison with some other light sources, LED has merits such as increased life expectancy, fast response, pollution free, and high energy efficiency. Lately, due to development of LED with high brightness and capacity, LED has widely used in many industrial fields such as automotive, aviation, display, transportation and special lighting applications. Since the high heat generation of LED chips can cause a reduction in lifetime, degradation of luminous efficiency, and variation of color temperature, studies have been carried out on the optimization of LED packaging and heat sinks. In this study, experiments on measuring the heat generation rate of LED and the cooling performance of a heat sink were carried for analyzing the thermal characteristics of LED lighting system in free convection. From the results, dimensionless correlation on the cooling performance of heat sink in natural convection was proposed with Nusselt number and Rayleigh number as a guideline for designing cooling device of LED lightings.

Optimization of an ammonia-cooled rectangular microchannel heat sink using multi-objective non-dominated sorting genetic algorithm (NSGA2)

The ever decreasing size of modern electronic packaging has induced researchers to search for an effective and efficient heat removal system to handle the continuously increasing power density. Investigations have involved different geometry, material and coolant to address the thermal management issues. This paper reports the potential improvement in the overall performance of a rectangular microchannel heat sink using a new gaseous coolant namely ammonia gas. Using a multi-objective general optimization scheme with the thermal resistance model as an analysis method in combination with a non-dominated sorting genetic algorithm as an optimization technique, it was found that significant reduction in the total thermal resistance up to 34 % for ammonia-cooled compared to air-cooled microchannel heat sink under the same operating conditions is achievable. In addition, a considerable decrease in the microchannel heat sink’s mass up to 30 % was achieved due to the different heat sink’s material used.

히트파이프를 적용한 LED조명용 핀확장형 냉각시스템 개발

With the advantages of power savings, increased life expectancy and fast response time over traditional incandescent bulb, LEDs are increasingly used for many applications including automotive, aviation, display, and special lighting applications. Since the high heat generation of LED chips can reduce service life, degrade luminous efficiency, and cause variation of color temperature, many studies have been carried out on the optimization of LED packaging and heat sinks. In this study, a fin expansion type cooling device using heat pipe, instead of a solid aluminum heat sink, was designed for LED security lightings based on thermal resistance analysis. Numerical analysis and experimental validation were carried out to evaluate its cooling performance.

Comparison of nongradient methods with hybrid Taguchi-based epsilon constraint method for multiobjective optimization of cylindrical fin heat sink

The primary aim of the paper is to compare the different nongradient methods of multiobjective optimization for optimizing the geometry parameters of a cylindrical fin heat sink. The methods studied for comparison are Taguchi-based grey relational analysis, e (epsilon) constraint method and genetic algorithm. The various responses that have been studied are electromagnetic emitted radiations, thermal resistance and mass of the heat sink. Since the responses are obtained using complex simulation softwares (HFSS—Ansoft for emitted radiations and CFD—Flotherm for thermal resistance), there is no way of calculating the derivates of the objective functions. Hence, the Taguchi design of experiments design is used to derive the linear regression equations for the responses studied, which are then taken as the objective functions to be optimized. A new hybrid method known as Taguchi-based epsilon constraint method has been proposed in this paper for obtaining nondominated Pareto solution set. The results obtained using the proposed method show that the Pareto optimal set is competitive in terms of diversity of the solutions obtained. It is not likely that there exists a solution, which simultaneously minimizes all the objectives using any of the multiobjective techniques implemented. The value path analysis has been done to compare the trade-off among the design alternatives for the chosen multiple objective parameter optimization problem.