Water-cooled Plate Research Articles

Experimental Study on the Impact of Lubricant on the Performance of Gravity-Assisted Separated Heat Pipe

Gravity-assisted separation heat pipes (GSHPs) are extensively utilized in telecommunications base stations and data centers. To ensure year-round cooling, integrating GSHPs directly with a vapor compression refrigeration system is a viable solution. It is unavoidable that the refrigeration system’s lubricant will infiltrate the heat pipe loop, thereby affecting its thermal performance. This paper examines the performance of a GSHP, which features a water-cooled plate heat exchanger as the condenser and a finned-tube heat exchanger as the evaporator, when the working fluid (R134a) is contaminated with a lubricant (POE, Emkarate RL-46H). The findings are compared with those from a system free of lubricant. The experimental outcomes indicate that the presence of lubricant degrades the heat transfer efficiency, particularly when the filling ratio is adequate and no significant superheat is observed at the evaporator’s outlet. This results in a 3.86% increase in heat transfer resistance. When the charge of the working fluid is suboptimal, the average heat transfer resistance remains relatively constant at a 3% lubricant concentration yet increases to approximately 5.27% at a 4–6% lubricant concentration, and further to 12.32% at a 9% lubricant concentration. Concurrently, as the lubricant concentration fluctuates between 3% and 9%, the oil circulation ratio (OCR) varies from 0.02% to 0.11%.

Structural optimization of serpentine channel water-cooled plate for lithium-ion battery modules based on multi-objective Bayesian optimization algorithm

Maintaining the battery within its optimal operating temperature range while preventing thermal runaway is crucial. Serpentine channel water-cooled plate (SCWCP) has been widely employed in battery pack cooling. The challenge lies in enhancing the cooling efficiency of SCWCP while minimizing energy consumption. Due to the high efficiency and robustness of the multi-objective Bayesian optimization (MOBO), it is employed to systematically optimize the SCWCP for lithium batteries. The width, depth, and turning radius of the serpentine flow channels are optimized to minimize both the maximum battery module temperature (Tmax) and the pumping power (PP) of the SCWCP. The MOBO process integrates structural parameter adjustments into Computational Fluid Dynamics (CFD) simulations through an automated iterative approach. Subsequently, a Pareto front is generated based on Tmax and PP, and the K-means clustering algorithm identifies four design solutions with different performance orientations. Compared with the initial design, Tmax of the optimal design decreases slightly, but with a reduction in PP of 71 %. Compared to other evolutionary algorithms, the MOBO algorithm exhibits superior computational efficiency in providing an optimal design solution set at a lower computational cost.

Investigation on the Influence of the Condenser Length and Its Coupling Effect With Elevation on the Performance of Loop Heat Pipe

Abstract The effects of condenser length and evaporator/condenser elevation on the performance of a loop heat pipe (LHP) in a gravity field were investigated, respectively, as well as their coupling effect. The refrigerant R40 was selected, and the condenser length was altered by changing the number of fins connected to the water-cooled plates. The experiments were conducted at three evaporator/condenser elevations: zero elevation, favorable elevation, and adverse elevation. The experimental results indicated that the evaporator temperatures of LHP with three different condenser lengths are very close when the LHP operates in variable conductance mode (VCM). However, an excessively long condenser will increase the LHP thermal resistance in VCM. In constant conductance mode (CCM), the longer the condenser, the lower the evaporator temperature. As the heat load increases, the LHP first exhibits gravity-driven mode and then capillarity-gravity-driven mode at a favorable elevation. The positive coupling effect on reducing the evaporator temperature by extending the condenser length and running at a favorable elevation manifests that the influence of condenser length is very small in gravity-driven mode, while in capillarity-gravity-driven mode, the effect of operating at a favorable elevation gets weakened, and the positive effects of the two factors cannot be simply calculated by the linear superposition principle. Additionally, reverse flow and flash evaporation were also observed and analyzed in depth. These results and conclusions can be used to guide the design of the condenser and the installation of LHP for ground applications.

Ultra-thin vapour chamber based heat dissipation technology for lithium-ion battery

A powerful thermal management scheme is the key to realizing the extremely fast charging of battery electric vehicles. In this scheme, a water-cooled plate is set at the bottom of the battery modules, which has a remarkable heat dissipation ability but increases the temperature difference between the top and bottom of the battery. This temperature difference problem is more obvious during the high-rate charge/discharge process; in particular, in the area of battery tabs, which are usually located far from the cooling plate, heat accumulates, risking thermal runaway. To address this problem, a thermal management method based on an ultrathin vapour chamber (UTVC) is proposed in this paper to improve temperature uniformity and reduce the highest temperature of batteries. According to the number of applied UTVCs, a unilateral UTVC (U-UTVC) and a bilateral UTVC (B-UTVC) cooling approach were presented, the effectiveness of which was verified by a set of thermal performance experiments. The test data show that the temperature differences in the batteries under the U-UTVC and B-UTVC schemes are 39.77% and 73.54% lower than those under the traditional method at a 25 °C ambient temperature and a 1.39C charge rate, respectively. The temperature difference on the battery surface with the B-UTVC scheme is approximately 3 °C at 25 °C and 40 °C ambient temperature.

The influence of feedback and convection on imposed heating conditions when using gas-fired radiant panels in fire testing

Gas-fired radiant panel arrays (RPAs) are a common experimental tool used in fire science and material testing. Unlike devices such as Cone Calorimeter or the Fire Propagation Apparatus (FPA), RPAs typically consume gaseous fuel within a porous medium through which fuel is burnt. When RPAs are used, thermal feedback from the surface of heated samples, as well as the effects of hot gases within the zone of convective influence of the RPA will cause an increase in the surface temperature of the RPA. To investigate this, experiments were conducted using a gas-fired RPA. Target samples made from vermiculite board, concrete, and a water-cooled aluminium plate were exposed to various severities of pre-calibrated incident radiant heat fluxes (HF). It was confirmed that the presence of a target sample led to an increased surface temperature for the RPA of nearly 80 °C (for a calibrated incident HF of 144 kW/m2). This increased surface temperature results in an incident HF nearly 78% higher than the pre-calibrated value at the sample's surface. Based on the results in this paper, a correction method has been proposed which can be used by gas-fired RPA users to account for the increase in incident heat fluxes.

Performance Evaluation and Optimization of Series Flow Channel Water-Cooled Plate for IGBT Modules

The stability in the operation of insulated gate bipolar transistor (IGBT) modules plays a crucial role in wind power generation. It is essential to improve the thermal performance of the heat sink of IGBT modules in wind power converters and reduce the power consumption of liquid cooling systems, in order to optimize the heat dissipation of IGBT modules in wind power converters. In this paper, a simulation model of the liquid-cooled heat sink of the IGBT module is established and the performance of three different series flow channel structures is compared by computational fluid dynamics (CFD). Moreover, based on the orthogonal test design, the three factors (channel width, channel height, and cold plate wall thickness) affecting the performance of the water-cooled plate were ranked and optimized. The results show that the water-cooled plate with double-helical-type flow channel structure has the best comprehensive performance. In addition, for the double-helical-type structure, the optimal combination of channel structure parameters about channel width, channel height, and cold plate wall thickness is obtained. After optimization, the maximum IGBT temperature, thermal resistance, and pressure drop of the cold plate are reduced by 3.13%, 5.78%, and 18.87%, respectively, compared with the double-S structure in parameter case one. The proposed methods and results are expected to provide theoretical guidance for the thermal management of IGBT modules in wind power converters.

Suppressing the Eddy Current Damping of the Permanent Magnet Linear Synchronous Motor by Setting the Toothed Cooling Plate

To enhance the linear motor thrust density, scholars have focused extensively on cooling systems. Conventional cooling plates induce eddy current damping in the time-varing magnetic field, decreasing the dynamic characteristics of the motor. Therefore, a toothed cooling plate is proposed, which effectively reduces the metal water-cooled plate’s eddy current damping and has good heat dissipation capacity. The layered model is used to determine the damping of the cooling plate covered on the armature, and the factors affecting the damping are concluded. Eddy currents on the cooling plate are vectorized in this structure via laser cutting. On the basis of the model, a scheme with a secant spacing of 1/3 pole pitch is chosen, then a comparison of three different structural types follows. The variation characteristics of their damping are described in detail. Finally, the thermal network model analysis and the temperature rise experiment are conducted to summarize the heat dissipation characteristics of the toothed cooling structure.

Cooling System Design and Thermal Analysis of Modular Stator Hybrid Excitation Synchronous Motor

Hybrid excitation synchronous motor has the advantages of uniform and adjustable electromagnetic field, wide speed range and high power density. It has broad application prospects in new energy electric vehicles, wind power generation and other fields. This paper introduces the basic structure of hybrid excitation motor with modular stator, and analyzes the operation principle of hybrid excitation motor. The cooling structure of the water-cooled plate is designed, and the effects of the thickness of the water-cooled plate and the number of water channels in the water-cooled plate on the heat dissipation capacity of the water-cooled plate are analyzed by theoretical and computational fluid dynamics methods. The effects of different water cooling plate structures on water velocity, pressure drop, water pump power consumption and heat dissipation capacity were compared and analyzed. The influence of different inlet flow velocity on the maximum temperature rise of each part of the motor is analyzed, and the temperature of each part of the motor under the optimal water flow is analyzed. The influence of the traditional spiral water jacket cooling structure and the water-cooled plate cooling structure on the maximum temperature rise of the motor components is compared and analyzed. The results show that the water-cooled plate cooling structure is more suitable for the modular stator motor studied in this paper. Based on the water-cooled plate cooling structure, the air-water composite cooling structure is designed, and the effects of the air-water composite cooling structure and the water-cooled plate cooling structure on the maximum temperature rise of each component of the motor are compared and analyzed. The results show that the maximum temperature rise of each component of the motor is reduced under the air-water composite cooling structure.

Combined particle image velocimetry and thermometry of turbulent superstructures in thermal convection

Turbulent superstructures in horizontally extended three-dimensional Rayleigh–Bénard convection flows are investigated in controlled laboratory experiments in water at Prandtl number ${Pr}=7$ . A Rayleigh–Bénard cell with square cross-section, aspect ratio $\varGamma =l/h=25$ , side length $l$ and height $h$ is used. Three different Rayleigh numbers in the range $10^{5} < {Ra} < 10^{6}$ are considered. The cell is accessible optically, such that thermochromic liquid crystals can be seeded as tracer particles to monitor simultaneously temperature and velocity fields in a large section of the horizontal mid-plane for long time periods of up to 6 h, corresponding to approximately $10^{4}$ convective free-fall time units. The joint application of stereoscopic particle image velocimetry and thermometry opens the possibility to assess the local convective heat flux fields in the bulk of the convection cell and thus to analyse the characteristic large-scale transport patterns in the flow. A direct comparison with existing direct numerical simulation data in the same parameter range of $Pr$ , ${Ra}$ and $\varGamma$ reveals the same superstructure patterns and global turbulent heat transfer scaling ${Nu}({Ra})$ . Slight quantitative differences can be traced back to violations of the isothermal boundary condition at the extended water-cooled glass plate at the top. The characteristic scales of the patterns fall into the same size range, but are systematically larger. It is confirmed experimentally that the superstructure patterns are an important backbone of the heat transfer. The present experiments enable, furthermore, the study of the gradual evolution of the large-scale patterns in time, which is challenging in simulations of large-aspect-ratio turbulent convection.

Study on the Effect of Spoiler Columns on the Heat Dissipation Performance of S-Type Runner Water-Cooling Plates

To solve the problem of low heat dissipation efficiency for the conventional S-type runner water-cooling plate of the fan converter IGBT module, two new water-cooling plates were designed with rectangular and elliptical column structures in the S-shaped runner of the water-cooling plate. The heat dissipation performance, the fluidity of cooling water, and pressure drop of different spoiler column structures were compared using Fluent software for the simulation and experiment. The comparative results show, compared with the water-cooling plate without a spoiler column in the flow channel of the control group, that the spoiler column structure in the flow channel significantly improved the heat dissipation performance of the water-cooling plate. When the inlet velocity of the water-cooling plate was 2 m/s, the highest temperature inside the water-cooling plate with a rectangular spoiler column structure was 12.25 °C, lower than the control water-cooling plate. The highest temperature inside the water-cooled plate with an elliptical structure was 12.40 °C, lower than the control water-cooled plate. The obstructive effect of the elliptical spoiler column structure on water flow was smaller than in the rectangular spoiler column structure. The fluidity of the cooling water inside the elliptical spoiler column structure water-cooling plate was better. When the inlet velocity of the water-cooling plate was 2 m/s, the cooling water flowing through the former was 282 L more than the latter in half an hour. Compared to the pressure drop, we found that in the design group, the pressure drop of the water-cooled plate with a rectangular spoiler column structure was 40,988.3 Pa. The pressure drop of the water-cooled plate with an elliptical spoiler column structure was 25,576.6 Pa. The difference between the two was 15,411.7 Pa, which proves that the energy loss inside the latter is smaller. To further explore the relationship between the heat dissipation and energy consumption of the two types of water-cooled plates, the comprehensive evaluation index η was calculated, ηb = 26.2, ηc = 31.6; therefore, ηb was significantly smaller than ηc. The overall performance of the water-cooled plate with an elliptical spoiler column structure was superior.

Effects of directional solidification on hardness and microstructure in Al–3wt.%Cu–1wt.%Li alloy

Solidification is probably one of most important phase transformations in materials manufacturing. Additionally, a wide range of solidification microstructural features is obtained depending on processing parameters. Mechanical properties of the cast are influenced by the microstructure obtained after solidification. The aim of this work is to investigate how solidification conditions affect solidification and the resulting microstructure of the Al– 3wt.%Cu–1wt.%Li (ternary system) alloy. The alloy was solidified unidirectionally upward through a water-cooled steel plate. Results include secondary dendritic arm spacing (SDAS), hardness and microstructure analysis using optical microscopy. Results showed that SDAS values tended to increase as the distance from the heat-exchange surface increased (P). Conversely, hardness decreases as P increased.

Numerical study of thermal stress of a silicon mirror forming a beam of synchrotron radiation

Numerical simulation of heat transfer in a mirror for focusing a synchrotron radiation beam and its thermally stressed state has been carried out. The choice of the method for cooling the mirror through contact with the water-cooled plates, which provides the specified limitations on thermal deformation, has been substantiated. The modes of heat transfer, implemented under different conditions of heat transfer at the boundary of the mirror with water-cooled plates, are compared.

Modeling Laminar-to-Turbulent Transition in the Panel Test Facility Arcjet

A computational fluid dynamics (CFD) laminar-to-turbulence transition model was developed for the NASA Ames Research Center’s 20 MW Panel Test Facility (PTF). Surface pressure, heat flux to a water-cooled plate, and surface temperature on a tile plate coated with reaction-cured glass were measured across several conditions in the facility and compared with laminar and fully turbulent CFD simulations. The potential for bypass transition in the PTF nozzle was assessed via application of the Langtry–Menter four-equation transitional shear-stress transport (SST) model. Results from the transition model were inconsistent with measurements. Flow interaction with a boundary-conditioning plate feature inside the nozzle was also investigated as a potential source of laminar-to-turbulent transition, using two turbulence models with specified transition locations. The Baldwin–Lomax turbulence model was configured to simulate a transition at the upstream edge of the boundary conditioning plate and produced results consistent with the surface pressure measurements, but not the cold-wall heat flux. Finally, the SST turbulence model was calibrated to transition at the upstream edge of the boundary conditioning plate and produced results consistent with both the surface pressure and cold-wall heat flux measurements. The SST-based model demonstrated reasonable agreement with surface temperature measurements on the reaction-cured glass tile, albeit with some discrepancies.

A thermoelectric generator and water-cooling assisted high conversion efficiency polycrystalline silicon photovoltaic system

Solar energy has been increasing its share in the global energy structure. However, the thermal radiation brought by sunlight will attenuate the efficiency of solar cells. To reduce the temperature of the photovoltaic (PV) cell and improve the utilization efficiency of solar energy, a hybrid system composed of the PV cell, a thermoelectric generator (TEG), and a water-cooled plate (WCP) was manufactured. The WCP cannot only cool the PV cell, but also effectively generate additional electric energy with the TEG using the waste heat of the PV cell. The changes in the efficiency and power density of the hybrid system were obtained by real time monitoring. The thermal and electrical tests were performed at different irradiations and the same experiment temperature of 22°C. At a light intensity of 1000 W/m2, the steady-state temperature of the PV cell decreases from 86.8°C to 54.1°C, and the overall efficiency increases from 15.6% to 21.1%. At a light intensity of 800 W/m2, the steady-state temperature of the PV cell decreases from 70°C to 45.8°C, and the overall efficiency increases from 9.28% to 12.59%. At a light intensity of 400 W/m2, the steady-state temperature of the PV cell decreases from 38.5°C to 31.5°C, and the overall efficiency is approximately 3.8%, basically remain unchanged.

Development and Analysis of a Modular LED Array Light Source

Light emitting diodes (LEDs) have experienced rapid technological development in the past decade, making them a winning alternative to conventional light sources in many applications. LED arrays allow precise control of the desired irradiance profile in a target area by adjusting the position and output power of individual LEDs. However, despite increased efficiency, many LEDs still transform a large proportion of the input electrical power into heat, requiring an efficient cooling system. This paper presents a modular LED array light source mounted on a water-cooled aluminum plate. Novel electronic LED driver modules, connected via a serial communication bus in a daisy-chain topology, were developed with the ability to set the operating current of individual LEDs. A modular layout of cooling and mounting system and LED driver modules, as well as a specialized design for the LED soldering footprint, was able to house a variety of common commercial LEDs, enabling easy adjustment of the lighting system to the required application and size of the irradiated area. In a prototype of one plate containing 10 LEDs, individual LED radiance was optimized for a better irradiance homogeneity in the target area. Array characterization showed a low standard deviation of the irradiance of 1.8% and a good fit between measured and calculated irradiance. A test of the array at elevated temperatures showed moderate LED radiance degradation and a wavelength shift of the measured spectra after extended use.

The study of the destruction of heat-resistant chamotte concrete during its sharp heating and cooling

The article investigates the destruction of heat-resistant chamotte concrete of various classes: low-cement and medium-cement with the addition of quartz sand (to increase alkaline resistance) and with the addition of metal fiber (to reduce cracking) after exposure to thermal shock. Two methods for determining the heat resistance of concrete were used, in which the destruction of the material was evaluated using ultrasound using the method of a water-cooled plate and the method of one-sided heating-cooling. Studies conducted using the method of unilateral heating-cooling, revealed the formation of macrocracks in samples of low cement concrete. This method turned out to be more sensitive when evaluating concrete destruction.

Study on the Destruction of Heat-Resistant Chamotte Concrete During Sharp Heating and Cooling

This study investigates the destruction of heat-resistant chamotte concrete of various classes: low-cement and medium-cement after exposure to thermal shocks. The influences of the addition of quartz sand (to increase alkaline resistance) and the addition of metal fiber (to reduce cracking) were also studied. Two methods were used to determine the heat resistance of concrete, according to the material destruction: a water-cooled plate method based on ultrasound and a method of unilateral heating-cooling. The results obtained via the method of unilateral heating-cooling revealed the formation of macrocracks in samples of low-cement concrete. This method was found to be more sensitive for evaluating concrete destruction.

Method for obtaining junction temperature of power semiconductor devices combining computational fluid dynamics and thermal network

Keeping the highest junction temperature of Insulated Gate Bipolar Transistor (IGBT) modules below the critical temperature is the key to ensuring the stability and reliability of power supplies in accelerator facilities. However, the existing junction temperature extraction methods are not suitable for liquid cooling IGBTs and can be improved in terms of speed and accuracy. In order to investigate the junction temperature of IGBT modules and the characteristics of their water-cooled plates, an electro-thermal model combining the thermal network method and the computational fluid dynamics analysis is proposed. Because the power loss is corrected by the double-pulse test, and the thermal resistance of the cold plate is improved by computational fluid dynamics simulation, the accuracy of the model is improved. The thermal network method guarantees that the model is fast and can be easily applied to various operating conditions. The method is used to analyze the performance of two cold plates, select the cooling conditions, and further increase the switching frequency on the premise of ensuring the reliability of the IGBT module. The accuracy of the method has verified by experimental results, and the applicable conditions and the estimated junction temperature error are also analyzed.

Conceptual Design of the Power Supply for Magnetic Island Divertor Configuration on J-TEXT

The ac power supply system of the magnetic island divertor coil is widely applied to reduce the peak thermal load of the boundary target plate. It was found that this system should have the current frequency in the range of 0-100 Hz and the amplitude of 5 kA at 100 Hz. In this article, a new main circuit is proposed for the variable-frequency power supply system. The proposed circuit consists of a six-pulse, thyristor rectifier and a parallel, H-bridge inverter. The control strategy applies the carrier phase-shifted, sinusoidal pulsewidth modulation (CPS-SPWM) to form an almost sinusoidal current and calculate the LC filter parameters of the bus and inverter. Based on the requirements and load parameters of the power supply, it is found that the voltage and current double-closed loop PI control accelerates the system dynamic response and improves the nonlinear, load adaptability of the system. Moreover, the phase-shifting transformer with high-overload capability is applied in the proposed power supply to reduce the volume of the transformer and in advance charging. On the other hand, the water-cooling mode is adopted and the structure of water-cooled plate is designed. Moreover, optimal device and layout selection is performed to achieve reasonable modularization. Finally, the proposed method is applied to complete the main components of the space layout of the power supply. In the studied cases, the power density of 0.42 W/L is obtained.

Temperature Field Calculation and Water-Cooling Structure Design of Coreless Permanent Magnet Synchronous Linear Motor

In this article, a water-cooled structure with water-cooled plates between the primary double-layer windings field of the primary structure under short-term high overload conditions and periodic operations is calculated. Second, the heat dissipation effects of two different waterway topologies are designed and compared. Based on the thermal network analysis model and multiphysical field coupling model, the heat dissipation effect of the water-cooled motor is obtained. In order to obtain the maximum sustainable working current that the motor can withstand under water-cooled conditions, a fast calculation model-response surface model-is established and the electromagnetic performance of the water-cooled motor is obtained. The analysis results show that the temperature rise of the water-cooled motor decreases greatly, and the average thrust increases by 2.73 times. Finally, the calculated and tested results of the prototype are compared and analyzed.