Surface Heat Source Research Articles

Twice-topology optimized heat sinks for enhanced heat transfer performance: Numerical and experimental investigation

Since the heat dissipation problem is always confusing and hindering the computing power improvement of electronic chip, an effective thermal management strategy is critical to relieve these problems. In this work, a new twice topology optimization design method combining topology optimization and image processing to design heat sinks is presented, which extends topology optimization from 2Dimention (2D) to 3Dimention(3D). Firstly, on the horizontal design domain, the conventional topology optimization is conducted for the minimization of average temperature/standard deviation. Then the optimal shape of liquid domain is converted into 1D flow routine by thinning algorithm. After that, another topology optimization is performed on the flow channel cross-section plane to get the best cross-section shape of channels. The liquid domain of the final heat sink is then obtained by scanning the optimized flow channel cross-section along the 1 Dimension (1D) flow routine and solving the interference by introducing cylinder joints. Finally, two kinds of twice topology optimized heat sinks including TTOHS-1 with minimized temperature variation as optimal goal and TTOHS-2 with minimized average temperature as optimal goal are generated by combining the liquid domain and a cuboid using Boolean Operation. The performance of heat sinks is numerically investigated, and the results indicate that the thermal performance of TTOHS-1 and TTOHS-2 are much better than that of the traditional heat sink with straight channels (TSCHS). When Re = 689, the average temperature and the maximum temperature of the heat source surface of TTOHS-1 are decreased by 4.99 % and 6.29 % respectively, compared to the TSCHS. The Nusselt number is increased by 46.16 % while the thermal resistance is reduced by 33.13 %. At last, the thermal and flow performance of the TTOHS-1 is studied by conducting experiments, showing that the numerical results agree well with that of the experiment.

Effective ignition energy for capacitor short-circuit discharge in explosive environments

Capacitors short-circuit discharge in an explosive environment can ignite and detonate the surrounding explosive media, causing dangerous accidents. At low voltages, this kind of discharge constitutes a micro-nano discharge; because the discharge gaps here are of the order of only microns to nanometers, the discharge process, electrode energy consumption, explosive media ignition energy, and other energy relationships are unclear. To study the relationships between the capacitor storage energy and various kinds of dissipation energies under short-circuit discharge, a model comprising conical and spherical cylinder microbumps is proposed based on the cathode surface morphology obtained by three-dimensional profiling and scanning electron microscopy, respectively. Then, the second-order non-chi-squared differential equations were established based on the principle of energy conservation and heat balance to deduce the relationships between the cathode surface temperature and height of the microbump, conical angle, and spherical radius; further, the energy consumed by the anode surface is calculated based on the theory of heat transfer. Using heat conduction theory, the energy consumed by the microbumps on the cathode surface is calculated, and the energy consumed on the anode surface is deduced using the surface heat source as the loading heat source. The residual energy of the capacitor is calculated from the discharge time and voltages before and after discharge, and the effective energy of the gas is calculated using the law of conservation of energy. Finally, the discharge channel energy, electrode energy consumption, and end residual energy of the discharge capacitor are used to derive the effective ignition energy of the explosive gas. This research is of great significance for the design of intrinsically safe circuits with high power.

Study of Heat Flow at Substrate during Sputtering of Copper-Titanium Sandwich Target.

The purpose of this work is to study the kinetics of the heat flow heating the substrate, which is generated by a two-layer sandwich magnetron target when sputtered in argon. Its novelty resides in the application of the COMSOL Multiphysics to study the kinetics of thermal processes during sputtering of a target of the new type. The analysis was performed for a sandwich target with internal copper and external titanium plates when the discharge power varied in the range of 400-1200 W. The heating of the external target plate is described by a two-dimensional homogeneous Fourier equation. The solution to the equation reveals how the kinetics of the external plate's surface temperature distribution depends on the discharge power. To study the heat flow heating the substrate, the external plate is presented in the form of an additive set of small-sized surface heat sources. Previously unknown features of the thermal process are established. It is shown that numerical modeling adequately describes the experimental results.

Flow-field characteristics of the thermal plume above an elliptical high-temperature heat source surface

The thermal plume formed by the high-temperature elliptical heat source surface during the smelting process is often captured and removed by the local exhaust system. Accurately mastering the flow-field characteristics of such high-temperature elliptical heat plumes is helpful for efficient design of local exhaust systems. In this paper, the effects of the ratio of long and short axes (5/4 ≤ ξ ≤ 5/1) and the intensity of heat source (80 ≤ F ≤ 160 W) on the axial and radial velocity distribution of thermal plume in an elliptical heat source are investigated by numerical simulation combined with experimental validation. The results show that in the range of ξ ≤ 5/1, the axial dimensionless velocity distribution of the elliptical plume field and the spreading range of the plume field are mainly affected by ξ instead of F. For 5/4 ≤ ξ ≤ 5/1, the maximum axial velocity Um appears at 1.7 to 2.7 times Z/L (plume height to heat source long axis ratio). For ξ ≤ 5/2, the height at which the cross-sectional velocity field transitions to a circular distribution aligns with the height of Um. It is found that the plume velocity field is characterized by applying the point source model for ξ ≤ 5/3, and vice versa for the linear source model. The plume flow rate formulation obtained by modifying the linear source model for ξ > 5/3 has a better predictive ability in the Z/L ≤ 5 region. This study provides a reference for the design of ventilation systems for elliptical surface heat sources.

Experimental and numerical study of structural parameters on the heat transfer performance of submerged cooling system

Immersion direct contact cooling effectively transfers heat from electronic components to a cooling solution without additional thermal resistance, due to its high energy density, low power consumption, system simplicity, and integrated thermal management for electronic devices. Current scholarly research on immersed structures predominantly focuses on surface temperature effects, with a scant investigation into internal flow and temperature field distributions concerning boundary layers. This study addresses structural optimization in immersion cooling systems, employing experimental and simulation methods to elucidate the thermal mechanisms by which structural optimization impacts the performance of chip immersion cooling systems. The research examines the impact of panel spacing and liquid level height on the thickness of velocity and thermal boundary layers, as well as the combined effects of natural and forced convection under three distinct cooling modes. Analysis reveals that heat pipe immersion cooling can reduce the heat source junction temperature to 40.7 °C under a 60 W power dissipation, a 47.2 % decrease from the bare heat source temperature. Reducing panel spacing disrupts the thermal boundary, enhancing forced convection and lowering the junction temperature by up to 10.1 % (6.5 °C). As liquid level height increases, the junction temperature initially decreases and then rises, with an optimal height of 175 mm for the best overall heat transfer effect. At low flow velocities (0.04 m/s), the vertical buoyancy-induced flow velocity at the heat source surface (24.2 × 10-6 m/s) exceeds the horizontal forced convection velocity (0.78 × 10-6 m/s), indicating that buoyancy changes due to density differences are significant and must be considered.

Model-Based Sensitivity Analysis of the Temperature in Laser Powder Bed Fusion.

To quantitatively evaluate the effect of the process parameters and the material properties on the temperature in laser powder bed fusion (LPBF), this paper proposed a sensitivity analysis of the temperature based on the validated prediction model. First, three different heat source modes-point heat source, Gaussian surface heat source, and Gaussian body heat source-were introduced. Then, a case study of Ti6Al4V is conducted to determine the suitable range of heat source density for the three different heat source models. Based on this, the effects of laser processing parameters and material thermophysical parameters on the temperature field and molten pool size are quantitatively discussed based on the Gaussian surface heat source. The results indicate that the Gaussian surface heat source and the Gaussian body heat source offer higher prediction accuracy for molten pool width compared to the point heat source under similar processing parameters. When the laser energy density is between 40 and 70 J/mm3, the prediction accuracy of the Gaussian surface heat source and the body heat source is similar, and the average prediction errors are 4.427% and 2.613%, respectively. When the laser energy density is between 70 and 90 J/mm3, the prediction accuracy of the Gaussian body heat source is superior to that of the Gaussian surface heat source. Among the influencing factors, laser power exerts the greatest influence on the temperature field and molten pool size, followed by scanning speed. In particular, laser power and scan speed contribute 38.9% and 23.5% to the width of the molten pool, 39.1% and 19.6% to the depth of the molten pool, and 38.9% and 21.5% to the maximum temperature, respectively.

Experimental study on the effect of adjacent near-wall heat sources on the particle deposition

Adjacent near-wall heat sources are widely used in indoor environments. It is important to investigate the particle deposition under the influence of coupled thermal plumes arising from adjacent near-wall heat sources to improve indoor air quality and control harmful particle deposition. Thus, this study scrutinizes the behavior of thermal plumes emanating from adjacent near-wall heat sources, focusing on the deposition of particles with diameters of 0.3 μm, 0.5 μm, 1.0 μm and 3.0 μm on the wall behind the heat sources. These findings are juxtaposed with the pattern of particles with varying sizes situated above the single near-wall heat source and away from the heat sources. The study delves into the impact of varying surface temperatures and the distance from the wall behind the heat sources, as well as the top surface of the heat source, on particle deposition in 29 distinct cases. The results indicate that the deposition velocity of particles with the same size is highest above the adjacent near-wall heat sources, followed by that of a single near-wall heat source, and finally, locations away from the near-wall heat source. Also, the decay rate loss coefficient of particles with the same size above the adjacent near-wall heat sources increases with a decrease in the distance of the heat sources from the wall behind them, an increase in the temperature of the heat sources, and a reduction in distance from the top surface of heat sources.

The Phenomenon of a Cathode Spot in an Electrical Arc: The Current Understanding of the Mechanism of Cathode Heating and Plasma Generation

A vacuum arc is an electrical discharge, in which the current is supported by localized cathode heating and plasma generation in minute regions at the cathode surface called cathode spots. Cathode spots produce a metallic plasma jet used in many applications (microelectronics, space thrusters, film deposition, etc.). Nevertheless, the cathode spot is a problematic and unique subject. For a long time, the mechanisms of spot initiation, time development, instability, high mobility, and behavior in magnetic fields have been described by approaches that caused some controversy. These spot characteristics were discussed in numerous publications over many years. The obscurity and confusion of different studies created the impression that the cathode spot is a mysterious phenomenon. In the present work, a number of typical representative publications are reviewed with the intention of clarifying problems and contradictions. Two main theories of cathodic arcs are presented along with an analysis of the experimental data. One of the approaches illustrates the cathode heating by Joule energy dissipation (volume heat source, a sharp rise in current density, etc.), nearly constant cathode potential drop, and other certain initial conditions. On the other hand, a study using a mathematically closed approach shows that the spot initiation and development are determined not by electron emission current rise but by a rise in arc power density, affecting heat sources including the energy of ion flux to the cathode (surface heat source).

Experimental and numerical analysis of variable cross-section channel liquid cooling plate for server chips thermal management

Utilizing high-performance chips results in increased heat generation, necessitating more effective heat dissipation method. To address challenges in microchannel liquid cooling plates for server chips cooling the study presents the variable cross-section channel liquid cooling plate designs. To investigate the effect of channel structure on the performance of liquid cooling plate, two types of samples, one featuring side wall ribs and bottom cavities (SC) and the other featuring side wall ribs and bottom waves (SW), are evaluated through experimental analyses under various heating power and flow rate conditions. Comparing their performance to a conventional rectangular channel (RC) liquid cooling plate, their heat transfer and flow attributes were assessed. Finally numerical analysis was conducted to investigate the flow behavior inside the channel and extreme performance prediction were made using the numerical study. Results demonstrate that the SC and SW designs outperform the RC in terms of heat transfer capabilities, despite having the weaker flow characteristics. Under 300 W heat source power, the SW variants enable the heat source surface temperature to stay below 77.8 °C with a 194 mL/min flow rate. Notably, the SW variant showcases lower average heat source surface temperature and demonstrates lower pressure drop compared to the SC variant. As the flow rate increases, the heat transfer efficiency of the SW variant is further amplified while simultaneously highlighting the relatively suboptimal flow behavior of the SC variant. Predictive numerical models underscore that the SW variants offers improved thermal performance when subjected to high heat source power scenarios. Remarkably, under the heat source power of 500 W, a mere augmentation in flow rate proves sufficient to reduce the heat source temperature below the prescribed threshold value. The combination design of side wall ribs and bottom waves should enable a low cost, simple and high efficiency electronics cooling.

Magnetic field effect on mixed convection flow inside an oval-shaped annulus enclosure filled by a non-Newtonian nanofluid

The phenomenon of flow around a static or rotating circular cylinder has significant applications in various engineering fields, such as building, bridge, and structure engineering. It can be used to control flow-induced vibration, blowing or suction, moving surfaces, acoustic thriller, and synthetic jet. Additionally, there is a need to enhance heat transfer rates in many life and industrial applications, including cavity shape enhancement, heating or cooling spread inside a cavity, heat dissipation in electronic devices, thermal mixing in storage units, solar collectors, desalination, and journal bearing lubrication. This study explores the effect of a horizontal magnetic field and a rotating inner circular cylinder on mixed convection within a two-dimensional oval-shaped enclosure filled with a non-Newtonian nanofluid. The Galerkin Finite Element Method (GFEM) is utilized for analysis, with the enclosure undergoing differential heating and cooling on the inner cylinder wall and the enclosure wall, respectively. The nanofluid consists of water infused with copper nanoparticles. The study explores various simulation parameters, including the Richardson number (Ri), Hartmann number (Ha), the inclination angle of the enclosure (β), power-law index (n), circle center eccentricity (e), and nanoparticles volume fraction (φ). It has been observed that as the Ha and n index increase for different Ri values, a wavy trend in local Nusselt number (Nu) profiles along the heat source surface is observed. Additionally, the heat transfer rate decreases with increasing Ri for various combinations of Ha and n index. Under specific conditions, such as Ri = 0.001, Ha = 60, e = 0, φ = 0.09, and β = 90, the results show that, compared to a Newtonian fluid (n = 1), the heat transfer rate exhibits percentage gains of approximately 6.31% for a pseudo-plastic fluid (n = 0.6) and 8.47% for a Dilatant fluid (n = 1.4). The convective heat transfer was significantly enhanced when the eccentricity of the cylinder was positioned in the lower or upper regions of the oval-shaped enclosure, particularly at e = - 0.3. The highest heat transfer rates were observed at β = 60 and 240.

A PARAMETRIC STUDY ON THE THERMAL HOMOGENEITY OF VAPOR CHAMBER IN A BATTERY COOLING SYSTEM

For the battery cooling system, the large temperature difference of the coolant between the inlet and outlet leads to a decrease in the thermal homogeneity of batteries. To improve the thermal homogeneity, a designed composite liquid cooling system was analyzed combined with a grooved vapor chamber and a cooling plate. The parametric study on the thermal homogeneity was conducted including the height, width, length of grooved wick, filling ratio, flow rate of coolant, heat flux, and inclination angle. The results show that a preferable thermal homogeneity can be obtained at 20% filling ratio as the height and width of the channel increase, especially under the positive inclination angle of 20°. The heat source surface can be kept uniform within the temperature difference of 5°C in spite of the temperature rise of coolant up to 11.5°C under the flowing rate of 8.32 × 10<sup>-4</sup> kg/s. An empirical correlation of the "suppression ratio," containing the structural and operating parameters, is summarized to evaluate the suppressing function of the vapor chamber on the temperature difference of coolant. This research is aimed to provide a scientific basis for predicting the thermal homogeneity of the vapor chamber in a battery liquid cooling system.

NUMERICAL STUDY OF THERMAL MANAGEMENT FOR A CYLINDRICAL HEAT SOURCE BY PCM COMBINED WITH ANNULAR FINS

In the study, annular fins are used to improve the thermal management performance of the phase change material (PCM) towards a cylindrical heat source. A two-dimensional axisymmetric model is established and the influence of fins on the temperature of the heat source is studied in conjunction with the melting process of PCM. The effects of the positions of a single annular fin are investigated. Results show that the lower the individual fin is in the PCM, the faster the melting rate and the lower the temperature, which is because the PCM above the fins can absorb more heat from the upper surface of the fin through natural convection. Maintaining a constant total volume of fins, the effect of multiple annular fins is studied. The results show that multiple annular fins have larger heat transfer areas and more uniform fin distribution, resulting in lower temperature and temperature difference of the heat source surface. Furthermore, the use of multiple fins of unequal height, with bottom fins being higher, is found to be more effective. The best improvement in the thermal management performance of the system is achieved when the height of the fins is 4, 8, and 11 mm from top to bottom, respectively.

Three-dimensional transient heat transfer analysis of micro-plasma arc welding process using volumetric heat source models

Abstract The micro plasma arc welding process is associated with different physical phenomena simultaneously. This results in complexities to comprehend the actual mechanism involved during the process. Therefore, a robust numerical model that can compute the weld pool shape, temperature distribution, and thermal history needs to be addressed. Unlike, other arc welding processes, the micro plasma arc welding process utilizes thin sheets of thickness between 0.5 and 2 mm. However, joining thin sheets using a high-density arc welding process quickens the welding defects such as burn-through, thermal stresses, and welding-induced distortions. The incorporation of a surface heat source model for computational modeling of the high energy density welding process impedes heat transfer analysis. In that respect, researchers have developed numerous volumetric heat source models to examine the welding process holistically. Although, selecting volumetric heat source models for miniature welding is a significant task. The present work emphasis developing a rigorous yet efficient model to evaluate weld pool shape, temperature distribution, and thermal history of plasma arc welded Ti6Al4V sheets. The computational modeling is performed using a commercially available COMSOL Multiphysics 5.4 package with a finite element approach. Two different prominent thermal models, namely, Parabolic Gaussian and Conical power energy distribution models are used. A comparative analysis is carried out to determine the most suitable heat source model for evaluating temperature distribution, peak temperature, and thermal history. The analysis is done by juxtaposing the simulated half-cross-section weld macrographs with the published experimental results from independent literature. The numerical results showed that the proximity of top bead width magnitude was obtained using the Parabolic Gaussian heat source model for low heat input magnitude of 47.52 and high heat input magnitude of 65.47 J·mm−1, respectively. In terms of percentage error, the maximum top bead width percentage error for the Parabolic heat source model is 13.26%. However, the maximum top bead width percentage error for the Conical heat source model is 18.36%. Likewise, the maximum bottom bead width percentage error for the Parabolic heat source model and the Conical heat source model is 12.3 and 25.8%, respectively. Overall, it was observed that the Parabolic heat source model produces the least deviating outcomes when compared with the Conical distribution. It was assessed that the Parabolic Gaussian heat source model can be a viable heat source model for numerically evaluating micro-plasma arc welded Ti6Al4V alloy of thin sheets.

Study on the influence of processing technology on the properties of 2024-T3 aluminum alloy

2024-T3 aluminum alloy is widely recognized for its low density and excellent mechanical properties. However, it has some shortcomings at high temperatures. Using Abaqus simulation technology, the surface heat source during the VIES (Variable Input Energy Source) treatment process was simulated, with the energy originating from the discharge channel. Through orthogonal experimental methods, it was indicated that the distribution and depth of the molten pool varied under different process parameters. Meanwhile, electric spark surface strengthening mainly affected the surface of the workpiece, with minimal impact on the internal structure. When the impact frequency is constant, increasing the input current enlarges the maximum heat flux density (Qmax) at the center, leading to an expansion of the molten pool area. Conversely, when the input current is constant, increasing the impact frequency shortens the contact time between the electric spark and the plate, resulting in reduced heat input from the electric spark. Consequently, the surface molten pool area decreases.

A maximum temperature rise model of the shear band in bulk metallic glasses

Based on mechanisms applicable to bulk metallic glasses (BMGs), such as a superposition principle of an instantaneous finite surface heat source temperature field and a flow model about the shear-band velocity, a maximum temperature rise model of shear bands in BMGs was deduced, ΔTmax=σycpΔupl·vSB2πα. The model describes the dependence of the maximum temperature rise on the yield strength and the shear-band velocity in BMGs. It can be calculated that the maximum temperature rise of BMGs is between 1 K ∼ 30 K at room temperature through these two parameters. A critical temperature, TC, of almost 0.8∼0.9Tg is introduced, at T<TC, the change of the yield strength with temperature in BMGs basically conforms a cooperative shear model (CSM), and at T>TC, a significant reduction of the yield strength in BMGs can be attributed to avoiding failure due to localized material softening.

Material flow and heat transfer characteristics in flat-top laser composite arc-based directed energy deposition

In this study, a novel flat-top laser composite arc-based directed energy deposition process is proposed, and the material flow and heat transfer behaviors are investigated for both arc-only and hybrid flat-top laser modes. Transient CFD models are developed to simulate the energy of the laser and arc using the surface heat source and double-ellipsoid body heat source models, respectively, and validated through experimentation. The results show that the high-temperature metal fluid flows outward from the center of the molten pool and then backward in the front part. The flat-top laser does not alter the flow field pattern but allows for the spread of more hot liquid metal towards the lateral edges. Furthermore, it is discovered that the flat-top laser reduces the contact angle and promotes a stable molten pool temperature.

Temporal and Spatial Surface Heat Source Variation in the Gurbantunggut Desert from 1950 to 2021

Based on data from the Gurbantunggut Desert, the largest fixed/semi-fixed desert in China, and ERA5-Land reanalysis data, the long-term variations and spatial surface heat source (SHS) differences in the Gurbantunggut Desert are discussed herein. The results show the following: (1) The hourly SHS at the Kelameili station during the 2013–2021 period was a weak heat source at night; contrastingly, it was a strong heat source during the day. The duration of the hourly SHS increased gradually from January to July, but it decreased gradually from July to December. The daily SHS showed obvious seasonal variation, reaching the maximum in summer and the minimum in winter. The ERA5-Land reanalysis can reproduce all the variation characteristics of the SHS well. (2) The climatology (i.e., multi-year mean) of the monthly SHS intensity was lower than 50 W/m2 during the January–March and September–December periods in the Gurbantunggut Desert, indicating a weak heat source. On the other hand, the climatology recorded in April–August was higher than 50 W/m2, with a strong heat source. From the perspective of spatial distribution, the eastern and western regions of the Gurbantunggut Desert show strong heat sources, while the central region shows weak heat sources. The spatial distribution of the first and second modes of the empirical orthogonal function (EOF) decomposition reflected the consistent spatial variability and a north–south (or east–west) polarity variation of the monthly SHS in the Gurbantunggut Desert, respectively. (3) The yearly SHS showed negative anomalies during the 1950–1954, 1964–1982 and 2004–2015 periods, and positive anomalies during the 1955–1963, 1983–2003 and 2016–2021 periods in the Gurbantunggut Desert. Additionally, the time series of the SHS anomalies was positively correlated with the Interdecadal Pacific Oscillation (IPO) index. During the negative IPO phase, the yearly SHS showed a negative anomaly in the Gurbantunggut Desert, while the yearly SHS showed a positive anomaly during the positive IPO phase in most regions of the Gurbantunggut Desert.

Experimental and simulation study of a U-shaped water-cooled sleeve heat pipe radiator for high heat flux density

Effective heat dissipation methods are desperately needed to ensure heat transfer of the large quantity of heat generated by radioactive isotopes in restricted places. This study employs the Bell-Delaware method to design a U-shaped water-cooled sleeve heat pipe radiator (UWC-HP) intended for heat dissipation on a 16 cm2 surface area with a heat flux density of 200 W/cm2. We have established a 3D model, which was experimentally validated, showing an error within 5 %. Subsequently, as the refrigerant and structural design of the condenser segment are crucial factors leading to the limitations of UWC-HP, this study aims to evaluate the impact of the condenser segment on the heat dissipation performance. Specifically, we investigated the effects of different cooling water temperatures, flow rates, and fin designs on the heat dissipation performance of the UWC-HP. Based on this, We found that the rib height, the number of ribs, and the rib material can strengthen the performance of the heat sink by a maximum of 12.3 %, 10.1 %, and 3.7 %, respectively. The heat sink optimized by orthogonal experiments has a maximum heat source surface temperature of 506.22 K and Nu of 101.85, which reduces the maximum surface temperature of the heat source by a maximum of 22 K and strengthens the heat sink capacity of heat pipes by 20 %. This article achieves efficient heat transfer for isotopic decay heat in a confined space by designing a heat pipe heat exchanger. It reduces the equipment's temperature and enhances the safety of the nuclear reactor.

Numerical analysis on thermal-hydraulic performance of optimized microchannel heat sink with slant ribs and quatrefoil rib-elliptical groove complex structures

A novel microchannel heat sink (MCHS-SREGQR) arranged with the spoiler element structure of the slant rib-elliptical groove-quatrefoil rib is proposed to meet the heat dissipation demands of electronic devices with high heat flux. The strategies for heat transfer enhancement are as follows: Firstly, the elliptical grooves are periodically arranged in the sidewalls of the microchannel and the quatrefoil ribs are set one-to-one at the centre of the grooves. The two structures complement each other's strengths and weaknesses. Secondly, the slant ribs are symmetrically arranged along the centreline of the channel. The slant ribs tend to expand along the flow direction, and produce diversion, guiding and gathering effects on the fluid, thus enhancing flow efficiency of the fluid domain in all aspects. Lastly, a novel quatrefoil rib is put forward, with a special structural design that both effectively inhibits the flow dead regions around the corners of the rib and significantly increases fluid turbulence. Three-dimensional numerical simulations are used to evaluate the effects of slant rib relative position, slant rib relative transverse spacing, and overall rib relative height on pressure drop, heat transfer capacity, and temperature field uniformity of the microchannel. Furthermore, the hydrothermal performance of MCHS-SREGQR is analyzed in comparison with a traditional straight rectangular microchannel and six other microchannels arranged with similar spoiler elements. The results indicate that when the Reynolds number is 696, the temperature at the heat source surface of MCHS-SREGQR decreases by 52.3% and the thermal resistance decreases by 66.6%, while the Nusselt number increases by 131% and the temperature uniformity increases by 76.8%. In addition, the field coordination number Fc increases by 131% and the performance evaluation criterion PEC can be achieved as 1.179.

Experimental study on air impinging jet for effective cooling of multiple protruding heat sources

Air Impinging Jet is an effective cooling method for various applications, ensuring optimal performance and reliability of heat-generation systems. In the present work, a novel technique of cooling discrete protruding heat sources mounted in a rectangular channel by using a double air jet is introduced experimentally. A constant and uniform heat flux is produced from protruding heat source surfaces where the bottom and the upper channel walls are insulated. The effects of various parameters on the heat source cooling performance such as the Nusselt number for single and double air jets are obtained. Various parameters such as the air Reynolds number, aspect ratio, double jet position ratio, and jet inclination angle are investigated. The results show that those parameters effectively affect the average temperatures and the standard deviation of all protruding heat sources. It is indicated that the maximum value of the average Nu number occurs at the heat source just underneath the impinging air jet compared to other downstream heat sources. The highest average Nu is achieved at a position ratio of 3/7 and an inclination angle of 10o. The cooling system accomplishes an acceptable Nu and temperature uniform distribution for a position ratio of 4/7 compared to the other position ratios. The improved performance and longevity of heat sources are achieved by the innovative double-air jet method, which archives a consistent temperature distribution for all projecting heat sources.