Types Of Heat Sinks Research Articles

Experimental investigation of the heat transfer characteristics of CO2 at supercritical pressures flowing in heated vertical pipes

Supercritical CO2 shows great potential as a working fluid in power plant cycles due to its moderate critical pressure of 7.38 MPa and critical temperature of 30.98 °C, closely matching typical heat sink temperatures. Understanding the heat transfer characteristics of sCO2 is crucial for designing cycle components. This publication presents a systematic analysis of sCO2 heat transfer in two heated vertical pipes with 4 and 8 mm inner diameters, with both upward and downward flow at pressures of approximately 7.75, 8.00, and 9.50 MPa, and flow inlet temperatures between 5 and 40 °C, based on 196 experiments. The study investigates a range of mass fluxes from 400 to 2000 kg/m2s and heat fluxes from 10 to 195 kW/m2, resulting in a heat to mass flux ratio of 6 to 275 J/kg. The findings reveal enhanced, normal, and deteriorated heat transfer within the experimental dataset. Buoyancy effects are identified as the main cause of deteriorated heat transfer in the investigated parameter range, with flow acceleration showing no significant influence on heat transfer. A new proposed dimensional criterion categorises 36 out of 119 experiments with upward flow in the deteriorated heat transfer regime, accompanied by temperature peaks rising to 47 K. Thermal inflow lengths range from 0 to 480 inner pipe diameters, with some experiments not achieving a thermally fully developed flow over the entire pipe length. Based on a comparison with approximately 8950 experimental data points, two Nusselt correlations are found, capable of reproducing the experimental results with a mean absolute deviation of around 30 %. This publication provides valuable data for validating numerical models and developing correlations to predict the heat transfer of supercritical fluids.

Fabrication of microchannel heat sink using additive manufacturing technology: A review

Additive manufacturing is a cutting-edge process that enables the creation and development of complex shapes, opening new avenues for advanced heat sink designs that maximize heat transfer while minimizing pressure drop. This review provides an overview of recent results and insights from global researchers on the additive manufacturing of microchannel heat sinks. It discusses various novel microchannel heat sink types fabricated using additive manufacturing and the complexities involved in their fabrication. Additionally, the review explores geometric configurations, the application of computational optimization methods, and the impact of surface roughness on heat transfer and pressure drop. The primary focus is on the fundamental advantages of additive manufacturing in addressing complex heat transfer designs. However, the review also highlights limitations restricting its benefits in specific applications, such as material handling and availability. This review identifies future challenges for creating novel heat sinks with complex geometries and opportunities for advancements in heat transfer technology.

CFD simulation and geometric optimization of a novel baffle heat sink for power electronics cooling

The electric drivetrain of an electric vehicle typically has two fluid circuits: an oil circuit for lubrication and a water-glycol circuit for cooling. Eliminating the water-glycol circuit can result in a more compact and lighter drivetrain. However, this requires the drivetrain components to be cooled with oil as coolant, which has inferior heat transfer properties compared to water-glycol mixtures. This is particularly challenging for the power modules in the power electronics unit, which exhibit some of the highest heat fluxes in the drivetrain. This study focusses on the design and optimization of a novel type of heat sink for laminar flows with baffles to guide the flow in four different directions. This has two main advantages: the baffles act as fins and increase the heat transfer area and they introduce a swirling motion in the oil thereby disturbing the boundary layers continuously. Computational fluid dynamics simulations using Ansys Fluent are performed to evaluate the thermohydraulic performance of the heat sink. The influence of design parameters such as the height and thickness of both fins and baffles and the baffle spacing in horizontal, upward and downward direction was evaluated by simulations with several combinations of the design space, considering manufacturing constraints. The optimization of the design showed that the fin thickness, horizontal baffle spacing and baffle length should be as small as possible, while there were optimal values for fin height, upward and downward baffle spacing, streamwise baffle spacing and baffle thickness. The simulations show that the thermal resistance of the baffle heat sink can be 19% lower than that of a benchmark pin fin heat sink at equal pumping power.

Comparative analysis of numerical models of plate-fin heat sinks with forced convection for thermoelectric energy generation

Plate-fin heat sinks under forced convection are economical dissipaters employed in a wide variety of sectors. These types of heat sinks are commonly used in power generation by means of commercial thermoelectric generator modules. The design of the heat sink is a key factor in these power generation systems since it greatly affects the efficiency of the direct conversion from heat into electrical energy. Here, we analyse several numerical models of plate-fin heat sinks under forced convection with and without air flow bypass. The predictions of both hydraulic and thermal parts of these models are compared with our own experimental data. Results reveal that Lindstedt and Karvinen model (2012) is the more accurate one, with discrepancies with respect to measurements below 12% for most of the cases studied.

Improvement of heating and cooling performance for thermoelectric devices in medical storage application

Thermoelectric devices provide several advantages over typical refrigeration systems, including compact size, quiet operation, minimal energy use, and environmentally friendly. By harnessing these benefits, we have developed a blood storage system that has the potential to transform the way blood products are preserved and safeguarded. Thermal performance was evaluated using a variety of scenarios, including thermal fin material and emissivity, voltage operation, heat sink type (I, U, O type), and tube load. This research used thermoelectric devices, Styrofoam materials, thermal fin and the heatsink to design the thermoelectric storage cabinet with heat insulation function. The aims to improve the performance of thermoelectric devices by optimizing the thermal fin design during heating/cooling storage mechanisms. Our findings emphasize the importance of thermal radiation, particularly in circumstances with low natural convection and high surface emissivity. Thermal performance is optimized when heating storage elements are incorporated into aluminum finned tubes and run at an input voltage of 8V in a 25 °C ambient temperature. In addition, using U-shaped cooling fins in cooling conditions results in superior cooling performance. The outcomes of this study highlight the possibility and potential benefits of using thermoelectric devices to heat and cool medical storage, notably blood storage applications. The insights gained here contribute to advancing the efficiency and sustainability of medical storage systems, ultimately benefiting healthcare and the environment.

Enclosed thermal management method for high-power photovoltaic inverters based on heat pipe heat sink

Photovoltaic (PV) inverter plays a crucial role in PV power generation. For high-power PV inverter, its heat loss accounts for about 2% of the total power. If the large amount of heat generated during the operation of the inverter is not dissipated in time, excessive temperature rise will reduce the safety of the devices. This paper proposes a closed PV inverter structure based on heat pipe and liquid cooling which overcomes the noise, dust and other problems caused by traditional air-cooling heat dissipation method and reduces cost of the volume occupied inside the body. Heat is dissipated through heat pipes, which are efficient heat transfer units. A simulation model of the actual cabinet was established using computational fluid dynamics (CFD), and the maximum junction temperature in the inverter was investigated under different coolant temperatures, flow rates, cooling liquid and heat loads. The results showed that the liquid cooling heat dissipation structure can effectively dissipate the heat inside the cabinet. The impact of two different types of heat sink used for power modules on temperature uniformity was studied. The results indicated that the 9-heat pipe type heat sink has better heat dissipation and uniform hot spots performance, the maximum heat source temperatures in the chip and capacitor were reduced by 9.91?C and 7.49?C respectively. Finally, the performance of the two types of radiators under different heat loads was studied.

Experimental study on collaborative enhancement of led heat dissipation characteristics by pulsating heat pipe and heat pipe

The objective of this research is to experimentally evaluate the specific impact of a collaborative heat sink composed of gravity heat pipes (GHP) and pulsating heat pipes (PHP) on the thermal efficiency of LED light sources. The heat sink developed in this experiment is designed to improve the thermal management system, ensuring that LED operate within a safe temperature range, which is crucial as the performance of LED is directly affected by their junction temperature. An HP-PHP collaborative heat sink was employed in the experiment, where PHP served as heat dissipating fins to enhance its thermal performance, while HP handles the majority of the heat transfer tasks. The results showed that under forced convection conditions, the HP-PHP collaborative heat sink can increase the maximum thermal power capacity of LED to 192 W. The HP-PHP collaborative heat sink can reduce the substrate?s temperature to below 70.5 ?C in passive mode when the LED input power does not exceed 96 W. Additional experimental results show that the minimum thermal resistance of the collaborative heat sink is 0.19 K/W under natural-convection conditions, under forced convection conditions, this value drops to 0.15 K/W, which still lower than the non-collaborative heat sink. These results demonstrate that the contact thermal resistance between HP and PHP significantly enhances the thermal performance of the collaborative heat sink. Therefore, this collaborative type of heat sink is an effective method for cooling high power LED.

Experimental Study on the Effect of In/Out Radial-Finned Heat Sink with PCM under Constant and Intermittent Power Mode in Power LEDs

The findings of the experimental study into optimizing the heat transfer rate of a PCM-based heat sink for high-power LEDs are presented in this work. The study investigated five heat sink types, with and without PCM. The LED case and junction temperatures, LED module temperatures, heat storage and release rate analyses, analyses of three types of cyclic operation modes, luminous flux, and heat sink thermal resistance were all examined independently. The results indicated that the PCM-based LED heat sink had improved thermal performance. The LED junction temperature of the PCM-equipped E-20 heat sink is nine degrees Celsius lower at 10 W than that of the heat sink without PCM. Furthermore, the E-20 heat sink with PCM extends the LED module’s critical lifespan. As a bonus, the E-20 with PCM had a 38.19 percent lower thermal resistance at 10 W than the E-20 without PCM. According to these results, the heat sink E-20 emits 715 lm at 10 W when operated without a phase-change material (PCM). With the same input power, the luminous flux of an E-20 equipped with a heat sink and a phase-change material (PCM) is 750 lm, a gain of 4.7%. Finally, clearly recommend the heat E-20 sink with PCM suitable for high-power LED thermal management system.

Experimental investigation of forced convection heat transfer for different models of PPFHS heatsinks with different fin-pin spacing

Cooling of electronic components is one of the most important concerns of manufacturers. Using heatsinks with different models is one of the recommended methods for cooling. To compare 12 types of heatsinks, including 3 types of fin-pin heatsinks with rectangular pins, 3 types of fin-pin heatsinks with circular pins, 3 types of fin-pin heatsinks with conical pins, and 3 types of simple fin heatsinks in 5, 7, and 9 fin types regarding forced displacement heat transfer, an experiment was conducted. A special setup designed and built for these types of heatsinks was used to conduct the test. The setup had dimensions of 100 cm × 12 cm x 3 cm with an opening of 120 cm × 120 cm for placing a fan to create airflow with variable speeds and a place for placing the heatsink at the end of the wind tunnel under variable temperatures. The test results showed that the maximum error in the two experimental tests was 6 %. Also, the results showed that in all 4 types of heatsinks, 7-fin pin types had 4 to 20% lower thermal resistance and 20 to 100% higher convection heat transfer coefficient compared to the 5- and 9-fin pin types respectively. When comparing the heatsinks with the same number of fins, it was observed that the 7 and 9-fin types of heatsinks with conical fins have lower thermal resistance and higher convection heat transfer coefficient than other types of heatsinks with the same number of fins, The conical fins having more than 81 % convection heat transfer coefficient compared to the plate fin heatsink. It was also observed that in the 5-pin fin heatsink design, the plate-fin heat sink had the lowest amount of heat resistance due to its higher surface area with the flowing air current.

Comparison of Heat Sinks with Different Perforations Number

In this paper, the influence of perforation number Np is experimentally studied (or in the other word, the effect of perforation space Ps on the heat sink performance). Three types of rectangular heat sinks were investigated; two types have been perforated by lateral holes (4 mm the hole diameter) distributed on two rows in the fin. First one has 12 holes in a fin (its Ps is 14.3mm) called (PHS-12p). Second heat sink has 8 holes in a single fin (its Ps is 20mm) called (PHS-8p). These two perforated types compared with the third heat sink, which has no perforation (solid heat sink). The comparison was investigated, presented and discussed. The experiment was conducted by forced convection device. The obtained results showed that dissipated heat, Nusslet number, and convective heat transfer coefficient were increased by using perforations compared with non-perforated heat sink. The use of more perforations has a positive effect on heat dissipation. The enhancement in heat transfer was 6.57% for PHS-12P, while PHS_8P improved by 1.75% only at Re 20000. Moreover, the heat sink weight decreases with the use perforated heat sink compared with the solid heat sink.

Assessment of cooling performance of mini/micro-channel stacked double layer heat sink

A study is accomplished here to investigate the performance of a novel double-layer mini/micro-channel stacked heat sink (DL-MMCHSHS). The hydraulic diameter and aspect ratio of mini-channel heat sink are 0.12 cm and 3, respectively. The width of the fins between two channels is 0.04 cm. The total width of two runners is the same, and its width is 1.44 cm. The heat dissipation potential of this new type of heat sink is investigated. It was observed that the pressure loss is reduced by using the DL-MMCHSHS instead of a single-layer micro-channel heat sink (SL-MCHHS). The reduction in the pressure loss reduces the pumping power, which leads to decrease in operating costs of the system. For the total flow rate of 345.69 cm3/min, the pressure loss reduces about 35.41% by using the DL-MMCHSHS instead of a SL-MCHHS. The uniformity index in the range of 0.077 to 0.192 is achieved in this study. For the total flow rate of 346.64 cm3/min, the uniformity index enhances about 60% with boosting the flow rate ratio from 0.5 to 3.5. For the total flow rate of 1039.26 cm3/min, the thermal resistance increases about 76.22% as the flow rate ratio increases from 0.5 to 3.5.

Review on PCM Heat Sink for Electronic Thermal Management Application

A significant challenge in thermal management has arisen as a result of the rising demand for high-performance electronic devices. The efficiency, size, and weight of conventional cooling methods like liquid and air cooling are constrained. Due to their high storage of latent heat capacity and isothermal phase transition behavior, phase change materials (PCMs) have become a promising thermal management solution. The purpose of this experimental study is to evaluate the performance of a PCM heat sink for electronic thermal regulation. The PCM heat sink is made up of a PCM module attached to a typical heat sink. To improve heat dissipation capabilities, the PCM module uses a PCM material with a suitable phase change temperature and encapsulation. The experimental setup involves simulating real-world operating conditions by applying controlled heat loads to electronic components. By observing temperature changes, thermal resistance, and transient response, the PCM heat sink’s thermal performance is assessed. To evaluate the superiority of the PCM heat sink, a comparison is made with traditional air-cooled and liquid-cooled heat sink configurations. The experimental investigation’s findings show that the PCM heat sink performs better in terms of thermal management than traditional cooling techniques. The phase change process used by the PCM efficiently absorbs and stores extra heat produced by electronic parts, improving temperature regulation and lowering temperature gradients. Lower component temperatures and higher operational reliability are the results of the PCM heat sink’s improved thermal resistance and heat dissipation efficiency. A further benefit of the PCM heat sink’s isothermal behavior during the phase transition is that it prevents temperature spikes and lessens the effects of heat stress on the electronic devices. The long cooling times provided by the PCM material’s high latent heat storage capacity allow for prolonged operation without affecting device performance. This experimental study concludes by demonstrating the efficiency of a PCM heat sink for electronic thermal management. The design of heat sinks with PCM integration offers notable enhancements in temperature control, thermal resistance, and system overall reliability. The results of this research help to advance thermal management strategies, which makes it easier to create efficient electronic devices with better cooling capacities.

Effects of different water-cooled heat sinks on the cooling system performance in a data center

Data center, as a special building form, has attracted much attention because of its increasing energy consumption. In order to reduce the energy consumption of data center caused by cooling system, research on the water-cooled heat sinks used to cool chips has become increasingly important with the steep increase in the heat flux density of data centers. To explore the effect of different water-cooled heat sinks on cooling system performance, a server water-cooled system for the server cabinet was built, and the chip heat dissipation performance, optimal thermal management, and system energy consumption were simulated by equipping a cooling tower and two types of fin-type water-cooled heat sinks (A-type and B-type). By comparing the effects of A- and B-type heat sinks on the server water-cooled system performance, the optimal water working condition was obtained under different atmospheric conditions by minimizing the system power consumption to guarantee that the chip temperature is no higher than 70 °C. It was found that the optimal cooling water flow rate fluctuates in a large range under different atmospheric conditions. A server water-cooled system equipped with B-type can achieve significant energy savings compared to those from A-type system when the atmospheric relative humidity and temperature are high. Considering a case study from Tianjin, China, it is shown that the month-averaged power usage effectiveness in June is 1.2 for A-type and 1.14 for B-type systems.

Topology optimized novel additively manufactured heat sink: Experiments and numerical simulations

Topology optimization is an effective method for designing high-performance heat sinks with reduced weight and size. The integration of topology optimization with additive manufacturing technology can effectively leverage the benefits of topology optimization to enhance the design process. In this study, nine types of heat sinks are designed by density-based topology optimization and fabricated via the laser powder bed fusion technology. Three different optimization goals including the minimization of temperature variance, thermal compliance and the temperature difference between the heat source surface and side surfaces are considered in design configurations. We develop a high-fidelity computational fluid dynamics model to investigate the velocity and temperature distributions of the cooling fluid around various fins, and conduct the corresponding experiments to test the thermal performance of the developed heat sinks. The results show that topology optimized fins can significantly enhance heat transfer capability of the heat sink. As the cooling fluid velocity increases from 0.3 m/s to 1.9 m/s, topology optimized heat sinks exhibit superior thermal performance with the highest heat transfer coefficient of 305 W·m−2·K−1 and the highest Nusselt number of 202. This research proves the powerful capability of laser powder bed fusion technology on manufacturing novel peculiar fins and provides a theoretical and experimental guidance for novel compact heat sink in the future designs.

Experimental and numerical analysis of effect of combined drop-shape pin fins and plate fins type heat sink under natural convection

As the junction temperature of a light-emitting diode (LED) is inversely proportional to its lifespan and efficiency. This study investigates the thermal performance of heat sink-based model with a drop-shaped pin fin for LED cooling under natural convection, experimentally, and numerically. The study used three distinct drop form pin fin arrays with variable vertical fin spacing (Sv = 25, 50, and 75 mm), with the best array being used in subsequent studies with variations in drop-shaped pin fin size (diameter DD and apex length LD ). The heat transfer coefficient and Nusselt number were obtained in the quantitative analysis of thermal performance. A numerical model with Boussinesq approximation for natural convection is used for this study and well-validated with experimental results. A qualitative investigation was also carried out utilizing numerical research to investigate velocity streamlines and their impacts on heat transfer enhancement in various configurations. An experimental test with conventional plate fin, circular pin fins were done for the verification of the test setup results and their results were compared with results calculated from the standard correlations presented in previous well-known literature. The maximum heat transfer coefficient was found to be 12.80 W/m2K for drop form pin fins with vertical fin spacing (Sv ) equal to 75 mm, a diameter of 6 mm, and a length of 7.2 mm, and the corresponding Nusselt number was 94.85. Also, the maximum enhancement in Nusselt number was found to be (Nu/Nu plate fin) 3.11 corresponding to the conventional plate-fin heat sink. This comparison will help the industrialists determine innovative passive cooling technology for electronic devices such as LED street lights.

Heat transfer characteristics of thermally and hydrodynamically developing flows in multi-layer mini-channel heat sinks

In this study, a novel type of air-cooled heat sink is proposed, which consists of several layers of mini-channels. In this design, the hydraulic diameter is smaller than in conventional types of heat sinks, such as plate-fin heat sinks, and consequently, the achievable heat transfer rates are higher. To predict the cooling performance of this heat sink, an innovative analytical method is proposed, results from which are complemented by an extensive number of numerical simulations of the simultaneously developing flows, thermally and hydrodynamically, inside a rectangular channel of the heat sink. The results of the analytical method are compared against two- and three-dimensional simulations and good agreement is found, while from the simulations, correlations are proposed for the Nusselt number in these flows. Finally, the performance of the proposed heat sink is compared to a plate-fin heat sink. This comparison reveals that entropy generation in the latter is around 27% higher than in the former, and suggests a promising advantage of the proposed heat sink design.

Numerical study of different micro-channel structures on fluid flow and heat transfer performance

This research mainly proposed three new types of micro-channel heat sink structures. Numerical simulations and simulation calculations were carried out on the heat sink structure. The three groups of inlet flow rates were used as the main variables to analyse the three new types of heat sinks, model flow characteristics and heat transfer performance. In addition, it was compared with the traditional rectangular micro-channel heat sink (RT-MCHS). Based on and compared with RT-MCHS, three new microchannel heat sinks, reverse concave microchannel heat sink (RC-MCHS), co-directional concave microchannel heat sink (CC-MCHS) and convex reverse concave microchannel heat sink (CRC-MCHS), were designed and studied numerically. The comparative analysis of MCHS design performance includes fluid flow characteristics, fluid heat transfer performance and heat transfer efficiency. The effects of inlet velocity on the Darcy friction coefficient, pressure drop, Nusselt number, average outlet temperatures and efficiency factors were studied numerically as inlet velocity from 1 m·s-1 to 5 m·s-1. The results show that the optimal strategy in the new design is the CRC-MCHS, which can hinder the flow of fluid and enable sufficient heat exchange between the liquid and the substrate. In addition, at the optimal inlet flow rate of 3 m·s-1, the outlet water temperature of CC-MCHS is the lowest, indicating the heat transfer performance of the electronic components is the best.

Performance improvements of microchannel heat sink using Koch fractal structure and nanofluids

With the rapid development of microelectronics technology, the heat flux density in the micro-component system is very high. Therefore, the design of new and efficient cooling and heat dissipation devices has become an urgent problem to be solved. We use the Koch fractal structure and nanofluid to create a new type of microchannel heat sink. In this paper, a single-phase method is used to numerically study the flow and heat transfer properties of TiO2-water nanofluids in microchannels and optimize the structure with Koch fractal baffles. The effects of various volume fractions of nanofluids and baffles with varying structures on the inlet and exit pressure drop, flow resistance coefficient, substrate temperature, and Nusselt number (Nu) in the microchannel are investigated. In the Reynolds number (Re) range of 100–1000, the Nu of nanofluid increases with the increase of Re and the Nu increases from 18.19 to 60.41, which increases by 3.32 times, and the flow resistance of nanofluid falls by 1.79 times. Nanofluids' improved heat transfer factors are not all larger than one. The critical point is Re = 439, indicating that the combined heat transfer performance of nanofluids is superior to that of deionized water within the Re range of 100–439.

Topology optimization of heat sink in turbulent natural convection using k-ω turbulent model

The geometric structure of two-dimensional (2-D) heat sinks cooled by turbulent natural convection is optimized using a density-based topology optimization approach. The governing equations are the coupled equations of the k-ω turbulent equation, which is one type of the Reynolds-Averaged Navier-Stokes (RANS) equations, and the thermal convection-diffusion equation based on the Bousinessq approximation. In order to facilitate topology optimization, we make some modifications to the original governing equations to control the fluid/solid distribution by introducing a material density as the design variable. Specifically, several penalization terms are added to the original k-ω turbulent model for immersing the solid material, and the thermophysical properties are interpolated to obtain a generalized thermal equation suitable for both the fluid and solid materials. During the optimization process, the design variable is updated according to the gradient information obtained through adjoint-based sensitivity analysis. In numerical examples, the effects of the Grashof number and the solid thermal conductivity on optimal configurations are, respectively, investigated for two types of heat sinks. The numerical results indicate that the Grashof numbers and the solid thermal conductivity can significantly affect the optimal results; the flow channels will become narrower to accommodate the flow and heat transfer conditions with the increase of the Grashof number; and the design characteristics and heat transfer performance vary greatly for increasing the solid thermal conductivity when the conductivity is low, while at the case of high conductivity, this variation slows down obviously.

Comparative experimental study of heat sinks with piezoelectric pump

How to effectively cool highly integrated electronic devices is a hot and challenging research problem. To improve the cooling performance of microchannel systems, a new piezoelectric pump-based cooling system is proposed in the paper, which includes a piezoelectric pump with umbrella-shaped valves and microchannel-based heat sinks. We theoretically analyzed the effects of flow rates and heat transfer coefficients on the cooling performance when using four different types of microchannel-based heat sinks. Then, the piezoelectric pump and those heat sinks were fabricated, and the maximum output flow rate was experimentally measured. A CPU with a fixed power input was chosen to experimentally access the overall heat transfer coefficient of the heat sinks. The theoretical and experimental results revealed that the cooling performance of the proposed system was related to both the output flow rate and the overall heat transfer coefficient of the heat sinks. At last, we demonstrated that the piezoelectric cooling system, equipped with the heat sink of the tandem Y-shape bifurcation microchannel, had the best cooling performance: the CPU temperature was stabilized within 60.6 °C when the working power of the CPU was fixed at 30 W, resulting in a cooling efficiency up to 51.12%.