Vapor Chamber Research Articles

An efficient solar water desalination system using natural vacuum pressure

An innovative design of a solar natural vacuum desalination (SNVD) system is proposed and investigated. To obtain a vacuum pressure in a desalination chamber its height is considered as 9.5 m. The waste heat in the system is efficiently utilized for both brine and distilled water. Seawater is preheated by the produced warm water, then, it is heated again by the outlet rejected hot brine before it is charged into the evaporation chamber. In addition, inlet pure water to a flat-plate collector is preheated by the condensation latent heat of the evaporated vapor from the evaporation chamber. Later, the outlet hot water from the collector is used as a heat source to the evaporation process. An optimum design of the system components was provided under the actual weather conditions for the shortest day of the year. It was found that the collector area is required to be 23 m2 to produce 66.6 liter of distilled water during. A mathematical modeling of the system was provided to establish a transient simulation and investigate the hourly performance of the system. Based on the annual performance of the system, the system can produce 76.5 liter of distilled water daily that is corresponding to 3.5 liter per one quadratic meter of collector. The annual average specific productivity of the system is obtained as 1.44 liter per kWh of solar radiation. Moreover, the maximum annual production is estimated as 92.88 liter of distilled water per day. Accordingly, the evaporation ratio (ER) is dependent on the solar irradiation and the annual average is found 0.0175 (or 1.75 %) where the gain output ratio (GOR) was estimated as 0.97 on yearly average basis.

Electro-osmosis Aided Thin-Film Evaporation from a Micropillar Wick Structure.

The heat-dissipating capacity of a surface having micropillar wick structures, which resembles the evaporator section of a vapor chamber, is mainly limited by the liquid flow rate through the porous structure (permeability) and the capillary pressure gradient. The efficacy of a regular vapor chamber is determined from two parameters, namely, the dry-out heat flux and temperature of the evaporator surface. These two parameters possess a counter relation to each other. The work described herein introduces and evaluates the performance of a novel idea of electro-osmosis-aided thin-film evaporation from a micropillar array structure. This study is conducted using a discretized approach that is validated against the thin-film evaporation model and additionally the electro-osmotic flow model with pre-existing pressure gradient conditions. The unique feature of this approach is that it results in an increment in the magnitude of dry-out heat flux without significantly changing the surface temperature, wherein the increase in permeability is due to the addition of electro-osmotic flow. This comprehensive model considers various geometries, zeta potentials, and extremal electric fields and establishes the beneficial effects of the application of an external electric field. The results are used to predict the sensitivity and the dependence of the dry-out heat flux and the evaporator surface temperature on these parameters. For a host of electro-osmotic parameters considered herein, a maximum increment of up to 320% in the dry-out heat flux is observed for an external electric field of 105 V/m. The study, therefore, conclusively demonstrates the beneficial impact of electro-osmosis in enhancing the dry-out heat flux without any significant Joule heating.

Assessment of an Exhaust Thermoelectric Generator Incorporating Thermal Control Applied to a Heavy Duty Vehicle

The road transport industry faces the need to develop its fleet for lower energy consumption, pollutants and CO2 emissions. Waste heat recovery systems with Thermoelectric Generators (TEGs) can directly convert the exhaust heat into electric energy, aiding the electrical needs of the vehicle, thus reducing its dependency on fuel energy. The present work assesses the optimisation and evaluation of a temperature-controlled thermoelectric generator (TCTG) concept to be used in a commercial heavy-duty vehicle (HDV). The system consists of a heat exchanger with wavy fins (WFs) embedded in an aluminium matrix along with vapour chambers (VCs), machined directly into the matrix, that grant the thermal control based on the spreading of local excess heat by phase change, as proposed by the authors in previous publications and patents. The TCTG concept behaviour was analysed under realistic driving conditions. An HDV with a 16 L Diesel engine was simulated in AVL Cruise to obtain the exhaust gas temperature and mass flow rate for each point of two cycle runs. A model proposed in previous publications was adapted to the new fin geometry and vapour chamber configuration and used the AVL Cruise data as input. It was possible to predict the thermal and thermoelectric performance of the TCTG along the corresponding driving cycles. The developed system proved to have a good capacity for applications with highly variable thermal loads since it was able to uncouple the maximisation of heat absorption from the regulation of the thermal level at the hot face of the TEG modules, avoiding both thermal dilution and overheating. This was achieved by the controlled phase change temperature of the heat spreader, that would ensure the spreading of the excess heat from overheated to underheated areas of the generator instead of wasting excess heat. A maximum average electrical production of 2.4 kW was predicted, which resulted in fuel savings of about 2% and CO2 emissions reduction of around 37 g/km.

Use of High-Frequency Ultrasound Waves for Boiler Water Demineralization/Desalination Treatment

Isolated ultrasonic vibrations were used to treat feed water from a 20 bar steam-producing water tube boiler. Physical treatments such as ultrasounds and reverse osmosis (RO) are recommended as the most eco-friendly for this purpose. A novel bench-scale prototype delivering 6 L/h of treated water was designed and built. The ultrasonic atomization of raw water with 1.7 MHz piezoelectric transducers and subsequent humidification and dehumidification of drag airflow was the innovating sequence of operations used as a treatment technique. To ensure greater humidification capacity to the drag air, the energy available from the thermal inertia of the liquid column (raw water) in the prototype vaporization chamber was used to heat this air flow. After a single pass of raw water through the bench-scale prototype, a 98.0% reduction in conductivity and a 99.0% decrease in the content of total dissolved solids were obtained at a drag air temperature of 70 °C. Compared to RO, two of the main advantages of the proposed ultrasonic wave method are the elimination of the use of chemical agents in the pre-treatment phase and a significant reduction in maintenance costs by membrane replacement.

A two-phase liquid immersion cooling strategy utilizing vapor chamber heat spreader for data center servers

• A two-phase liquid immersion cooling strategy for servers was developed. • Gradient capillary wicking structures were employed in the vapor chamber. • Thermal performance of the vapor chamber was carefully evaluated. • A minimum total thermal resistance of 0.05 °C/W was obtained at 500 W. The 5th generation communication technology dramatically increases the cooling demands of data center servers, and the thermal management strategies should possess the crucial characteristics of relatively compact structure, high cooling efficiency, and reliable operation as well as energy saving. In general, cooling electronics effectively could significantly drive the efficient power utilization for the electronic devices. As an efficient heat dissipation solution, liquid immersion cooling is a potential and prominent candidate to cool high-power-density electronics by submerging them into a pool of dielectric liquid. In this paper, a two-phase liquid immersion cooling strategy using vapor chamber heat spreader was developed and investigated to tackle the continuously increasing demands in heat dissipation of data center servers. In order to promote the circulation of the working liquid and improve the heat transfer performance, gradient capillary wicking structures were innovatively employed in the vapor chamber. Systematic experimental investigations were conducted to fully study the thermal performance of the vapor chamber. The results indicated that the vapor chamber could effectively transport 500 W heat load with the heat source temperature below 85 °C, and could cope with a maximum heat load up to 900 W without dry-out, at which a vapor chamber thermal resistance of 0.046 °C/W was attained. Additionally, compared to other advanced cooling methods reported in literatures, the proposed two-phase liquid immersion cooling strategy using the vapor chamber exhibited a higher heat transfer performance, providing a promising means for high-power data center servers cooling.

A phase separation inlet for droplets, ice residuals, and interstitial aerosol particles

Abstract. A new inlet for studying the aerosol particles and hydrometeor residuals that compose mixed-phase clouds – the phaSe seParation Inlet for Droplets icE residuals and inteRstitial aerosol particles (SPIDER) – is described here. SPIDER combines a large pumped counterflow virtual impactor (L-PCVI), a flow tube evaporation chamber, and a pumped counterflow virtual impactor (PCVI) to separate droplets, ice crystals (∼3–25 µm), and interstitial aerosol particles for simultaneous sampling. Laboratory verification tests of each individual component and the composite SPIDER system were conducted. Transmission efficiency, evaporation, and ice crystals' survival were determined to show the capability of the system. The experiments show the SPIDER system can separate distinct cloud elements and interstitial aerosol particles for subsequent analysis. As a field instrument, SPIDER will help explore the properties of different cloud elements and interstitial aerosol particles in mixed-phase clouds.

Room temperature ferromagnetism in oxygen-deficient gallium oxide films with cubic spinel structure

Oxygen-defective gallium oxide (Ga2O3-x with 0.4 < x < 0.7) thin films with cubic spinel structure were deposited on c-cut epi-polished sapphire wafers using thermal evaporation technique by keeping specific values of oxygen partial pressure in the evaporation chamber. The preparation method and post-treatment conditions induced distinct oxygen stoichiometries in the films which exhibit a ferromagnetic-like behavior at room temperature. Despite the measured saturation magnetization values do not exhibit a straightforward correlation to the oxygen stoichiometry of the films, the presence of oxygen vacancies and defects is presumably the origin of the unconventional magnetic behavior. Strong magnetic irreversibility exhibit by the magnetization measurements performed using field-cooling and zero-field-cooling protocols indicate the presence of disordered magnetic moment distributions which are likely non-collinear. Theoretical and experimental results available in the literature corroborate with the assumptions that oxygen vacancies and defects appear as the main reason for room-temperature ferromagnetism. All films exhibit soft magnetic behavior at room temperature, exhibiting remanent magnetizations between 7% and 20% of the saturation magnetization which saturated magnetic moments is estimated as 0.43 and 1.24 Bohr magneton per oxygen vacancy. The present results extend the functionalities of this interesting material, which is already investigated for applications in several technological areas, for possible uses in the areas of spintronics and emerging areas of the optospintronics.

Deployment of vapour chambers for electronic heat dissipation: state-of-the-art

Miniaturization and high performance are the two principal requirements of modern electronics. All commercial applications demand reliable performance at high operational efficiency for prolonged service life. In order to meet all these requirements, the cooling system should be able to handle large heat fluxes packed in compact spaces and take away the heat as soon as possible to avoid overheating of the chip. Phase change heat transfer devices can handle large heat fluxes on account of latent heating. Lately, vapour chambers (VCs) are found to be promising heat spreaders as they are passive two-phase heat transfer devices. They effectively eliminate the hotspots, transferring high heat fluxes with better efficiencies and offer lower thermal resistance compared to the conventional cooling techniques. A detailed review of the latest research and advancements in the field of VCs is presented in this paper, including the effect of different thermo-physical parameters on their performance. Finally, all the major findings are summarized, including the future scope of development in a systematic manner.

Anisotropic Hemiwicking Behavior on Laser Structured Prismatic Microgrooves.

The wicking phenomenon, including wicking and hemiwicking, has attracted increasing attention for its critical importance to a wide range of engineering applications, such as thermal management, water harvesting, fuel cells, microfluidics, and biosciences. There exists a more urgent demand for anisotropic wicking behaviors since an increasing number of advanced applications are significantly complex. For example, special-shaped vapor chambers and heating atomizers in some electronic cigarettes need liquid replenishing with various velocities in different directions. Here, we report two-dimensional anisotropic hemiwicking behaviors with elliptical shapes on laser structured prismatic microgrooves. The prismatic microgrooves were fabricated via one-step femtosecond laser direct writing, and the anisotropic hemiwicking behaviors were observed when utilizing glycerol, glycol, and water as the test liquid. Specifically, the ratios of horizontal wicking distance in directions along short and long axes were tan 0°, tan 15°, tan 30°, and tan 45° for samples with cross-angles of 0°, 30°, 60°, and 90°, respectively. The vertical water wicking front displayed corresponding angles under the guidance of laser structured prismatic microgrooves. Theoretical analysis shows that the wicking distance is mainly dependent on the cross-angle θ and surface roughness, in which the wicking distance is proportional to cos(θ/2). Driven by the capillary pressure forming in the narrow microgrooves, the liquid initially filled the valleys of microgrooves and then surrounded and covered the prismatic ridges with laser-induced nanoparticles. The abundant nanoparticles increased the surface roughness, leading to the enhancement of wicking performance, which was further evidenced by the larger wicking speed of the sample with more nanoparticles. The mechanism of anisotropic hemiwicking behaviors revealed in this work paves the way for wicking control, and the proposed prismatic microgrooved surfaces with two-dimensional anisotropic hemiwicking performance and superhydrophilicity could serve in a broad range of applications, especially for the advanced thermal management with specific heat load configurations.

A parametric study on the performance of vapor chamber in association with pillar distribution

The performance of vapor chamber is significantly affected by the wick structure, height of the vapor cavity, pillar structure, working fluid, filling ratio, and heat source area. Besides, it can also be influenced by the pillar distribution, which has not been extensively studied in prior literature. Therefore, the present study investigates the influence of pillar distribution on the vapor chamber performance. Totally 11 different vapor chamber models are fabricated and tested, and water is selected as a working fluid for all the samples. The examined geometric features include different mesh layers, mesh sizes, wick structure in condenser surface, pillar distributions, and vapor core space. The results showed that the evaporator with a single-layered mesh provided the thermal resistance of 0.19 K W−1, while triple-layered mesh yielded a thermal resistance of 0.24 K W−1. Moreover, the 2 × 200 mesh offered a maximum heating load of 161 W with a thermal resistance of 0.18 K W−1 against the maximum heating load of 120 W and 75.6 W by the 2 × 150 and 2 × 100 mesh, respectively. The experimental results showed that increasing the pillar numbers alone may not always reduce the thermal resistance, a better pillar distribution can help to direct the vapor flow and improve the performance of the vapor chamber. The proposed vapor chamber with a novel X-wing patterned pillar distribution can offer a thermal resistance of 0.19 K W−1 at a heating load of 146.6 W.

Direct Integration of Optimized Phase-Change Heat Spreaders Into SiC Power Module for Thermal Performance Improvements Under High Heat Flux

Silicon carbide (SiC) power modules are attractive in many applications due to the superiority of their semiconductor characteristics. However, power modules are subjected to repetitive thermo-mechanical stress caused by the mismatch of the coefficient of thermal expansion between different layers of materials. Moreover, the relatively smaller die size of SiC chips makes the heat flux increase significantly, which brings new challenges to the thermal management and reliability of SiC power modules. To tackle these challenges, this article proposes a new thermal enhanced packaging method based on vapor chamber (VC) phase change heat spreader (PCHS) for SiC power modules, achieving the advantages of high thermal conductivity, low weight, low cost, and low thermal stress. In this new design, SiC <small>mosfet</small> bare dies are directly soldered on the top of VC-PCHS, which not only act as heat spreaders but also conduct the drain current of <small>mosfet</small>s. The integrated VC-PCHS is optimized based on thermal and thermomechanical performance. An SiC power module prototype directly integrated with VC-PCHS is built using a new fabrication process. Both the simulations and experiments demonstrate significant improvements in thermal and thermomechanical performance. The modules integrated with VC-PCHS can operate under 200 W of power dissipation per die (632 W&#x002F;cm²) without exceeding the maximum rated junction temperature. This article reveals the potential of directly integrating phase change cooling components inside power modules, providing a new solution to improve the thermal performance and reliability of SiC power modules without adding complexity and energy consumptions to external cooling systems.

Capillary Performance of Nanoporous Aluminum Braided Wicks Prepared by Anodic Oxidation

With the rapid development of two-phase heat exchangers, the further improvement of the capillary performance of their internal wick faces a great challenge. As an important technology in the surface treatment of aluminum alloys, anodic oxidation has been widely used to develop various functional nanostructures. In this study, nanopores with diameters of 30–40 nm were fabricated on the surface of aluminum fibers through anodic oxidation under an oxalic acid system. Results showed that anodizing increased the specific surface area of the aluminum braid by 163 times, and changed its surface wettability from hydrophobic to superhydrophilic. A significant reduction in the effective capillary radius can substantially increase the capillary force of aluminum braids on the basis of capillary theory. Therefore, the nanoporous aluminum braids can be used as a novel wick in the vapor chamber to improve its capillary performance. Capillary rate-of-rise tests with ethanol and acetone were performed to characterize the capillary of this novel wick structure. Infrared thermal imaging was utilized to monitor the capillary rise of aluminum braided wicks. The capillary force of the anodized wicks was greater than that of a normal wick, and the maximum capillary rise height was 81 mm. The nanoporous aluminum braided wicks prepared by anodizing could be applied in heat transfer.

Studies on heat transfer characteristics of vapor chamber under periodic-pulsed heat source

In a high-power microwave device, the intense electron beam causes a high-heat-flux on the collector’s inner surface which results in an instant temperature increase which eventually causes the output power to drop. The vapor chamber is one of the passive cooling devices effective for high-heat-flux heat dissipation. To study the heat dissipation capacity and the surface temperature control effect of the vapor chamber, a numerical heat transfer model of the vapor chamber is proposed based on the effective thermal conductivity method. The accuracy of the steady-state heat transfer analysis and the applicability of the transient simulation are verified by comparing with experimental data, and the heat transfer are calculated under the condition of periodic pulsed heat sources. Lastly, the transient performance of a vapor chamber relative to a copper heat spreader of the same external dimensions is investigated as a function of the wick effective thermal conductivity, pulsed heat flux, and pulse duration. The transient behavior of the vapor chambers are examined to find a performance threshold to determine if the performance is superior to that of a copper heat spreader. The present work provides a basis to understand the advantages and limitations of metal heat spreader in pulse mode operation of vapor chamber and plays a vital role in the design of improving transient performance.

Ultrathin aluminum wick with dual-scale microgrooves for enhanced capillary performance

With the burgeoning development of electronic devices with higher heat flux, thinner volume, lighter weight, and flexibility, heat pipes and vapor chambers are facing big challenges, especially in fabricating high-performance wicks within limited space. Microgrooves have gained increasing interest for the ability to be directly curved on the substrates, whereas the capillary performance enhancement hits a bottleneck. In this study, a chemical-free ultrathin aluminum wick with dual-scale microgrooves was fabricated via two-step laser texturing in 0.3 mm thick AA6061. The resultant surface, composed of main microgrooves and periodic sub-microgrooves in the ridges and valleys, demonstrated enhanced capillary performance via capillary rise rate experiments. The interaction of liquids in dual-scale microgrooves, that was the pumping effect and the flow resistance reducing effect, would be the main reason for the capillary performance enhancement. The ultrathin aluminum wick with dual-scale microgrooves exhibited a K/Reff about 1.322 µm with a shallow depth of about 100 µm, increased by 11.3% compared with that of single-scale microgrooves due to the assistance of the sub-microgrooves. This wick kept the ability to transport liquid under bending angles of 90 and 135°. Moreover, the wicking performance of different liquids decreased with the decrease of surface tension to viscosity ratio. The ultrathin aluminum wick with dual-scale microgrooves showed enhanced capillary performance, which was among the best with thickness less than 200 µm to our knowledge. This work provides insight into the design of high-performance wicks within limited space and weight.

Topology optimization of vapor chamber internal structures consisting of evaporator and condenser

This paper studies the integrated topology optimization of vapor chambers consisting of evaporator and condenser. Firstly, the patterning is regarded as a fundamental access-maximization problem and classified into two general categories: (1) “area to point” (AP) flow problem for condenser wick design and (2) “area to line” (AL) flow problem for evaporator wick design. Then, the branch-patterned disc with first order assembly of flow channels is deduced, where the design domain is divided into 18 identical sectors for both condenser and evaporator. A fluid dynamic model is established to analyze the flow characteristics of the working fluid driven by capillary force. Based on this, a generative topology optimization model with a bifurcation rule is developed to produce the hierarchical capillary flow channels that minimize the global resistance for AP flow problem and AL flow problem, respectively. Unlike the commonly used Eulerian framework for topology optimization, the generative topology optimization used in this paper is carried out essentially in a Lagrangian framework, where capillary flow channels undergoing changes of volume, of positions, of inclined angles and of shapes are described by a set of parameterized level-set surfaces which can move, deform, overlap and merge freely upon the underlying FEM grids. The generated constructal wick structures exhibit dichotomous, hierarchical and branching characteristics. Numerical comparisons show that the new wick structures can contribute to the vapor chambers with better thermal performance.

Optimization of the coupling groove parameters of composite porous vapor chamber

The recently developed composite porous vapor chamber (CPVC) with central and radial grooves shows small thermal resistance and good thermal performance under high heat fluxes. However, the groove parameters are difficult to optimize due to their coupling relationship and the lack of sound scientific ground. This paper addresses the issues by proposing an optimization method based on design of experiments (DOE) and response surface methodology (RSM) with the help of a developed decoupling strategy. In this method, a decoupling strategy inspired by the golden section rule is proposed to break the coupling relationship between groove parameters. Then DOE and RSM analyses are performed to provide data for single-objective and multi-objective optimization of groove parameters. Results indicate that, due to the decoupling strategy, the total number of sampling points is reduced by about 40% and the ratio of effective sampling points is increased by about 65.43% in DOE analysis. The influence of the groove parameters is nonmonotonic, and groove depth (T) has the greatest effect on the thermal hydraulic characteristics of CPVC, while the influence of central circular diameter (D) and groove width (W) is similar. The effect trend of the number of grooves (N) is contrary to that of W at small values due to the dramatic decrease of W. The thermal hydraulic performances can not reach the minimum or maximum value simultaneously, and the groove parameter configuration of D = 29 mm, W = 3.7 mm, T = 2.1 mm and N = 16 can be chosen as the optimal, leading to the decrease of the maximum temperature and the maximum temperature difference on the condensing surface, and the liquid pressure drop by 0.005 K, 0.015 K and 9.68%, respectively, compared with the initial design. The proposed method may pave a more objective and scientific alternative to design the structural parameters of CPVC.

Thermal performance evaluation of a novel ultra-thin vapor chamber with Laval-like nozzle composite wick under different air cooling conditions

Driven by the continuously increasing cooling demands of electronic devices, ultra-thin vapor chambers (UTVCs) possessing the characteristics of easy-fabrication, low-cost and high-performance are urgently required. In this research, an integrated composite wick with multi-artery channels structure was proposed, which imitates the Laval nozzle in porosity. The designed wick was not only better for liquid reflow and vapor diffusion, but also for supporting the upper and lower covers instead of supporting columns. Under the heat load of 50 W, the UTVC introduced a reduction in maximum temperature difference for 67.7% compared with copper plate with the identical dimensions under natural convection. Under the heat load of 180 W and cooling air flow rate of 72.8 CFM, the UTVC's minimum spreading resistance reaches about 0.063 °C/W. The experimental results and LED's practical applications both indicate that the UTVC enhanced cooling capacity remarkably and yield a notable favorable performance for the heat dissipation of high-power electronic devices.

Rapid boiling and subsequent cooling of water in ultra-thin vapor chamber: A molecular dynamics study

The interfacial interaction between water (H2O) molecules and hot/cold surface is of crucial importance to enhance thermal energy transport in ultra-thin vapor chamber. In this regard, a typical case focusing on the rapid boiling of liquid H2O film on hot surface (900 K) and subsequent cooling of vapor H2O molecules on cold surface (300 K) is carried out firstly, by tracking the spatiotemporal motion of H2O molecules and investigating the associated thermal energy transport. The potential energy of H2O molecules plays a dominant role in conveying thermal energy from the hot surface to the cold surface. Moreover, the impacts of hot surface temperature and surface wettability are studied. It is found that the higher degree of heating at the hot surface above 900 K is detrimental to the overall performance of thermal energy transport. The combination of hydrophilic hot surface and hydrophilic cold surface brings the highest performance of thermal energy transport than the other three combinations (hydrophilic hot surface and hydrophobic cold surface, hydrophobic hot surface and hydrophilic cold surface, hydrophobic hot surface and hydrophobic cold surface). The present work provides atomistic insights into the rapid boiling and subsequent cooling related interfacial interaction between H2O molecules and hot/cold surface, as well as the impacts of surface heating and wettability, which are informative to the design of ultra-thin vapor chamber in thermal management.

Thermal Investigations of Hemispherical Shell Vapor Chamber Heat Sink

In the current study, a hemispherical shell vapor chamber (HSVC) was proposed and manufactured. A unique system of the HSVC consists of a very short evaporator space and a large condenser area with an inner and outer surface. The HSVC has a bottom surface that can be easily attached to the heat source and its radius varies from 0.045 m (near the bottom surface) to 0.078 m at the top with a curved side. An entirely new design of the integrated section of the large condenser with the evaporator section was verified using a new but simple concept. The current hemispherical shell vapor chamber (HSVC) was made from stainless steel. The current HSVC was specified with an outer/inner diameter of 78/70 mm at the top, a depth of 47 mm in the inner surface area, a total height of 60 mm, 30 mm at the bottom of the inner center, and a diameter of 45 mm on the surface of the outer bottom area. Three different models were manufactured and tested to verify which HSVC reached a high thermal performance. The effects of various operation parameters such as the filled volume ratio, heat load, coolant flow velocity, orientation, and so forth, were investigated experimentally. The experimental results showed that the optimum charge amount in terms of temperature difference is 20–30% of the charging ratio, and the condenser area has a direct effect on the thermal performance. Moreover, a one-dimensional thermal resistance model was tested to predict and simulate the thermal performance of the current system associated with various empirical correlations. Furthermore, the CFD (Computational Fluid Dynamics) model can simulate a lot of detailed flow behavior inside the HSVC. Both simulation methods can predict the thermal performance of the HSVC, and they can help to design the system with a focus on the optimum configuration of the design target for any application.

A novel composite vapor chamber for battery thermal management system

With the worsening problem of environmental pollution, the electric vehicles are becoming relevant more than ever before. The battery thermal management system (BTMS) is the key to ensure safety of the electric vehicles (EV). A novel composite vapor chamber (NCVC) is proposed in this paper which can cool and preheat the battery pack. The NCVC consists of a vapor chamber and five heat pipes, which not only has good thermal conductivity, but also has excellent temperature uniformity. The heat transfer resistance of the NCVC is analyzed in this study, while the cooling and preheating performance is experimentally verified. The results of the cooling performance test show that the NCVC can be started in about 240 s, and the minimum thermal resistance is 0.0355 °C/W. The preheating performance experiment shows that the NCVC can raise the battery cell temperature to 20 °C in about 275 s. In this paper, the thermodynamic simulation of the battery pack with the NCVC is also carried out. The simulation results of the two scenarios show that the NCVC can operate normally under a certain range of temperature. The NCVC proposed in this paper can provide a new solution for the BTMS.