Heat Dissipation Ability Research Articles

Design and Demonstration of a 100 kW High-Frequency Matrix Core Transformer for More Electric Aircraft Power Distribution

The rapid development of more electric aircraft (MEA) raises the demand for high-power converters with significant weight and volume reduction for onboard power distribution. The isolated dc/dc converter using the medium-frequency transformer (MFT) is a feasible solution. To design an MFT with improved electromagnetic and thermal performance, a matrix core transformer (MCT) architecture is proposed with accurate models in this article. With superior heat dissipation ability, the high current windings can be effectively cooled with both natural and forced air convection. In addition, an optimization methodology for MCT design is presented. As a result, the prototype of a 100-kW, 50-kHz MCT with an additive manufactured bobbin is built. The results of both finite element analysis (FEA) simulation and experimental study in a full power dual active bridge (DAB) with the MCT prototype are presented to verify the theoretical design. The power density and efficiency of the MCT reach 17.7 kW/L and 99.63%, respectively.

Mimicking ‘sea-urchin’ like heirarchical carbon structures self-assembled from carbon fibers for green EMI shielding

Self-assembled structures offer myriad opportunities to explore them for a wide range of applications. Herein, ‘sea-urchin’ like hierarchical structures were obtained from self-assembly of carbon fibers (CF) assisted by refluxing in an acid medium. This unique template-free synthesis of carbon urchins (CU) yields different sizes when the chemical ambiance (pH) around the CF varies. Electromagnetic (EM) pollution has recently gained attention due to the widespread usage of electronics and requires lightweight and reliable solutions to suppress EM interference. Polymer nanocomposite-based shielding serves as an effective solution due to its ability to be tuned as per the commercial requirement. To this end, dispersing flakes of nanoparticles in a polymer matrix has been researched widely but is not amenable to suppressing the EM interference. Herein, the self-assembled structures offer micro-spikes resulting from the sea-urchin-like carbon structure coupled with the incoming field and facilitate the absorption of the EM radiation. The spatial distribution of CU was controlled in different polymeric matrices (thermoplastic, Ethylene vinyl acetate (EVA) and thermoset, epoxy) to realize the potential of these hierarchical structures in EMI shielding applications. The composites with CU show shielding effectiveness (SET) in the range of -45 dB to -52 dB in the X-band, and the green index is close to 1. The shield with the highest SET also showed a quick heat dissipation ability, an added advantage in terms of applicability. Our results begin to suggest that CU can be blended with a wide range of plastics to develop a universal solution in designing lightweight composites for EMI shielding applications.

Current status of various coolant applications in machining of nickel-base superalloys

Nickel-chromium super-alloys are preferred over steel as they provide excellent performance over a broad temperature range of cryogenic temperature to 1400 Fahrenheit. These alloys possess both high impact and tensile strength, thus it is one of the most desirable raw material for aeronautical and marine industries. Apart from all these advantages, they are very hard to machine and a huge magnitude of heat arises during machining operations which directly affects the product quality and surface texture of the finished products. To overcome all these problems, many researchers have implemented different types of coolants to minimize temperature generation, surface roughness, and tool wear. Coolants also harm both human health and the ecosystem if it is not handled properly and their disposal remains a challenge to our civilization. To overcome these challenges most industries preferred biodegradable vegetable oil base coolants over conventional mineral oil coolants. Researchers are continuously working on different methods to intensify the thermal conductivity and heat-dissipating capability of the coolants. This gave birth to a new era of coolants, where nanoparticles are mixed in a base oil to intensify their lubricating and cooling properties. These types of coolants are known as nanofluids which are colloidal mixtures made by the combination of nanoparticles and a base fluid. Nanofluids are now renowned in the entire world because of their high thermal conductivity, lubrication, and heat dissipation abilities. These papers provides a concise review of the effects of the several cutting fluids such as synthetic oil, mineral oil, vegetable oil, and nanoparticle-based cutting fluid on various machining outputs such as surface roughness and wear on tool interface while machining of the nickel-based alloy under an MQL environment. A concise review of different nanofluid preparation techniques is also included in this paper to acquire close knowledge about the manufacturing of different nanofluids.

Improvement of 2.8 μm laser performance on LD side-pumped LuYSGG/Er:LuYSGG/LuYSGG bonding crystal

We demonstrate the laser performance of 970 nm LD side-pumped LuYSGG/Er:LuYSGG/LuYSGG bonding crystal in a frequency range of 50–800 Hz. The thermal distribution simulation implies that the bonded Er:LuYSGG crystal possesses a higher cooling efficiency compared with the un-bonded one. The maximum average power of 20.76 W is realized at a frequency of 150 Hz and a pulse width of 200 μs, corresponding to a slope efficiency of 23.94 % and optical-to-optical conversion efficiency of 19.22 %. A single laser wavelength of 2797.5 nm is observed. The M2 factors of the bonding rod are 6.80/6.74, indicating a relatively high beam quality. Therefore, the LuYSGG/Er:LuYSGG/LuYSGG bonding crystal exhibits an improvement of laser performance operated at 2.8 μm due to excellent heat dissipation ability, which is a promising gain element and can be applied to the harsh radiation environment.

Absorption Dominated Directional Electromagnetic Interference Shielding through Asymmetry in a Multilayered Construct with an Exceptionally High Green Index.

Fabricating green electromagnetic interference (EMI) shields is the need of the hour because strong secondary reflections in the vicinity of the shield adversely affect the environment and the reliability of the neighboring devices. To this end, the present work aims to maximize the absorption-based EMI shielding through a multilayered construct comprising a porous structure (pore size less than λ/5), a highly conducting entity, and a layer to match the impedance. The elements of this construct were positioned so that the incoming electromagnetic (EM) radiation interacts with the other layers of the construct before the conducting entity. This positioning of the layers in the construct offers a high green shielding index (gs) and low reflection coefficient (R ∼ 0.1) with an exceptionally high percent absorption (up to 99%). Polyurethane (PU) foams were fabricated using the salt-leaching technique and strategically positioned with carbon nanotube (CNT) papers and polycarbonate (PC)-based films to obtain symmetric and asymmetric constructs. These structures were then employed to gain mechanistic insight into the directional dependency of shielding performance, gs, and heat dissipation ability. Interestingly, maximum total shielding effectiveness (SET) of -52 dB (88% absorption @8.2 GHz) and specific shielding effectiveness/thickness (SSEt) of -373 dB/cm2g were achieved for a symmetric construct whereas, for the asymmetric construct, the SET and SSEt were -37 dB and -280 dB/cm2g, respectively, with an exceptionally high gs of 8.6, the highest reported so far. The asymmetricity in the construct led to directional dependence of the absorption component (% SEA, shielding effectiveness due to absorption) and heat dissipation, primarily governed by the electrical and thermal conductivity gradient, respectively. This study opens new avenues in this field and reports constructs with an exceptionally high green index.

Investigations on physical and mechanical properties of Mg composites and foams fabricated by powder metallurgy using NaCl

The demand for metallic foams is increasing rapidly because of their very low density, high heat dissipation ability, high vibration damping capacity, and high energy absorption capacity. In the present work, Mg composites and foams are prepared using salt as space holder material using the powder metallurgy technique. Salt in different volume fractions (0 %, 25 %, 50 %, and 75 %) was mixed with Mg, and Mg/salt composites were fabricated. Density, porosity, and hardness of fabricated Mg/salt composites were investigated. Then, the sintered Mg/salt composites were dipped in water for the dissolution of salt. Density, porosity, and compressive strength of fabricated foams were investigated. The density and hardness of Mg/salt composites increased with an increase in the volume fraction of salt. The highest density (1.93 g/cc) and hardness (26 BHN) were obtained for Mg/salt composite fabricated using 75 vol% of salt. While for Mg foams, porosity increased with an increase in the volume fraction of salt and the highest porosity of 64 % was observed in Mg foam fabricated using 75 vol% of salt. On the other hand, compressive strength decreased rapidly with an increase in the volume fraction of salt. The compressive strength of Mg foam fabricated using 75 vol% of salt was only 3.44 MPa, therefore not suitable for most industrial applications. But, for Mg foam fabricated using 25 vol% of salt, comparatively high compressive strength (22.5 MPa) and high porosity (36 %) were obtained. Because of their very low density (1.15 g/cc) and sufficient strength, fabricated Mg foams can be used for various applications in automobiles and other industries.

Application of Nanofluid Electrochemistry in Heat Dissipation of Permanent Magnet Synchronous Motors

In order to solve the problem of heat dissipation of permanent magnet synchronous motors, a technology using the principle of nanofluid electrochemistry is proposed. The main content of this technology is based on the characteristics and applications of nanofluids; according to the experimental system, the preparation and experimental parameters of nanofluids were determined; finally, by studying the influence of ultrasonic oscillation time and dispersant on the stability of nanofluids, it was concluded that the improvement of the thermal conductivity of nanofluids contributed to the improvement of the heat transfer rate of nanofluids. Experimental results show that when the volume fraction is 0.5, the increase rate of thermal conductivity is 1.51, the increase rate of convective heat transfer coefficient is 20.33, and the increase rate of convective heat transfer coefficient is greater than that of thermal conductivity, which shows that nanofluids have very good heat dissipation ability. It is proved that the technical research of nanofluid can meet the heat dissipation requirements of a permanent magnet synchronous motor.

Thermal Coupling Simulation of Electro-Hydrostatic Actuator Subjected to Critical Temperature Conditions

Electro-hydrostatic actuators (EHAs) are emerging transmission techniques originated from aerospace industry and being introduced to various application fields, such as ships, robots, construction machines, and machine tools. Despite the advantages of high efficiency, easy maintenance, electrified power, etc., EHAs are usually self-contained integrated devices, resulting in low heat dissipation ability. Therefore, thermal coupling models are necessary for the evaluation of each design option during the EHA development. In this paper, a thermal coupling model was established for EHA thermal characteristic analysis during the detail design stage. The disciplines of electrics, mechanics, system level hydraulics, losses, and control are implemented by lumped parameter modeling while the disciplines of thermodynamics and fluid dynamics are simulated by computational fluid dynamics (CFD). Subsequently, a simulation analysis focusing on the critical temperature conditions was conducted, and the dynamic thermal and power responses were achieved. The simulation results are applicable to gain confidence for EHA detail design work as well as proved the functions of the proposed model as a practical development tool.

Van der Waals Epitaxy of c-Oriented Wurtzite AlGaN on Polycrystalline Mo Substrates for Enhanced Heat Dissipation.

The epitaxy of III-nitrides on metallic substrates is competitive due to the advantages of vertical carrier injection, enhanced heat dissipation, and flexible application in various III-nitride-based devices. However, the serious lattice mismatch, atom diffusion, and interface reaction under the rigorous growth conditions have caused enormous obstacles. Based on the thermal and chemical stability of the graphene layer, we propose the van der Waals epitaxy of c-oriented wurtzite AlGaN on the polycrystalline Mo substrate by high-temperature metal-organic chemical vapor deposition. The insertion of a graphene layer interrupts the chaotic epitaxial relationship between the polycrystalline metal and epilayers, resulting in the single-crystalline orientation along the wurtzite (0002) plane and residual stress release in AlGaN because of the weak van der Waals interaction. We also demonstrate that the epitaxy of AlGaN on Mo metal possesses enhanced heat dissipation ability, in which the epilayer temperature is controlled at only 28.7 °C by the heating of a ∼54 °C hot plate. The heat dissipation enhancement for the present epitaxial structures provides a desirable strategy for the fabrication of efficient ultraviolet devices with excellent stability and lifetime.

Investigation on the two-phase flow and heat transfer behaviors in a new central uniform dispersion-type heat exchanger

In order to improve the temperature uniformity of multiple chips, a new central uniform distributed heat exchanger (CUD) is designed. Firstly, adopting ethanol solution as coolant, the cooling ability of the heat exchanger is numerically investigated by using VOF gas-liquid two-phase flow model, and the two-phase flow experimental system is established to verify the correctness of the numerical results. The results show that the Tavg (average temperature of heat sources) error range between the experimental and numerical values is 1 K ~ 3 K, and the relative error of SDT (standard deviation of temperature) is 6% ~ 10%. This verifies the accuracy of the numerical simulation method. Secondly, the two-phase flow boiling heat transfer behavior are compared with that of single-phase flow with water as coolant. The results show that with the increase of inlet flow, the thermal resistance and average temperature of two-phase flow change are less than that of single-phase flow. This indicating that two-phase flow has better advantages in improving the temperature uniformity of multiple heat sources. Thirdly, the heat transfer characteristics of radiators with different Wi are studied. Compared with Case1, the boiling heat transfer coefficient of Case3 and Case4 can be increased by 12.3% and 18.3%, respectively. However, Case3 is a better choice by weighing the pressure drop. Finally, the prediction functions of the boiling heat transfer coefficient and pressure drop is established, and the multi-objective genetic algorithm is used to obtain the best parameters of this heat exchanger. The average heat transfer coefficient of the optimized heat exchanger can be increased by 7.56%, and the pressure drop can be reduced by 3.54% compared to the exchanger before optimization. Furthermore, the heat dissipation ability of the optimized heat exchanger design is studied numerically. The simulated results are in good agreement with the optimization results.

Binary Promoter Improving the Moderate-Temperature Adhesion of Addition-Cured Liquid Silicone Rubber for Thermally Conductive Potting.

The strong adhesion of thermally conductive silicone encapsulants on highly integrated electronic devices can avoid external damages and lead to an improved long-term reliability, which is critical for their commercial application. However, due to their low surface energy and chemical reactivity, the self-adhesive ability of silicone encapsulants to substrates need to be explored further. Here, we developed epoxy and alkoxy groups-bifunctionalized tetramethylcyclotetrasiloxane (D4H-MSEP) and boron-modified polydimethylsiloxane (PDMS-B), which were synthesized and utilized as synergistic adhesion promoters to provide two-component addition-cured liquid silicone rubber (LSR) with a good self-adhesion ability for applications in electronic packaging at moderate temperatures. The chemical structures of D4H-MSEP and PDMS-B were characterized by Fourier transform infrared spectroscopy. The mass percentage of PDMS-B to D4H-MSEP, the adhesion promoters content and the curing temperature on the adhesion strength of LSR towards substrates were systematically investigated. In detail, the LSR with 2.0 wt% D4H-MSEP and 0.6 wt% PDMS-B exhibited a lap-shear strength of 1.12 MPa towards Al plates when curing at 80 °C, and the cohesive failure was also observed. The LSR presented a thermal conductivity of 1.59 W m−1 K−1 and good fluidity, which provided a sufficient heat dissipation ability and fluidity for potting applications with 85.7 wt% loading of spherical α-Al2O3. Importantly, 85 °C and 85% relative humidity durability testing demonstrated LSR with a good encapsulation capacity in long-term processes. This strategy endows LSR with a good self-adhesive ability at moderate temperatures, making it a promising material requiring long-term reliability in the encapsulation of temperature-sensitive electronic devices.

Methodology For Calculating Automotive Oil Radiator

The paper highlights the relevance of the problem of determining the amount of heat supplied by an internal combustion engine to a liquid cooling system when creating typical series of unified heat exchangers for tractor and combine engines (power units). A properly designed cooling system further guarantees the maintenance of the optimal thermal mode for the engine operation. A methodology for calculating the coolant characteristics of the cooling system was proposed in order to prevent possible problems related to increased parts wear, early loss of oil lubricating properties, the engine (individual units) and rubbing parts overheating, a decrease in engine power and a deterioration in the quality of the fuel-air mixture entering the cylinders.Research purpose To develop a methodology for calculating the amount of heat to be dissipated by the oil radiators of a liquid cooling system (lubrication system) being exposed to various load and engine speed modes.Materials and methods It was proposed to determine the amount of heat to be dissipated by the liquid-oil heat exchanger of the engine lube oil cooling system.Results and discussion The calculation method for oil radiators presents the calculation of the heat obtained by oil during the operation of 37-110 kilowatts automotive engines. The heat-dissipating ability of the oil surface is determined. A parameter taking into account the oil radiator heat flow is identified. The graphs of the oil surface and heat flux dependence on the engine power are presented.Conclusions The method for calculating the temperature and dynamic characteristics of the automotive engine cooling system has been developed. It makes it possible to carry out research on the radiator thermal and technical characteristics in various operating modes of machines and coolants of systems, various heat exchanger structural materials (metal, polymer), with an error of 1.5-8.0 percent.

Enhanced Mechanic Strength and Thermal Conductivities of Mica Composites with Mimicking Shell Nacre Structure

As the main insulation of high-voltage motors, the poor mechanical and thermal conductivities of mica paper restrict the motor’s technological advances. This paper prepared multilayer toughening mica composites with a highly ordered “brick-mud” stacking structure by mimicking the natural conch nacre structure. We investigated the mechanical, thermal, and breakdown properties by combined study of tensile strength, stiffness, thermal conductivity, and breakdown strength at varying mica and nanocellulose contents. The results show that thermal conductivity of the mica/chitosan composites were gradually enhanced with the increase in mica content and the composite shows the optimal synthetic performance at 50 wt% mica content. Further addition of the nanocellulose can extremely enhance the thermal conductivities of mica/chitosan composites. The composite with 5 wt% nanocellulose obtained the maximal thermal conductivity of 0.71 W/(m·K), which was about 1.7 times that of the mica/chitosan composite (0.42 W/(m·K)) and much higher than normal mica tape (0.20 W/(m·K)). Meanwhile, the breakdown strength and tensile strength of mica/chitosan/nanocellulose composite also demonstrated substantial improvement. The application of the mica/chitosan/nanocellulose composite is expected to essentially enhance the stator power density and heat dissipation ability of large-capacity generators and HV electric motors.

Hybrid-Strand Winding Topology With Improved Power Density in Automotive Electric Machines

The rectangular profile conductor with a large cross section requires less slot space and has better heat dissipation ability than the traditional round profile one. But its application in automotive propulsion electric machines is thwarted by high ac winding losses and temperature rise under high-speed operations. This article proposes a novel stator winding topology with hybrid strands based on the ac losses' distribution characteristics and the theoretical relationship between the eddy current suppressing ability and the geometric parameters. The new winding can effectively reduce the ac loss and the peak temperature in the winding at high-speed operation. Meanwhile, it can maintain a high filling rate. Therefore, the machine's maximum rotating speed and power density can be effectively improved. In experimental validation, a winding sample with this new topology is manufactured and compared with the conventional one formed by rectangular wires. It shows the proposed method can reduce the winding ac loss by up to 12% and the temperature rise by 10–21%. It is validated to have considerable industrial potential in the future development of automotive motors.

Defining the link between oxidative stress, behavioural reproductive suppression and heterothermy in the Natal mole-rat (Cryptomys hottentotus natalensis)

Sub-lethal effects, such as oxidative stress, can be linked to various breeding and thermophysiological strategies, which themselves can be linked to seasonal variability in abiotic factors. In this study, we investigated the subterranean, social living Natal mole-rat (Cryptomys hottentotus natalensis), which, unlike other social mole-rat species, implements heterothermy seasonally in an attempt to avoid exercise-induced hyperthermia and relies solely on behavioural reproductive suppression to maintain reproductive skew in colonies. Subsequently, we investigated how oxidative stress varied between season, sex and breeding status in Natal mole-rats. Oxidative markers included total oxidant status (TOS measure of total peroxides present), total antioxidant capacity (TAC), OSI (oxidative stress index) and malondialdehyde (MDA) to measure oxidative stress. Breeding and non-breeding mole-rats of both sexes were captured during the summer (wet season) and winter (dry season). Seasonal environmental variables (air temperature, soil temperature and soil moisture) had a significant effect on TOS, OSI and MDA, where season affected each sex differently. Unlike other social mole-rat species that use both physiological and behavioural means of reproductive suppression, no oxidative costs to reproduction were present in the Natal mole-rats. Males had significantly higher MDA than females, which was most apparent in summer (wet season). We conclude that the significant oxidative damage in males is a consequence of exercise-induced oxidative stress, exacerbated by increased burrow humidities and poorer heat dissipation abilities as a function of body mass. This study highlights the importance of both breeding and thermophysiological strategies in affecting oxidative stress.

Composition dependence of thermophysical properties for liquid Zr–V alloys determined at electrostatic levitation state

The thermophysical properties of liquid Zr–V alloys covering a whole composition range were systematically measured by an electrostatic levitation technique. A series of maximum undercoolings from 150 to 386 K (0.2 TL) was achieved for 11 different liquid alloys under containerless state and radiative cooling conditions, where Zr83.5V16.5 and Zr20V80 alloys displayed the strongest undercooling ability. The densities of liquid Zr–V alloys were measured over a wide temperature range from overheated to undercooled states, and the results exhibited a linear dependence on temperature for all 11 compositions. Two typical solidification pathways were observed for hypoeutectic alloys. Except for a slowing down of decreasing tendency near a eutectic Zr57V43 alloy, the liquid densities of Zr–V alloys almost decrease linearly with increasing V content. Accordingly, the thermal expansion coefficients of Zr–V alloys were also derived from containerless measurements, and they showed an increasing tendency with V content. Since thermal radiative dominated the heat transfer process, the ratio of isobaric specific heat to hemispherical emissivity was directly deduced from the thermal balance equation, leading to a quadratic relationship with temperature. It was found that the increase of V content enhanced the ability of radiative heat dissipation below 16.5 at. % V content.

Multiple Dielectric-Supported Ridge-Loaded Rhombus-Shaped Wideband Meander-Line Slow-Wave Structure for a V-Band TWT

A multiple dielectric-supported ridge-loaded rhombus-shaped meander-line (MDSRL-RSML) slow-wave structure (SWS) is proposed for a V-band wideband traveling wave tube (TWT). The high-frequency and transmission characteristics of the SWS are investigated. The proposed structure can realize stable output via attenuator and special phase-velocity jumping. Particle-in-cell (PIC) results indicate that, for a 7 kV, 0.1 A sheet-beam, the average output power can reach 60 W at 60 GHz and a 3 dB bandwidth of 9 GHz, with the corresponding gain and electron efficiency of 30.8 dB and 17.2%, respectively. Compared with the dielectric-supported rhombus-shape meander-line (DS-RSML) SWS, the proposed structure has a wider bandwidth, higher gain, more stable structure, and better heat dissipation ability, which make it a good candidate source in millimeter-wave communications.

Optimization of open micro-channel heat sink with pin fins by multi-objective genetic algorithm

Micro-channel heat sink is an effective way to solve the heat dissipation problem of electronic devices because of its compact structure and outstanding heat dissipation ability. In order to obtain the high efficiency and low resistance micro-channel heat sink, a new structure of open rectangular micro-channel heat sink with pin fins was proposed to enhance heat transfer. The orthogonal test method was used to design the experiment, and the 3-D software SOLIDWORKS was used to establish 25 groups of open rectangular micro-channel heat sink with pin fins structure model which has different structural parameters. The numerical calculation was carried out with ANSYS FLUENT simulation software and the experimental values with the structural parameters of the micro-channel heat sink as variables were obtained. According to the simulated experimental values, the objective functions of thermal resistance and pumping power were constructed, and the agent model between objective functions and the optimization variables were established. The Pareto optimal solutions of objective functions were calculated by non-dominated sorting genetic algorithm, which was analyzed by k-means clustering analysis and five clustering points were obtained, and five clusters points were compared and verified by simulation. it was found that there was effective tradeoff points between the highest and lowest points of the five clustering which can make both the pumping power and thermal resistance within the optimal range, so as to obtain the optimal micro-channel heat sink.

Optimization of random silica-polymethylpentene (TPX) radiative coolers towards substantial cooling capacity

In the context of global warming, radiative coolers with high solar reflectance and strong emissivity in the atmospheric window can cool the substrate as well as the ambient air. Silica at its nano or micro-scale being randomly dispersed into a uniform transparent polymer can form scalable radiative coolers for large-scale application. Promising cooling performance has been reported for silica-polymers compared with conventional cooling materials, but their performance can be largely influenced by various fabrication parameters. So far, how fabrication parameters influence the emissivity and the cooling performance has not been experimentally demonstrated and the cooling capacity of silica-polymers reported was not substantial compared to other superior radiative coolers. In this work, random silica-polymer has been optimized experimentally. Lab measurement and experimental testing of six fabricated silica-polymers under subtropical and desert climates indicated that due to the complexity of the thermo-radiative balance, high emissivity and strong selectivity are both indispensable in the production of high cooling power. If combined with superior reflectors with higher solar reflectance and especially the emissivity in 8–13 μm enhancing the heat dissipation ability, substantial cooling capacity can be achieved: under the harsh desert climate with average peak solar radiation over 1100 Wm-2, the combination presented sub-ambient temperature of maximum 4.7 °C when air temperature reached its peak and the maximum daytime and night-time sub-ambient temperatures were 12.5 °C and 15.9 °C respectively.

Study of heat dissipation characteristics of loop heat pipe with heat sink of composite material

In this study, a new heat dissipation device with a composite heat sink of a loop heat pipe (LHP) system was evaluated for efficient cooling of electronic components. To improve the heat dissipation ability of the high heat flux chip and its local hot spot area, LHP, which had a gas–liquid phase change as the main mechanism of heat dissipation, was selected to remove heat. The experimental results showed that the average temperature performance was improved after the graphene copper foil heat sink was fitted, and the maximum temperature under the heat loads of 80 W, 90 W, 100 W, and 120 W was reduced by 3.8 °C, 5.7 °C, 6.5 °C, and 7.7 °C, respectively, compared with without a heat sink. The hot spot temperature increased linearly with an increase in the inlet water temperature. Increasing the ambient temperature within a certain range had little effect on the heat-dissipation effect of the hot spots. To interpret the experimental results, the hot spot heat transfer performance of the evaporation section of the LHP with a composite heat sink was set up by the equivalent thermal resistance model. The CFD simulated results were in good agreement with the experimental values. This indicated that the heat sink significantly reduced the hot spot temperature and improved the cooling uniformity largely. When the transverse thermal conductivity of the heat sink is sufficiently high, the increase in longitudinal thermal conductivity is more effective in reducing the hot spot temperature than the transverse thermal conductivity. Moreover, it has been suggested that the hot spots and heating power play a major role in the actual electronic structure and heat dissipation design. In summary, the study proposes a valuable method for improving the uniform cooling of chips, which was conducive to the heat management of the system.