Fin Heat Sink Research Articles

Enhancement of Natural Convection Heat Transfer from Perforated Fin

A comprehensive theoretical and experimental study was carried out on the thermal performance of a pin fin heat sink. An experimental model was shows that have the capability of predicting influence of effective surface area of pin fin on thermal heat transfer coefficient. Pin fin array are used in many applications to enhance heat transfer and also shows enhancement of heat transfer coefficient for different material of fin. Several different type of experiment test were run out with corresponding variation including the material of pin fin and different perforation on pin fin. Perforation with circular cross section are along the height of pin fin and there number varies from 1 to 3. The result indicates that the material having higher thermal conductivity with higher number of perforation gives more heat transfer coefficient. The effect of perforation on heat transfer was investigated.

Optimization of Horizontal Plate Fin Heat Sink in Natural Convection for Electronics Cooling by Simulated Annealing Algorithm

In this study, the simulated annealing (SA) algorithm was adopted to optimize the geometry of horizontal plate fin heat sink by the extreme entransy dissipation principle. The alculation of the entransy dissipation rate was presented in detail. Using the entransy dissipation rate as the objective condition, the geometry optimization of the fin heat sink was conducted. To verify the results, the heat source temperature and the entropy generation rate were also calculated in the procedure. It is found that the entrasy dissipation rate, entropy generation and heat source temperature have the similar trend. The extreme entransy dissipation principle and minimization of entropy generation play similar roles in the geometry optimization of plate fin heat sink.

Two-phase flow maldistribution in minichannel heat-sinks under non-uniform heating

In the present study, two-phase heat transfer characteristics in minichannel heat sinks under non-uniform heating were experimentally investigated. Pin–fin and strip-fin minichannel heat sinks were fabricated on a thin brass plate such that the channel dimensions were 25mm wide×26mm long×1mm deep. 2mm×5mm spot-heater was attached on the backside of the minichannel heat-sinks to simulate the non-uniform heating. The surface temperature distribution caused by the non-uniform heating was measured using the thermocouples attached on the 9 uniformly spaced locations of the minichannel heat-sinks. It was observed that the two dimensional expansion of vapor in the pin–fin minichannel heat-sink allowed improved distribution of vapor and thereby lower vapor quality. The temperature rises at the hot-spot locations was also significantly lower in the pin–fin minichannel heat-sink, which means pin–fin structure is more suitable for hot-spot cooling. The effects of mass flow rate and heat flux on heat transfer capability were explored and the total thermal resistances of the heat-sinks were also evaluated and discussed.

An investigation into flow boiling heat transfer and pressure drop in a pin–finned heat sink

Heat-transfer coefficient and pressure drop measurements are reported for a heat sink comprising pin–fins with a cross section of 1mm by 1mm and a height of 1mm. The pin–fins were manufactured on a 50mm square base plate in a square, in-line arrangement with a pitch of 2mm. The data were produced while boiling de-ionised water at atmospheric pressure. The mass flux range was 40–200kg/m2s and the heat flux range was 30–470kW/m2.The test section was heated from below by an electrical heating method that is normally associated with a constant heat flux boundary condition. However, because of the variation in single-phase liquid temperature in the entrance zone and the variation in the heat-transfer coefficient, the interceding aluminium and copper material is shown to produce a non-uniform heat flux with a near isothermal wall boundary condition. The heat conduction effect in the wall is taken into account in the analysis of the data and in the calculation of the heat-transfer coefficients.Heat-transfer coefficients and pressure drops are reported for single-phase and boiling flows, with subcooled and saturated boiling data obtained. The single-phase results are shown to be reasonably independent of position. The measured boiling heat-transfer coefficients are shown to be associated with flow pattern and to be confined, as the capillary length for water is much larger than the flow passage dimensions. This is true of the saturated and subcooled boiling data, as slugs were observed in subcooled liquid flows. The criterion for the onset of slug flow is not compatible with that associated with macro-scale flows. All of the boiling data were obtained at wall superheats substantially above the values associated with nucleate boiling. They therefore have a nucleate and convective component. The convective component is shown to be the most dominant.The water data are compared with R113 data obtained in a previous study. The R113 data are shown to be associated with slug and annular flow, and are, in the main, not confined, with its capillary length similar to the channel flow dimensions. The R113 flow pattern transition criteria are comparable to macro-scale values. Some consistency in behaviour is shown to exist in the slug heat-transfer coefficients obtained with water and R113.

Numerical Studies on Natural Convection Heat Transfer – Fins with Closed Top

Fins are extended surfaces provided to enhance the heat transfer rate of a system. Several attempts have been made in the past to augment the heat transfer rate by using fins of various geometries. In the present study an array of rectangular fins with closed top, standing on a vertical base is analysed under natural convection conditions using commercial CFD code ANSYS FLUENT©. The numerical model is validated with the available experimental results for fins with open top under natural convection conditions. The plate fin heat sink is analysed for a constant heat duty of 60 W. The height, thickness and length of the fins are taken to be constant throughout the analysis. A detailed study is carried out to examine the dependency of the base plate temperature on the thickness of the closed top and on the number of fins. It is concluded based on the analysis that heat fins with closed top are found to have a decreased base plate temperature compared to the conventional rectangular fins.

Heat transfer performance of submerged impinging jet using silver nanofluids

Silver–water nanofluids used in this paper, has been prepared by a one step method adopting an ultrasound-assisted membrane reaction. Experimental investigations on heat transfer of submerged jet in plate and pin–fin heat sinks were carried out with different concentrations of silver nanofluids. The results indicate that the silver nanoparticles can be uniformly distributed in the base fluid with an average grain size of 4.8 nm. The used surfactant had a great influence on the viscosity of the nanofluids. Compared with the base fluid (water and surfactant), the heat transfer coefficient of the nanofluids, for the same jet velocity, increases in average by 6.23, 9.24 and 17.53 % for the silver nanoparticles weight fractions of 0.02, 0.08 and 0.12 %, respectively. Compared with water, the heat transfer coefficient is enhanced by 6.61 % with a silver nanoparticles weight fraction of 0.12 %. The Nu of pin fin heat sink are obviously higher than that of plate one, at corresponding Re. The exit of nanoparticles can intense internal energy transmission of fluids, and then enhance the heat transfer, while the Re is small.

Least material optimization of natural-convective heat sinks

In this study, the least material optimization of natural convective heat sinks subject to a localized heat source is performed. An analytic method for predicting the thermal resistances of fin array and heat sink base is presented. The presented analytic method is shown to predict the experimental results well within 5%. Based on the analytic results, a method for minimizing the height of natural convective heat sinks is proposed. The minimum required heat sink height is shown to increase as the targeted thermal resistance decreases. As the heat source localization intensity increases, both the minimum fin height and substrate thickness are shown to increase. The minimum heat sink height increases as the ambient temperature increases when the radiation heat transfer is eliminated, while it is nearly independent from the ambient temperature when the radiation heat transfer is augmented.

MODELING AND THERMAL ANALYSIS OF HEAT SINK WITH SCALES ON FINS COOLED BY NATURAL CONVECTION

Heat removal is often a significant endeavor in LED luminaries. A lower junction temperature of LED impacts efficiency, life, performance & reliability. This work addresses thermal performance of few popular designing approaches on Fins of heat sink and it’s correlation with junction temperature (also referred as soldering point temperature) of LEDs cooled by natural convection. A comparative thermal simulation results has been presented on basic rectangular fins, pin fins and trapezoidal scaled tapered fins using SolidWorks Thermal Simulation. It is observed that thermal mass, exposed surface area & geometric placement of fins plays a key role in deciding performance of fins and Heat Sink. A high power LED array is used as uniform heat load of 65 watt. An optimized heat sink has typical functional dependencies on material, fin structure, ambient temperature of surrounding fluid, orientation with respect to gravity, color, texture and conductivity of interface layer used between LED and heat sink.

Pyrolytic Graphite Heat Sinks: A Study of Circuit Board Applications

Pyrolytic graphite (PG) is of interest as a heat sink and heat exchanger material because it has a thermal conductivity greater than copper with a density less than aluminum. However, its anisotropic molecular structure creates a significant challenge to the realization of practical thermal performance benefits. The current computational study compares the performance of a high-thermal conductivity PG, Pyroid® HT, to aluminum over a design space that focuses on circuit board component cooling. The applications considered in this paper include flat-plate thermal spreaders and finned heat sinks. The results are presented in a form that can be used to provide material and geometry selection during preliminary design. The competition between the size of the heat source, the thickness of the spreader, its size, and the strength of the forced convection is quantitatively presented. In addition, the thicknesses that provide the optimal performance are determined and the performance is compared with a thickness that would be approximately cost neutral. A single isotropic analytical fin model is used to quantitatively establish the fin sizes and aspect ratios that would demonstrate the largest performance benefit if made from PG. Finally, the impact of Pyroid® on the size of finned heat sinks is examined.

COP Improvement of Thermoelectric Cooler through the Optimization of Heat Dissipation System

This paper presents theoretical and experimental works on the effect of heat transfer for a thermoelectric (TE) cooling system. The study focuses on thermal performance of the system through the optimisation of heat dissipation system for two prototypes that have aluminium and copper heat sink design, respectively. The study revealed that heat sink base area and fin height influenced thermal performance.

SIMULATION OF FIN GEOMETRIES FOR HEAT SINK IN FORCED CONVECTION FLOW

In recent decades peoples are moving towards high power density and smaller package size especially in electronic systems. This demands an effective cooling mechanism in order to prevent the electronics components from overheating. The CFD analysis is carried out on the performance of different pin fin heat sink in forced convection flow. In this paper, the overall performance of heat sink is designed and analysis for different parameters like the dimensions of the pin fin, fin density, longitudinal and transverse spacing and size of the heat sources, heat sink material, velocity and arrangement of pinfins. Finally the results are compared with the Computational Fluid Dynamics (CFD) software STARCCM+. The results from STARCCM+ software are in close arrangement with theoretical solutions.

Geometry optimization of a cylindrical fin heat sink using mine blast algorithm

The heat sinks are utilized in electronic devices to eliminate heat from the chip and efficiently transmit it to the environment. Therefore, the optimal geometry sizes of fin heat sinks are the point of concern for manufacturers and designers. For this reason, the importance of optimization techniques particularly metaheuristics is understood. The design variables are width of heat sink, number of fins, fin height, and fin diameter. The various responses that have been considered are electromagnetic emitted radiations, thermal resistance, and mass of the heat sink investigated separately and simultaneously (multi-objective). Mine blast algorithm (MBA), as a recently developed optimizer, is inspired from explosion of mines. The optimum dimensions and values for each response have been obtained by the MBA and have been compared with other optimization methods in the literature. In terms of thermal resistance and mass responses, the MBA has offered better values, while for the emitted radiations, the obtained results obtained by Taguchi-based gray relational analysis (TGRA) was preferred. For manufacturing point of view, the MBA and TGRA both suggested better and efficient design. In addition, the value path analysis has been carried out to compare the trade-off among the considered responses. Finally, parametric sensitivity analyses have been implemented for design parameters, and discussions and comparisons have been carried out for the effects of each decision variable. By considering all responses, width of heat sink and fin height are considered as the most important and effective design parameters, respectively.

Orientation effects on natural convection heat dissipation of rectangular fin heat sinks mounted on LEDs

Light emitting diode (LED) is facing thermal challenges when highly integrated in high power lighting system. Rectangular fin heat sink is widely used in LED lighting apparatuses. Experimental and numerical study of the orientation effects on the fluid flow and heat transfer of rectangular fin heat sinks under natural convection conditions are carried out. The performance evaluations for different rectangular fin heat sinks in 8 orientations are conducted. Denser fin arrays are found more sensitive to orientation. The experimental results agree well with the present prediction and previous experimental data. Correlations in a simple form Nu=CRam are proposed for various orientations seldom investigated before. The exponent m is found almost the same in orientation of 45°, 135°, 225°, and 315°. Furthermore, the computational results show that the mismatch between the heat transfer area and the natural convection flow and the blockage of the convection flow are the two dominant factors that deteriorate heat transfer of the rectangular fin heat sinks.

Thermal performance of a PCM heat sink under different heat loads: An experimental study

This paper reports the results of an experimental study to quantify the effect of heat transfer performance of a phase change material (PCM) based plate fin heat sink matrix under constant and intermittent heat loads. n-Eicosane with a melting temperature of 36.5 °C is used as the phase change material. Such heat sinks, in general require heat transfer enhancement techniques, because of the low thermal conductivity associated with PCMs. A plate fin matrix made of aluminum is used in the present study to augment the heat transfer. The performance of the heat sink matrix with and without PCM is compared. Additionally, a heat sink filled with PCM, but without any fin is used for baseline comparisons. A series of experiments was conducted at a constant power level of 5–10 W (corresponding to a flux of 2–4 kW/m2) in steps of 1 W. Extensive experimental investigations were carried out at varying power levels by applying the heat flux intermittently by keeping the input heat constant. A step heat input is also applied for a fixed duration at various usage modes usually encountered in the thermal management of portable electronic devices. Parametric studies have been conducted by changing the PCM volume fraction, which is defined as the ratio of the volume of the PCM to the difference between the total empty volume of the heat sink and the volume occupied by the fins and the effect of these on the thermal performance of the plate fin heat sink matrix for both melting and solidification are elucidated in this study.

Electricity Generation from a Solar Parabolic Concentrator Coupled to a Thermoelectric Module

The concept of generating electricity from the sun's energy using a parabolic concentrator and a thermoelectric (TE) module is presented in this study. The proposed TE solar concentrator was composed of a parabolic dish collector with an aperture of 1.5 m that was used to concentrate sunlight onto a receiver plate with an area of 10 × 10 cm2. One BiTe-based TE module installed on the receiver plate was used to convert the concentrated solar thermal energy directly into electric energy. A rectangular fin heat sink coupled with a fan was used to release heat from the cold side of TE module and a tracking system was used to continuously track the sun. The effects of fan orientation and air flow rate were investigated. Under maximum heat flux, the TE module was able to produce 1.32W at 0.42 m3/min of the air flow rate (pushing air), corresponding to 2.89% conversion efficiency. The proposed concept seems to be reliable and merits further investigation.

自然对流下LED集成芯片整体式热管散热器性能实验研究

In order to solve the problem of cooling LED multi-chip LED module,an integrated heat pipe heat sink was designed and fabricated. Heat dissipation experiments were conducted to study effects on heat load,filling ratio and inclination angle on the thermal performance of the heat sink in nature convection. The results show that the efficient heat transfer of the heat pipe can reduce the thermal resistance of the heat sink effectively and the optimum filling ratio is 30% in this research.Inclination angle in the range of 0°- 50° has little effect on heat transfer capability of heat pipe at lower heat load. When the angle reaches 75°,heat transfer of heat pipe and thermal resistance of heat sink are all subject to a significant deterioration. The time heat sink enters stable state is about30 min and is not affected by the magnitude of the power. However,the heat sink works stably after40 min when angle is 75°. Compared to traditional parallel plate fins and sunflower fins heat sink,the chip junction temperature with integrated heat pipe heat sink is smallest.

Experimental Investigation of the Fluid Dynamics of a Finned Heat Sink under Operating Conditions

An experimental study has been made of the fluid dynamics performance of electronic equipment designed to cool a heat sink in the form of a finned duct. The apparatus consists of a channel of rectangular section containing the finned duct. A forced airflow is driven by three fans placed in parallel in the inlet and in the outlet sections of the channel. In order to investigate a full range of flow rates, different sets of fans were used in the inlet section. Measurements were made of static pressures at different channel positions by pressure taps connected to a micro manometer, and of the flow rate by a Venturi meter. The experimental working conditions of the active fans were consistent with the manufacturers’ characteristic curves. Values of the local friction coefficient compared well with published correlations. The experimental working points agreed very well with the theoretical curve of the pressure drop and the hydraulic diameter was demonstrated to be of the appropriate size for this fluid dynamics problem.

Study of Combined Rice Husk Gasifier Thermoelectric Generator

The use of a rice husk gasifier as a cook stove is limited to the domestic sector of developing countries primarily because it needs electrical energy to drive a blower for the gasification process. To solve this problem, we investigated the feasibility of attaching commercial thermoelectric (TE) modules made of bismuth–telluride materials to the gasifier's side wall, thereby creating a TE generator system that utilizes a proportion of the gasifier's waste heat. A rice husk gasifier TE generator (TE-RSG) having an internal diameter of 16cm was fabricated and tested. The TE generator system consisted of two commercial TE modules, a metal sheet wall which acted as one side of the gasifier's structure and served as the hot side of the TE modules and a rectangular fin heat sink at the cold side of the TE modules. A blower was used to suck the ambient air to cool the heat sink and blow the air from the heat sink to the reactor of the gasifier. Gasification was conducted in a temperature range of 500-700°C and gasification agent, air feeding rate of 18.6 m3/h. The results revealed that the electrical power output and the conversion efficiency depend on the temperature difference between the cold and hot sides of the TE modules. At the temperature difference of approximately 60°C, the unit achieved a power output of 3.9W and a conversion efficiency of 2.01%. Through a comparison of results between the theoretic model and the experimental system, the reasonability of this system model has been verified.

Heat Sink Fin Number Variation Analysis on Single Chip High Power LED

Thermal management of high power LED is crucial the reliability and performance of the LED affected by the heat produced during photon emission. Heat sinks are utilized to dissipate the heat and to lower the operating junction temperature of LED. This paper demonstrates a simulation work done to evaluate the influence heat sink fin number on the junction temperature and stress of single chip LED package using Ansys version 11. The heat sink with fin number of 4 fins, 6 fins and 8 fins were used and compared. Results showed that increase in heat sink fin number significantly reduces the junction temperature of the LED package.

Improvement of thermal efficiency in computer heat sink using functionally graded materials

This article presents a new method for improvement of thermal efficiency in the heat dissipation process from electrical components by replacing the conventional heat sink material with functionally graded materials. For physical properties of functionally graded material, the linear and power-law functions are used. An approximate analytical approach based on the mean value theorem is applied for analyzing the thermal behavior of heat sink. The obtained results in the present study reveal that replacing the heat sink fin material with functionally graded material leads to a significant energy saving in heat sinks since the heat transfer enhances between the fin surfaces and surrounding fluid. Alternatively, the rate of energy saving varies as a function of in-homogeneity index of fin material. It is hoped that the obtained results in the present study arouse interest among the thermal designers and heat sink industries.