Maximum Temperature Drop Research Articles

Design of radiative cooling covers for automobiles with maximized cooling power

Due to the capability of cooling objects without energy consumption by emitting thermal radiation into outer space, radiative cooling technologies have found broad applications in different scenarios. Despite the high demand for cooling automobiles under sunlight, there is no specialized design of a radiative cooling cover for automobiles. This paper demonstrates the first specialized radiative cooling cover for automobiles. As the overall cooling power is linearly proportional to the surface area, we designed a conch-shaped foldable radiative cooling film car cover to maximize the surface area within a limited space, resulting in a total cooling power of 5,726.8 W. As a result, the maximum temperature drop can reach 27 °C under strong solar irradiance (800 Wm−2). In addition, we further demonstrate the effects of the surface coverage on the cooling performance by measuring the temperature drop at different surface coverages (100 %, 90 %, 40 %, and 10 %). It is found that the radiative cooling cover can effectively cool the inner temperature of a car even with a small surface coverage. In addition, it confirms that enlarging surface area is an effective way to improve cooling performance. Our results open new possibilities in designing radiative cooling covers that can achieve large cooling power within a limited footprint. The design principle can be extended and generally applied to other radiative cooling devices for various applications.

Al2O3/graphene/PVDF‐HFP radiative cooling coating reinforced heat dissipation of BIPV modules

AbstractBuilding integrated photovoltaic modules, applied to industrial and commercial buildings, generally used metal as the backsheet. In summer, the operating temperature of modules is as high as 70°C, resulting in instability of output power and service life. Therefore, it is very important to reduce the operating temperature of photovoltaic modules. In this work, Al2O3/graphene/poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) composite radiative cooling coatings were prepared and utilized for reinforcing heat dissipation of photovoltaic modules. The results indicate that 0.75 wt%Al2O3/1wt%graphene/PVDF‐HFP composite coating exhibited a thermal diffusivity of 3.24 μm2/s and an average emissivity of 0.94. The maximum temperature drop of the coating in the outer door reached 5.8°C. In addition, a mini photovoltaic module coated with the composite coating achieved the cooling effect of 2.4°C, and the output power and conversion efficiency were increased by 5.8% and 7%, respectively. This demonstrates that the heat conduction radiative cooling coating possesses potential applications for improving the reliability of photovoltaic modules.

Nucleate boiling enhancement on hybrid graphene-nanoplatelets/carbon nanotubes coatings for light-emitting diode cooling

This study explores the remarkable enhancement of light-emitting diode (LED) cooling through nucleate boiling using hybrid coatings of graphene-nanoplatelets (GNP) and carbon nanotubes (CNT). The introduction of oxygenated functional groups in the cured GNP and CNT coatings fosters improved hydrophilicity, promoting water intercalation within the nanostructures. The hybrid cured GNP/CNT coating demonstrates superior nucleate boiling performance compared to individual cured GNP and CNT coatings, owing to complementary mechanisms. Cured CNT facilitate efficient water permeation by enabling water molecules to infiltrate through their inner cores and intertwining tube spaces, while cured GNP offer an escape route for trapped water molecules and absorbed latent heat due to their layer-by-layer arrangement of graphene sheets with broadened interlayers. As compared to the bare copper surface, the LED cooled using the hybrid cured GNP/CNT coating exhibits a maximum temperature drop of 20.7 °C and an enhancement up to 1212 % in heat transfer coefficient, surpassing the cured GNP and CNT coatings. Moreover, the hybrid cured GNP/CNT coating improves the LED illuminance by 16.6 %, validating its potency in improving cooling performance. These findings highlight the potential of GNP/CNT hybrid coatings in advancing nucleate boiling cooling technologies and offer valuable insights into optimizing LED performance for high-quality lighting solutions.

Experiment for the performance of a thin membrane inclined automatic wicking dew-point evaporative cooling device based on simulation results

The traditional indirect evaporative coolers necessitate a continuous operation of water pumps to ensure the wetting of wet channel walls. However, excessive water spraying can lead to a thickened water film, negatively impacting heat transfer efficiency and generating an additional pressure drop. Identifying suitable water supply strategies and exploring materials for the wet channel that possess good moisture retention and evaporation characteristics has drawn research attention over the years.In this study, an automatic wicking dew-point evaporative cooling device, whose structure was determined by corresponding optimal performance simulation research, was designed and manufactured. The thin film exhibits a certain inclination angle between the dry and wet channels to form a triangular channel to enhance support and increase heat transfer area. Utilizing the automatic water absorption characteristics of the membrane for water supply instead of spraying, makes the water more uniform and heat exchange more efficient. A comprehensive study was conducted on the effects of different operating parameters (working-to-intake air ratio, intake air velocity, water temperature, intake air temperature, and intake air humidity) on the performance of the device. The results indicate that the cooler performs best in high-temperature, low-humidity environments. When the inlet temperature, humidity, and velocity are within the range of 25–45 °C, 20–80 %, and 0.5–2.5 m/s, respectively, with a water temperature of 22 °C and an air-to-water flow rate ratio of 0.5, the maximum temperature drop can reach 14.8 °C, and the cooling capacity per unit area ranges from 13 to 150 W/m2. The wet-bulb efficiency and dew-point efficiency increased from 52.4 % and 33.6 % to 110.6 % and 88.5 %, respectively. When the air velocity increases from 0.5 m/s to 2.5 m/s, the product air temperature increases by 3.1 °C, and the wet-bulb efficiency and dew-point efficiency decrease by 25.1 % and 17.5 %, respectively. However, the variation trends of unit area cooling capacity and energy efficiency ratio (EER) are opposite. The optimal operating conditions are proposed with an air volume ratio of 0.5 and a water temperature range of 22–26 °C. Finally, the temperatures of the product air and water were observed during long-term operation testing to evaluate the stability of the device.

Optimization of airflow organization in fan-wall data center via baffles

The utilization of natural fresh air for cooling server rooms in fan-wall data centers effectively reduces the operational duration of air conditioning, resulting in enhanced energy efficiency. Nonetheless, there are few researches available on the optimization of airflow organization in fan-wall data centers. In this study, baffles are installed at the inlet of racks to achieve uniform airflow distribution. The thermal performance of rack is investigated with respect to the influence of the arrangement direction, width, angle size, and angle direction of baffles. The results reveal that: (1) The heat distribution in the racks near the air inlet is uneven, with heat accumulating in the middle and lower parts, leading to significant fluctuations in inlet temperature. (2) Placing baffles vertically on both sides of racks inlet can effectively improve the thermal distribution within the rack in fan-wall data center. (3) The optimal working condition is achieved when baffles are arranged on both sides of the rack inlet, with a width of 7 cm and an angle of 15°, and the angle direction is the same as the airflow direction. This effectively mitigate hotspots within the rack, with the maximum temperature drop within the rack hotspot reaching approximately 13.66 °C.

Diatomite-Based Recyclable and Green Coating for Efficient Radiative Cooling.

Radiative cooling is a promising strategy to address energy challenges arising from global warming. Nevertheless, integrating optimal cooling performance with commercial applications is a considerable challenge. Here, we demonstrate a scalable and straightforward approach for fabricating green radiative cooling coating consisting of methyl cellulose matrix-random diatomites with water as a solvent. Because of the efficient scattering of the porous morphology of diatomite and the inherent absorption properties of both diatomite and cellulose, the aqueous coating exhibits an excellent solar reflectance of 94% in the range of 0.25-2.5 μm and a thermal emissivity of 0.9 in the range of 8-14 µm. During exposure to direct sunlight at noon, the obtained coating achieved a maximum subambient temperature drop of 6.1 °C on sunny days and 2.5 °C on cloudy days. Furthermore, diatomite is a naturally sourced material that requires minimal pre-processing, and our coatings can be prepared free from harmful organic compounds. Combined with cost-effectiveness and environmental friendliness, it offers a viable path for the commercial application of radiative cooling.

Lithium-ion battery thermal management system using MWCNT-based nanofluid flowing through parallel distributed channels: An experimental investigation

In the present research, a newly designed liquid-based battery thermal management system (BTMS) for lithium-ion batteries (LIBs) is developed and its thermal performance at different discharge rates (C-rates) is experimentally examined. The influence of various performance parameters such as the number of channels, flow configurations, working fluids, and C-rates on the cooling performance of the proposed BTMS is evaluated. Pure water, binary fluid (70 % water + 30 % ethylene glycol (EG)), and multi-walled carbon nanotubes (MWCNTs)-based nanofluids at different volume fractions (ϕv) (0.15 %, 0.30 %, and 0.45 %) in the binary fluid are used in this study and their cooling effectiveness to keep battery temperature within ideal ranges is compared. The experiments are performed at 0.5C, 1.2C, and 2.1C rates and it is discovered that nanofluids provide superior cooling performance compared to water and binary fluid mixture. Results demonstrate that the cooling performance is enhanced with the number of channels, nanoparticle concentration, and flow configurations. Nanofluid with 0.45 % ϕv of MWCNTs shows the maximum drop in battery temperature which is about 8.7 °C for configuration I, 11.8 °C for configuration II, and 17.1 °C for configuration III, respectively. Among all the flow configurations, configuration III gives the best cooling effectiveness and lowers the average temperature of cells by 10–17.01 °C using different working fluids. Configuration III also enhances the battery temperature uniformity and maintains the maximum temperature deviation within the battery module (∆Tmax) inside 1.5–2.4 °C for different working fluids at a 2.1C rate, which is well below 5 °C, and hence it helps to prevent the thermal runaway (TR) condition. Additionally, nanofluid with 0.45 % ϕv increases pressure drop (Δp) by 23.98 % and 17.91 % compared to water for single and dual channel arrangements, respectively.

Performance investigation of a liquid immersion cooling system with fish-shaped bionic structure for Lithium-ion battery pack

A battery thermal management system (BTMS) is crucial for the safety and performance of lithium-ion batteries (LIBs) in electric vehicles. To improve the BTMS in terms of cooling performance and pumping cost, an innovative liquid immersion battery cooling system (LIBCS) using flow guides with fish-shaped holes is proposed. The design of this flow guide is grounded in conformal mapping technology and bionics principles. An electrochemical-thermal model for the battery module is established by the Multi-Scale Multi-Domain approach with the Newman, Tiedemann, Gu, and Kim model. The simulation and experimental results show good agreement, with mean absolute errors of 0.0174 V, 0.126 °C, and 0.042 Pa for LIB voltage, maximum temperature, and average pressure drop, respectively. Furthermore, the effects of four different battery pack structures on the performance of LIBCSs under different operating conditions are investigated. For LIBs at a 3C discharge rate, the LIBCS using common flow guides decreases the maximum LIB temperature by 5.3 % at a mass flow rate of 0.00273 kg/s compared to the without flow guide case, but it increases the pump power consumption by 81.4 %. However, using flow guides with circular holes or fish-shaped holes reduces the maximum LIB temperature by 9.2 % and 12.2 %, respectively, compared to LIBCS using common flow guides, while maintaining maximum temperature differences within 5 °C. Interestingly, the LIBCS using flow guides with fish-shaped holes reduces the pump power consumption by 42.1 % and 11.8 %, respectively, compared to the common flow guide and flow guide with circular holes cases under the same operating conditions. Additionally, the comprehensive performance factor of LIBCS using flow guides with fish-shaped holes improves by 24 %, 39.3 % and 7.3 % at a mass flow rate of 0.00273 kg/s, respectively, compared to cases using no flow guide, common flow guides and flow guides with circular holes, indicating greater value for application in practical engineering.

Performance of adjustable multilayer film based on radiation cooling and electrochromism

Energy and environmental challenges caused by the excessive consumption of fossil fuels are major concerns worldwide, and the use of automotive air conditioning can increase total fuel consumption by 10% to 30%, thereby exacerbating these problems. To reduce the energy consumption for automotive air conditioning, a multilayer-film design based on radiative cooling and electrochromic modulation is proposed for regulating the temperature inside vehicles. The designed multilayer-film not only passively realizes temperature drop but also actively regulates the entry of solar radiation, which can help the vehicle air conditioning system to adjust the interior temperature autonomously. To verify its effectiveness, a film-applied empty box device is designed for radiometric temperature measurement. Experimental results indicate that the maximum interior temperature drop of the multilayer film increases by approximately 9.8 ℃ compared with that of single-layer films in the sunlight irradiation, and dynamic temperature regulation of about 4.6 ℃ can be achieved by adjusting the transmittance of the multilayer film. To study the environmental adaptability of the multilayer film, experiments are conducted on an outdoor film-applied device during the summer and winter in Shenyang, China (<inline-formula><tex-math id="Z-20241025175516">\begin{document}$\rm 41^\circ44'N, 123^\circ39'E$\end{document}</tex-math></inline-formula>), the place which is characterized by a typical temperate continental climate. Results indicate that under high temperature conditions of 30–40 ℃ in summer, the maximum internal temperature drop of the multilayer film reaches 12.9 ℃; while under low temperature conditions of 0–15 ℃ in autumn and winter, the maximum internal temperature drop is only 1.9 ℃, preventing the interior temperature from being too low. In addition, the maximum interior temperature drop increases with the solar radiation intensity and ambient temperature increasing. Therefore, the proposed multilayer-film design, with its potential for temperature self-regulation, provides a promising solution for reducing energy consumption and improving passenger comfort.

Evaluation of Phase Change Materials for Pre-Cooling of Supply Air into Air Conditioning Systems in Extremely Hot Climates

This research investigates the use of phase change materials (PCMs) in thermal energy storage (TES) unit-based cooling systems to increase the efficiency of air conditioners (ACs) by reducing the air inlet temperature. This study aims to evaluate different configurations of PCM enclosures, and different PCMs (paraffin and salt hydrate), by changing the speed of inlet air to achieve heat reduction of inlet air. The study includes experimental and simulation investigations. Every configuration simulates the hot-season atmospheric conditions of the UAE. A duct containing enclosures of paraffin RT-31 and salt hydrate (calcium chloride hexahydrate) was used for the simulation study using ANSYS/Fluent. A conjugate heat transfer model employing an enthalpy-based formulation is developed to predict the optimized PCM number of series and optimum airflow rate. Four designs of the AC duct were modelled and evaluated that contained one to four series of PCM containers subjected to different levels of supplied air velocities ranging from 1 m/s–4 m/s. The simulation study revealed that employing four series (Design 4) of PCM enclosures at a low air velocity of 1 m/s enhanced the pre-cooling performance and reduced the outlet air temperature to 33 °C, yielding a temperature drop up to 13 °C. The performance of salt hydrate (calcium chloride hexahydrate) was observed to be better than paraffin (RT-31) in terms of the cooling effect. Characterization of paraffin wax (RT-31) and salt hydrate was performed to establish the thermophysical properties. The experimental setup based on a duct with integrated PCM enclosures was studied. The experiment was repeated for three days as the repeatability test incorporating RT-31 as the PCM and a 3 °C maximum temperature drop was observed. The drop in the outlet air temperature of the duct system quantifies the cooling effect. Net heat reduction was around 16%.

Optimization of microchannel heat sink based on multi-objective particle swarm optimization algorithm for integrated circuit chips cooling

The microchannel heat sink is an effective way to solve the heat dissipation problem in integrated circuit chips. In order to obtain the high efficiency and low resistance microchannel heat sink, the three variables (△h, f, g) were selected as the design variables, and the thermal resistance and pumping power were selected as objective functions. Then, the RSM, multi-objective particle swarm optimization algorithm and K-means clustering method were comprehensively applied to the multi-objective optimization of the microchannel heat sink with turbulence to obtain the five representative solutions (Case A–Case E), and the results were verified by CFD. The research shows that the maximum relative errors between Pareto optimization values and numerical simulation values of thermal resistance and pumping power of the five groups representative solutions are 0.637% and 1.187%, respectively. The Pareto optimization values are in good agreement with the numerical simulation values, and there is an effective tradeoff point between the five representative solutions of the Pareto optimal solution to make both the pumping power and thermal resistance within the optimal range. Compared with before optimization and the research results of Han Wang et al. [Appl. Therm. Eng. 2022;215:118849], the comprehensive heat transfer performance of the optimized microchannel heat sink has been improved, where the comprehensive heat transfer performance of the Case B ( Δ h = 0.0400 mm, f = 0.0979 mm, g = 0.5000 mm) is the best. The maximum temperature and pressure drop of the optimized microchannel heat sink can be reduced by 3.045% and 7.659%, respectively. Compared with the research results of Han Wang et al. [Appl. Therm. Eng. 2022;215:118849], the temperature distribution more uniform and the pressure drop of the microchannel heat sink after optimization (Case B) decreased by 7.058%. This optimization method can provide a reference for the optimization design of the microchannel heat sink structure parameters for integrated circuit chips cooling.

Coupling effect of radiative cooling and phase change material on building wall thermal performance

Phase change material (PCM) featured with high latent heat thermal energy storage capacity and isothermal phase transition is employed into building walls decorated with radiative cooling (RC) coating, in order to modify the cooling effect on building thermal performance. Numerical analysis indicates that the RC coating causes exterior temperature of P-RC walls lower than ambient temperature, achieving maximum exterior temperature drop of 13.63 °C. Thermal buffer effect of PCM enables to shave the temperature peak and shift the temperature valley, inducing exterior temperature of the P-RC wall to fluctuate slightly in comparison to the RC wall. Interior temperature of the P-RC wall is found to approach to target temperature tightly. PCM located closer to the outside completes phase transition more rapidly, which is beneficial to levelling radiative cooling of RC coating. Exterior temperature of P-RC walls increases with augment of solar radiation intensity, ambient temperature and indoor temperature. Augment of PCM thickness, ambient temperature or indoor temperature is conducive to interior temperature. Latent heat thermal energy storage of PCM enlarges effective thermal capacity of walls, which is favorable to maintain interior temperature within target temperature. In conclusion, studied results highlight that radiation cooling can be improved by PCM, with substantial benefits to develop passive cooling available to building energy conservation.

Experimental and numerical study on liquid film cooling performance under heated wall condition

Liquid film cooling is broadly applied in the thermal protection of liquid rocket engine. An experimental system of liquid film cooling for a heated curved stainless-steel wall is built in this study to investigate the effects of jet mass flow rate, jet angle, and nozzle diameter on the cooling performance. The temperature distribution of the heated wall is demonstrated with infrared thermography technology and the flow spreading shape of the liquid film is captured with high-speed camera. A numerical liquid film cooling model based on the volume of fluid (VOF) coupled Level-set method is established to calculate the evaporative heat absorption and spreading shape of liquid film. The experimental study indicates that the peak film thickness in the hydraulic jump region increases with the jet mass flow rate, such as the peak film thickness increases from 265.15 to 632.25 μm at Q = 100–600 mL·min−1. Besides, a jet angle of 35 degree can maintain the maximum wall temperature drop of 29.4 °C. In addition, the simulated peak film thickness presents a minimum deviation of 5.2 % from the experimental data. The numerical model provides important reference for the study of liquid film cooling performance of the liquid rocket engine.

An experimental investigation on coalescing the potentiality of PCM, fins and water to achieve sturdy cooling effect on PV panels

Improving the efficiency of silicon photovoltaic (PV) panels is of utmost importance to achieve Sustainable Development Goal 7. The energy loss aided by the heat generation of PV panel is the leading cause of the degradation of PV panels' efficiency as well as its longevity. A novel cooling system with PCM, fins and still water is propounded in this research as a solution. The proposed configuration utilizes the latent heat of fusion of PCM and the latent heat of evaporation of water to achieve effective cooling in a passive approach. HS 29 PCM is chosen in context with the location and system thermal characteristics. The results highlight that the per day output of the proposed configuration is 8.12% and 9.39% higher than the PV panel without cooling for the observed two selected days respectively. The maximum power enhancement was 20.25% and on average 8.57% improvement is obtained relative to reference PV. The thermal characteristics revealed that the temperature of the cooled panel was below 50 °C while the PV panel without cooling reached about 73 °C. The average and maximum temperature drops are observed to be 10.14 °C and 16.7 °C respectively. The maximum enhancement in power conversion efficiency was 20.13% when compared to the uncooled PV panel. Furthermore, corrosion analysis and thermal stress assessment are performed to ensure the longevity of the system. The energy saving is scaled to a 1 MW large-scale PV system and the results show ∼367 MWh of annual energy savings and ∼ 2 ktoe of reduction in CO2 emissions. The inclusion of a cooling strategy significantly improves the performance of the PV panel and contributes further in attaining SDG 7.

High fidelity analysis and optimization of a quarter wavelength thermo-acoustically driven refrigerator

High fidelity CFD analysis is done to investigate the coupling of a thermoacoustic engine and refrigerator (TAE & TAR) within a straight tubular quarter-wavelength resonator under high pressure conditions. A parametric study aims to optimize TAE efficiency (η) and TAR coefficient of performance (COP). Firstly, the TAE is modelled to ascertain the optimum position of the TAE stack based on the acoustic power (Ẇ) and efficiency (η). The TAE achieved a drive ratio near 20 %. It was found that the optimum normalized position (xn) for the TAE stack is at 0.43 for highest Ẇ of 78.3 W and 0.25 for highest η of 9 %. Secondly, Thermo-Acoustically Driven Refrigerator (TADR) is developed by incorporating both TAE and TAR stacks in tandem following optimal positioning of the TAR stack. Finally, the performance of the TADR is optimized by altering the TAR stack material, the TAE hot end temperature, and the working fluid. The optimal TAR stack position was found to be the closest to the TAE stack. The material with lower thermal conductivity (Mylar) outperformed the higher conductivity (Steel). Furthermore, Increasing the TH from 1,000 K to 1,200 K significantly increased the cooling power. Argon demonstrated the highest η and COP compared to Air and Helium, however, the highest cooling power was achieved using Helium. Two TADR configurations were considered: a) Helium with stacks at xn = 0.43 (TAE) and xn = 0.77 (TAR), prioritizing cooling power, achieving 60.87 W at 5 K temperature difference; b) Argon with stacks at xn = 0.25 (TAE) and xn = 0.58 (TAR), favoring efficiency, achieving up to 22.815 % overall efficiency at 5 K temperature difference, and a maximum temperature drop of 34 K below ambient (300 K).

Exergy and economic analysis of a photovoltaic panel cooling with air bubble induced water jacket

Solar photo voltaic (PV) panel performance is greatly affected by the rise in temperature of the PV panel. To increase the electrical conversion efficiency of the PV panel, assessments are made under various cooling circumstances. To assess the efficacy of the PV panel using a water-cooling system in the climate of Manipal, India, experimental studies were conducted in this research. The purpose of this research is to evaluate and compare various cooling strategies, such as Heat sink, water jacket, air bubble cooling and combination of these techniques. Air bubbles are introduced inside the cooling jacket, which generates turbulence motion and cools the PV panel. The cooling system is inspected while running at different panel temperatures. The percentage drop in maximum panel temperature is found to be highest at 15.36 % for the panel attached with water jacket and air bubble with heat sink combination. Also, the power output of the panel is found to be the highest for the above combination with the increase of 9.31%.

Novel integration of dual evaporator loop heat pipe for improved electric vehicle battery thermal regulation

The Battery Thermal Management System (BTMS) plays a crucial role in ensuring the efficient and safe operation of Hybrid Electric Vehicles (HEVs) and/or Electric Vehicles (EVs). Among various heat transfer techniques, Loop Heat Pipes (LHPs) have demonstrated their potential for effective heat transfer from Li-ion batteries due to their high heat transfer rates over a longer distance. The conventional design of LHPs poses challenges for constructing robust battery pack modules, particularly in electric vehicles (EVs). This complexity arises from the separation of liquid and vapor lines at either the top or bottom of the evaporator, along with the inclusion of a compensation chamber. Furthermore, the evolving requirements of BTMS highlight the necessity for efficient heat removal from multiple locations. To address these requirements, a novel Dual Evaporator Loop Heat Pipe (DE-LHP) has been developed as a BTMS solution featuring separate vapor and two liquid lines positioned at the uppermost section of each cylindrical evaporator. The developed DE-LHP is tested as a BTMS solution with a 3S4P battery module (10Ah capacity) at different charging and discharging rates (1C, 1.5C, and 2C) in surrounding temperatures ranging from 30 °C to 45 °C. When the thermal performance of the DE-LHP-equipped BTMS was compared to a module without BTMS, a drop in maximum cell temperature was noted. At an ambient temperature of 35 °C, the DE-LHP BTMS achieved temperature reductions of 22.8 %, 22.6 %, and 18.8 % at charging rates of 1C, 1.5C, and 2C, respectively. In addition, at a threshold temperature of 60 °C, the module with DE-LHP BTMS demonstrated enhanced discharging capability from 41 % State of Charge (SOC) to 0 % SOC for a 1.5C discharging rate and from 59 % SOC to 0 % SOC for a 2C discharging rate compared to the module without BTMS. Furthermore, when the module was exposed to ambient temperatures ranging from 30 °C to 45 °C, the DE-LHP BTMS maintained a temperature difference across the battery module of less than 3.5 °C for all charging rates and 1C and 1.5C discharging rates.

Thermochromic Conductive Fibers with Modifiable Solar Absorption for Personal Thermal Management and Temperature Visualization.

Thermal management textiles provide an energy-efficient strategy for personal thermal comfort by regulating heat flow between the human body and the environment. However, textiles with a single heating or cooling mode cannot realize temperature regulation under dynamic weather. Furthermore, monocolor textiles do not satisfy aesthetic requirements in a garment. Here, we develop a thermochromic (TC) conductive fiber with a coaxial structure composed of a conductive core and thermochromic shell. The TC conductive fiber-woven fabric has the ability of low-energy dynamic thermal management by combining Joule heating and modulation of solar absorption. Compared with commercial white fabrics, TC conductive fabrics exhibit a maximum temperature drop of 2.5 K, while the temperature of colored commercial fabrics is 7.5-16 K higher than that of commercial white fabrics in the hot. In the cold, the combination of Joule heating and the photothermal effect can provide desired thermal comfort for humans. Meanwhile, heat obtained from solar absorption brings the temperature of a fabric to a predetermined level, which saves energy of 625 W/m2 compared to a conductive-fiber-based textile. In addition, TC conductive fabrics with trichromatic evolution provide a sensitive and instant temperature visualization capable of identification of invisible and intense infrared radiation. These results provide another path to expand potential applications of wearable, flexible electronics.

Performance Evaluation of a Wet Medium Made of Mangosteen Peels for a Direct Evaporative Cooling System

The present study aimed to investigate an alternative evaporative cooling pad material made from mangosteen peel (MP) waste. Mangosteen peels were used to fill a 150 mm thick mesh container with a packing density of 180 kg/m3. A wind tunnel was constructed and utilized to experimentally evaluate the cooling performance of this organic-waste-based pad under hot and humid conditions (31–34 °C and 55–70% RH). The performance parameters assessed included pressure drop, temperature drop, saturation effectiveness, cooling capacity, and coefficient of performance (COP). The influence of air velocity (0.7, 1.0, 1.4, and 1.8 m/s) on these parameters was also examined. The results revealed that the saturation effectiveness of the MP pad ranged from 53% to 77% within the considered air velocity range. The maximum temperature drop (4.6 °C), saturation effectiveness (77%), cooling capacity (0.6 kW), and COP (3.5) were achieved when the system operated at 1.4 m/s. A comparative study showed that, at this velocity, the MP pad provided performance nearly equivalent to that of the commercial cellulose paper pad, except for the pressure drop. This result affirms the potential of mangosteen peels as a suitable wet medium for evaporative cooling applications.

Optimization of liquid cooling for prismatic battery with novel cold plate based on butterfly-shaped channel

For maintenance of the batteries working at appropriate temperature, an effective thermal management system is required to handle the heat production during the operating process. In this work, a novel butterfly-shaped channel structure is designed and integrated into the liquid cooling system for the 50 Ah ternary prismatic battery module. First, a comparison of the cooling performance between the butterfly-shaped design and other traditional designs was investigated regarding the maximum temperature, temperature difference, and pressure drop. The calculation results of the desirability function revealed the optimal overall performance of the butterfly-shaped channel. Secondly, the inlet width, outlet width, and the height were set to be 8, 12, and 2 mm respectively while the channel width was adjusted to be 9 mm between the positive and negative terminals upon optimizing structural parameters. Accordingly, the maximum temperature was reduced to 32.72 °C while pressure was dropped to 25.7 Pa as well, demonstrating a 29.1 % decrease compared to the previous configuration. Finally, the effect of the mass flow on the thermal performance of the battery module was carried out. As the coolant mass rate of flow increased, the maximum temperature and temperature difference of the battery module decreased accordingly while the descent rate gradually slowed. In addition, when the mass rate of flow was controlled at 5 g·s−1, the maximum temperature was 30.86 °C, with a 4.96 °C temperature difference where the pressure loss of each cold plate was 338.57 Pa.