Heat Sink Configuration Research Articles

Design and Performance Evaluation of Thermoelectric Cooling System Integrated with PCM (Phase Change Material)

A thermoelectric system integrated with PCM (Phase Change material) for cooling vaccines has been introduced, thermal management techniques (i) using high performance heat sink on sides(hot, cold) of module (ii) integration of PCM (ice) on cold side were analysed. Experimental results infers that, by adopting water cooled heat sinks at hot side and air cooling at cold side of module, a COP of 0.124 with minimum cooling temperature (Tc) of 6°C (at 130 minutes) is attained by the system. Performance simulations were carried with CFD (computational fluid dynamics) model of system for different heat sink configurations (with or without integration of PCM). Simulation results shows that, (i) in the absence of PCM, a COP of 0.261 and 0.245 is achieved by the system for heat sink configuration of fin and fan on both sides, fin and fan on hot side and fan on cold side respectively, (ii) COP is improved to 0.406 with integration of PCM and is 55.55% higher, considering the same heat sink configuration (fin and fan on both sides), with cooling temperature of 4°C.

Enhanced performance of thermoelectric cooler with phase change materials: An experimental study

The thermal management of a thermoelectric cooler (TEC) has a significant impact on its cooling performance. The heat generated in the hot side of the TEC system reduces the performance and lifespan. Therefore, an efficient thermal management technique is vital for ensuring the TEC to operate at optimum temperature. In this study the performance of TEC is investigated by varying input voltage, air velocity at hot side, heat sink configuration and fill volume of PCM in the heat sink. A 54 W Bismuth Telluride based TEC was chosen for this study and OM35 was used as the phase change material (PCM). The three configurations of aluminium heat sink used in this study are square pocket, rectangle pocket and circular pocket. The input voltage to TEC is varied from 2.5 V to 12.5 V. The results show that, both the cold and hot side temperature of TEC increases when the input voltage is increased. The changes in air velocity at the hot side of the TEC from 1 m/s to 3 m/s reduced the temperature on both the cold and hot side of TEC. Among the three configurations of heat sink, square pocket heat sink with fully filled PCM showed better performance compared to other configurations. Moreover, the heat sink with a square pocket filled with PCM provided cold and hot side temperatures of 27 °C and 58.7 °C respectively when compared to 34 °C and 68.3 °C for the similar operating conditions without PCM. The results indicate that the performance of TEC can be significantly improved by the use of heat sinks filled with PCM.

An experimental study for thermal management using hybrid heat sinks based on organic phase change material, copper foam and heat pipe

Phase change materials (PCMs) are a better choice for thermal management if their low thermal conductivity could be dealt with as this limits the heat transfer rates during charging and discharging processes. For the use of phase change materials in practical applications, therefore, it is important to improve their thermal conductivity, phase change materials thermal conductivity can be improved by integrating it with high thermal conductive materials. In this study, copper foam and heat pipe (HP) are integrated with Phase Change Material (PCM RT-64) to analyze the cooling performance of the heat sink. Different heat sink configurations are investigated at two different heat fluxes 2 & 3 kW/m2 for the same charging and discharging time of 6000 s to determine the best cooling arrangement. Results depicted that the base temperature of the heat sink increased with increasing heat flux. At both heat fluxes, hybrid cooling (PCM-Cu Foam-HP) showed the best performance compared to other combinations. At heat flux of 2 kW/m2 and 3 kW/m2 hybrid system with cooling fan reduces the base temperature by 38 % and 39 % respectively, as compared to the empty heat sink. Setpoint temperature analysis also showed that fan hybrid cooling is the best configuration.

Staggered oriented airfoil shaped pin-fin heat sink: Investigating the efficacy of novel water based ferric oxide-silica hybrid nanofluid

Nowadays, electronic components are one of the essential parts of almost every smart device. To efficiently transfer the desired amount of heat, recent studies have focused on investigating the potential of advanced thermal coolants and heat sink configurations. Current study reveals the potential of novel water-based hybrid nanofluid of silica (SiO2) and ferric oxide (Fe2O3) for cooling high-heat-generating electronic devices. The experimental work was conducted to inspect the heat transfer characteristics of a uniquely designed staggered oriented airfoil shaped pin-fin heat sink employing Fe2O3-SiO2 hybrid nanofluid with different mixture ratios (25%:75%), (50%:50%), (75%:25%). Airfoil shaped pin-fins offer less resistance to fluid flow and maximum effective area due to their unique shape and delayed separation of fluid at the rear end. All the mixture ratios were tested at three different heating powers (75, 100, 125 W) with varying Reynolds number in laminar flow regime. Experimental results revealed that the fluid having a mixture ratio of 50:50 showed the least thermal resistance followed by 25:75 and 75:25. Maximum enhancement of 17.65% in average Nusselt number was observed against the heating power of 75W. Pumping power was found to increase with the supplementation of nanoparticles in base fluid, while a little variation was observed among different mixture ratios. Finally, the results were compared with recently published studies, which revealed that the airfoil shaped fins have better thermal characteristics and offer less resistance to fluid flow.

Thermal Performances of Hybrid Pin Fin with Connector Heat Sink Under Natural Convection

Heat transfer in engineering applications has shown progress, especially in electronic devices that raise the need for better heat sink designs. In addition, the generation of heat in devices and electronic circuits has also augmented, leading to the problem of heat dissipation. This study investigates the thermal and fluid flow characteristics of different geometrical configurations of pin fin heat sink under natural convection. The heat sink models studied are Hybrid Pin Fin with Connector Heat Sink (HPFWC HS) and Pin Fin with Connector Heat Sink (PFWC HS). All heat sinks models were simulated using CFD Ansys to analyse each heat sink’s thermal performances and flow fields. The results show that adding wings to the HPFWC HS significantly increased heat dissipation. In terms of heat transfer characteristics, the HPFWC HS has about a 5.78% increase in Nusselt number compared with HPFWC HS. The reason is that the heat sink HPFWC HS has wings around it, and these wings help to promote vortex formation around the fins, which leads to a higher heat transfer coefficient. A fin spacing of 15mm is the best spacing for the heat sink compared to other fin spacing.

Effect of phase change temperatures and orientation on the thermal performance of a miniaturized PCM heat sink coupled heat pipe

ABSTRACT This study reports the results of experimental and numerical investigations on the thermal performance of a miniaturized phase change material (PCM) heat sink coupled with heat pipe. Initial studies are conducted on two different configurations of PCM heat sink with heat pipe (i) HSHP (i.e., PCM coupled at evaporator of heat pipe) (ii) HPHS (i.e., PCM coupled at condenser of the heat pipe). The results showed a superiority of HSHP over HPHS by up to 98.8% in the charging cycle. Experiments are conducted on HSHP with different melting temperature PCMs. The HSHP with high melting temperature PCM showed high thermal performance.

Numerical study of oblique fins under natural convection with experimental validation

3D numerical simulations are performed in order to investigate the thermofluids characteristics of the oblique fin heat sink under natural convection. Detailed parametric study is carried out on the effects of geometrical parameters, including main channel width, oblique channel width, fin length, fin width, offset ratio, and fin rotational angle. Through detailed sensitivity analysis, it is found that fin oblique angle and fin rotational angle are the most critical parameters affecting the performance of oblique fins; followed by the main channel width, fin length, and offset ratio. Yet, the effects of fin width and oblique channel width are very minor. Based on sensitivity analysis, an optimum oblique fin heat sink configuration is obtained and a novel symmetrical oblique fin is proposed and compared with the continuous fin heat sink. Subsequently, an experimental verification is made to validate the results of the optimum oblique fin heat sink. The simulation is in line with the experimental data, and the proposed oblique fin heat sink offers more than 3 °C reduction in the maximum heat sink temperature when compared to the continuous fin heat sink.

Numerical Study of Single-Layer and Stacked Minichannel-Based Heat Sinks Using Different Truncating Ratios for Cooling High Concentration Photovoltaic Systems

The present research aims to discuss and analyze the performance of truncated single-layer and stacked mini-channel-based heat sinks employed for the cooling of a single-cell high concentrating photovoltaic systems. The truncating technique of the fins at the entrance and exit regions from the internal fluid mini channels is opted to reduce the energy, raw material costs and time of the manufacturing process of the mini channels. This proposed solution is constrained by several metrics such as the thermal management and the overall performance of the high concentrating photovoltaic system. In the current research, the use of a truncating ratio of 31% has yielded minimum cell temperature and maximum electrical efficiencies for both single-layer and stacked mini-channel-based heat sinks, while a truncating ratio of 65% has enabled more uniform cell temperature distribution. Moreover, a truncating ratio of 65% has qualified the highest water outlet temperature and the lowest pressure drops relatively compared to the conventional mini-channel-based heat sink configurations. The highest water temperature has reached up to 52.7 ∘C by the stacked mini-channel-based heat sink with a truncating ratio of 65% under a geometrical concentration ratio of 2000× and a mass flow rate of 0.001kgs−1. For both the single-layer and stacked mini-channel-based heat sinks, the use of a truncating ratio of 65% has driven the upper hands to achieve higher ratio of the thermal power to the pumping power (RTP). The maximum RTP values have been recorded by the single-layer mini-channel-based heat sink with a truncating ratio of 65% equal to 23.61 ×106 and 233.06 ×103 at a mass flow rate of 0.008kgs−1 and 0.001kgs−1, respectively, under 2000×.

Performance enhancement of heat sink with branched and interrupted fins

Efficient cooling of the electronic device is of paramount importance for its safe and reliable operation. Therefore, the present study makes a performance analysis of branched and interrupted fins to explore the possibility of heat transfer enhancement, while keeping the overall heat sink volume fixed, using numerical simulations. Six different heat sink configurations have been considered, i.e., continuous fin, interrupted fins, fins with one side branch, branched fin symmetrically placed at the tip of primary fin, fins with tertiary branch, interrupted and branched fin symmetrically placed at the tip of primary fin. The temperature difference between the fin base and the ambient (ΔT) has been varied in the range of 10 °C to 60 °C (1.1 × 105 ≤ Ra ≤ 6.1 × 105). The results have been analyzed in terms of heat transfer rate (Q), specific heat transfer rate (Q/m), effectiveness, and Nusselt number (Nu). With the branching of fins, not all designs of heat sinks yield better performance. The design in which the secondary fins are placed symmetrically and at the farthest position from the base plate, dissipates maximum heat with a weight reduction of 12.26% compared to the continuous fin.

Thermal management of Electronics: Numerical investigation of triangular finned heat sink

The micro pin fin heat sink is an innovative method to enhance heat dissipation from the electronic system. The various geometrical configuration of the triangular micro pin fin heat sink (TMPFHS) for the fluid and heat transfer characteristics is numerically investigated in the present work. Finally, the best configuration is proposed. Three different configurations of triangular pin fin have been considered (i) uniformly varying the fin height ranging 0.25 mm-0.75 mm. (ii) Orientation of fin both in the clockwise and counter-clockwise direction (30°, 40°, 50o, and 60°) (iii) Change in the direction of fins facing upstream fluid from forward triangular to backward triangular between two successive rows and vice versa. A 3-Dimensional numerical simulation is carried out for a triangular finned heat sink arranged staggered manner subjected to 10 W/cm2. A single-phase laminar flow is considered for Reynolds numbers ranging from 100 to 900 using coolant water. Results reveal that the heat dissipation rate for all the configurations increases substantially with the rise in pressure drop. A Non-dimensional parameter thermal performance index (TPI) is employed to access the superior heat sink in maximum dissipation and minimum pressure drop. The TPI with alternate forward and backward arrangement outperforms all other configurations of the range 1.01–1.44.

Heat transfer and pressure loss performances for additively manufactured pin fin arrays in annular channels

Additive manufacturing technology with metal powder has facilitated the production of innovative and even more complex heat sinks. The layer-additive process offers a wide range of geometries that may be exploited for advanced cooling purposes and the final identification of the best heat sink configuration has to deal with other constraints imposed by the specific application. This contribution focuses on the thermal and fluid dynamic characterization of water cooling annular channels for applications in internal combustion engine components, where also the load-bearing capacity is requested together with the cooling performances. The heat transfer inside the annular channel was enhanced by pin fins arrays that were manufactured by selective laser melting technology in AISI 316L stainless steel. Four pin fins arrays that differ in dimensions and geometries were experimentally tested over a range of mass flow rates to compare their pressure losses and heat transfer performances against those of the smooth annular channel. Furthermore, the test coupons were analysed through optical non-destructive techniques to characterize their geometrical morphology in terms of conformity with the designed model, surface roughness and waviness. In the investigated channel Reynolds number range (from 2000 to 12,000), the pin fins arrays with the largest height-to-pin diameter ratio show better thermal performances (Nu/Nu0 always greater than 2), however their heat sink efficiencies are above unity only for Re < 3000. In addition, the 45° oriented pin arrangement seems the most promising geometry due to high thermal efficiency, lighter weight and slightly lower manufacturing cost.

Numerical simulation of heat sinks with different configurations for high power LED thermal management

This study performed a steady-state numerical analysis to understand the temperature in different heat sink configurations for LED applications. Seven heat sink configurations named R, H-6, H-8, H-10, C, C3, and C3E3 were considered. Parameters like input power, number of fins, heat sink configuration were varied, and their influence on LED temperature distribution, heat sink thermal resistance and thermal interface material temperature were studied. The results showed that the temperature distribution of the H-6 heat sink decreased by 46.30% compared with the Cheat sink for an input power of 16 W. The result of the H-6 heat sink shows that the heat sink thermal resistance was decreased by 73.91% compared with the Cheat sink at 16 W. The lowest interface material temperature of 54.11 °C was achieved by the H-6 heat sink when the input power was used 16 W. The H-6 heat sink exhibited better performance due to more surface area with several fins than other heat sinks.

Experimental analysis of a heat sink for electronic chipset cooling using a nano improved PCM (NIPCM)

The impacts of a phase changing substance (PCM) and a nano-improved phase changing substance (NIPCM) on the thermal performance of a heat sink to be used for an electronic chipset are investigated in this work. The paraffin with suitable melting temperature was utilized as the base PCM, and 1.0% weight fraction of nano-silica (SiO2) was used with paraffin while preparing NIPCM. A plate fin heat sink was established during the experimentation. The investigations were performed with three different configurations of heat sinks. The first configuration was the plain heat sink without amalgamation of any PCM, which was labeled as HS. It was further integrated into PCM and NIPCM based thermal dissipation systems, and named as PCM-HS and NIPCM-HS, respectively. The effects of varying power levels on three distinct heat sink modules (HS, PCM-HS, and NIPCM-HS) were explored in passive working modes. It has been discovered that the PCM may greatly boost the system's thermal performance, and that the NIPCM, when compared to the PCM, can further improvise the performance under passive cooling conditions. When compared to the PCM, the nano-PCM module can improve heat sink’s thermal management through delaying heating time by up to 220%.

Simulation of hybrid nanofluid flow within a microchannel heat sink considering porous media analyzing CPU stability

Current article aims to numerically scrutinize and compare the forced convection in three different configurations of a 3D heat sink. Two models of porous were designed aiming to evaluate the effects of nanomaterial and metallic foam to the conventional solid heat sink on thermal performance. In these two models, porous material with the same volume fraction was located in two different positions to have different contact areas with the solid. MWCNT-Fe 3 O 4 hybrid nanofluid has been utilized as coolant working fluid. Validations were carried out in the critical case of 47 W for pure water through comparison with previous experimental work in which the whole surface of the CPU is covered with porous media. According to the results, at the constant Reynolds number, the heat sinks, which are consist of metallic foam, have better cooling performance and are able to decrease the surface temperature of heat sink more. • Microchannel heat sink performance has been studied. • Multi-wall carbon nanotube-Fe3O4 hybrid nanofluid has been utilized. • Validations were carried out with comparison with previous experimental article. • The thermal resistance of model 2 is 2% lower than that of model 1.

Tailoring the fluid flow distribution in a parallel mini-channel heat sink under multiple-peak heat flux

Parallel micro/mini-channel heat sinks are widely used for the efficient cooling of electronic devices to avoid functional damage and lifetime shortening due to overheating. This study addresses the optimization of fluid flow distribution in parallel mini-channel heat sinks subjected to a non-uniform multiple-peak heat flux to eliminate the temperature hotspots. A 3D heat sink comprising of 16 parallel straight mini-channels is used as a model for study, each mini-channel having the dimension of 1 mm in width, 2 mm in height and 34 mm in length. In particular, an original optimization algorithm is developed to adjust the inlets of these mini-channels according to the temperature distribution on the heating base surface. The fluid flow distribution is thereby tailored, leading to the reduced peak temperature on the heating surface. The effectiveness and robustness of the optimization algorithm are tested and discussed.Results obtained show that the maximum temperature can be reduced by 10 K and 7 K for two-peak and five-peak heat flux cases, respectively, by using the proposed optimization method. The heat sink configuration with optimized channel inlets could always provide smaller thermal resistance than that of the equal channel inlet configuration under different average heat flux or total mass flow-rate conditions. At the same pressure drop, tailoring the flow distribution of the cooling fluid is more effective in reducing the thermal resistance than simply increasing the mass flow rate of the cooling liquid. This optimization method could also be generalized as an efficient thermal management technology for electronic cooling.

Energy and exergy analyses of new cooling schemes based on a serpentine configuration for a high concentrator photovoltaic system

High concentrator photovoltaic is expected to play an increasingly important role in electrical energy production. Controlling multijunction solar cell temperature within the recommended conditions is a key challenge that limits the functionality of this growing technology making the identification of an efficient cooling method an essential requirement. Hence, in this research, new heat sink configurations based on a serpentine design are studied and compared with the straight channel arrangement. To assess the performance of the high concentrator photovoltaic, a 3D model is built for the multijunction cell and heat sink and impact of the heat sink configuration, mass flow rate, and concentration ratio are investigated. The results include solar cell temperature distribution, thermal resistance, pumping power, thermal and electrical energy and exergy efficiencies. The study shows that the straight channel is not recommended for concentration above 1000×, whereas the centre inlet serpentine design can maintain a uniform temperature distribution for the system for concentration up to 2000×. Temperature non-uniformity varies between 18 °C and 5 °C. The highest overall energy and exergy efficiencies reached 78% and 35.2% respectively at concentration of 2000×. The results prove the effectiveness of implementing a serpentine design as a new cooling scheme for the system.

Numerical analysis on the thermal performance of microchannel heat sinks with Al2O3 nanofluid and various fins

• A single-phase three-dimensional flow model compares different finned microchannels. • The fin shape has significant effects on microchannel heat transfer characteristics. • A zigzag fin gives the highest rate of heat removal to hydraulic power loss ratio. • The zigzag fin gives a 9 K lower contact temperature and 60% higher Nusselt number. • Higher thermal performance is achieved with the Al 2 O 3 nanofluid compared to water. The hydraulic and thermal performance of microchannel heat sink configurations for high performance electronic cooling applications is investigated by numerical modelling. Conjugate heat transfer simulations are obtained through the silicon walls and the fluid domain of a square base prism heat sink traversed by 50 parallel rectangular cooling ducts, under a 150 W/cm 2 constant heat flux input through the base. Al 2 O 3 nanofluid coolant with a nanoparticle volume fraction ranging from 0 to 3% is supplied at 298 K, over the Reynolds number range 100 to 350, modelled as a single-phase homogeneous medium. Rectangular, twisted, and zig-zag fins are inserted into the plain rectangular duct to enhance the heat transfer rate. The zig-zag fin and 3% Al 2 O 3 nanofluid provide the best thermal performance, with a 6.44 K lower average heated wall contact temperature, 60% higher Nusselt number, and 15% higher second law efficiency than without fins and plain water cooling. Twist in the microchannel fin unexpectedly reduced the microchannel pressure drop by 2% to 15% compared to a straight fin, possibly due to the more evenly distributed axial mass flux across the microchannel.

Experimental study of the thermal performance of a PCM in heat sinks

Phase change materials (PCMs) can be great solutions as heat sink for energy storage in microgravity conditions. To guarantee the reliability of the systems, the thermal behavior of the PCMs and their degradation should be understood. Two different configurations of heat sink devices, a cylindrical and a finned hollow parallelepiped based on phase change material (PCM), were investigated. The hydrated salt sodium phosphate dibasic dodecahydrate (Na2HPO4·12H2O) was used as the PCM material, in three different volumes. Were also investigated the effect of copper sponges in the effective thermal conductivity, and the thermal property degradation in the finned heat sink by the sequential heat cycles. The PCM was replaced in each experiment and two power supply heat flux levels were studied. In the second heat sink configuration, consisting of finned heat sink hollow block provided with internal fins, the PCM was not replaced, to observe its property degradation. Power supplied in finned devices varied from 75W to 100W. Experimental results showed a reduction of approximately 50% in the maximum temperature of the heat sink when the copper sponge is inserted. Gaps in hydrated salt decrease the thermal conductance of the heat sink. The PCM thermo-physical properties degradation is negligible for a few numbers of continuous heating cycles. In the case of finned block device, it was observed a variation of 6% in latent heat storage at the first cycles when the same test was realized several times. Contact area loss increased up 15% at the end of the experiments.

The Effect of Hydraulic Diameter on Flow Boiling within Single Rectangular Microchannels and Comparison of Heat Sink Configuration of a Single and Multiple Microchannels

Phase change heat transfer within microchannels is considered one of the most promising cooling methods for the efficient cooling of high-performance electronic devices. However, there are still fundamental parameters, such as the effect of channel hydraulic diameter Dh whose effects on fluid flow and heat transfer characteristics are not clearly defined yet. The objective of the present work is to numerically investigate the first transient flow boiling characteristics from the bubble inception up to the first stages of the flow boiling regime development, in rectangular microchannels of varying hydraulic diameters, utilising an enhanced custom VOF-based solver. The solver accounts for conjugate heat transfer effects, implemented in OpenFOAM and validated in the literature through experimental results and analytical solutions. The numerical study was conducted through two different sets of simulations. In the first set, flow boiling characteristics in four single microchannels of Dh = 50, 100, 150, and 200 μm with constant channel aspect ratio of 0.5 and length of 2.4 mm were examined. Due to the different Dh, the applied heat and mass flux values varied between 20 to 200 kW/m2 and 150 to 2400 kg/m2s, respectively. The results of the two-phase simulations were compared with the corresponding initial single-phase stage of the simulations, and an increase of up to 37.4% on the global Nu number Nuglob was revealed. In the second set of simulations, the effectiveness of having microchannel evaporators of single versus multiple parallel microchannels was investigated by performing and comparing simulations of a single rectangular microchannel with Dh of 200 μm and four-parallel rectangular microchannels, each having a hydraulic diameter Dh of 50 μm. By comparing the local time-averaged thermal resistance along the channels, it is found that the parallel microchannels configuration resulted in a 23.3% decrease in the average thermal resistance R¯l compared to the corresponding single-phase simulation stage, while the flow boiling process reduced the R¯l by only 5.4% for the single microchannel case. As for the developed flow regimes, churn and slug flow dominated, whereas liquid film evaporation and, for some cases, contact line evaporation were the main contributing flow boiling mechanisms.

Experimental investigation of factors affecting two-stage thermoelectric generator integrated with phase change materials

In light of limitations in the performance of thermoelectric materials, this study proposes a two-stage thermoelectric generator (TEG) system integrated with phase change materials (PCMs). Three sets of experiments were designed to investigate the factors influencing the proposed TEG-PCM system. Two of them examined the effects of different heat sink configurations on the heat generated with and without paraffin wax as the PCM. The third experiment investigated the thermoelectric performance of the proposed system using a single-cavity heat sink with different PCMs. The results show that the heat source had a greater influence on the performance of the system than the thermal resistance of the heat sink. The PCM reduced the second-stage voltage, but it lasted for a long time. The configuration of the heat sink had a greater influence on the second-stage voltage (U2) than the first-stage voltage (U1). Although the mean value of U1 for the four-cavity configuration without PCM was slightly larger than that of the single-cavity configuration by 10 mV, the maximum value of U2 for the latter was larger than that of the former by 60 mV. The single-cavity configuration is thus more suitable for the two-stage TEG system. Under a 10 W power supply, the properties of different PCMs significantly influenced the duration of voltage in each stage while U1 was maintained at 600 mV. The results show that the factors considered here influenced the performance of the two-stage TEG-PCM system in the order of heat source &amp;gt; thermal resistance of the heat sink &amp;gt; type of PCM.