Heat Sink Research Articles

Performance comparative study on passively cooled concentrated photovoltaic (PV) using adsorption/desorption and heat sink cooling methods: Experimental investigations

Concentrated photovoltaic (PV) is a suitable solution for reducing the cost of a PV system by focusing solar radiation on the panel with cheap collectors. However, increasing the radiation on the PV panel resulted in a higher operating temperature. The elevated temperature harms the panel's efficiency, which results in a reduced output of the generated power and PV's short life span. Considering these concerns, researchers introduced many cooling methods for more efficient and prolonged PV life. The adsorption/desorption cooling method is a new trend in PV cooling that utilizes atmospheric water harvesters to capture water from the atmosphere at night and release part of the PV heat in the daytime by evaporation of the adsorbed water. This article uses silica gel as the atmospheric water harvester to cool low-concentrated PV in the presence/absence of metal heat sinks. Three configuration designs are investigated for PV cooling: (i) cooling the concentrated PV with silica gel bed, (ii) cooling the concentrated PV with a combination of aluminum heat sink and silica gel bed, and (iii) cooling the concentrated PV with aluminum heat sink only. The work was conducted experimentally over 3 consecutive days, and the three configurations were tested at the same period and compared. It was found that the configuration, which uses a combination of a heat sink and silica gel bed, performs best with an average PV temperature reduction of 9.8 °C and enhanced generated power of 29.8 %.

Structural analysis of selective laser melted copper-tin alloy

Additively manufactured complex geometries from copper alloys with high thermal and mechanical properties have drawn the attention of researchers. The present contribution explores the additive manufacturing (AM) of copper-based alloys from powder particles intended for heat sink and heat exchange applications. Selective laser melting (SLM) parameters featuring low laser beam power (160 W), moderate scanning speed (320 mm/s), and high energy density (200 J/mm³) were employed to fabricate dense components from CuSn10 particles. The present work deal with structural analysis and precision investigation of microfabrication, particularly in Struts, Tubes, and Fins. Mechanical properties (compression and hardness) for Strut structure, differential pressure evaluations for Tube structure, and analyses of thermal and electrical conductivities for Fin structure were investigated. The results showed an improvement in strength compared to those of pure copper, facilitating ease of AM. The obtained results affirm the feasibility of AM, demonstrating the successful creation of complex and combined solid-porous structures using SLM process from Cu alloys. A comprehensive structural investigation and characterization of the Cu–Sn alloy is presented here, aiming to establish a standardized approach for analysing Cu alloys. The results indicate that small-scaled structures fabricated via CuSn10 alloy exhibits a thermal conductivity of 34.3 W·m⁻¹·K⁻¹, an electrical conductivity of 4.72×10⁶ S/m, a hardness of 119 HV-50, a uniform surface roughness of 6 µm, and can withstand a force loading of 1 kN.

Heat transfer augmentation in heat sink with fin-bars inserted in cooling channel

Adding obstacles and obstructing fluid flow in cooling channel to induce whirl velocity enhances thermal performance in heat sinks. An analysis is presented of conjugate heat transfer in a heat sink with transversely inserted bars in the flow channel. The numerical study seeks to maximise the dimensionless thermal conductance subject to constant total volume. The study contrasts a standard heat sink without a bar with cooling channel inserts with one, two, three, and 4 bars. To improve the surface area for heat transfer, the extended surfaces are placed longitudinally at various points in the cooling channel. A high-density heat flux is applied at the bottom wall of the heat sink and coolant with an inlet velocity vin between 4.26 and 7.26 m/s is pumped in a forced convective laminar condition to eliminate the heat. A computational fluid dynamic (CFD) code incorporated in Ansys fluent is used to solve the mathematical models. The numerical analysis indicates that the configuration featuring 3 bars inserted at the roof of the cooling channel exhibits the highest global thermal conductance, achieving a 53 % increase over other configurations. All configurations with 3 bars inserted up, down, left and right, maintain a constant pump power of 3.5 W across a Reynolds number range of 857–1461. Bars positioned at the roof of the cooling channel experience the lowest outlet and inner wall temperatures, whereas those at the floor exhibit the highest temperatures. The optimised design meets the highest porosity limit of 0.8.

Lauric acid based form-stable phase change material for effective electronic thermal management and energy storage application

Poor thermal management in electronic systems can lead to higher junction temperatures, accelerating failure mechanisms and reducing component lifespan. Integrating efficient thermal management techniques, such as heat sinks, is essential for ensuring durability and efficiency of electronic equipment. Heat sinks have limited capacity, but integrating phase change materials (PCMs) enhances cooling performance by harnessing latent heat storage. However, leakage and low thermal conductivity limit PCM's effectiveness. The current study developed highly conductive leakage-proof PCMs based composites using an ultrasonic and vacuum impregnation method with lauric acid as base, hexagonal boron nitride and expanded graphite as additives. The results demonstrate persistence of chemical integrity, as proven by FTIR analysis, and complete encapsulation of PCMs inside the expanded graphite structures. The form-stable composite PCMs exhibit a 450% increase in thermal conductivity and 77% photo-transmittance decrease compared to base PCMs. Despite a trade-off of a 11.5% reduction in latent heat, the composite demonstrates thermal stability up to 220 °C. Further, excellent chemical and thermal reliability is maintained even after 500 cycles. Furthermore, in thermal management for heat sink, the form stable composite efficiently dispersed heat, resulting in a 16 °C decrease in peak temperature compared to the heat sink without the composite.

Thermal emitter performance of ultra-broadband solar metamaterial absorber based on metal-insulator-metal device structure

In this paper, we have designed a solar absorber with ultra-broadband absorption. The structure has seven layers with a metal-dielectric periodic film stack and a metallic copper substefficiency. The metal-dielectric periodic membrane stack and the dielectric are continuous to form a metal/dielectric composite microstructure. It has a very high absorption efficiency at 280 nm–2893 nm. The absorption efficiency in this wavelength range is 96.26% and absorption efficiency at AM 1.5 is up to 95.66% by finite difference time domain method (FDTD) simulation. The thermal radiation absorption efficiency of the structure is 93.69% at 1000K and 94.5% at 1200 K, which can also be used in the manufacture of the heat sink due to its high thermal radiation absorption efficiency. Our proposed solar absorber has good incidence angle insensitivity (0°–60°) and good polarization independence (0°–90°). These advantages enable our absorbers to be widely used for solar absorption and emission and offer a variety of design options for ideal absorbers.

Performance evaluation of photovoltaic-phase change material-thermoelectric system through parametric study

The dual-directional photovoltaic-thermoelectric generator (PV-TEG) system offers higher performance. However, there may be scenarios where the PV and TEG devices receive different levels of irradiation, leading to variations in performance. Under these conditions, the impact of using a PCM heat sink on the system's thermal management effectiveness has not yet been clearly established. Given these considerations, this study builds a coupled heat transfer-laminar flow-electromagnetic numerical model to explore the variations in system performance when subjected to different radiation intensities. The investigation also explores the implications of integrating PCM with varying thicknesses and melting points. Based on the obtained data, it can be concluded that when the PV and TEG devices are exposed to different radiation intensities, the system exhibits distinctly different performance. The highest power output and conversion efficiency are more than 0.16 W and 16 % for the PV device, and 0.08 W and 1 % for the TEG device. Furthermore, using thicker PCM allows the PV and TEG devices to maintain higher output power and efficiency for a longer period, surpassing the performance of systems with thinner PCM. Moreover, the PCM with a melting point of 301.15K has demonstrated the best potential for thermal management in the PV-TEG system.

Hydrothermal performance of a heat sink using Plate-fins: Experimental and numerical investigations

The development of electronic devices is accompanied by the generation of significant heat. A novel plate-fins design with various orientation angles of 30°, 35°, 37.5°, 40° and 45° was studied. The plate-fins design aims to boost the performance by increasing the surface area and redirecting airflow towards the heat sink plate. The experimental results obtained by this work were employed to validate the numerical results for pin-fins heat sink. A three-dimensional computational domain was investigated using ANSYS Fluent 19.1. The air flow was turbulent and modelled using k-ω turbulent flow. The plate-fins with an orientation angle of 37.5ᴼ exhibit the optimum hydrothermal performance among other configurations. Equally, several optimisation parameters including the number of rows, the diameter and thickness of the pins and the width of the plate-fins were investigated. It was observed that the heat sink with two rows of plate-fins outperformed other designs. This configuration resulted in a significant reduction of 2 % in hot spot temperature and a notable reduction of 60.8 % in pressure drop.

Computational study on the impact of geometric parameters on the overall efficiency of multi-branch channel heat sink in the solar collector

Enhancing the thermal performance of electronic devices is a persistent challenge. Liquid-cooled Multi-branch-channel heat sinks (MBCHSs) offer a promising solution. The present study focuses on optimizing MBCHS hydrothermal efficiency and temperature uniformity. Various MBCHSs, including a foundational case and cases denoted as 1 through 4, have been developed to assess the impact of geometric parameters on performance. Using a performance evaluation criterion (PEC), it quantitatively assesses hydrothermal improvements in each model. Additionally, this study explores the use of a water-based ternary hybrid nanofluid (THNF) with GO-Al2O3-ZnO ternary hybrid nanoparticles in an optimized multi-branch channel. Furthermore, an analysis and generation of entropy were examined. The COMSOL software has been employed for the simulation of the problem in this study. This promising fluid replacement for pure water demonstrates superior performance and temperature control. The findings indicate that among the various cases, case 2 exhibits the highest PEC. At Reynolds number 500, the optimal MBCHS geometry (case 2) featuring THNF with a volumetric fraction of 0.06 exhibits a 16.63% higher Heat Transfer Coefficient (HTC) compared to pure water. In contrast, MBCHS, with the same volumetric fraction, demonstrates a 29.82% lower Nusselt number. Contrastingly, at a volumetric fraction of 0.06, MBCHS displays a pressure drop 70.27% higher than that of pure water. Overall, the PEC of MBCHS with a volumetric fraction of 0.06 has decreased by 41% compared to pure water. At Reynolds number 500, lamina-shaped nanoparticles exhibit a 50.34% and 56.56% higher HTC in comparison to spherical and pure water, respectively. Moreover, the PEC for lamina-shaped nanoparticles at Reynolds 500 undergoes a 49.58% and 62.37% reduction when compared to spherical and pure water, respectively.

Cooling Optimization of Integrated Planar Spiral Inductor with Heat Sink

Cooling Optimization of Integrated Planar Spiral Inductor with Heat Sink

Numerical analysis of mono and hybrid nanofluids-cooled micro finned heat sink for electronics cooling-(Part-I)

This study explores the thermohydraulic performance of metallic-oxide and carbon-additives-based mono and hybrid nanofluids-cooled micro pin-fin heat sink by adopting the multiphase Eulerian model. The circular configuration is adopted for micro pin-fins, with the staggered arrangement and constant heat flux applied at the base of the heat sink. The mono and hybrid nanofluids are based on an aqueous solution of Ag, MgO, GNP, MWCNT, Ag-MgO, and GNP-MWCNT mono and hybrid nanoparticles, and a pressure drop (Δp) range is applied across the heat sink. The heat transfer and fluid flow performance are evaluated in terms of temperature difference (ΔT), thermal resistance (Rth) of the heat sink, average heat transfer coefficient (havg), average Nusselt number (Nuavg), pumping power (PP), overall performance (OP), and performance evaluation criteria (PEC), whereas the velocity, temperature, pressure coefficient, and flow streamline contours present the qualitative depiction of flow distributions across the heat sink. The results revealed that under certain Δp conditions, the GNP dispersed mono nanofluid showed the highest thermal performance of the micro pin-fin heat sink compared to the water as a coolant. The optimal nanoparticle loading (φ) is found between 0.50 % and 0.75 % of GNP nanoparticles. The maximum enhancement in PEC is achieved at 60 % for φ of 0.50 % and 0.75 % for both Δp of 1120 Pa and 1470 Pa, respectively. At an optimum Δp, the higher average havg, Nuavg, and lower Rth are achieved.

Experimental study on the flat loop heat pipe with minichannel wick under low heat flux

Stable operating under low heat flux condition is crucial for loop heat pipe. To investigate the performance of the flat loop heat pipe under low heat flux, a visual structure of evaporator with longitudinal replenishment characterized by minichannel wick is proposed and fabricated. The minichannel wick increases the permeable area and reduces flow resistance to enhance the heat transfer capacity. However, under low heat flux condition, excessive liquid permeation into the vapor line and the local reverse vapor flow may deplete the liquid storage in the compensation chamber, resulting in a wick temperature increase of 4.7 °C under extreme condition. Lowering the heat sink temperature does not necessarily lead to a lower stable wick temperature in specific cases but rather poses operational challenges and further raises the stable wick temperature by 9 °C. By visualizing the flow structure, it is found that arduous vapor–liquid prestart distribution leads to prolonged circulation establishment time and higher wick temperature, resulting in a higher stable wick temperature. As the heat flux increases, the effect of prestart distribution on the stable wick temperature weakens as the redistribution capability improves.

Comparative study of two-phase flow approaches for modeling conjugate heat transfer in a three-dimensional wavy microchannel-heat sink with CuO-water nanofluid

This study aims to numerically investigate the conjugate heat transfer (CHT) and the changes in the hydraulic and thermal terms of laminar flow (300 ≤ Re ≤ 800) in a 3-D wavy microchannel heat sink (MCHS). The obtained results from different nanofluid flow simulated models will be compared. The numerical simulation approaches used include single-phase, mixture, Eulerian, DPM, and DDPM. The effect of adding 1%, 3%, and 6% concentration of CuO nanoparticles (100 nm) in deionized water as the base fluid is examined on various parameters such as local and axial temperature, heat transfer convective coefficient, friction factor, Nusselt number (Nu), velocity distribution, and thermal and hydraulic boundary layer parameters. The substrate surface, due to its larger area surface and the amplitude of the sinusoidal wave, has a greater impact on the nanofluid flow as a channel bottom conjugate surface compared to others. The results obtained from the different models show close agreement with each other for various cases. For example, at Re = 304, the average Nu and friction factor for pure water are approximately 10.43 and 0.0260, respectively. For water with 0.01 concentration of CuO nanoparticles, Nu is found to be in the range of 10.43–10.78, and the friction factor ranges from 0.260 to 0.290, depending on the approach used for simulation. This shows a 2% increase in Nusselt number compared to a 0.05% increase in the friction factor. Moreover, these values increase by approximately 5.7% and 11.3% on average with an increase in CuO nanoparticle concentration to 0.06. Additionally, the DPM and DDPM models show a 15% difference in the scattering of CuO nanoparticles compared to the Eulerian-Eulerian models. The single-phase model presented in this study yields similar results to the multiphase approaches. Furthermore, the PEC parameter increases by about 1.9% with the addition of CuO nanoparticles at a concentration of 0.06.

Neural network-based regression for effective parametric study of micro-pin fin heat sinks

Neural network-based regression for effective parametric study of micro-pin fin heat sinks

Effect of high blood flow on heat distribution and ablation zone during microwave ablation-numerical approach.

Microwave ablation has become a viable alternative for cancer treatment for patients who cannot undergo surgery. During this procedure, a single-slot coaxial antenna is employed to effectively deliver microwave energy to the targeted tissue. The success of the treatment was measured by the amount of ablation zone created during the ablation procedure. The significantly large blood vessel placed near the antenna causes heat dissipation by convection around the blood vessel. The heat sink effect could result in insufficient ablation, raising the risk of local tumor recurrence. In this study, we investigated the heat loss due to large blood vessels and the relationship between blood velocity and temperature distribution. The hepatic artery, with a diameter of 4 mm and a height of 50 mm and two branches, is considered in the computational domain. The temperature profile, localized tissue contraction, and ablation zones were simulated for initial blood velocities 0.05, 0.1, and 0.16 m/s using the 3D Pennes bio-heat equation, temperature-time dependent model, and cell death model, respectively. Temperature-dependent blood velocity is modeled using the Navier-Stokes equation, and the fluid-solid interaction boundary is treated as a convective boundary. For discretization, we utilized elements for the wave propagation model, elements for the Pennes bio-heat model, and elements for the Navier-Stokes equation, where represents the computational domain. The simulated results show that blood vessels and blood velocity have a significant impact on temperature distribution, tissue contraction, and the volume of the ablation zone.

Multi-objective optimization of a non-uniform sinusoidal mini-channel heat sink by coupling genetic algorithm and CFD model

Wavy mini-channel heat sinks (MCHS) can disrupt the development of the thermal boundary layer, resulting in superior performance compared to straight MCHS. For complete utilization of the coolant, this study proposed and optimized a non-uniform sinusoidal MCHS with varying wavelength or varying amplitude along the flow direction. The optimization for five design variables was accomplished through a multi-objective genetic algorithm, where the thermal resistance θ or the pressure drop Δp were defined as two objectives. The computational fluid dynamics (CFD) software was employed to solve all direct problems encountered during the evolutionary process. Compared to the straight MCHS with different channel widths, the optimal designs achieved reductions of 27.74 % in θ or 59.51 % in Δp. Simultaneously, all the optimal values of the wavelength ratio and amplitude ratio indicate that enhancing the heat transfer performance downstream is more efficient. It was observed that among the five design variables, the number of wave cycles is the most relevant parameter with a Spearman’s correlation up to 0.983. Subsequently, a multiple-criteria decision-making approach was employed to ascertain the best compromise solution to balance the two objectives. Although the θ of the best compromise solution could be higher by 38.57 % than that of the lowest θ solution, the Δp presents a more substantial reduction of 92.45 % after the trade-off. Compared to the straight MCHS with the same Δp, the best compromise solution with varying wavelength reduces the θ and the standard temperature deviation by 26.20 % and 76.98 % respectively, while lowering the average base temperature by 3.07 K. Therefore, the optimal non-uniform wavy MCHS, along with the optimization approach presented, is meaningful for practical applications.

Investigation of thermal performance at forced convection in plate-fin heat sink

Interest in studies on more effective and faster heat dissipation in microelectronic equipment has increased in recent years due to the cooling area and equipment size limitations. This study attempts to focus on the effect of different fin geometry parameters on pure forced convection heat transfer. Total surface areas of plate-fin heat sinks were kept constant and were carried out for ten different heat sinks in these analyses. The Ansys-Fluent 2023 R1 commercial package program was used to perform the thermal and hydrodynamic performance analyses. Three-dimensional turbulent forced convection heat transfer analyses at heat sinks were subjected to fluid flow (500≤Re≤3000). The effects of gap between fins, fin thickness, fin height, fin number, and air velocity on the heat transfer and the friction factor were obtained and discussed for heat sinks. It was observed that there was a maximum difference of 0.27 % between the maximum temperatures obtained as a result of this analysis and the experimental study results in the literature. Among the ten cases examined (from Case 1 to Case 10), the highest heat transfer coefficient was obtained in Case 2 (number of fins 6, gap between fins 4 mm, fin height 17 mm and fin thickness 2 mm) at Re = 3000. The heat transfer coefficient of Case 2 was 41.29 % higher than the heat transfer coefficient of Case 4 at Re = 3000; though, the friction factor of Case 2 is 55.93 % higher than Case 4. Also, a useful correlation for the heat transfer coefficient was generated for the fin geometric parameters and Reynolds number.

Chemically reactive and mixed convective hybrid nanofluid flow between two parallel rotating disks with Joule heating: A thermal computational study

An electrically conducting and magnetically influenced three-dimensional flow of modified nanofluid between two rotating disks is investigated in this study. Nanometer-size particles of two distinct materials (Al2O3, Ag) suspended in water in the hybrid nanofluid are considered. The Joule heating effects, mixed convection, chemical factor, and exponential heating are considered in this study. The physical problem under these assumptions is transformed into a system of equations. To convert partial differential equations (PDEs) into systems of ordinary differential equations (ODEs), the suitable similarity variables are introduced. The reduced system is numerically solved using bvp4c, a well-known higher-order algorithm. The effects of significant variables on the profiles of velocity, temperature, and concentration are depicted graphically. We have chosen the pertinent parameters in the specific intervals; [Formula: see text][Formula: see text][Formula: see text][Formula: see text][Formula: see text], [Formula: see text][Formula: see text][Formula: see text] and [Formula: see text]. The interactions between a number of significant factors, including skin friction and Nusselt and Sherwood numbers at the higher and lower disks, are shown in tables. The results demonstrate that the local skin fraction decreases as the mixed convection factor is increased, which physically increases the heat transmission rate between the two discs. Furthermore, as the magnetic field and radiation number rise, the rate of heat transfer at the lower and top discs decreases. The numerical results in the form of a table are compared with the available literature, and our results beat the previously published work. The results described here are desirable choices for thermal uses such as automotive cooling systems, solar thermal systems, engineering, medical areas, heat sinks, or current energy storage since they have demonstrated higher thermal characteristics and stability than simple nanofluids (NFs). In Table 6, a comparative numerical study is presented for the various of state variables with the available literature, where the present study is validated.

Numerical Investigation of Nanofluid’s Heat Transfer Performance in Passive Residual Heat Removing System of AP1000 Nuclear Reactor

The Passive Heat Removal system (PHRS) is designed to remove the residual heat from the core in case of a station blackout, failure of emergency core cooling system, or failure of feedwater supply through the Passive Residual Heat Removal Heat Exchanger (PRHR HX). PRHR HX consists of a C-shaped tube bundle as a heat exchanger and the In-Containment Refueling Water Storage Tank (IRWST) as a heat sink. A temperature distribution of this passive heat removal system of an AP1000 Reactor is generated using COMSOL Multiphysics and the heat transfer coefficient is calculated to illustrate the effectiveness of the PHRS. A comparison of the heat transfer coefficient between the IRWST filled with water and nanofluid has been generated using the PRHR HX design. Thermophysical properties of nanofluids have been calculated in the process of calculating the heat transfer coefficient. Numerical results show the difference in temperature reduction of Al2O3, TiO2, and Ag as opposed to water in the IRWST. Time-dependent heat conduction of water and nanofluid results contribute to the effective analysis of passive heat removal systems and provide information for the safe operation of AP1000 reactors. By the end of 2024/2025, two VVER-1200 power stations with a combined capacity of 2400 MW will be operating in Bangladesh. For safety and licensing reasons, heat transfer simulation of VVER-1200 can be performed using COMSOL software.

Growth Restriction of Copper Nanocones at the Microgroove’s Bottom and Adjacent Sidewall Regions of Finned Heat Sinks

Growth Restriction of Copper Nanocones at the Microgroove’s Bottom and Adjacent Sidewall Regions of Finned Heat Sinks

Liquid metal-based flexible heat sink for adaptive thermal management

The deformable heat sinks are critical for flexible electronics, wearable personal thermoregulation and energy management. However, the available soft polymer materials with poor thermal characteristics face challenges in achieving efficient heat transfer. Herein, we report an excellent flexible heat sink enabled by a gallium-based liquid metal (LM) for adaptive thermal management. The flexible heat sink is prepared by embedding LM droplets and copper particles into the elastic matrix forming solid–liquid multiphase composites, achieving a considerable thermal conductivity (3.5 W/mK@300 % stretching deformation), outstanding high-temperature resistance, and excellent conformity. The cooling and hydrodynamic characteristics of the flexible heat sink with different structures, including parallel (plane), S-type (plane), and annular (three-dimensional) channels, are investigated and optimized by the thermal experiment and developing the fluid–structure coupling numerical simulation. The results show that the maximum temperature and heat flux achieved by the S-type heat sink are 36.7 °C and 0.68 W/cm2 respectively, due to the secondary flow enhancing convection thermal transfer intensity. The annular heat sink has outstanding advantages in suppressing temperature and improving uniformity because the thermal transfer path is optimized by stretching, especially for larger deformation. Furthermore, the annular heat sink has been proven feasible for lithium battery cooling and pre-insulation.