Characteristics Of Heat Sink Research Articles

Heat transfer characteristics of chip heat sink based on composite wick micro heat pipe array

A double L-shaped heat pipe sink that uses a micro heat pipe array is proposed for heat dissipation and temperature uniformity in high-power electronics chip cooling for the first time in this work. The radiator is composed of two L-shaped micro heat pipe arrays filled with copper foam wick (the composite wick structure) and aluminum flat fins, which can reduce the temperature of hotspots of electronics effectively and has good inclination adaptability. Through experiments, the heat transfer performance is studied under different copper foam filling lengths, liquid filling rates, and inclination angles. Then, a numerical simulation of the effect of different fin parameters on the radiator is conducted using Icepak. The composite wick structure effectively enhances the heat transfer capability of the radiator. Results show that the average thermal resistance of the micro heat pipe array with a composite wick structure is 0.258 K/W, indicating a 23 % reduction compared with that of a single wick structure double L shape heat pipe sink. The double L shape heat pipe sink solves the phenomenon of chip temperature jump caused by the hotspots of high heat flux. The average temperature of the chip surface can be controlled below 62 ℃ when the localized heat flux is 200 W/cm2. Simulation results show that optimization of the fin structure can stabilize the temperature of the 214 W chip at 70.1 ℃, which is reduced by 8.7 % than before optimization.

Experimental study on boiling heat transfer and pressure drop characteristics of hybrid jet microchannel heat sink

Hybrid jet microchannel cooling can improve the non-uniform temperature distribution, significant pressure drop in microchannel, and the uneven heat transfer coefficient in jet impact. The heat transfer and pressure drop characteristics of a hybrid jet microchannel heat sink were investigated experimentally using deionized water as the working fluid. The experiments were carried out under the operating conditions of mass fluxes from 200 ∼ 600 kg/m2s, subcooling degrees from 20 ∼ 40 K, jet-to-target spacings from 1 ∼ 2.5 mm, and outlet pressure of 1 atm. The results show that increasing jet-to-target spacing and mass flux and decreasing subcooling can improve the heat transfer coefficient, and the maximum heat transfer coefficients increase by 58 %, 73 %, and 50 %, respectively. A heat transfer correlation for the hybrid jet microchannel is proposed with a mean absolute error of 6.5 % based on the experimental data. Since large jet-to-target spacing has more expansion space and is closer to the length of the potential core, increasing jet-to-target spacing results in higher critical heat flux at low mass flux. Compared to the heat sink with higher jet-to-target spacing, the pressure drop of the heat sink with the lower one is significantly affected by the mass flux due to the superposition of size effect of the channel and gas–liquid friction. In addition,the slope that pressure drop curves increase with the decrease of jet-to-target spacing rises with the mass flux, while it is not apparent with the subcooling. As the subcooling and jet-to-target spacing rise and the mass flux decreases, the coefficient of performance will increase.

Study on the flow and heat transfer characteristics of a hybrid nanofluid jet impingement microchannel heat sink with airfoil fins

AbstractDue to the continuously increasing power density of electronic devices, the improvement of the temperature uniformity and the reduction of the irreversible energy losses became crucial in these studies on enhanced cooling capacity of the heat sinks. In this paper, a jet impingement microchannel heat sink with airfoil fins (AF‐JIMHS) is proposed. The AF‐JIMHS with reversed fins arrangement has very high comprehensive heat transfer performance. The increase of the internal tangent circle radius and chord length of fin can improve the temperature uniformity of the AF‐JIMHS bottom surface and reduce the irreversible energy losses, at the expense of reducing its comprehensive heat transfer performance. Although the increase of the tangent arc length of fin reduces the temperature uniformity and increases the irreversible energy losses of the AF‐JIMHS, it improves the comprehensive heat transfer performance in a specific parameter range. The increase of fin height improves temperature uniformity of the AF‐JIMHS, while reducing its irreversible energy losses and improving its comprehensive heat transfer performance. Compared with the AF‐JIMHS with uniform height fins, the one with decreasing height fins has higher comprehensive heat transfer performance and lower irreversible energy losses. Moreover, the AF‐JIMHS with increasing height fins has better temperature uniformity.

Fluid flow and heat transfer characteristics of a microstructured microchannel heat sink under flow boiling condition

A microchannel heat sink (MCHS) is known as a heat dissipation device from the miniaturized electronic components and devices due to its capability to dissipate high heat flux from smaller surface area. However, the higher pressure drop and the uneven heat removal along the channel length are the noticeable disadvantages of MCHS. Though there are attempts to address these shortcomings, no existing study has been found to study the effect of positions of microstructures (micro-pin fin and blind holes) and combined effect of micro-pin fins and blind holes under flow boiling condition. Therefore, in the present study, an attempt has been made to logically explain the effect of various arrangements and positions of pin fins and blind holes in the selected twenty-four uniformly distributed stations on the thermohydraulic performance of MCHS through numerically predicted results. The objectives of the study have been attained using the following three analyses, flow boiling, (i) with saturated fluid inlet conditions (inlet Re = 500), (ii) with different inlet subcooling (20, 40, and 60 °C), and (iii) with different heat flux conditions (100, 150, 200 and 250 W/cm2). From the study, it is observed that the pin fin enhances heat transfer in single-phase flow and delays the phase change by disturbing the flow. The blind holes act as nucleation sites and help phase change heat transfer. It is also observed that the ratio of single-phase and two-phase length and arrangement of microstructures in these two regions predominately dominate the heat transfer and fluid flow characteristics of the microchannel heat sink. The optimum performance (maximum heat transfer coefficient and minimum pressure drop) is achieved when twelve pin fins are placed in the upstream half and twelve blind holes are located at the downstream half of the channel. However, design improvement is possible through more computational and experimental analysis.

Heat Transfer Enhancement of Microchannel Heat Sink Using Sine Curve Fins

In this study, numerical simulations are conducted to investigate the effects of initial models (parallel and symmetrical arrangement) using interruption fins on the flow and heat transfer characteristics of microchannel heat sink (MHS). The results indicate that MHS with symmetrical fin arrangement has a higher Nusselt number and lower thermal resistance. The vortices perpendicular to the flowpath is the main factor of affecting the heat transfer characteristics. Because of the higher vorticity, the channel with symmetrical fins achieves higher heat transfer performance. To further improve the heat transfer performance, three modified models (models III–V) are obtained by adopting the methods of staggered, reducing fin quantity, and adding pin fins, respectively. The staggered arrangement of fins can deepen the secondary flow in the channel, and the additional vortices are formed with adding pin fins, which can enhance heat transfer capacity in models III and V. On the other hand, reducing the number of fins can damage some vortices, which can actually reduce heat transfer performance. It is worth noting that both the staggered fins and the pin fins significantly increase the pressure drops of the channel, while reducing the fins number leads to an obvious decrease in the pressure drop.

Numerical Analysis of Fluid Flow and Heat Transfer Characteristics of Novel Microchannel Heat Sink

Microchannel heat sinks have gained prominence in the field of thermal management, offering compact and efficient solutions for dissipating heat flux from high performance electronic devices. Escalating heat flux in modern electronic devices, such as those found in telecommunication equipment, industrial automation equipment, solar devices, and data centre servers has driven the continuous development of microchannel heat sink to achieve efficient thermal management. The critical challenge in thermal management for these devices is to develop a microchannel that enhances heat transfer performance and minimises pressure drop. Heat transfer and pressure drop are two competing factors that determine the practicability of the design for real world application. Improvement in heat transfer performance usually results in an increase in pressure drop and pumping power. This study addresses the challenges of designing microchannel through comprehensive numerical analysis of fluid flow and heat transfer characteristics of a novel design that combines ribs, secondary channels, and tertiary channels. The numerical results showed that the novel microchannel design achieves a favourable balance between heat transfer and pressure drop, demonstrating its potential to be used in application where high heat transfer and efficiency are paramount. To assess the performance of the microchannels, thermal resistance, a measure of system’s resistance to heat transfer is used. At the same pumping power, thermal resistance in the new design is consistently lower compared to other designs.

Experimental study on the flow and heat transfer characteristics of pin-fin manifold microchannel heat sink

A manifold microchannel radiator with a cylindrical pin-rib microchannel is designed and fabricated to enhance the heat dissipation capability of the manifold microchannel radiator, and its flow and heat dissipation capability are investigated by experiments. The fabrication and experiment of the manifold pin-rib microchannel radiators are introduced in detail. The heat dissipation capability of manifold pin-rib microchannel radiators at different flow rates is compared. The result shows that the manifold pin-rib microchannel radiator has excellent heat dissipation performance. When HFE7100 is used as the working medium, the average heated surface temperature of the manifold pin-rib microchannel radiator is about 100°C at the thermal flux density of 1000 W/cm2.

Performance and parameter optimization design of microchannel heat sink with different cavity and rib combinations

Microchannel heat sinks play a crucial role in dissipating heat in microelectronic systems in computer data centers. To enhance their thermal performance, this study proposes a combined microchannel design consisting of various cavity shapes and straight ribs, and analyzes its heat transfer and flow performance through numerical simulation. The heat transfer characteristics of microchannel heat sink with different straight rib structures are compared. Moreover, the four parameters including the relative length (α), relative width of the cavity (β), relative length of straight ribs (γ) and relative width of straight ribs (λ) are investigated, and the effects of Reynolds number variation on heat sink Nusselt number (Nu), friction coefficient (f) and thermal enhancement efficiency (η) are studied. The optimization process employs an artificial neural network and a multi-objective genetic algorithm to determine the optimal compromise solution and heat sink model, utilizing the Nusselt number and friction coefficient as evaluation indices. The results show that rectangular rounded straight rib is the straight rib structures with the best comprehensive thermal performance, with an average η approximately 9.7 % higher than that of the non-straight ribbed heat sink model. Furthermore, the variation in the four studied parameters yields distinct effects on the Nusselt number, friction coefficient, and thermal enhancement efficiency. Notably, the optimal performance is achieved when Nu = 13.59679 and f = 0.11855, with corresponding parameter values of α = 0.1575, β = 0.3931, γ = 0.0714, and λ = 1.2149. Ultimately, these results provide valuable insights into the structural optimization of microchannel heat sink cavity and straight rib combination models.

Study on heat transfer characteristics of matrix rib micro-jet heat sink based on SiC nanofluids

Study on heat transfer characteristics of matrix rib micro-jet heat sink based on SiC nanofluids

Pressure drop and thermal resistance characteristics of plain-fin heat sink with impingement flow

Pressure drop and thermal resistance characteristics of plain-fin heat sink with impingement flow

Rheological behaviour of Carreau liquid past a wedge surface with binary chemical reaction

The time-dependent stream of rheological Carreau nanoliquid carrying microbes through a rotating lodge through porous media in addition to irregular heat source or sink characteristics is the subject of this article. Due to the fact that the Carreau liquid can reveal the rheology of liquids with short-chain suspended particles, liquid crystals, surfactants, and human and animal blood, it is helpful to depict a range of physical problems. The influence of infinite shear rate thickness is combined to provide the mathematical formulation. Both the static and moving physical features are covered in great depth. Prior to using the finite element technique to solve revised equations numerically, pertinent similarity transformations are used to get equations in their dimensionless form. According to the findings of our study, the temperature and the thickness of the thermal boundary layer that corresponds to that temperature both improves the function that the thermal radiation factor plays in shear thickening and thinning liquids. Additionally, a moving wedge has a greater velocity than a static wedge. The thermophoresis factor's rising function is the concentration field. Furthermore, by increasing the Piclet number's magnitudes, the profile of microbes is diminished.

Developing an Integrated Soft-Switching Bidirectional DC/DC Converter for Solar-Powered LED Street Lighting

In the current era marked by the growing adoption of renewable energy sources, the use of photovoltaic-powered LED streetlights, known for their enhanced efficiency and extended lifespan, is on the rise. This lighting solution encompasses essential components such as a photovoltaic (PV) panel, an energy storage system, LED luminaires, and a controller responsible for supervising power distribution and system operations. This research introduces a novel approach involving a ZVS (zero-voltage switching) bidirectional boost converter to manage the interaction among the PV panel, LED lights, and battery storage within the system. To elevate system efficiency, a modified version of the conventional bidirectional boost converter is employed, incorporating an auxiliary circuit encompassing a capacitor, inductor, and switch. This configuration enables soft switching in both operational modes. During daytime, the converter operates in the buck mode, accumulating solar energy in the battery. Subsequently, at night, the battery discharges energy to power the LED lights through the converter’s boost operation. In this study, the PET (photo-electro-thermal) theory is harnessed, coupled with insights into heatsink characteristics and the application of a soft-switching bidirectional boost converter. This integrated approach ensures optimal driving of the LED lights at their ideal operating voltage, resulting in the generation of optimal luminous flux. The proposed LED lighting system is thoroughly examined, and theoretical outcomes are validated through simulations using the PSCAD/EMTDC version 4.2.1 software platform.

Flow and heat transfer behaviour of nucleating agent-enhanced nanofluids through manifold mini-channels

Improving the thermal performance of mini-channels is crucial. The nature of working nanofluids and the mini-channel structure can have a significant impact on the thermal efficiency of mini-channels. This study investigated the flow and heat transfer characteristics of a manifold mini-channel heat sink (MCHS) structure. The working fluids were composite nano-phase change emulsions (NPCE), which were prepared from eicosane, eicosanol, and metal oxide particles (nano-MgO). They possess low supercooling, high thermal conductivity, and high stability. Using these NPCEs, convective heat transfer studies were conducted in the two mini-channels. The impacts of the channel type, NPCEs, and Re on the heat transfer characteristics, flow characteristics, and overall performance were investigated. The results showed that the prepared NPCE can improve the heat transfer coefficient in mini-channels compared to water. The incorporation of nano-MgO particles effectively enhanced the heat transfer capacity with the highest enhancement (17.7%) in the heat transfer coefficient compared to water. The addition of alcohol further enhanced the heat transfer performance. A mixture of 6 wt% eicosane + 1 wt% nano-MgO + 0.6 wt% eicosanol yielded the highest enhancement in the heat transfer coefficient of 29.7%. In addition, a manifold mini-channel was found to have a better comprehensive performance than a rectangular mini-channel. The maximum reductions in pressure drop and thermal resistance of the manifold MCHS were 51.2% and 53.9%, respectively, compared to the rectangular mini-channel. Overall, the evaluated performance indicators of the manifold MCHS with composite nanofluid were 17.9% higher than those of the rectangular MCHS.

Interplay of geometry and shape-engineered-nanoparticles for efficient thermal performance in forced convection-based electronic cooling

Efficient and lightweight heat sinks for microelectronic cooling are pivotal for developing energy-efficient next-generation devices with huge processing power and significant heat dissipation over small scales. Microchannel heat sinks offer a solution not only for cooling electronics but also in applications of energy harvesting, defense, and biomolecular dynamics. An accurate understanding of transport phenomena at these scales can guide us toward minimizing frictional losses and thermal entropy for efficient thermal management. In this study, we numerically investigate the hydrothermal characteristics of a wavy microchannel heat sink integrated with nanofluids containing nanoparticles of different shapes. Our primary objective is to enhance thermal performance by studying the effects of four distinct nanoparticle shapes: spheres, cylinders, platelets, and blades. The nanoparticle concentration is varied within the range of 0.02–0.08, while the Reynolds number is set within the laminar regime (200–800). By decoupling the different contributions to system entropy and exergy, we aim to gain insights into the underlying physics behind thermal performance enhancement using shape-based nanofluids. Our findings reveal a significant increase in convective heat transfer coefficient, up to 50.63%, as well as notable exergy savings of up to 65.56%.

Influence of novel ogive shape ribs and cavities on local flow dynamics and thermal characteristics of microchannel heat sink

This study proposes using novel ogive-shaped ribs and cavities to enhance the thermal performance of a microchannel heat sink (MCHS). A three-dimensional conjugate numerical model was employed to investigate the impact of these modifications, i.e., ogive shape ribs and cavities, on the hydro-thermal performance of MCHS in laminar flow regime (Reynolds number 100–1000). The results show that flow separation occurs on the trailing edge of ogive ribs, promoting convective heat transfer by disrupting the boundary layer and enhancing fluid mixing on the downside of ogive ribs due to the formation of recirculation zones. Conversely, stagnant zones are created inside the ogive cavity due to very low fluid local velocity which results in a decrease of local Nusselt number. The study reports a 41.34% maximum improvement in Nusselt number for MCHS with ogive ribs on side channel walls and a maximum thermal enhancement factor of 1.42 for MCHS with ogive ribs on the bottom channel wall.

Experimental investigation on flow and heat transfer characteristics of the drop-pressure microchannel heat sink with gradient distribution pin fin arrays and narrow slots

Aiming to improve the problem of excessive pressure drop in microchannel heat sink (MCHS), a drop-pressure microchannel heat sink with gradient distribution pin fin arrays and narrow slots (DP-MCHS-PS) was proposed and its hydraulic properties were experimentally studied. Due to the addition of narrow slots, the pressure drop of the DP-MCHS-PS tends to increase less with the gradual increase of the volume flowrate. The pressure drop of the DP-MCHS-PS decreases by 56.3 % and 52.7 % when compared with the conventional gradient distribution and uniform distribution; Meanwhile, the temperature distribution within the microchannel was studied and found that although the heat transfer performance of the DP-MCHS-PS was decreased, the uniformity of surface temperature distribution was still retained. The study also comprehensively evaluated the heat transfer performance of the DP-MCHS-PS in terms of the effect of the average absolute temperature difference, heat transfer coefficient, Nusselt number and pump power on the thermal resistance, also investigated the effect on surface temperature in the presence of hot spots on the chip surface.

Numerical investigation on flow and heat transfer characteristics in honeycomb-like microchannel heat sink encapsulated with phase change material

The present study proposes a novel model to numerically investigate the flow and heat transfer characteristics of a honeycomb-like microchannel heat sink (MCHS) encapsulated with phase change material (PCM). Compared with a single MCHS, the hybrid MCHS combines the advantages of microchannels in terms of micro efficiency with the isothermal phase change effect of PCM. The finite volume method is used to discretize the three-dimensional flow and heat transfer processes within the hybrid MCHS. Special attentions are paid to the effects of PCM, geometric parameters and local hot spots on the temperature uniformity and flow heat transfer performance. The results show that the honeycomb inflow structure design and the thermal management characteristics of PCM phase change cooling exhibit better temperature uniformity and cooling performance. The overall performance of the heat sink is best at microchannel height of 0.09 mm and inlet number of 5 under the range of parameters studied. Adjusting the channel height from 0.06 mm to 0.09 mm at a volume flow rate of 10 mL∙min−1 can reduce the thermal resistance by 51 % and the pumping power by nearly 20 %. Increasing the number of microchannel inlets results in better heat transfer performance, but this improvement comes at the expense of larger pressure drop. When a local hotspot occurs, the hybrid MCHS can reduce the temperature peak by 2–5 K, achieving a smoother temperature distribution.

Comparative study on hydraulic and thermal characteristics of minichannel heat sink with different secondary channels in parallel and counter flow directions

Comparative study on hydraulic and thermal characteristics of minichannel heat sink with different secondary channels in parallel and counter flow directions

Transient Cooling of Millisecond-Pulsed Heat Sources by a Jet Impingement Heat Sink with Metallic Phase Change Material

Thermal management has become a critical issue for the reliable operation of electronic devices, especially for pulsed heat sources with high heat flux. The intense temperature rise in a short period puts forward high requirements on thermal management. In this work, a heat sink combining the confined jet impingement with metallic phase change material (PCM) is proposed for the thermal management of millisecond-pulsed heat sources. A transient model is established to simulate the conjugated heat transfer. The heat transfer characteristics of a jet impingement heat sink and the temperature responses under millisecond heat pulses are obtained, and the effects of jet structure and metallic PCM thickness on the cooling performance are analyzed. Results show that the jet impingement with a jet diameter of 2 mm and an impingement height of 2 mm can achieve effective cooling on a 3 × 3.5 mm2 heat source, and the surface temperature is 62.2 °C for a constant power density (150 W/cm2). Under the millisecond heat pulses with a peak power density of 600 W/cm2 and a duty cycle of 0.25, the temperature on the heating surface fluctuates in the same period with the heat pulses, and the maximum temperature reaches 66.9 °C for a heat sink without metallic PCM. An appropriate PCM thickness should be smaller than 0.1 mm so that the phase change can be cycled within heat pulse intervals, and the maximum temperature can be maintained around the phase change temperature (61.5 °C).

Characteristics of MEMS Heat Sink Using Serpentine Microchannel for Thermal Management of Concentrated Photovoltaic Cells

This work explains the simulation-based study to understand the thermohydraulic characteristics (thermal resistance and pumping power) of a MEMS heat sink using serpentine microchannels employed for thermal management of concentrated photovoltaic cells; the planar dimensions of both are 1 cm by 1 cm. In this study, water is the coolant and the MEMS heat sink is constructed in silicon. Over the Reynolds number varying from 50 to 1000 and for concentration ratio of 20, the thermal resistance and pumping power of a MEMS heat sink using serpentine microchannel, in comparison with that using straight microchannel, is lower and higher, respectively; the benefit of switching microchannels outweigh the cost as up to 64% reduction in thermal resistance is achieved with just 126% rise in pumping power. Studies are done for understanding the contribution of geometry of the serpentine microchannel on the characteristics of the MEMS heat sink. Irrespective of the geometry, rise in Reynolds number leads to the rise and decrease in the pumping power and thermal resistance, respectively. For a particular Reynolds number, decrease in hydraulic diameter, rise in offset width, and decrease in offset length led to rise in pumping power and decrease in thermal resistance. The contribution of concentration ratio on characteristics of MEMS heat sink using serpentine microchannel is investigated and found to be independent of concentration ratio. Nusselt and Poiseuille numbers of serpentine microchannel are provided for the benefit of heat sink designers; these parameters are higher for serpentine microchannel in comparison with a similar straight microchannel.