Polymer‐based thermal management materials have many irreplaceable advantages not found in metals or ceramics, such as easy processing, low density, and excellent flexibility. However, their limited ...thermal conductivity and unsatisfactory resistance to elevated temperatures (<200 °C) still prevent effective heat dissipation during applications with high‐temperature conditions or powerful operation. Therefore, herein highly thermoconductive and thermostable polymer nanocomposite films prepared by engineering 1D aramid nanofiber (ANF) with worm‐like microscopic morphologies into rigid rod‐like structures with 2D boron nitride nanosheets (BNNS) are reported. With no coils or entanglements, the rigid polymer chain enables a well‐packed crystalline structure resulting in a 20‐fold (or greater) increase in axial thermal conductivity. Additionally, strong interfacial interactions between the weaved ANF rod and the stacked BNNS facilitate efficient heat flux through the 1D/2D configuration. Hence, unprecedented in‐plane thermal conductivities as high as 46.7 W m−1 K−1 can be achieved at only 30 wt% BNNS loading, a value of 137% greater than that of a worm‐like ANF/BNNS counterpart. Moreover, the thermally stable nanocomposite films with light weight (28.9 W m−1 K−1/103 (kg m−3)) and high strength (>100 MPa, 450 °C) enable effective thermal management for microelectrodes operating at temperatures beyond 200 °C.
A highly thermoconductive, high‐temperature stable, and superflexible paper is fabricated via a rational construction of 1D rigid rod‐like aramid nanofibers and 2D boron nitride nanosheets (BNNS). Significantly, the rod‐like nanofiber morphology and rigid molecular chain can enable more efficient phonon transport through the 1D/2D configuration. Hence, the heat sink paper paves the way for thermal management of new and powerful components.
Thermal management systems (TMSs) are indispensable for practical applications of lithium-ion battery packs. In this study, phase change material (PCM) nano-emulsions with enhanced energy storage ...capacity, excellent dispersion stability, low viscosity and good thermal reliability were employed as coolants for high-performance liquid cooling thermal management systems (LCTMSs) for the first time. The maximum temperature (Tmax) and maximum temperature difference (ΔTmax) in a 5S4P battery pack were measured to evaluate the thermal management performance of these coolants. When a 10 wt% OP28E nano-emulsion was used at a flow rate of 200 mL min−1, Tmax and ΔTmax were 1.1 °C and 0.8 °C, respectively, lower than those based on water, at a discharge rate of 2C. The increase in OP28E mass fraction of the nano-emulsion led to a gradual decrease in Tmax and ΔTmax at identical discharge rates. Simulation studies were also conducted and validated by comparing with the experimental results. It was revealed that, Tmax and ΔTmax decreased with increasing flow rate of the coolants, and the thermal management performance of the 10 wt% OP28E nano-emulsion was always better than that of water. This work sheds light on improving the performance of LCTMSs by using PCM nano-emulsions.
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•The OP28E nano-emulsion had enhanced energy storage capacity and low viscosity.•PCM nano-emulsion was employed as a novel coolant for a LCTMS.•Tmax and ΔTmax of battery pack decreased with increasing OP28E concentration.•LCTMS performance based on 10 wt% OP28E nano-emulsion was better than that of water.
•Adjusting the cooling temperatures for the batteries and cabin independently.•Researching the backpressure control method to differentiate the evaporation.•Realizing the di-function of battery ...cooling or heating directly by refrigerant.•Investigating the refrigerant-based cabin-and-battery mixed heating management.
A refrigerant-based thermal management system (TMS) for electric vehicles (EVs) is proposed and analyzed, aiming to tackle the conflict between the cabin thermal comfort and the battery thermal safety, and to realize the battery heating or cooling directly by the refrigerant without supplementary devices. Compared with the traditional EV TMSs, an electronic expansion valve (EEV) is equipped after the battery cooling/heating device in the refrigerant branch circuit. The performance of the proposed new TMS is investigated by mathematical simulations in conditions of the standardized New European Driving Cycles (NEDC) and different climates. The simulation results indicate that both the temperatures of the cabin air and the battery pack can be well controlled by the proposed TMS. In the cabin-and-battery mixed cooling mode for summer, the cooling temperatures for the cabin and the battery can be adjusted independently, and the cabin air can be cooled to the target temperature effectively as well as the battery thermal safety is guaranteed. In the cabin-and-battery mixed heating mode for winter, the high temperature refrigerant flows through the battery cooling plate and heats the batteries with the latent heat of condensation, and the battery preheating can be completed within 15 min and 9 min in the condition of 0 °C and 7 °C ambient temperature, respectively. Besides the thermal behaviors of the cabin and the battery, the controls of the compressor and the valves are also investigated to verify the practical feasibility of the proposed TMS.
Personal thermal management (PTM) materials have attracted increasing attention owing to their application for personal comfort in an energy‐saving mode. However, they normally work in the same media ...such as in the air, and little is known about what will happen in other media like water. In this study, a system for cross‐media thermal management (CMTM): passive cooling in air and thermal insulation underwater is proposed. Hybrid aerogels comprising thermoplastic polyurethane (TPU) matrix and superhydrophobic silica aerogel particle (SSAP) for CMTM are designed and synthesized using a thermally induced phase separation and self‐templating strategy. The TPU matrix endows the aerogels with super stretchability (500%), shape memory, and outstanding healing recovery rate (89.9%), which are ideal characteristics for potential wearable usage. Additionally, the TPU and SSAP endow the aerogel with high solar reflectivity and infrared emissivity, thus achieving a sub‐ambient cooling of 10.6 °C in air. Moreover, the SSAP endows the aerogels with low thermal conductivity (0.052 W m−1·K−1) and high hydrophobicity (143°), enabling the aerogels for underwater thermal insulation. The CMTM performance of the aerogels makes them for potential uses in cross‐media environments such as reefs and islands where cooling in air and thermal insulation in water are required.
Silica – thermoplastic polyurethane hybrid aerogels with excellent stretchability and healability are designed and synthesized for cross‐media thermal management – passive daytime radiative cooling in air and thermal insulation in water, which is facilitated by high solar reflectance, high IR emissivity, high contact angle, and low thermal conductivity of the hybrid aerogel.
In recent years, energy and environmental issues have become more and more prominent, and electric vehicles powered by lithium-ion battery have shown great potential and advantages in alleviating ...these issues. Compared with other batteries, lithium-ion batteries have the advantages of high specific energy, high energy density, long endurance, low self-discharge and long shelf life. However, temperature of the battery has become one of the most important parameters to be handled properly for the development and propagation of lithium-ion battery electric vehicles. Both the higher and lower temperature environments will seriously affect the battery capacity and the service life. Under high temperature environment, lithium-ion batteries may produce thermal runaway, resulting in short circuit, combustion, explosion and other safety problems. Lithium dendrites may appear in lithium-ion batteries at low temperature, causing short circuit, failure to start and other operational faults. In this paper, the used thermal management methods of lithium-ion batteries are introduced and their advantages and disadvantages are discussed and compared. At the same time, the prospect of future development is put forward.
•Thermal management of lithium-ion batteries for EVs is reviewed.•Heating and cooling methods to regulate the temperature of LIBs are summarized.•Prospect of battery thermal management for LIBs in the future is put forward.•Unified thermal management of the EVs with rational use of resources is promising.
The electronic equipment developing towards miniaturization and high integration is facing the danger of high heat flux and non-uniform temperature distribution which leads to the reduction of life ...and reliability of electronic devices. The micro heat sinks have gained significant attention in heat dissipation of electronic devices with a high heat flux due to its large heat transfer surface to volume ratio, compact structure and outstanding thermal performance. In this review, we present the advantages and shortcomings of thermal enhancement technologies in different structural micro heat sinks. Moreover, the non-uniform temperature distribution which includes the temperature rising along the flow direction and hotspots, especially, the random hotspot with high heat flux, has been the serious issues in the thermal management of electronic devices. They are the main challenges for the efficient operation and service life of electronic components. Thus, it is urgent to develop an effective and economic process in automatic adaptive cooling of random hotspots. The purpose of this article is to introduce the existing thermal enhancement technologies in micro heat sinks and the reduction of non-uniform temperature distribution. Finally, the barriers and challenges for the developments of thermal management of electronic devices by micro heat sinks are discussed, and the future directions of the research topic are provided.
The thermal stress of power electronic components is one of the most important causes of their failure. Proper thermal management plays an important role for more reliable and cost-effective energy ...conversion. As one of the most vulnerable and expensive components, power semiconductor components are the focus of this paper. Possible approaches to control the semiconductor junction temperature are discussed in this paper, along with the implementation in several emerging applications. The modification of the control variables at different levels (modulation, control, and system) to alter the loss generation or distribution is analyzed. Some of the control solutions presented in the literature, which showed experimentally that the thermal stress can be effectively reduced, are reviewed in detail. These results are often mission-profile dependent and the controller needs to be tuned to reach the desired cost-benefit tradeoff. This paper analyzes also the many open questions of this research area. Among them, it is worth highlighting that a verification of the actual lifetime extension is still missing.
After nine years (the maximum three consecutive terms) on the Editorial Board of the IEEE Transactions on Electron Devices (TED), Prof. Richard Carter, Lancaster University, U.K. (Vacuum Electron ...Devices), Dr. Youichi Momiyama, Socionext, Japan (MOS Devices and Technology), Prof. Guofu Niu, Auburn University, USA (Bipolar Devices), and Prof. Rama Venkatasubramanian, Johns Hopkins Applied Physics Lab, USA (Thermal Management) have stepped down from their Editor positions in the respective fields.
•The heat generation and transfer modeling approaches of LIB are introduced.•The advantages and disadvantages on various multi-physical BTMS are summarized.•The emerging techniques in emergency ...battery thermal barrier are examined.•A novel BTMS framework is proposed based on CHAIN.
New energy vehicles have significant prospects in reducing greenhouse gas emission and environmental pollution. Lithium-ion batteries are the favored power source in electric vehicles because of their high energy density and long service life. The battery performance depends noticeably on the temperature. Battery thermal management system, which can keep the battery pack working in a proper temperature range, not only affects significantly the battery pack system performance but is also vital for the safety and stability. This article mainly summarizes the thermal management models in the literature which can predict heat generation, heat transfer and the temperature distribution within the battery cell, module and pack. The multi-physical battery thermal management systems are divided into three categories based on different methods of cooling the phase change materials such as air-cooled system, liquid-cooled system, and heat-pipe-cooled system. The emergency battery thermal battier methods are also summarized in multi-scale included material scale, battery management system and supplementary system. Finally, we propose a novel digital solution for full-lifespan thermal management control of EV power system based on CHAIN framework that helps improve the power battery temperature control strategy applying multiple working conditions.
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Galvanic Skin ResponsesIn article 2301104 by Young Min Song, Woon‐Hong Yeo, and co‐workers, a soft, field‐deployable, wearable bioelectronic system is introduced for detecting outdoor workers' stress ...levels with negligible motion artifacts and controllable thermal management.
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