Performance Of Heat Sink Research Articles

Smart microchannel heat exchangers with Built-In graded SMA vortex generators that responds to random hotspots

Heat sinks with built-in shape memory alloy vortex generators (SMA-VGs) can respond intelligently to temperature variations in a channel without the need for external control. However, ordinary vortex generators fail to respond effectively to random hot spots because the coolant temperature in the channel accumulates along the path. Therefore, this study proposes a smart heat sink with graded SMA-VGs to intelligently recognize the locations of hotspots. The influence of the overheating area was reduced, and the temperature uniformity of the device was improved using the temperature field change of the heat sink to drive the deformation of the vortex generator. In this paper, the principle of smart microchannel heat sinks that can respond to random hotspots is analyzed, and the effects of adaptive pitch adjustment on the temperature and flow of the channel with local hotspots are investigated. Subsequently, graded SMA-VGs are designed and manufactured, and the cooling performance of the smart heat sink is experimentally investigated. The experimental results show that, when compared with traditional coil vortex generators, a channel with built-in graded SMA-VGs performs better in heat transfer while using lower pumping power, resolving the problem of random hotspots in high heat flux devices and demonstrating broad application prospects.

The effect of inlet velocity profile on entropy generation and hydrothermal performance of a pin-fin heatsink with biologically prepared silver/water nanofluid coolant: Two-phase mixture model

The prediction of heat transfer characteristics numerically depends on several factors such as the numerical method, the boundary and operating conditions, etc. The present paper investigated the influence of using the uniform and non-uniform inlet velocity profiles on the heat transfer coefficient (h), pumping power (W˙p), temperature uniformity (θ), and thermal and frictional entropy generation rates (S˙th and S˙fr) in a pin-fin heatsink with silver/water nanofluid (NF) coolant. The numerical study is conducted utilizing the two-phase mixture scheme. The results proved that h is almost the same for two inlet profiles with the maximum deviation of 0.2%. θ and W˙p, however, for uniform profile is nearly 2.52–1.86% and 15–26% higher than those for the other case at Reynolds numbers of 500–2000, respectively, indicating a lower temperature uniformity and higher power consumption for uniform velocity profile. The figure of merit was obtained as 1.19–1.36 at Re numbers of 500–2000; indicating the better hydrothermal performance of the non-uniform inlet velocity profile over the other case. In addition, S˙th was almost the same for both cases due to same mean temperature and temperature gradients. However, S˙fr for non-uniform profiles was 4.41–8.84% lower than that for other profile at Reynolds numbers of 500–2000.

Heat transfer augmentation of natural convection heat sink through notched fin design

A novel notched fin heat sink with a central opening is proposed in the present study to augment the heat transfer performance of the natural convection heat sink under horizontal configuration. Thermal and airflow behavior in the heat sinks were studied using both experimental and numerical methods. The results showed that the performance of the conventional heat sink can be enhanced by optimizing its fin design. The basic heat sink model provided a 17% reduction in thermal resistance when its fin height and fin spacing were doubled, and it was accompanied by a 21% increase in surface area. The heat sink with a notched fin design with a less surface area offered a 13% lower thermal resistance compared to the basic model by entraining more airflow into the interior fin region. Providing a central opening in the notched fin heat sink can further reduce the thermal resistance by about 13%. This study also analyzed the influence of emissivity of the heat sink on natural convection conditions. The findings demonstrated that the heat sink with an emissivity of 0.9 can reduce the thermal resistance by nearly 23% compared to one with an emissivity of 0.15.

Thermal performance evaluation of PCM-MF composite heat sinks under varying ambient conditions

This study focuses on the effect of ambient conditions and choice of phase change material (PCM) on the thermal performance of a metal foam(MF)-PCM composite heat sink. The PCMs considered are paraffin wax (PF), docosane (DOC) and eicosane (EIC) and their melting temperature ranges are 44.5–60.1 °C, 40.3–44.5 °C and 36.3–38.1 °C, respectively, as obtained from differential scanning calorimetry measurements carried out at a heating/cooling rate of 0.5 °C/min. Experimental investigations are carried out at different ambient conditions (temperature varying from 25 to 45 °C) for three different heat input levels of 5, 10 and 15 W (1.39, 2.78, 4.14 kW/m2). Thermal performance of two types of metal foams (copper (Cu) and aluminum (Al)) are evaluated to arrive at the proposed composite heat sink configuration. Due to the introduction of metal foam into the PCM a maximum reduction of 15.1% in the peak temperature is observed (at heat flux of 2.78 kW/m2 at an ambient temperature of 25 °C) and the time taken to reach a set point temperature of 50 °C is enhanced by 1.8 times (at heat flux of 4.14 kW/m2 at an ambient temperature of 25 °C) for the considered fixed duration experiments. Furthermore, rise in ambient temperature is found to significantly increase the maximum temperature attained in the heat sink coupled with reduction in the duration of latent heat phase of PCM. Effect of ambient temperature on the thermal performance of the PCM-MF composite heat sink is demonstrated by evaluating the variation of Nusselt number as a function of modified Stefan and Fourier number during the PCM-charging (heating) process. Low melting point PCM-MF composite (EIC-MF-Cu) is recommended for normal (25 °C) and intermediate (35 °C) ambient conditions at low heat input load (≤ 1.39 kW/m2); while DOC-MF-Cu exhibits better performance if the conditions involve high heat input (2.78 to 4.14 kW/m2) and higher ambient temperature (≤ 45 °C). Also, high melting point PCM based composite heat sink (PF-MF-Cu) showed better readiness for subsequent charge-discharge cycles at elevated ambient temperature (35 and 45 °C) due to its higher melting/crystallization point.

Hydrothermal performance analysis of microchannel heat sink with embedded module with ribs and pin-fins

A new microchannel heat sink with embedded modules with ribs and pin-fins is proposed as an effective solution to realize microchannel heat dissipation within low-temperature co-fired ceramic substrates. Enhance heat dissipation with the following strategies: 1. microchannel cooling within the low-temperature co-fired ceramic substrate to shorten the heat transfer path; 2. embedding embedded modules in the substrate to reduce the overall thermal resistance; 3. creating ribs and pin-fins on the embedded modules to enhance convective heat transfer. The impacts of relative rib height, relative pin-fin height, and relative number of auxiliary channels on the heat transfer performance, temperature uniformity, and pressure drop were investigated. The performance of the proposed design has been compared to the performance of similar designs like straight rectangular microchannels, microchannels with pin-fins embedded modules, and microchannels with ribs embedded modules. Under the condition of Reynolds number 458, the heat transfer performance is improved by 63.91%, the temperature uniformity is improved by 67.65% and the pressure drop is increased by only 10.24%. The heat transfer performance of the microchannel heat sink with embedded modules with ribs and pin-fins can be effectively improved by adjusting the height of the pin-fins and the ribs height on the embedded module.

Optimization of elliptical pin-fin microchannel heat sink based on artificial neural network

Conjugate fluid-solid heat transfer in a pin-fin microchannel heat sink is an effective way to dissipate heat from the heating surface with high heat flux. The introduction of fins increases the heat exchange area and enhances flow turbulence, while it increases the flow resistance at the mean time. The thermal-hydraulic performance of heat sink is affected by fin shape, density and flow parameters. In this paper, contrived numerical simulations of the flow and heat transfer process in elliptical pin-fin microchannel heat sink are carried out, including 2033 cases with different fin sizes, numbers and flow velocities. The simulation results show that the flow velocity and fin transverse width are the main factors affecting heat transfer and fluid flow. Three artificial neural networks are established to predict the average temperature, the temperature non-uniformity of heating surface and the pressure drop of microchannel. The predicted results show that the pump power and heating surface temperature are contradictory objectives. A microchannel with the optimal thermal-hydraulic performance is selected. It has numerous fins which are longer in the flow direction. The empirical correlations for Nusselt number and friction coefficient of the optimal microchannel are proposed.

Performance analysis and optimal design of a water-cooled thermoelectric component for air cooling based on simulation and experiments

In the present study, a water-cooled thermoelectric component model for air cooling is established. To validate the present model, the results of transient and steady-state experiments are compared with numerical calculations. The effects of different air flow rates and water flow rates on the TEC performance and thermal-hydraulic characteristics of the plate-fin heat sinks (PFHS) are studied. The heat transfer and flow characteristics (JF) and coefficient-of-performance (COP) are adopted as optimization goals. A standard design of experiment (DOE) method called a partial factorial design (PFD) is applied in this experimental plan. The significant influential factors are distinguished from six parameters in the PFHS (fins width, fins length, substrate thickness, fins number, fin thickness, and fins height). The number and height of fins have a great effect on the heat transfer and flow characteristics of the PFHS, while the width of the PFHS and fin height have a great effect on the COP of the TEC. The aim is to maximize the response variable JF of the PFHS under the criterion of COP of the TEC. A three-level Box-Behnken design (BBD) based on the response surface methodology (RSM) has been established for predicting and optimizing the response variables JF and COP with the design constraints. The predicted results also indicate that the model proposed in this study is reasonable and accurate and can be used for describing the heat transfer and flow characteristics and coefficient-of-performance with the limitations of the factors studied. This work is expected to provide help in the analysis and optimization of thermoelectric components.

Numerical Study About Nanofluids of Spherical and Tube-Shaped TiO2 Nanomaterials on the Thermal Performance and Entropy Generation of Different Cross-Section Microchannel Heat Sinks

We numerically evaluated the thermal performance of microchannel heat sinks, considering rectangular, hexagonal, and circular cross-sections. Moreover, as a passive heat transfer augmentation technique, dimples were added to improve the rectangular microchannel heat sinks. These simulations use nanofluids based on TiO2 nanoparticles or nanotubes dispersed in bidistilled water as working fluids. The mathematical model considered variable thermophysical properties of the nanofluids; for this purpose, polynomial fittings correlate the dependence of the thermophysical properties on the temperature. We considered a heat flux of q″ = 50 W/cm2 at the microchannel’s lower surface as a boundary condition along with laminar flow conditions. The numerical simulations allowed the Nusselt numbers and entropy generation calculation, which were the basis for the thermal performance calculation. Regarding the effect of TiO2 nanoparticles shape, spherical TiO2 nanoparticles based nanofluids using rectangular microchannels improve the Nusselt number. Moreover, the frictional entropy decreases with nanofluids based on TiO2 nanotubes, but the thermal entropy decreases with nanofluids based on TiO2 nanotubes. Incorporating dimples in the rectangular microchannel enhances the Nusselt numbers and lowers the entropy generation. Considering the Reynolds number range and from the perspective of Nusselt number and entropy generation, we concluded that the microchannels must be operated at a high Reynolds number to improve the microchannel heat sinks thermal performance.

Theoretical and experimental research on flow boiling heat transfer in microchannels for IGBT modules

Two-phase microchannel heat sink has received extensive attention due to its small size, high heat transfer efficiency, good temperature uniformity, and low working fluid charge. Heat flux and mass flow rate are important parameters that affect the heat transfer performance of two-phase microchannel heat sink. For different heat fluxes, if the mass flow rate is not reasonable, dry-out may occur, which will significantly reduce the heat transfer performance. In order to further explore the influence of mass flow rate and heat flux on heat transfer characteristics, the flow boiling heat transfer performance and flow regimes under different mass flow rates and heat fluxes were studied for a two-phase microchannel heat sink using R245fa as the working fluid. The results showed that when the mass flow rate was 100 kg/(m2·s), the boiling heat transfer coefficient of R245fa showed a trend of increasing firstly and then decreasing with the increase of the heat flux. At a higher heat flux, the local dry-out in the microchannels began to appear, and the heat transfer performance decreased significantly. And the higher the heat flux was, the more serious the dry-out was. There was no obvious dry-out phenomenon when the mass flow rate was 150–300 kg/(m2·s) and the heat flux was below 500 kW/m2. The research provided a valuable reference for exploring the influence of the mass flow rate and the heat flux on the flow boiling heat transfer characteristics of the microchannel heat sink.

The experimental analysis on the influence of Non-closed droplet shape and location on Thermal/Flow performance of pin fin heat sinks

With the rapid development of electronic technology, high-performance chips and integrated circuits have been used more and more widely. Due to the extremely high heat transfer coefficient, the boiling heat transfer of working medium in micro pin fin channel have attracted more and more attention, and how to effectively meet the requirements of efficient heat dissipation in small space is an important issue. This paper focuses on the irregular structure of pin fin array with a non-closed pin shape, who retains the streamline structure as droplet shape and enhances the heat transfer performance. In this paper, a visualized experimental analysis on the influence of non-closed droplet pin shape and location on thermal/flow performance of pin fin heat sinks have been conducted. Through macroscopic performance and microscopic bubble dynamic behavior, the inner influence law of pin shape, stream orientation, location on thermal/flow performance have been studied. Results show that from macroscopic view, the non-closed pin shape of the micro pin fin array has a great influence on the flow and boiling characteristics. With the increase of Reynolds number, the pressure drop undergoes three stages: rapid rise, rapid decline and then rise again. Similarly, the variation tendency of convective heat transfer coefficient also get through such three stages. All of which corresponding to the flow pattern changes, indicating four heat transfer stages: film boiling, transition period, nucleate boiling, and single-phase flow heat transfer. Besides, for the scale as 40 < Re < 200 as well as 400 < Re < 800, the heat transfer appearance of non-closed droplet pin fin is better than that of droplet one. While for different stream orientations, the general performance of stream orientation with the opening part opposite the upstream direction is better. For the different locations of the front, middle and rear region, the bubble growth diameter in the front region is much larger than that in the middle region of the channel, and more growth time is required, with the bubble disappear - appear- reappearance interval as 0.536 s and 6.110 s respectively. While the growth time and waiting time of the front region with stream orientation B is 4.85 s as well as 0.86 s, which is much shorter than that of the front region with stream orientation A. Through the visual observation of the bubble dynamic behavior in the front section of the micro pin fin array, it could be concluded that with the increase of heat flux,the bubble diameter increases with time. Furthermore, the bubble growth/migration diameter increases first and then decreases with the increase of Re. Moreover, the bubble diameter in zone II is larger than that in zone III. Generally, the comprehensive performance of the non-closed droplet with stream orientation B is the best over the droplet as well as stream orientation A pin fin array, when it is at the range as 300 < Re < 800. Under comprehensive consideration, non-closed droplet with stream orientation B design is recommended, under operating conditions with Re > 300.

Thermal performance of open microchannel heat sink with NACA airfoil shaped pin fins

ABSTRACT The main purpose of this study is to numerically investigate the effect of pin-fin National Advisory Committee for Aeronautics (NACA) airfoil on the heat transfer performance of a single open microchannel heat sink with a fixed surface area and a constant wall heat flux. It was found that the helical flow within the microchannel and the converging–diverging flow near the two sides of the microchannel, caused by the periodically arranged NACA airfoil shaped pin fins with an attack angle, dominate the overall heat dissipation ability of the heat sink. The heat dissipation ability can be further improved by increasing the attack angle and Reynolds number. Of the airfoils considered, the symmetrical airfoil NACA0012 in no attack angle case presents the smallest pressure drop, but also the smallest thermal performance value, which can still achieve a Nusselt number improvement of 35.15% and a thermal performance factor (TPF) improvement of 1.38%, compared to the no-fin case. The NACA airfoil effect can be improved when asymmetric airfoils are considered. In terms of overall thermal performance, the NACA6412 would be the best choice. Its percentage increases in the Nusselt number and TPF can be further enhanced by up to 57.62% and 35.43%, respectively, compared to the no-attack-angle NACA0012 case.

Experimental and numerical investigations on the intermittent heat transfer performance of rectangular cavity plate fin phase change material based heat sink

Thermal management of equipment in confined spaces is of great importance for the safe operation of equipment. Solid-liquid phase change materials (PCM) can be applied to the thermal management of intermittent electronic equipment because of their large isothermal latent heat absorption capacity. In this paper, experimental and numerical research on the thermal performance of an intermittent rectangular cavity plate fin PCM-based heat sink is carried out, which can be applied to heat dissipation in narrow spaces with high heat flow. The optimal PCM-based heat sink structure is obtained by numerical simulation based on the Taguchi method, and the enthalpy method is used to model the phase change process. Temperature testing and visualization experiments are used to visually present the PCM-based heat sink's internal temperature distribution and validate the numerical model. The effects of fin structure parameters, heating power, cooling air speed and number of intermittent cycles on thermal performance (base temperature, liquid fraction and operating time) are analyzed for different structured PCM-based heat sinks. The results show that the PCM-based heat sink with 8 fins, 15 mm fin height and 2 mm fin thickness has the longest stage C at the critical base temperature of 348 K and reaches the maximum operating time of 1193 s during the charging cycle. The natural convection in stage C of the charging cycle plays a crucial role in prolonging the operating time. Meanwhile, increasing the number of intermittent cycles can result in longer operating time and lower critical base temperature. As the number of intermittent cycles increases from 1 to 8, the temperature difference between the maximum and minimum temperature of the base during the whole cycle is reduced from 48 K to 25 K, and the temperature fluctuations gradually decrease.

Thermal performance improvement of a heat-sink using metal foams for better energy storage systems

Newly, energy storage systems and harvesting energy equipment are modern and important topics in engineering problems, but they still face the efficiency problem. Using the advantages of micro-scale flow and metal porous materials can be applied to improve the performance of these systems. So, the present investigation provides a numerical study on a heatsink employing various arrangements of metal foams inside a heat sink (in the direction and against the fluid flow). The influences of diverse fluid flow characteristics, metal foams' permeability and thermophysical properties of the coolant (using CuO-MgO/water nanofluids) on the thermal efficiency of the heatsink are examined. Then, the variations of convective heat transfer coefficient and pressure loss for all variables are investigated, and performance evaluation criteria are defined to distinguish the simultaneous impacts of improving heat exchange against incrementing the pressure loss. It indicates the metal foams located in the direction of the flow perform better than those located against the flow, which increases the performance evaluation criteria (PEC) of the heatsink between 1.18 and 1.55 depending upon the permeability of porous media. Also, using the nanofluids in the presence and absence of metal foams decreases the heatsink performance. Investigating the impacts of volumetric flow rate illustrates that thermal performance increases by increasing the flow rate. In addition, outcomes reveal that although adding metal foams and nano-additives and increasing volumetric flow rate enhance the frictional entropy generation rate, the total amount of entropy generation rate decreases due to more contribution of the thermal entropy generation rate, that reduces by those variables.

Multiple Phase Change Material-Based Heat Sink for Cooling of Electronics: A Combined Experimental and Numerical Study

Abstract This paper reports an investigation of the thermal performance of an energy storage heat sink incorporated with multiple phase change materials (PCMs). A six-cavity cylindrical heat sink heated at the base is chosen for the investigations with Docosane, n-Eicosane, and Tetracosane as candidate PCMs. The phase transition of PCMs has been visualized with a digital camera and three-dimensional numerical simulations. The results show that the latent heat exploitation process of PCMs in a heat sink with multiple PCMs is different from the single PCM heat sink, where the PCMs in all cavities melt distinctly rather at a time, thereby opening up windows for obtaining deeper insights that can lead to better performing heat sinks. A trained artificial neural network (ANN) with 78 representative heat sink configurations based on the arrangement of the PCMs in the cavities as input and charging and discharging times as output is used to swiftly drive the optimization engine. Finally, multi-objective optimization is performed using the artificial bee colony algorithm with simultaneous consideration of two conflicting objectives (i.e., maximizing charging cycle time and minimizing discharging cycle time) of the heat sink. From the optimization study, best performing nondominated Pareto optimal heat sink configurations are obtained and validated with the in-house experimental results. From the investigations, it is found that the heat sink configurations with multiple PCMs perform on par with the single PCMs in the charging process and show a superiority of up to 24% in discharging process over a heat sink with single PCMs in terms of time to reach set point temperature.

Secondary flow through lateral passages to improve hydrothermal performance of liquid-cooled microchannel heat sinks

This study proposes a simple cost-effective concept to improve hydrothermal performance of liquid-cooled microchannel heat sinks utilized in high power density electronics. It consists of parallel microchannels comprising interdigitated cavities on sidewalls interconnected using lateral passages. With suitable misalignment of cavities in adjacent microchannels, secondary flow forms in lateral passages which can improve the heat sink performance. Different cavity shapes are chosen and hydrothermal performances are compared with that of a simple straight-channel heat sink. 3D numerical simulations are performed on a model consisting of a Gallium Nitride substrate as the heat source, a Silicon heat sink, and liquid deionized water as the coolant considering temperature-dependent thermophysical properties of Silicon and water. Compared to the base case, heat sink with prismatic cavities and lateral channels has the largest shrinkage of hotspot area and reduces hotspot temperature by 1.6 °C at Reynolds number of 160. This configuration enhances the average Nusselt number by 20.2% at the same Re. Moreover, implementing backward cylindrical cavities with lateral channels improves the Coefficient of Performance and Performance Enhancement Factor by 31.7% (at Re=40) and 22.7% at (Re=160), respectively. At the end, performance improvements proposed in the previous works are provided within an itemized review table.

Investigation of the hydrothermal phenomena in a wavy microchannel with secondary flow passages through mid-wall inflection points

Advancement in manufacturing processeshas fuelled research in microchannel heat sinks to meet the demands of modern microelectronics. The heat sink design in the present study considers longitudinally wavy microchannels incorporating secondary flow passages. The secondary flow has been investigated for abrupt flow bifurcation (at 60° angle) and smooth flow bifurcation (at 30° angle). Further, these geometries were tested with different inlet–outlet configurations. The main objective of the paper is to study how a secondary flow would affect the flow profile and thermal performance of a wavy microchannel heat sink. The flow profile, pressure drop, temperature profiles, and average Nusselt number for a wide range of flow rates have been obtained and compared with those for the conventional design, and associated trends have been explored. Furthermore, the overall performance of the heat sink designs has been quantified by plotting the thermal enhancement factor (TEF) against a wide range of Reynolds numbers. The heat sink with flow bifurcation of 30° attains the highest value of Nuselt number below the flow rate of 1.8 × 10-6 m3/s, whereas above this flow rate, the Nusselt number value of the conventional wavy heat sink dominates the proposed heat sink designs. The study corresponds to the demands of modern microchips such as the 13th Gen Intel® Core™ processor and serves as a guideline for manufacturing heat sinks with wavy microchannels incorporating secondary flow passages.

Employing the (SWCNTs-MWCNTs)/H2O nanofluid and topology structures on the microchannel heatsink for energy storage: A thermal case study

The present study investigated the increase of heat transfer rate of the microchannel (heatsink) with high heat flux using topology structures and CNTs nanofluids. The heat transfers in the heatsink were studied using a three-dimensional finite volume method (FVM). Four nature-inspired topology structures were used: snowflake shape, honeycomb-shaped, ternate veiny, and spider netted, and their results were compared with straight microchannel heatsink (MHS). For testing the effect of nanoparticle concentration and type on heat transfer of heatsinks, two water-based nanofluids (SWCNT-Water) and (MWCNT -Water) were used. The temperature and pressure contours related to the proposed designs and two nanofluids were presented. The spider netted model had the highest heat transfer coefficient and the highest-pressure changes compared to other designs. For Reynolds number 550, the heat transfer coefficient and pump power (Pp) increased by 56.1% and 46.1%, respectively, when using SWCNT- H2O nanofluid. Based on the thermo-hydraulic performance of the models, spider netted increased heatsink performance by an average of 50.2%. The results also showed that nanofluids with a concentration of 5% significantly increase the heat transfer coefficient and pump power in the heatsink.

Numerical study on heat transfer characteristics of a pin–fin staggered manifold microchannel heat sink

• A pin-fin staggered manifold microchannel (PFSMMC) heat sink was designed. • The heat transfer characteristics of PFSMMC in single-phase flow were studied. • The staggered divider length-width ratio of PFSMMC was optimized. • The heat transfer characteristics of PFSMMC with different non-uniform heat sources were studied. Manifold microchannel(MMC) heat sink is an efficient thermal management solution for high heat flux electronic devices. A pin-fin staggered manifold microchannel(PFSMMC) heat sink is proposed to enhance the heat dissipation performance of the MMC heat sink in this paper. The heat transfer performance of the PFSMMC heat sink, the rectangular manifold microchannel(RMMC) and the pin-fin manifold microchannel(PFMMC) are compared by single-phase flow numerical simulation. The results show that the PFSMMC heat sink has better heat transfer capability and more uniform heating surface temperature. The effect of staggered divider length-width ratio on the heat transfer characteristics of PFSMMC heat sink is analyzed. The maximum heating surface temperature of PFSMMC heat sink has a valley with the increase of length-width ratio. The length-width ratio corresponding to the valley value of the maximum heating surface temperature is about 0.32. In addition, the heat characteristics of PFSMMC with different non-uniform heat sources are studied. The results show that the heating surface temperature uniformity deteriorates with the increase of length-width ratio, but the maximum heating surface temperature is lower at the length-width ratio of 0.32.

Electrical field combined nanofluid to enhance the thermal performance of vertical open microgrooves heat sink

• Electrical field combined nanofluid shows a 32.8% decrease of wall temperature. • Nanofluid combined electric field causes a circular low temperature area in the wall. • Electrical field affects meniscus, CPL and nanoparticle, resulting in enhancement. The open microgrooves heat sinks pose a promising application in the future of electronic devices cooling. However, there are problems with insufficient supply of working fluid and easy drying. In this paper, the above problems are solved by electrical field combined with nanofluid. The capillary characteristic and thermal performance of the open vertical microgrooves heat sink in the non-uniform electrical field with Al 2 O 3 /water nanofluid were experimentally studied. Experimental results show that at the input power of 4W, optimal concentration of 0.006 nanofluid and electric field cause a wall temperature reduction of 16.9 o C, which is about 24% lower than the pure base fluid under electric field. Moreover, a circular low-temperature phenomenon is found by the infrared imager. Thermal enhancement is attributed that electrical field causes fluctuations in the meniscus, enhanced capillary wetting length (CPL) and directional motion of particles. The long CPL of nanofluid is subjected to stronger electrical field force resulting in an intense evaporation, which poses a circular low temperature region.

Server processor heat sink analysis and modifications to improve its thermal performance

Heat generation in the electronic components of high-performance computing servers is a matter of concern. Heat generation adversely affects the performance of these servers, certain temperature limits are required for these server processors and other electronic components to work within suitable conditions. Furthermore, in order to improve CPU performance and functioning, the heat flux in today's processor packages is increasing day by day, even as server CPUs and other components shrink in size. The air-cooling technique is the most broadly utilized and efficient technique of the present accessible electronic cooling advances. In data centers, heat sinks with forced air are utilized to keep server processors and other electronic components cool. The cooling systems of electronic gadgets are a growing field of research. The aim of this work is to contribute to this research field by investigating the effects of inlet air properties on server processor heat sink thermal performance with a heat load of 140 W. The heat sink performance depends on various parameters. The influence of various geometries of lateral perforation on heat sink fin walls was numerically analysed in this study to improve the thermal performance of the server processor plate fin heat sink. The CFD Solver is used for analysing the performance of heat sink and the effect of lateral perforation shapes on heat sink fins. The three shapes of perforation are considered as square, circular, and hexagonal types, with the same cross-sectional area and pitch of inline arrangement. In comparison to plate fin heat sinks, the numerical results demonstrate that a laterally perforated finned heat sink has a lower base temperature and a low thermal resistance. The use of a perforated heat sink also saves material and reduces the weight of the heat sink.