Showing papers on "Thermal published in 2022"
TL;DR: In this article , a multi-way twisted tape (MWTT) was applied to enhance the thermal treatment of Linear Fresnel Reflector (LFR) unit, and the operating fluid is Al 2 O 3 -water and temperature dependent formulas were employed.
189 citations
TL;DR: In this article , the authors present a novel, structurally simple, multifunctional broadband absorber, which consists of a patterned vanadium dioxide film and a metal plate spaced by a dielectric layer.
Abstract: We present a novel, structurally simple, multifunctional broadband absorber. It consists of a patterned vanadium dioxide film and a metal plate spaced by a dielectric layer. Temperature control allows flexible adjustment of the absorption intensity from 0 to 0.999. The modulation mechanism of the absorber stems from the thermogenic phase change properties of the vanadium dioxide material. The absorber achieves total reflection properties in the terahertz band when the vanadium dioxide is in the insulated state. When the vanadium dioxide is in its metallic state, the absorber achieves near-perfect absorption in the ultra-broadband range of 3.7 THz-9.7 THz. Impedance matching theory and the analysis of electric field are also used to illustrate the mechanism of operation. Compared to previous reports, our structure utilizes just a single cell structure (3 layers only), and it is easy to process and manufacture. The absorption rate and operating bandwidth of the absorber are also optimised. In addition, the absorber is not only insensitive to polarization, but also very tolerant to the angle of incidence. Such a design would have great potential in wide-ranging applications, including photochemical energy harvesting, stealth devices, thermal emitters, etc.
150 citations
TL;DR: In this paper , the authors present a review of the progress in thermal management of solid-solid, solid-liquid, and solid-gas interfaces, and discuss how to tailor interfaces to minimize the resistance.
Abstract: As devices and circuits scale to ever smaller sizes and thermal management in them becomes more important, heat transport across their interfaces plays a crucial role in their development. While the study of interfacial thermal resistance goes back almost 90 years, its increasing importance has led to significant recent progress in theory, experiment, and simulation. This review chronicles this progress for solid-solid, solid-liquid, and solid-gas interfaces, discusses how to tailor interfaces to minimize the resistance, and mentions some of the remaining challenges.
99 citations
TL;DR: In the face of increasingly severe electromagnetic wave (EMW) pollution, the research of biomass-based carbon materials due to the advantages of being green, renewable, environment-friendly, porous and light has become...
89 citations
TL;DR: In this article , the authors proposed a fine-tuned artificial intelligent model to predict the thermal efficiency and water yield of the solar still, which consists of a traditional artificial neural network model optimized by a meta-heuristic optimizer called humpback whale optimizer.
87 citations
83 citations
TL;DR: In this article , a novel design on angled fins was proposed to improve the thermal transport for phase change materials (PCMs) in a shell-and-tube thermal storage unit, and a numerical model was built and verified by comparing with experimental observations on the melting front evolution and temperature history.
82 citations
TL;DR: In this paper, a novel design on angled fins was proposed to improve the thermal transport for phase change materials (PCMs) in a shell-and-tube thermal storage unit, and a numerical model was built and verified by comparing with experimental observations on the melting front evolution and temperature history.
82 citations
TL;DR: In this article , a two-dimensional numerical model is established and validated through comparing with experimental data in literature to study the enhanced heat transfer of adding longitudinal fins in a horizontal shell-and-tube heat storage unit.
75 citations
TL;DR: In this article , a numerical analysis intended to evidence the main hydrothermal and mass transport appearances featuring the convective flows of an exceptional nonhomogeneous micropolar mixture (i.e., 60% of ethylene glycol, 40% of pure water, and copper oxide nanomaterials) over an impermeable horizontal electromagnetic surface, which is heated convectively in the presence of a particular variable heat source.
73 citations
TL;DR: Li et al. as discussed by the authors constructed a resistance-based thermal model of the batteries considering the impact of the state of charge (SOC), battery temperature, and current on the battery heat generation.
Abstract: Flying car is an effective transport to solve current traffic congestion. The power batteries in flying cars discharge at a high current rate in the takeoff and landing phase, evoking a severe thermal issue. Flat heat pipe (FHP) is a relatively new type of battery thermal management technology, which can effectively maintain the temperature uniformity of the battery pack. We have constructed a resistance‐based thermal model of the batteries considering the impact of the state of charge (SOC), battery temperature, and current on the battery heat generation. The FHP model is developed based on segmental heat conduction model, and integrated into the battery model to form the battery‐FHP‐coupled model for a battery module. Experiments are carried out to verify its accuracy. Then, the battery thermal performance is analyzed under the different discharging conditions including constant discharge rates and dynamic discharge rates for flying cars. Under the condition of the flying cars, the battery maximum temperature appears at the end of takeoff stage, while the maximum temperature difference appears during the forward flight segment. Moreover, different FHP heat dissipation structures are studied to further improve the battery thermal performance. The configuration with the best performance is adopted for the battery pack, and it can meet the heat dissipation requirements of the pack at a discharge rate of 3C or that of flying cars. Finally, the influence of inlet cooling air velocity and temperature on battery thermal performance is investigated. According to the research results, air velocity has little effect on the battery maximum temperature at the discharge rate of flying cars, but it can obviously affect the temperature decrease rate. Besides, the battery maximum temperature and its temperature difference develop linearly with the air temperature.
TL;DR: In this paper , a smoothed particle hydrodynamics (SPH) method was employed to simulate the heat transfer process in porous media at the pore scale, and the effective thermal conductivity of a porous medium can be predicted through a simulation experiment of SPH.
Abstract: The smoothed particle hydrodynamics (SPH) method was employed to simulate the heat transfer process in porous media at the pore scale. The effective thermal conductivity of a porous medium can be predicted through a simulation experiment of SPH. The accuracy of the SPH simulation experiment was verified by comparing the predicted values with reference values for ideal homogeneous media and multiphase layered media. 3D simulation experiments were implemented in granular media generated by the PFC method. Based on the SPH framework, a concise method was proposed to produce unsaturated media by simulating the wetting process in dry media. This approach approximates the formation of liquid bridges and water films on granules. Through simulation experiments, the empirical formula of the variation in thermal conductivity with the degree of saturation was tested. The results showed that the reciprocal of the normalized thermal conductivity and the reciprocal of the saturation are linearly related, which is in line with the empirical formula proposed by Cote and Konrad.
TL;DR: In this article , the available data sets determining the thermal structure are combined into a mean model and the implications of the oberved contrasts for atmospheric motions, on small and large scales, are discussed.
Abstract: The available data sets determining the thermal structure are critically discussed and combined into a mean model. The implications of the oberved contrasts for atmospheric motions, on small and large scales, are discussed. Greenhouse models which allow a convective atmosphere below 35 to 50 km give a reasonable explanation of the high surface temperature. Surprisingly, however, the deep atmosphere is generally stable. The radiative imbalance thus drives the general circulation rather than local convection. A distinct tropopause occurs at the cloud tops. Above this, the atmosphere is very stably stratified and not far from radiative equilibrium. Gravity waves are present. The upper atmosphere, with its very large day-night temperature contrast, must be in motion away from the sun, but velocities are strongly limited to a sizable viscous dissipation.
07 Jan 2022
TL;DR: In this paper , hollow beaded Fe3C/N-doped carbon fibers were synthesized through convenient electrospinning and subsequent thermal treatment, and the special hollow morphology of the samples is conducive to achieve lightweight and broadband microwave absorption properties.
Abstract: Microwave-absorbing materials have attracted enormous attention for electromagnetic (EM) pollution. Herein, hollow beaded Fe3C/N-doped carbon fibers (Fe3C/NCFs) were synthesized through convenient electrospinning and subsequent thermal treatment. The special hollow morphology of the samples is conducive to achieve lightweight and broadband microwave absorption properties. The thermal treatment temperatures exhibit a significant impact on conductivity and EM properties. The broadest effective absorption bandwidth (EAB) is 5.28 GHz at 2.16 mm when the thermal treatment temperature is 700 °C, and the EAB can cover 13.13 GHz with a tunable absorber thickness from 1.0 to 3.5 mm when the thermal treatment temperature is 750 °C. The excellent microwave absorption properties of the samples are due to the synergistic effect of impedance matching and strong EM energy attenuation abilities. Hence, the magnetic hollow beaded Fe3C/NCFs are expected to be an attractive candidate material as a lightweight and efficient microwave absorber in the future.
TL;DR: In this article , a multiscale design of hypocrystalline zircon nanofibrous aerogels with a zig-zag architecture is presented, which leads to exceptional thermomechanical stability and ultralow thermal conductivity at high temperatures.
Abstract: Thermal insulation under extreme conditions requires materials that can withstand complex thermomechanical stress and retain excellent thermal insulation properties at temperatures exceeding 1,000 degrees Celsius1-3. Ceramic aerogels are attractive thermal insulating materials; however, at very high temperatures, they often show considerably increased thermal conductivity and limited thermomechanical stability that can lead to catastrophic failure4-6. Here we report a multiscale design of hypocrystalline zircon nanofibrous aerogels with a zig-zag architecture that leads to exceptional thermomechanical stability and ultralow thermal conductivity at high temperatures. The aerogels show a near-zero Poisson's ratio (3.3 × 10-4) and a near-zero thermal expansion coefficient (1.2 × 10-7 per degree Celsius), which ensures excellent structural flexibility and thermomechanical properties. They show high thermal stability with ultralow strength degradation (less than 1 per cent) after sharp thermal shocks, and a high working temperature (up to 1,300 degrees Celsius). By deliberately entrapping residue carbon species in the constituent hypocrystalline zircon fibres, we substantially reduce the thermal radiation heat transfer and achieve one of the lowest high-temperature thermal conductivities among ceramic aerogels so far-104 milliwatts per metre per kelvin at 1,000 degrees Celsius. The combined thermomechanical and thermal insulating properties offer an attractive material system for robust thermal insulation under extreme conditions.
01 Jan 2022
TL;DR: In this article , a shape-stable phase change composites (SSPCCs) with excellent flexibility was prepared in large scale via water-assisted melt blending, and the MXene nanosheets were dispersed well in the EPDM matrix during the melt blending processes with the assistance of water.
Abstract: Thermal therapy based on phase change materials (PCMs) has broad application prospects in the field of personal thermal care. Herein, a serious of EPDM/MXene/PW (EMP) based shape-stable phase change composites (SSPCCs) with excellent flexibility was prepared in large scale via water-assisted melt blending. The MXene nanosheets were dispersed well in the EPDM matrix during the melt blending processes with the assistance of water. With the introduction of a small amount of MXene nanosheets (only 0.8 wt%), the light-to-thermal conversion efficiency of SSPCCs were improved obviously. The melting phase change enthalpy and freezing phase change enthalpy of EMP-0.8 are about 120 J/g and 115 J/g, respectively. And after 200 times thermal cycles and 25 times light-thermal cycles, the phase change enthalpy of obtained EMP-0.8 SSPCC hardly changes. All the results show that the obtained EMP based SSPCCs can be fully utilized in the field of personal thermal therapy.
TL;DR: In this paper, a shape-stable phase change composites (SSPCCs) with excellent flexibility was prepared in large scale via water-assisted melt blending, and the MXene nanosheets were dispersed well in the EPDM matrix during the melt blending processes with the assistance of water.
Abstract: Thermal therapy based on phase change materials (PCMs) has broad application prospects in the field of personal thermal care. Herein, a serious of EPDM/MXene/PW (EMP) based shape-stable phase change composites (SSPCCs) with excellent flexibility was prepared in large scale via water-assisted melt blending. The MXene nanosheets were dispersed well in the EPDM matrix during the melt blending processes with the assistance of water. With the introduction of a small amount of MXene nanosheets (only 0.8 wt%), the light-to-thermal conversion efficiency of SSPCCs were improved obviously. The melting phase change enthalpy and freezing phase change enthalpy of EMP-0.8 are about 120 J/g and 115 J/g, respectively. And after 200 times thermal cycles and 25 times light-thermal cycles, the phase change enthalpy of obtained EMP-0.8 SSPCC hardly changes. All the results show that the obtained EMP based SSPCCs can be fully utilized in the field of personal thermal therapy.
TL;DR: In this paper , the steady hydromagnetic flow and heat transfer behavior of non-Newtonian (Cross) hybrid nanofluid with water as base fluid and SWCNT, and MWCNT as nanoparticles past a stretched cylinder has been analyzed.
TL;DR: In this paper , the authors presented three equivalent thermal circuit models with multiple input parameters, namely, the state of health (SOH), state of charge (SOC), current and temperature.
Abstract: This paper presents three equivalent thermal circuit models with multiple input parameters, namely, the state of health (SOH), state of charge (SOC), current and temperature. Typical physiochemical models include parameters such as porosity and tortuosity, which are not easily experimentally available; this model allows for model parameters such as the internal impedance to be easily estimated using more practical inputs. The paper models the internal impedance resistance of a LiFePO4 battery at five different ambient temperatures (5, 15, 25, 35, 45 °C), at three different discharge rates (1C, 2C, 3C) and at three different SOHs (90%, 83%, 65%). The internal impedance surface fit experimental measurements with a Pearson coefficient of 0.945. Three thermal models were then created that implemented the internal resistance model. The first two thermal models were 0D models that did not include the influence of the thermal conductivity of the battery. The first model assumed simple heating through internal resistance and convection energy loss, while the second also included the Bernardi Reversible heat term. The final third model was a 2D model that included all previous heat source terms as well as tab heating. The 2D model was solved using a simple Euler method and finite center difference. The R2 values for the 0D thermal models were 0.9964 and 0.9962 for the simple internal resistance and reversible heating models, respectively. The R2 value for the 2D thermal model was 0.996.
TL;DR: In this article , an impeller is set in the mixing zone in the rectangular T-junction to improve the mixing behavior of hot and cold fluids under the deflecting jet with the inflow momentum ratio of M R = 0.49.
TL;DR: In this paper , a multiscale 3D aerogel with a feather-like microstructure was designed for solar-powered water evaporation, which achieved a high energy efficiency of 88.52% and a low water consumption rate of 0.92 kg m−2 h−1 at a weak solar irradiance of 1.5°Sun.
Abstract: Solar‐powered water evaporation is a straightforward, practical approach to use solar energy for water desalination. Solar absorbers made from photothermal materials capable of effectively confining heat and pumping water to the evaporation surface are essential for a high energy efficiency. However, separate designs of water transport routes and thermal insulating layers are required to simultaneously achieve desired water and thermal managements. This work reports an integrated design for efficient multifunctional capabilities through rational assembly of spectrally modified Ti3C2Tx (SM‐Ti3C2Tx) nanosheets and polyvinyl alcohol (PVA) into a multiscale 3D aerogel with a feather‐like microstructure. The aerogel contains longitudinal struts with transversely parallel ligaments developed at an angle of ≈60° from the struts, resembling the microstructure of down feathers in penguins and thus leading to excellent thermal insulation. The hydrophilic porous ligaments serve as upward water transport channels, pumping the water to the evaporation surface while confining it within the ligaments to avoid oversaturation. These functional features endow the composite aerogel with a high energy efficiency of 88.52% and an evaporation rate of 0.92 kg m−2 h−1 at a weak solar irradiance of 0.5‐sun, indicating its great potential for practical solar‐powered water desalination under natural sunlight.
TL;DR: In this article , a review of thermo-photo catalysis is presented, where the authors clarify the definition (beyond photo-thermal catalysis and plasmonic catalysis), classification, and principles of thermophotonics and reveal its superiority over individual thermal and photocatalysis.
Abstract: Thermo-photo catalysis, which is the catalysis with the participation of both thermal and photo energies, not only reduces the large energy consumption of thermal catalysis but also addresses the low efficiency of photocatalysis. As a whole greater than the sum of its parts, thermo-photo catalysis has been proven as an effective and promising technology to drive chemical reactions. In this review, we first clarify the definition (beyond photo-thermal catalysis and plasmonic catalysis), classification, and principles of thermo-photo catalysis and then reveal its superiority over individual thermal catalysis and photocatalysis. After elucidating the design principles and strategies toward highly efficient thermo-photo catalytic systems, an ample discussion on the synergetic effects of thermal and photo energies is provided from two perspectives, namely, the promotion of photocatalysis by thermal energy and the promotion of thermal catalysis by photo energy. Subsequently, state-of-the-art techniques applied to explore thermo-photo catalytic mechanisms are reviewed, followed by a summary on the broad applications of thermo-photo catalysis and its energy management toward industrialization. In the end, current challenges and potential research directions related to thermo-photo catalysis are outlined.
TL;DR: In this article , a strategy for the fabrication of liquid manipulating surfaces with patternable and controllable wettability on Polyimide (PI) film based on femtosecond laser thermal accumulation engineering is proposed.
Abstract: Versatile liquid manipulating surfaces combining patternable and controllable wettability have recently motivated considerable attention owing to their significant advantages in droplet-solid impacting behaviors, microdroplet self-removal, and liquid-liquid interface reaction applications. However, developing a facile and efficient method to fabricate these versatile surfaces remains an enormous challenge. In this paper, a strategy for the fabrication of liquid manipulating surfaces with patternable and controllable wettability on Polyimide (PI) film based on femtosecond laser thermal accumulation engineering is proposed. Because of its controllable micro-/nanostructures and chemical composition through adjusting the local thermal accumulation, the wettability of PI film can be tuned from superhydrophilicity (~ 3.6°) to superhydrophobicity (~ 151.6°). Furthermore, three diverse surfaces with patternable and heterogeneous wettability were constructed and various applications were successfully realized, including water transport, droplet arrays, and liquid wells. This work may provide a facile strategy for achieving patternable and controllable wettability efficiently and developing multifunctional liquid steering surfaces.
TL;DR: In this article, a review of the development of Al2O3 reinforced polymer composites is presented, including surface modification, filler hybridization, and construction of Al 2O3 network by various processing methods.
Abstract: Thermal conductive polymer composites attract lots of research due to the continuous miniaturization and multi-function of electronic equipment. As a common ceramic, Al2O3 owns relatively high thermal conductivity, high electrical resistivity and satisfactory cost performance, which is considered as the high-quality filler to prepare thermal conductive and electrical insulated composites. This paper reviews current progress in the development of Al2O3 reinforced polymer composites. We firstly summarize the preparation methods of spherical Al2O3, then heat conduction mechanisms and main factors affecting thermal conductivity are introduced. Next, we focus on the common research of Al2O3 in improving the thermal conductivity of polymers, including surface modification, filler hybridization and construction of Al2O3 network by various processing methods, and some emerging applications of thermal conductive polymer composites are introduced subsequently. After a critique of recent studies, we identify several outstanding issues must be addressed if higher thermal conductivity is fully realized.
TL;DR: In this article , a facile and versatile ambient drying strategy was proposed to fabricate lightweight, wide-temperature flexible, super-hydrophobic and flame retardant silicone composite aerogels modified with low-content functionalized graphene oxide (FGO).
TL;DR: In this paper , the best topology of artificial neural networks, least-squares support vector regression, and adaptive neuro-fuzzy inference systems (ANFIS) are found by trial-and-error and statistical analyses.
TL;DR: In this paper , the impact of the Atangana-Baleanu (AB) time-fractional integral on second-grade fluid with ternary nanoparticle suspension across an infinite vertical plate was studied.
Abstract: The impact of the Atangana-Baleanu (AB) time-fractional integral on second-grade fluid with ternary nanoparticle suspension across an infinite vertical plate was studied in this paper. By generalized Fourier's law, the generalized fractional constitutive equation for the thermal flux explains a thermal process with memory. Closed-form solutions are calculated using Laplace transform and represented using Lorenzo and Hartley G–functions and integral forms. The numerical effects of physical and fractional parameters are presented.
TL;DR: In this article , the authors successfully prepared biomass-derived borocarbonitride (BCN) nanosheets with excellent electromagnetic wave absorption and thermal management properties by a general, green and economical strategy using biomass coconut shell as carbon source, and explored the effect of the coconut shell charcoal content on its performance.
TL;DR: In this article , a numerical model has been developed by coupling conjugate heat transfer with computational fluid dynamics (CFD) to capture the cell temperature and internal pressure evolution under thermal abuse, venting and subsequent combustion of 18650 lithium-ion batteries.