Nowadays, the ever-increasing demand for the computational power in the calculators, watches and LED lights require higher consumption rate from their portable energy source, which is typically ...coin-shaped batteries. The required power generates and accumulates a large amount of heat, which is a critical safety concern due to flammability of the included organic electrolytes. When heat dissipation is minimal from the electrode surface, the packaging boundary remains the sole heat transfer medium. In such case, although the center carries a minimal real estate compared to the rest of the electrode surface, the heat gets trapped, due to having the lowest reach to the heat-dissipating boundaries. For this purpose, a central heat sink component is anticipated for the coin-shaped batteries and the temperature profile across the cell is analytically derived. Subsequently, the role of the sink thermal conductivity and its scale as well as the thermal conduction of the boundary on the formation of steady state temperature profile has been analyzed. More specifically, the location of the maximum temperature rmax and its value Tmax is obtained and verified versus the extreme values of the thermal conductivities, the areal ratio of the heat sink, and the current density. The obtained results could be useful for the cost-effective design of the packaging materials (i.e. sustainable plastics and bio-degradable) with limited heat dissipation for the rechargeable batteries, particularly during the high power applications, in the presence of highly flammable electrolytes.
The urgent need for ultrahigh thermally conductive materials to keep up with the rapid development of the electronics industry has led to the exploration of hexagonal boron nitride nanosheets (BNNSs) ...as an ideal material for thermal transport/dissipation applications. BNNSs possess outstanding mechanical strength, electrical insulation, thermal conductivity, and low density, as well as remarkable oxidation resistance. This article provides a comprehensive review of various fabrication methods for BNNSs and compares their advantages and disadvantages. Additionally, the article discusses the impact of several BNNS properties, including thickness, size, interface, isotopic concentration, and defects, on their thermally conductive properties. Lastly, the review delves into the use of BNNSs as highly thermally conductive fillers in polymer-based materials, highlighting the significant effects of the content, directionality, dispersibility, and structure of BNNSs within the polymer matrix on the composite's thermally conductive properties. This review aims to spark new fabrication methods and improvements to achieve BNNS/polymer composites and promote their practical application as thermal transport/dissipation materials.
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•A scalable technique involves meltblowing and electrospinning is reported.•Two-level structured nonwovens for personal protective face masks are prepared.•The face masks show ...attractive filtration and radiative heat dissipation properties.•Airflow field of the nonwovens during filtration process is simulated using CFD.
The COVID-19 pandemic and airborne particulate matter (PM) pollution have posed a great threat to human health. Personal protective face masks have become an indispensable protective equipment in our daily lives. However, wearing conventional face masks for a long time cause swelter and discomfort on the face. Introducing thermal comfort into personal protective face masks becomes desirable. Herein, face masks that show excellent filtration performance and radiative heat dissipation effect are successfully designed and prepared by electrospining Nylon-6 (PA) nanofibers onto polyethylene (PE) meltblown nonwovens. The resultant PE/PA nonwovens have high PM filtration efficiency (>99%) with a low pressure drop (<100 Pa). Moreover, taking the advantage of the property of PE, the designed face mask posses high mid-infrared (mid-IR) transmittance and brings about high radiative cooling power, resulting in effective heat dissipation performance. This face mask design may provides new insights into the development of thermal comfort materials for personal protection.
This study aimed to extract the thermomechanical fatigue behavior of a CF/PEKK composite under low and ultrasonic frequency fatigue tests (LFFTs and UFFTs) in the presence of the self-heating effect. ...Preliminary increasing amplitude tests (IATs) were performed to obtain the minimum load level at which the self-heating is observable. Extracting the fatigue strength from T-σ curves for three mean stress levels resulted in constructing S-N curves for the LFFT regime at different load levels using a shift procedure. However, combining LFFT and UFFT results via S-N curve was impractical, while joining such results through the heat dissipation rate (q̇) was feasible for various constant amplitude tests and IATs. The derived σ-q̇ curves from combining LFFT and UFFT results and comparing the fracture mechanisms of CF/PEKK composite using fractography would make a step for bridging the transition zone between LFFTs and UFFTs and making the results transferable. The microscopy images obtained from fractography also confirmed the similarities of fatigue fracture mechanisms between LFFTs and UFFTs.
•LFFT and UFFT results are transferable using the heat dissipation rate concept.•Mean stress effect in S-N curves is derived through the application of thermography.•S-N curves obtained from combining LFFT and UFFT results showed a transition zone.•Combining LCF and VHCF regimes using S-N curve for CF/PEKK composite is unfeasible.
•Annular inverse opal surface was prepared by attenuating the coffee ring effect.•Its boiling heat transfer performance was investigated.•Its CHF and HTC were increased by 214% and 240%, ...respectively.•Its growth rate of the average bubble approaches 75%
The thermal management of electronic devices is increasingly recognized as an urgent, worldwide public technology concern. To cope with the large thermal shock under a high heat flux on the heat-generating devices, we present an annular inverse opal (AIO) surface with a gap for liquid replenishment via attenuating the coffee ring effect. Thermal capillary effect generated in the structural surface can not only drive the liquid backflow to effectively alleviate the irreversible dry spot caused by pure water evaporation during critical heat flux (CHF), but also decrease the Leidenfrost temperature under such limited liquid–solid contact. By comparing it with the smooth silicon surface, the structural surface shows that the boiling heat transfer performance is significantly improved. The CHF was increased by 214% and the heat transfer coefficient (HTC) was increased by 240%. By phenomenological observation of the boiling point phenomenon, the average bubble growth rate increased by 75%. It is possible that the AIO structure can significantly improve the overall heat cooling performance of the heat exchange surface to ensure the normal operation of the electronic devices.
•The heat dissipation of the base surface is evaluated using vortex generators.•The effect of vortex generators’ angle is investigated with Reynolds number.•The rectangular shaped vortex generators ...cause highest heat transfer rate.•The Nusselt number descends with decreasing the angle of vortex generators.•The platelet shaped nanoparticles has highest cooling performance.
In the present study, the impact of different shapes of nanoparticles and vortex generators is analyzed to enhance the heat dissipation of the surface in the proposed single-channel heat sink. The assessment of hydrothermal proficiency of the heat sink is carried out for four different physical designs of vortex generators, including triangular, trapezoidal I, trapezoidal II, and rectangular shapes in which the Al2O3/water nanofluid with three different nanoparticles’ shapes (platelet, cylinder, and brick shaped) is utilized as a coolant, and the effect of two vortex generators angles on the cooling of the minichannel’s surface is evaluated. The outcomes exhibit that the nanofluid with platelet shaped nanoparticles augments the heat transfer rate between coolants and base surface in the minichannel heat sink more than other nanoparticles shapes, and the rectangular shaped vortex generators at the angle of 45 degrees have the highest thermal proficiency in the proposed heat sink. It is also obtained that when the rectangular vortex generators are considered, the Nusselt number of the single-channel heat sink is improved by 56% compared to the conventional case, and utilizing the nanofluids platelet shaped nanoparticles as a coolant enhances the Nusselt number by 40% compared to that of pure water.
The temperature control technology based on phase change material (PCM) demonstrates excellent performance in the field of battery thermal management. However, the compact and bulky structure of the ...traditional composite PCM (CPCM) module reduces the energy density of the battery pack greatly, and is unfavorable to the secondary heat dissipation. In this work, we develop a novel PCM cooling structure by substituting the common block-shaped CPCM (B-CPCM) module with serpentine CPCM (S-CPCM) plates. The S-CPCM plates with high shape stability provide a much larger surface area and many air flow channels in comparison to the B-CPCM module, thus endowing the module with outstanding secondary heat dissipation capability. For example, under the same fan power of forced air convection (5.2 W), the S-CPCM module delivers a much lower maximum temperature than the B-CPCM module (51.9 vs. 54.2 °C) during the repeated charge-discharge process. As highlighted here, on the basis of guaranteeing the cooling performance, the S-CPCM cooling structure also saves ~70% of the CPCM amount, and thereby the energy density of the battery module is increased by 13.8 Wh kg−1.
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•Novel serpentine composite phase change material (S-CPCM) plates are designed.•The S-CPCM cooling structure saves 70% of the CPCM amount in the battery module.•The energy density of the module with S-CPCM cooling is increased by 13.8 Wh kg−1•S-CPCM plates provide air flow channels and large surface area for heat dissipation.•The S-CPCM cooling structure shows much enhanced heat dissipation performance.
•The convective heat transfer performance of Triply Periodic Minimal Surface (TPMS) structures was studied through experiment and numerical simulation.•TPMS (Gyroid, Diamond, Iwp) structures has ...significant advantages in convective heat transfer performance compared with the traditional straight-ribbed heat dissipation structure.•The thermal performance of Diamond structure outperforms the straight rib by 84–205%, Gyroid structure outperforms the straight rib by 55–136%, and Iwp structure outperforms the straight rib by 16–53%.
Heat dissipation capacity is one of the bottlenecks in developing high heat release devices such as electronic chips and laser generators. TPMS exhibits good thermophysical properties and is expected to provide better heat dissipation solutions for high heat-releasing devices. However, studies on the convective heat transfer properties of TPMS structures are still insufficient. In this manuscript, research focuses on evaluating the convective heat transfer performance of several representative TPMS structures and elucidating their mechanism of enhanced heat transfer. The TPMS studied in this paper include Gyroid, Diamond, and Iwp, and their convective heat transfer performance is compared with that of Fins-structure. In addition, an experiment was carried out to verify the accuracy of the numerical simulation. The results showed that the numerical simulation results were in good agreement with the experiment, with an error of less than 6%. In the numerical simulation, the lattice size of the three TPMS is 20 × 20 × 20 mm3, the fluid is air, the heating surface is heated at a constant wall temperature of 373.15 K, and the Reynolds number is in the range of 166–940. Compared with the Fins-structure model, the Nusselt number of TPMS-Diamond is increased by 9–196%, that of TPMS-Gyroid is increased by 5.8–149%, while the TPMS-Iwp is increased by 6.8–43.5%. Among the three TPMS structures, the convective heat transfer performance of TPMS-Dimond is the best, which can be attributed to its geometric structures without the “through-holes,” which leads to a more substantial disturbance of the wall to the fluid, thereby enhancing the heat transfer.
Graded porous structures can improve the design performance with a smooth transition of material properties over the domain. We present a multi-physics topology optimization approach for designing ...functionally graded porous structures. As an application, we present a formulation to optimize heat dissipating structures to enhance structural and thermal performance. The pore size, resolution, and porosity of the structures can be controlled to obtain optimized mechanical and thermal performances. Several controlling schemes are introduced which can tailor the design of the porous structures. Design approaches based on the functional variation of porosity, pore size and sensitivity-based porosity control are employed. Numerical examples with different structural loads, thermal loads and boundary conditions are presented to verify the formulation and show the efficacy of the implementation. We also investigate the effect of the controlling parameters on the overall design. The proposed formulation shows good promise to design functionally graded porous structures with targeted porosity in multi-physics systems.
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•A design approach to generate porous structures guided by multi-physics topology optimization is presented.•Schemes to design functionally graded controllable porous structures based on porosity and pore size gradation are introduced.•A sensitivity-based controlling scheme is adopted to obtain physics based graded porous structures.
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