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In addition to photovoltaic cells, solar power plates, photovoltaic lights, and solar pumping water, solar energy is the primary source of heat from the sun. At the moment, researchers are looking at the use of nanotechnological and solar radiation to increase aeronautical efficiency. In this study, hybrid nanofluid flow linearly passes through a parabolic trough solor collector (PTSC) on the interior of solar aircraft wings to study heat transmission. Solar radiative flow was the term used to describe the heat source. The heat transfer efficiency of the wings is evaluated for several effects, such as a slanted magnetic field, viscous dissipation, play heating, and thermal radiative flow. Entropy generation study was performed on the Prandtl-Eyring hybrid nanofluid (P-EHNF). The Keller box technique was used to solve the predicted energy and momentum equations. As a typical fluid, EG (ethylene glycol) is used to disperse the nanosolid particles, which consist of copper (Cu) and cobalt ferrite (CoFe2O4). A variety of control factors, including velocity, shear stress, and temperature outlines as well as a frictional factor and Nusselt number, are addressed in detail. Thermal radiation amplification and variable thermal conduction parameters appear to increase the efficiency of aircraft wings in terms of thermal transfer. Hybrid nanofluid is superior to conventional nanofluid in terms of heat transmission. Cu-EG has a low thermal efficiency between 3.8% and 4.8% than CoFe2O4-Cu/EG nanofluid.

The flow and thermal breakthrough phenomenon in a forced external circulation standing column well (FECSCW) directly affects heat transfer efficiency and load-carrying capacity. A numerical model for FECSCW is developed to analyze the migration of the temperature and velocity front under the flow and thermal breakthrough. The results indicated that thermal breakthrough began after simulation running 2.5 min and was completely formed after 12 min. The inlet water, which directly entered the production well without heat exchange with the aquifer, accounted for 12.8%. When the porosity of the backfill material decreased from 0.35 to 0, the coefficient of performance (COP) of the heat pump unit increased by 1.6% on average, and the thermal breakthrough strength decreased by an average of 45.3% within 25 min. Where seepage velocity near the well wall was greater than 1 × 10−3 m•s−1, faster velocity front migration was observed, while the migration advantage of the temperature front was more prominent outside of this region. Through quantitative analysis of flow and thermal breakthrough, temperature and velocity front migration, and COP change of heat pump unit, theoretical suggestions were provided for the thermal transfer mechanism near the thermal well wall. The extended research in this study can be applied to the design and optimization of forced external circulation standing column well system.

High-temperature thermal storage materials have received urgent attention for efficient thermal transfer in solar thermal power generation. Corundum ceramics doped with Fe2O3 and TiO2 were prepared via a pressureless sintering. A Fe2O3–TiO2 system with different Fe2O3/TiO2 ratios was applied to corundum ceramics. Phase composition, microstructural evolution, sintering properties, high temperature resistance and thermophysical properties were evaluated. The results indicated that Fe2O3 and TiO2 rendered the grains highly active and enhanced the bonding between grains due to existing stably in the lattice of corundum. In addition, decrease in the Fe2O3/TiO2 ratio led to a new phase of FeAlTiO5, which refined the grains. These effects gave the samples good sintering properties and thermal shock resistance, but the thermal expansion coefficient mismatch between FeAlTiO5 and corundum deteriorated the high-temperature (1300 °C) stability. Formula C1 (Fe2O3/TiO2 ratio of 9:1) sintered at 1600 °C had the optimum comprehensive properties, possessing a bending strength loss rate of 1.54% after 30 cycles of thermal shock (1100 °C-room temperature, air cooling) and a constant strength retention rate of approximately 71.34% after 90 h high-temperature cycle. The corresponding thermal conductivity and specific heat capacity were 18.81 W/(m·K) and 1.02 J/(g·K) at 25 °C, which was suitable as a high-temperature thermal storage material.

Owing to the impact of global warming, the weather becomes hotter than the past. Responding to the hot–humid climate, the Taiwan government intends to install air-conditioning in classrooms to provide comfort study environment. The thermal management of school buildings is separated into naturally ventilated and air-conditioning seasons based on the strategies of reducing energy use while maintaining thermal comfort. In this paper, the school buildings located in northern and southern Taiwan (Taipei and Kaohsiung) are selected as study objectives to simulate cooling load, thermal comfort, and the natural ventilation potential to discuss the parameters related to building envelope design. Through regression analysis of the 360 simulation cases, the Overall Thermal Transfer Value (OTTV) for Taipei and Kaohsiung are established. Besides, the coefficient of azimuth correction factor and area ratio correction factor are clarified for equivalent ventilation area. Through coupled analysis, the Pareto ranking method is used to obtain numerical solution sets corresponding to the index including OTTV and equivalent ventilation area. Consequently, a school building envelope design criteria for balancing the energy use and thermal comfort is proposed. According to the analysis results and the intersection of OTTV and equivalent ventilation area at Pareto front, it is confirmed that the restriction of the OTTV index is 20 W/m2 in Taipei and Kaohsiung; the equivalent ventilation area which guarantees no overheating risk during natural ventilation season is determined as 9.5 m2 in Taipei and 14.3 m2 in Kaohsiung. Furthermore, the influence level of the parameters is clarified that the area and shading performance of windows make a major influence on sensible cooling load; comparing to external shading, the window insulation performance is considerably less important. Overall, this study seeks the balance between energy use and thermal comfort then provide the efficient strategies at the initial design stage through the proposed criteria.

Considering the risk of leakage and the complexity of processing technology, a passive cooling first wall has been developed in the low magnetic side. The anticipated heat flux limit of the first wall is about 0.3 MW/m2. In order to enhance thermal transfer, the main materials of the first wall is made of copper alloy (CuCrZr) and graphite tile. A layer of flexible graphite is placed in the interface of CuCrZr and graphite tile to increase thermal contact resistance. Transient thermal analysis has been used to predict the whole heat transfer process for normal operating discharge in a day. Through the simulation, we can get the temperature change history of each component in 24 hours. The temperature and stresses of the passive cooling first wall are found to be within the acceptable limits. The maximum temperature of this first wall is about 307 °C which appears on the graphite tile. The results of the maximum temperature distribution are imported into the structure for calculation. Finally, the elasto-plastic fatigue analysis method is used to check the structural analysis results, and the results show that the structure meets the high parameter discharge mode of more than 480,000 times.

Large-caliber gun barrels are coated, on their internal surface, by hard and refractory metallic layers. The thermophysical properties of such coatings are generally very different of bulk materials ones, and liable to evolve following the thermal cyclings. Nevertheless, the knowledge of these properties is necessary for modeling the gun barrels behavior. In the present work, a photothermal microanalysis method has been used to measure the local thermal diffusivity within such a coating. The periodic excitation is localized on a micrometer-scale spot and the temperature evolution in the thermally excited zone is monitored by photoreflection on a spot with similar size. Local thermal properties are identified from thermal transfer function analysis, i.e., phase-lag evolution versus frequency. Results obtained on an aged chromium coating, on which several local diffusivity measurements have been undertaken along the depth, are presented. The diffusivity is higher near the surface than toward the interior of...

CNT nanoparticles have high tensile strength, excellent thermal transfer properties, and optimal chemical and physical stability. The lack of CNT stable dispersion in most of the fluids limits its industrial exploitation in heat transfer applications. Researchers are constantly making efforts for preparing stable dispersions of CNT. Luckily, the unique π-electron-rich structures of CNT open a variety of possibilities for modifications in their structure leading to alterations in their chemical and electronic properties. Normally, chemical and physical methods are used for CNT surface properties alterations to make it dispersible in various base fluids. This review provides a comprehensive survey of chemical and physical methods used to prepare stable CNT nanofluid as well as methods used to analyse CNT nanofluid stability. Chemical modifications are either done by covalent or non-covalent methods. Covalent methods utilized by researchers include reaction with acids, bases, organic and inorganic molecules, metals, metal complexes, polymers, etc. In non-covalent method, surfactants, biomolecules and natural products, polymers, IL and DES, polymers, etc. are used. Physical methods discussed herein include techniques like homogenization, crushing, etc. that deagglomerate CNT bundles. The application of extreme forces on CNT leads to distortion in electronic framework of CNT. Therefore, to avoid excess of physical and chemical treatments, a blend of techniques in appropriate ratio is proposed for CNT dispersion. The techniques that are used to analyse the stability of nanofluid such as UV–vis, TEM, SEM, turbiscan, zeta, and DLS are also reviewed. It could be concluded that there is need for development of low-cost and fast method for prediction of the stability of CNT nanofluid.

Non-contact warming of blood and intravenous (IV) fluids with temperature drop compensation is an unmet clinical need till now, for management of hypothermia in patients with urgent requirement of blood. Currently available technologies provide wet warming or dry warming with direct contact using hot water or with a hot plate, respectively. These conventional technologies need disposable cartridges to be used in conjunction with the warmer. The warmed fluids lose their temperature when passing through long IV lines and fails in its purpose at low flow rates. In this paper, a distributed non-contact warming method is introduced using infra-red radiations. The method incorporates a bag warming unit and an inline cartridge unit. Bag warming unit provides uniform distribution of infra-red thermal energy liberated from low cost infra-red light emitting diodes (IR LEDs) in horizontal and vertical planes of the fluid carrying bag. An inline cartridge, through which the IV line passes, reduces the drop in temperature just before the transfusion site using a cluster of IR LEDs. As per the In Vitro tests are carried out in to establish the safety and efficacy, the bag warming unit steadily rises the temperature to attain the cut off value with a temperature rise coefficient of 0.7 °C/min and the inline cartridge warms the fluid within 10 min at a thermal transfer rate of more than 1.5 °C/min. The fluid temperature is uniformly distributed within a narrow range of 36-38 °C. When the inline warmer is powered on, the drop-in temperature is reduced to zero for flow up to 5 ml/min. For flow rates more than 8 ml/min, the temperature drop is reduced more than half. For massive transfusion range, the temperature of the fluid remains within 38.5 ± 1.2 °C for flow rates in the range of 100-1500 ml/min.

Objective: Laser irradiation is being used for treatment of peri-implantitis. Therefore, this study aimed to assess the heat transfer from laser irradiation on an implant-supported, metal–ceramic f...

This work is based on a numerical study of the fluid-structure thermal coupling in a concrete slab intended for habitable heating. A rectangular cross-section pipe in which a hot fluid flow is installed in this concrete slab. The Navier-Stokes equations that govern this flow have been solved numerically. To this end, these equations have been discretized by an implicit finite difference method. The systems of algebraic equations thus obtained have been solved by the Gauss and Thomas algorithms. The conduction equation in the concrete slab was solved using the same methodology as that of flow. In fact, we have based on an algorithm that makes an unsteady solid medium interact with a fluid medium consisting of permanent states series while ensuring the equality of fluxes and temperatures on the common interface between both media at every moment. The numerical simulation of heat transfer and the thermal behavior of the heating slab were analyzed for different parameters influencing thermal diffusion. The results obtained by the numerical model adopted for the control of the fluid-structure coupling are in good agreement with those of the literature results.

International audience; This paper presents a thorough analysis of direct microwave heating as a sintering process of ceramic materials. It questions why susceptor-assisted microwave heating is used in most experimental works, although direct microwave coupling is preferable for taking advantage of the possible beneficial effects of the microwave field on the sintering phenomena. This issue was investigated by conducting both experiments and numerical simulations. The experiments consisted of sintering alumina and yttria doped zirconia powder samples in a 2.45 GHz resonant cavity with automatic thermal monitoring, whereas the numerical simulations coupled electromagnetics, thermal transfer and sample deformation. Alumina and yttria doped zirconia are widely used materials and they exhibit different microwave field behaviours (transparent and absorbent, respectively), which are representative of most ceramic materials. The influence of the insulating material was discussed by considering different sintering cell designs. The very low coupling capacity of alumina made its direct heating very difficult. It was therefore necessary to apply a strong electric field to heat it. This situation promoted the absorption of microwave energy by other elements such as the insulating material, leading to heating instabilities and degradation of the insulation cell. In the case of zirconia, its coupling properties change abruptly with increasing temperature. It is poorly absorbent at low temperature, highly absorbent at intermediate temperature and it finally becomes reflective at the end of the sintering process. The consequences of this behaviour are (i) a very difficult control of direct heating (ii) a propensity to form damaging hot spots and (iii) the impossibility to reach high temperatures without forming plasma. Therefore, this experimental and numerical study showed that direct microwave heating is not suitable for conducting reliable and homogeneous sintering of classical ceramics. This explains why susceptor-assisted heating is most of time preferred.

This paper reports the numerical simulations on buoyant thermal transfer inside the finite porous cylindrical annular region with a thin circular baffle attached to inner cylinder. The main objective of this investigation is to provide a detailed impact of baffle on flow and heat transport rates due to the direct relevance of this problem to the design of heat exchangers. The side walls of annular enclosure are maintained at uniform, but different temperatures, while the top and bottom walls are insulated. The Brinkman-extended Darcy model is adopted for the momentum equations, and simulations of the governing PDEs are performed using the ADI and SLOR algorithms. The predictions from the present simulations detected that the size and position of baffle has predominant impact on buoyant flow and thermal transport characteristics. It has been detected that the thermal dissipation rates could be enhanced by positioning the baffle near the upper boundary, while increasing the baffle length leads to the reduction of thermal transport. The size and location of baffle emerges out as an important quantity in regulating the global thermal transfer through modifying the flow regimes in the annular geometry. Interestingly, the magnitude of flow circulation enhances with an increase in Rayleigh and Darcy numbers for any baffle length and position.

Verifying the effects of heat transfer towards the rise of temperature in certain spaces which impact air control and conditioning. Climate change affects the rise of environmental temperatures, with the humid and tropical Indonesia not exempt from its effects. Many church buildings in Semarang, Indonesia, of which were previously partial to natural ventilation, have now opted to rely on Air Conditioning in order to cool their indoor temperatures. As a result, electrical consumption is now at an all-time-high, with the absence of proper adjustments needed to anticipate heat transfer from the outdoors from entering these buildings. Aside from skyrocketing expenses spent on electrical bills, the rise in energy consumption is also partial to uncontrollable energy waste. This research aims to provide a guide in designing the walls of church buildings, in order to reduce massive electrical consumption. Methods used in this research are calculations done through the software Psi-Therm as well as making considerations regarding Overall Thermal Transfer Value (OTTV) in order to provide the big picture of controllable thermal conductivity through church wall design. Research results entail a design model of heat transfer flow obstruction which will be beneficial for future church designs.

In this paper, the compound heat transfer of convection and radiation in an internal circulating fluidized bed for low temperature oxidation of pulverized coal was numerically simulated. The numerical prediction about the compound heat transfer characteristics and its relationship of convection and radiation was compared with the experimental measurements of low temperature radiation. The discrete ordinate model (DOM) was employed to investigate the radiation heat transfer in the low temperature oxidation internally fluidized bed, and user-defined function (UDF) was compiled by considering the effect of the particle flow emissivity on radiation heat transfer. The convection heat transfer coefficient increases with the increase of gas inlet volume flow rate and initial bed material height, however, thermal radiation coefficient was opposite. An increase of the thermal flux results in an increase of the surface temperature of the fluid and the heater surface, and the thermal transfer coefficient between bed material and heater surface is also increased. The results have the application reference to complex thermal transfer design of circulating fluidized bed systems wherein thermal radiation transfer must be considered as a significant mode.

Graphdiyne (GDY) exhibits great application potential. However, large-yield and scalable exfoliation of few-layered GDY nanosheets (GDYNSs) remains a huge challenge. Here, we reported a liquid-phase, facile and efficient hydrothermal exfoliation approach to produce mono- or few-layered GDYNSs, which can achieve 82 wt% of high actual yield and 5 mg/ml concentration. The GYDNSs were then dispersed in mineral oil (MO) to act as heat transfer nano fluids for the first time. Typically, at a fraction of 1.0 vol %, the nano-oils showed significantly enhanced thermal conductivity ((Keff/K0)-1) %, up to ∼122%. The low filler fraction and high thermal conductivity enhancement for this GYDNSs/MO nano-oil demonstrates several thermal transfer applications of heavy equipment. Our work provides reasonable insight into the exfoliation and thermal-fluid applications of GDYNSs.

The designs of fine tubes and thermal exchangers rely on the fabrication of copper and aluminum fin and tube heat exchangers. The heat was regulated through copper tubes and pipes by flowing water. The major objective of this work will be to enhance the rate of heat transmission by altering the existing tube and finish. The copper U-tube was replaced with the spline fin in the heat exchanger in this project. Pressure drop, speed, and heat transfer properties of the heat exchanger were evaluated using solid works and the study was conducted using computer fluid dynamics (CFD). From the results, it has been determined that the improvement of thermal transfer rate and efficiency in spline fin is up to 5 percent higher than the flat fin and also increases pressure and the higher pumping power in a heat exchanger by placing fluid within the fin through cross-flow.

Papers for the thermal transfer printing of UHF RFID antennas were prepared by coating and calendering. Real and imaginary components of the impedance of the UHF RFID antennas depended on their design, coating composition and conditions of paper calendering. Passive UHF RFID tags were constructed from antennas and chips whose real and imaginary components of impedance in the 860–960 MHz frequency band were at approximately the same level. The communication quality of passive UHF RFID tags was evaluated by measuring the reading range using the designed UHF RFID reading unit. The reading range of experimental UHF RFID tags with printed antennas on paper and commercial UHF RFID tags with chemically etched antennas on a PET film were identical in the 860 MHz frequency.

In the work, the authors investigated the possibility of using the results of analytical solutions of the linear differential equations of unsteady heat conduction with constant heat transfer coefficients to calculate the temperature of the material during heat treatment of leathers. Heat treatment of natural leathers as heat-sensitive materials is carried out under mild temperature conditions and high air moisture contents, the temperature does not undergo significant changes, and the heat transfer coefficients change almost linearly. When using analytical solutions, the authors made the assumptions that for small temperature gradients over the cross section of a thin body, the thermal transfer of matter can be neglected and for values of the heat and mass transfer Biot criteria less than unity, the main factor, limiting heat and mass transfer, is the interaction of the evaporation surface of the body with the environment; so, in solving the differential heat equation we can restrict ourselves to one first member of an infinite series. In this case, a piecewise stepwise approximation of all thermophysical characteristics with constant values of these coefficients at the calculated time intervals was applied, which made it possible to take into account the change in the transfer coefficients throughout the entire heat treatment process. Processing of experimental data showed that in low-intensity processes with reliable values of the transfer coefficients, it is possible to use the results of solutions of differential equations of unsteady heat conduction in heat transfer calculations. The results of the study of heat transfer during drying of leather confirm the laws of temperature change established experimentally. Together with experimental studies of drying processes, analytical studies are of great practical importance in the development of new methods for calculating heat and mass transfer in wet bodies.

The conditions for obtaining substances and intermediates using the available purified raw materials of coke chemistry were experimentally selected and improved. The technological process and the scheme of synthesis of the thermocouple dye of yellow 6Z is developed, using as a raw material isolated from coke resin and purified anthraquinone. Improved technology for the synthesis of thermocouple dye yellow 6Z is a little expensive and allows you to increase the output without degrading the quality of the final form of the dye. Translated printing is of great interest for the proposed printing of dispersion dyes of chemical fibers. Translational coloring of textile materials and products as one of the simplest, most economical and environmentally friendly technological processes. Initially, the method was printing has a number of indisputable advantages that make one of the most promising areas in the coloring of textile fabrics. The method of thermal printing is simple in technical design: in the presence of a printed substrate for the printing process is enough to have a thermal press or calender, which can be serviced by one operator, which saves capital costs for equipment and leads to minimizing the workplace. Translation printing is of great interest for dyeing textile materials and products as one of the simplest, most economical and environmentally friendly technological processes. Initially, the method was proposed for. The image printed on the fabric has a mirror image.The improved technology of synthesis of thermal transfer dye yellow 6C in comparison with the current technology takes place at a much lower temperature of 45±5oC (according to the current technology - 120±5oC) without pressure at the duration of the methoxylation reaction 6 hours (instead of 46 hours according to the current technology). This technological technique allows to increase up to 8% the yield of the target product in high quality.The yield of dye by advanced technology per loaded 2-bromobenzantrone is significantly higher compared to the yield of the current technology.In the process of improving the technology, the selected conditions for obtaining substances and intermediates using available purified raw materials of coke chemistry in the synthesis of thermal transfer dye yellow 6C anthraquinone were substantiated, the technological scheme of synthesis was drawn up final form of dye, the technological scheme of synthesis is made, using as initial raw materials the anthraquinone isolated from coke resin and allowed to increase with improvement an exit of a final form of dye.

The great advances in textile technology have led to the development of the upholstery fabrics industry in order to provide all that is new and distinctive to the consumer. The trend towards user comfort and elegance in the interior design of homes and so on has recently become more environmentally friendly. The nature of the textile’s materials, depending on the nature of use and functionality and the washing, cleaning and care to which it is exposed. There are some features that need to be washed repeatedly, others that need to be cleaned dry. There are other types that are exposed to constant upholstery, such as upholstery or furnishing, and others that are exposed to this, such as pillow coverings and so on. The structural composition of upholstery fabrics affected the required textile properties, whether natural, mechanical, aesthetic or functional. The structural structure affected the susceptibility of cellulose and blended upholstery fabrics to transfer printing technique. The study produced 9 raw samples of cotton and varying cotton /polyester blending,”100% cotton, 58% cotton /42% polyester, 68% cotton /32% polyester” then performed preliminary sample preparation and special finishing process of the cotton samples 100% and by applying transfer printing on 12 samples with different textile combination, namely, plain1/1, rib 2/2, rib 4/4.After studying the statistical results of the tests, it appears that the resistance of the raw and printed research samples varies due to the structural composition of the samples. Conclusion: It is evident that, with regard to the structure of raw and printed upholstery fabrics samples (depending on different factors studied namely structure and material) the abrasion resistance varies from one sample to another, Sample number (9) was the best abrasion resistance of the raw samples,(plain1/1- 68% cotton /32% polyester) , it was affected by 0.93% and from printed samples by transfer printing was sample number(14),( rib 2/2-58% cotton /42% polyester) ,it was affected by 1.07%.

The large-scale commercial application of phase change materials (PCMs) was seriously limited by the leakage, poor heat storage capacity and slow thermal response behavior. To address these issues, stearic acid/graphene oxide-attapulgite aerogel (SA/HGA-ATP) shape-stabilized PCMs were fabricated via hydrothermal method. The morphology, structural characteristics, thermal properties were determined and the effects of ATP percentage on the thermal properties of confined SA were studied synchronously. The nanofibers of ATP intercalated among GO sheets via grafting modification and formed fiber-bridging 3D-network. Due to the enhanced loading interspaces and suppressed volumetric shrinkage of hybrid matrix, SA/HGA-ATP exhibited excellent thermal energy storage capacity (190.9 J g−1) and ultra-high SA contents (approx. 98 wt%) without leakage. The intercalated nanofibers sheltered the oxygen-containing groups of matrices, leading to the promotion of thermal energy storage performance with increase of ATP contents. Besides, the as-prepared PCMs displayed outstanding thermal response behavior because the interconnected and fiber-bridged matrices provided continuous thermal transfer pathway. Due to the protection of matrix, the composite PCMs also exhibited superior structure stability and incomparable thermal energy storage/release reliability. Considering the outstanding thermal-physical properties and low-cost of ATP, the SA/HGA-ATP has the potential to be applied in the fields of thermal energy storage, conversion and utilization.

All engineering industries have proven that there is a demand to maintain heat transfer and in many engineering production processes, an increase in the rate of thermal transfer is required.. The solution lies in adding solid bodies made externally from heat-conducting materials called fins, which in turn have been the subject of very large engineering research by changing shapes, lengths, axis, thicknesses, etc., in order to raise the efficiency of performance in heat transfer to avoid industrial problems and accidents. The materials type and surface area have direct affect of the heat transfer rate depends on the types of materials used and the surface area of the fin. One of the most popular choice is the radial annular fin due to the cylindrical primary surface where the performance of the fins is a function of many parameters, namely the heat transfer coefficient, the fin efficiency and the fins’ thermal resistance. In this research work, an experimental study to investigate the effect of fin heat transfer performance characteristics elliptical fin shape at differnt at its major and minor axis ratio (a/b) with different cooling air velocities. As a results, the optimum ratio is found to be for an elliptical shape fins for forced convection.

Polymeric composites with good thermal conductive and improved mechanical properties are in high demand in the thermal management materials. Construction of a three-dimensional (3D) structure has been proved to be an effective method to obtain polymeric composites with improved through-plane thermal conductivity (TC) for efficient thermal management of electronics. However, the TC enhancement of the obtained polymeric composites is limited, mainly due to poor control of the 3D thermal conductive network. Additionally, achieving high thermal conductive properties and enhanced mechanical properties simultaneously is of great challenge for polymeric composites. In this work, a 3D boron nitride framework (BNF) with a well-defined vertically aligned open structure and designed wall density fabricated by a unidirectional freezing technique was applied. The as-prepared BNF/polyethylene glycol (PBNF) composites exhibit enhanced through-plane TC, excellent thermal transfer capability (ΔTmax = 34 °C), and improved mechanical properties (Young's modulus enhancement up to 356%) simultaneously, making it attractive to thermal management applications. Strong correlation between the TC and mechanical properties of the PBNF composites and the wall density of the BNF scaffolds was found, providing opportunities to tune the TC and mechanical properties through the controlling of wall density. Furthermore, the models between TC and Young's modulus of PBNF composites were established by using the data-driven method "sure independence screening and sparsifying operator", which enables us to predict TC and Young's modulus of the polymeric composites for designing promising composite materials. The design principles and fabrication strategies proposed in this work could be important for developing advanced composite materials.

The high gas-sensing performance of semiconductors is mainly due to the high surface-to-volume ratio because it permits a large exposed surface area for gas detection. This paper presents an evaluation study for the effects of nano-CuO coating parameters on the CO gas-sensing performance. The effects on gas-sensing performance and heat transfer efficiency of CuO coating were evaluated by investigating the effects of coating parameters (concentration, temperature, and solution speed) on thickness, grain size, and porosity. The CuO nanoparticle coatings were synthesized using the oxidation method at various operating conditions. Coating characteristics were investigated using X-ray diffraction, energy dispersive X-ray Spectroscopy, field emission scanning electron microscopy, and electrical resistivity meter. The average coating thickness, grain size, and porosity were around 13 μm, 48 nm, and 30%, respectively. The thermal transfer and gas-sensing properties of CuO coating were evaluated according to the total surface area of the coating formed at various operating conditions. The gas-sensing and thermal transfer performance were obtained from the optimization of coating parameters based on the coating morphology to achieve the highest contact surface area. The coating’s surface area was increased by 350 times, which improved the heat transfer efficiency of 96.5%. The result shows that the coating thickness increased with the increase in solution concentration and decrease the temperature. The results also show that the sensitivity of the coating for CO gas was increased by 50% due to the reduction of coatings grain size.

Improving heat exchangers thermal efficiency marks materials used, the energy obtained and cost savings directly. The improvement of heat exchange will also considerably increase heat efficiency and the economical nature of design and operation in applications requiring thermal transfer processes. Because of their small diameters, double tube heat exchangers are mostly suited for high temperature and high-pressure applications. They are inexpensive, but the amount of way they distribute to the other forms is relatively high. Numerous techniques were designed to achieve the necessary heat transfer rate at an economical pumping capability within the specified design and duration of the heat exchanger. The most popular and efficient techniques for heat exchangers to improve are helical inserts. Helical inserts. This article would investigate the performance of an ANSYS CFX tool for double tube heat exchangers with helical insert. A comparative analysis will be carried out in comparison to the heat exchanger without helical inserts for the heat flux and temperature distribution along the pipe.

In this paper, an analysis of three-dimensional transient thermal transfer is presented to evaluate the performance of a photovoltaic thermal module with an optimize structural design, incorporating direct use of an aluminum collector as the substrate. The effect of cross-sectional geometries and ratios of size and spacing was considered to optimize the performance of a photovoltaic-thermal (PVT) module. The temperature, velocity and pressure distributions were demonstrated in a steady state model using a finite element method. Simulation results indicated the temperature of the PVT module was increased by the solar irradiation incident with the panel, yet overall decreased by an increased flow velocity. In this study, we examine seven types of media used as the medium to cool the PVT module, where water was preferred, due to its higher specific heat capacity. Further, for multiple interconnected PVT modules, connecting method in parallel and series resulted in pressure drop for the PVT module. In addition, the simulations were compared to experimental data providing validation of the estimated operating temperature in agreement with simulation results, and the outcomes will provide an indication for preferred assembly of PVT modules for application in building integration and future product design.

There has been increasing interest in face recognition in the thermal infrared spectrum. A critical step in this process is face landmark detection. However, landmark detection in the thermal spectrum presents a unique set of challenges compared to in the visible spectrum: inherently lower spatial resolution due to longer wavelength, differences in phenomenology, and limited availability of labeled thermal face imagery for algorithm development and training. Thermal infrared imaging does have the advantage of being able to passively acquire facial heat signatures without the need for active or ambient illumination in low light and nighttime environments. In such scenarios, thermal imaging must operate by itself without corresponding/paired visible imagery. Mindful of this constraint, we propose visible-to-thermal parameter transfer learning using a coupled convolutional network architecture as a means to leverage visible face data when training a model for thermal-only face landmark detection. This differentiates our approach from models trained either solely on thermal images or models which require a fusion of visible and thermal images at test time. In this work, we implement and analyze four types of parameter transfer learning methods in the context of thermal face landmark detection: Siamese (shared) layers, Linear Layer Regularization (LLR), Linear Kernel Regularization (LKR), and Residual Parameter Transformations (RPT). These transfer learning approaches are compared against a baseline version of the network and an Active Appearance Model (AAM), both of which are trained only on thermal data. We achieve a 6.5% - 9.5% improvement on the DEVCOM ARL Multi-modal Thermal Face Dataset and a 4% improvement on the RWTH Aachen University Thermal Face Dataset over the baseline model. We show that LLR, LKR, and RPT all result in improved thermal face landmark detection performance compared to the baseline and AAM, demonstrating that transfer learning leveraging visible spectrum data improves thermal face landmarking.

The turbulent convective thermal transfer in channel heat exchangers (CHEs) is studied numerically via the CFD (Computational Fluid Dynamics) method. Deflectors are inserted on the hot bottom walls of the heat channel to enhance the hydrothermal characteristics. Various shapes of in-line deflectors are considered, namely: rectangular (a/b = 0.00), cascaded rectangular-triangular (a/b = 0.25, 0.50, and 0.75), and triangular (a/b = 1.00) shapes. From the obtained results, the inclusion of in-line deflectors with a/b = 0.75 has given the most significant thermal enhancement factor, which was higher than that for a/b = 0.00, 0.25, 0.50, and 1.00 by about 5.36, 5.06, 67.27, and 3.88%, respectively. Also, the in-line cascaded deflector’ case (a/b = 0.75) shows an increase in the enhancement factor (η) from 4 to 15.44% over the cases of one deflector (corrugated, rectangular, triangular, trapezoidal, arc, (+), S, 45° V, 45° W, T, Γ, and ε-shaped) or two deflectors (staggered corrugated). This highlights the effectiveness of in-line cascaded rectangular-triangular deflectors with a/b = 0.75 in improving the performance of the proposed exchanger for the conditions adopted.

The size effect on the thermal expansion of ZrO2/ZrW2O8 fabricated by the conventional thermal sintering process is investigated systematically. The small-sized sample with dense microstructure and few ZrW2O8 decomposition exhibits near-zero thermal expansion. While the microstructure and thermal expansion property of the large-sized sample deteriorates due to the serious decomposition of ZrW2O8. The finite element analysis is used to investigate the thermal transfer during the quenching, demonstrating that the smaller specific surface area (SSA) of the large-sized sample is the direct reason of the size effect, and the core causes are the instability of ZrW2O8 and the low thermal conductivity of the ZrO2/ZrW2O8. A thermal conductive pathway is further designed for the large-sized sample to verify and attenuate the size effect by increasing the SSA. The technique of ultra-low sintering temperature is urgently recommended to effectively solve the obstruction caused by the size effect.

The thermal management of MXene (Ti3C2Tx) plays a crucial role in its performance during various emerging applications. However, it is unclear how the inevitable oxidation structure of Ti3C2Tx influences the thermal dissipation, which might hinder its long-term performance and even create thermal damage. Here we show the thermal migration of a Ti3C2Tx flake with surface oxidation in film and water by combining ultrafast pump-probe technique with molecular dynamics (MD) simulations. The results demonstrate that the oxidation at the surface could facilitate interfacial thermal migration with shorter interfacial distances but would block the lateral thermal transfer. Besides, our results also identified that the slight oxidation could not obviously change the thermal decay of Ti3C2Tx nanosheets in water due to similar hydrogen bonds between water and interface. The research not only provides fundamental understanding of the thermal dissipation of MXene but also benefits for designing the thermal dissipation system to the MXene device.

The direct absorption solar collector (DASC) with nanofluids is a promising solar energy collection technology. However, various studies have focused on low-temperature applications of nanofluids, and the medium-temperature collection system that involves high-grade energy is always neglected. This study examines the photo-thermal properties of titanium nitride nanofluids with thermal transfer oil as the base fluids under different solar irradiation intensities. The irradiation surface layer reaches ∼160 °C under 5 suns, and a high-temperature gradient develops within the working fluid, producing a low collector photo-thermal efficiency that is below expectation. To overcome these disadvantages, the heat transfer change from thermal conduction to free convection within the fluid is achieved via reverse irradiation direct absorption solar collector (RI-DASC). The performance parameters of this RI-DASC, including the optical properties of nanofluids, steady-state equilibrium temperature, photo-thermal conversion efficiency, and energy utilization distribution are investigated in detail. The experimental results demonstrate that the temperature difference between the irradiation and non-irradiation surfaces for ∼0.005 wt% under 5000 kW/m2 are ∼50 °C and ∼10 °C in DASC and RI-DASC, respectively. The collector photothermal conversion efficiency of DASC (∼40%) is improved to ∼50% for RI-DASC, and the steady-state temperature is enhanced to 165 °C in RI-DASC.

Summary Efficient thermal energy storage technologies based on phase change materials (PCMs) that are capable of reversibly harvesting tremendous thermal energy during the isothermal phase transition have recently received unprecedented attention and are booming explosively in the exploitation of state-of-the-art multifunctional composite PCMs. In this regard, the smart integration of versatile metal oxides into PCMs has made significant contributions. However, a comprehensive review associated with the smart utilization of multifunctional metal oxides in PCMs is lacking. Here, we systematically summarize recent advances concerning the smart utilization of multifunctional metal oxides in PCMs for thermal storage, thermal transfer, energy conversion, and advanced versatile applications. This review aims to provide in-depth insights into the interactive relationships between multifunctional metal oxides and PCMs, thus providing a guide for the target design of high-performance multifunctional composite PCMs. We also highlight the current challenges and possible future research directions.

Modeling of pressure rise in SF6 GIS (Gas Insulated Switchgear) due to internal arc faults is a complex and challenging task, due to a large number of highly variable factors, which influence the whole process. This is especially the case in GIS with high rated short circuit currents, where the effects, such as material evaporation and erratic arc behavior, and consequently the pressure build-up rate, are much more pronounced. These severe conditions ultimately determine the design limits and must therefore be carefully investigated. The enhanced internal arc simulation model, presented in this paper, considers the impact of evaporation of different materials on gas properties and the pressure rise, as well as the dependence of released arc energy, thermal transfer and evaporation intensity on the state of gas. The experimental set-up and the test configuration, used to validate the calculation results, are evaluated and discussed. An evident finding, which is supported by measurements, is that the implemented improvements of the basic simulation model (introduced in the Technical Brochure 602 by the CIGRE working group A3.24) increase the prediction accuracy of GIS withstand performance during internal arc faults.

Controlling thermal anisotropy structure is important for emerging heat management applications such as thermal shield, thermal camouflage, and heat concentration. In this work, alternating stack epoxy composites (AECs) are prepared, inspired by the multilayer structure of an onion. Hexagonal boron nitride (h-BN) and expanded vermiculite (E-ver) are used as fillers in epoxy resin (Epon), taking as heat-dissipation layers and heat-insulation layers, respectively. Vertical heat isolation and local hotspot protection are endowed by the effective structural design. The temperature rise time of top surface is delayed by 404.2%, and the stabilized temperature is reduced by 10–15 °C (the bottom is heated to 120 °C); meanwhile, the whole composites are heated to 80 °C with good heat-dissipation performance, compared with those of homogeneous materials. There are two thermal phenomena synergistically in the anisotropy structure: excellent thermal protection when heating and good heat dissipation when cooling. Further, a thermal transfer mechanism of heat insulation and heat dissipation is analyzed based on numerical simulation and experiment. The multilayer epoxy composites are promising for the development of high-performance thermal products such as heat spreader, equipment cooling, and thermal hose.

This paper describes a new type of sensor that can monitor electrical signals for external stress or damage and heat transfer. It is composed of conductive pencil lead graphite, which is sensitive, affordable and easy-to-handle. This work was to detect mechanical damages in composites using Pencil Lead Drawn Paper Sensor (PLDPS). To measure electrical resistance (ER) via bending, by narrowing the distance between glass plates attached with PLDPD, ER increased stepwise while ER decreased with widening the distance reversely. The PLDPS can easily change the shape in a rectangular vortex. ER change responded well in tensile and flexural tests, while it showed leveling off under cyclic compression. Two-dimensional ER mapping was used during impact, drilling and heat transfer tests for detecting damage and thermal transfer. Compared to strain gauges, PLDPS can be applied inexpensively to detect damages successfully under various mechanical tests.

In the field of engineering, Biologically-inspired propulsion systems are getting the utmost importance. The theoretical analysis explores the effect of heterogeneous-homogeneous reactions on heat and thermal transfer analysis for incompressible Sutterby fluid. Using low Reynolds number and long wavelength assumptions, the governing system of equations of fluid transport problem is abridged and solved using the perturbation technique. The Nusselt number and skin friction coefficient are also incorporated in this contemplation. Particular attention is given to elastic parameters and Brinkman number and plotted their graph for velocity profile, temperature distribution, and concentration profile. It is initiated that momentum distribution profile is enhanced for higher values of elastic parameters, which is because less resistance occurs at the channel walls. The impact of heterogeneous and homogeneous reactions shows reverse bearing on the concentration field. Brinkman number (viscous dissipation effects) contributes to boosts the thermal profile for all the cases. Moreover, augmentation in skin friction is noticed by escalating the parametric values of damping and rigidity. The present study has a wide range of applications in biomedical engineering and biological functions i.e. electromagnetic peristaltic micro pumps.

We report microstructure, magnetocaloric effect and thermal transfer properties of highly orientated Nd0.8Pr0.2Co5 alloy prepared by powder metallurgical processing. Two spin-reorientation transitions of easy magnetization direction, easy plane to easy cone at TSR1 = 206 K, easy cone to easy axis at TSR2 = 242 K, are observed. The present textured alloy exhibits a rotating entropy change of 2.6 J/(kg·K) and refrigerant capacity of 155 J/kg under a magnetic field of 2 T, and high thermal conductivity of 11 W/(m·K). The sintered Nd0.8Pr0.2Co5 alloy with good combination of excellent magnetocaloric and thermal transfer properties are promising for scientific research and practical applications as room-temperature rotating magnetic refrigeration materials.

The continuous increase in the level of greenhouse gas (GHG) emissions and the increase in fuel prices are the main driving force to utilize various source of renewable energy. Among the clean energy technologies, solar energy is recognized as one of the most promising choice since it is free and provides clean and environmentally friendly energy. The objective of this paper is to improve the heating capabilities of evacuated tubes solar cookers that operates based on a closed loop thermosyphon action, and utilize thermal oil as the heating medium. Two identical evacuated tube solar cookers have been designed and built to study the influence of inserting metallic wires or nanographene particles on the thermal performance of the cooker. Also, the study was based on the thermal transfer of natural convection of the thermal oil movement within the evacuated tubes. The metallic wires and the nanographene particles are inserted inside the evacuated tube, which is filled with the heat exchange oil. One cooker is always tested without any modifications, i.e. taken as a reference point. The other cooker is the developed cooker, i.e. with wires or particles. Steel, aluminum and copper wires have been examined, and the number of wires has been varied between 5, 10 and 15. It has been found that the copper wires improve the rate of heat transfer compared with steel wires, aluminum wires and the nanographene particles. It has been also obtained that there is a critical number of wires, i.e. 10 wires, above that the rate of heat transfer by natural convection decreases and this is due to the increased friction which resists the natural convection currents. Finally, adding nanographene particles increases the viscosity of the oil, which increases the resistance to natural convection currents and consequently decreases the rate of heat transfer by natural convection.

Knowledge of borehole heat exchanger efficiency is necessary to optimize the design and performance of ground source heat pump systems. To evaluate the heat transfer performance of the wildly-used vertical U-pipe BHE, a novel one-dimensional numerical model was developed to assess the thermal transfer performance of the BHE from short-term (thermal response test) to long-term (a heating period) for engineering application. The proposed numerical model took into account the internal capacity of the borehole and the thermal resistance between the two legs of U-pipe which are often negligible in traditional one-dimensional numerical models. A thermal response test data from a case at Vorbasse, Denmark and the data from the TRNSYS model were used to validate the feasibility and reliability of the presented model. Then, both a short-term thermal response and a long-term temperature development of the fluid in BHE and surrounding ground were simulated and analyzed based on the model. Additionally, this study did a sensitivity analysis to see what effect the parameters have on the BHE efficiency. Hereby the impact of given assumptions can be able to estimate and the results can serve for the optimum design and control of GSHP systems.

Ceramic nanofibers with excellent thermal stability and low thermal conductivity are highly desired for high-temperature thermal insulation applications. However, the incompatibility of thermal stability and low thermal conductivity at high-temperatures largely limit the practical use of conventional single-phase ceramic nanofibers. Here, we report the preparation of multi-phase SiZrOC nanofiber membranes (NFMs) composed of amorphous SiOC and ZrO2 nanocrystals via electrospinning technique. The fabricated SiZrOC NFMs exhibited excellent high-temperature stability (∼1200 °C in Ar) and low thermal conductivity (∼0.1392 W m−1 K−1 at 1000 °C in N2). The decreased thermal conductivity is achieved through a synergistic mechanism, that the multi-phase interfaces and the ZrO2 nanocrystals create thermal transfer barriers to reduce the heat transfer, whilst the SiOC phase effectively suppresses radiative heat transfer. This unique combination of amorphous SiOC and ZrO2 nanocrystals provides a novel strategy to prepare high-performance thermal insulation materials, and the obtained SiZrOC NFMs are promising high-temperature thermal insulation materials.

Electrospun form-stable phase change materials (FSPCMs) emit 85–90 wt% of organic solvents and suffer from inherent poor thermal conductivity. We developed eco-friendly PEG/PVA/Ag composite fiber-based FSPCM by electrospinning an aqueous solution of PEG/PVA/AgNO3, followed by ultraviolet (UV) irradiation directly. The composite fibers with 45 wt% PEG showed an optimal smooth, cylindrical, and uniform morphology and a diameter of 80–300 nm. The UV irradiation process accelerating the formation of face-centered cubic Ag nanoparticles (AgNPs) and showed no significant effect on the morphology of the composite fibers. The composite fibers melted at 45.9 °C and had a latent heat of 67.5 J/g, which is comparable to that of the previously reported phase-change fibers. They exhibited robust thermal, chemical, and morphological stability after 2000 melting/cooling cycles. In addition, they also showed significantly high thermal energy transfer efficiency because of the presence of in-situ reduced AgNPs. These NPs acted as heat conductive bridges and facilitated the formation of continuous heat conduction networks or efficient percolating pathways for heat flow. Moreover, the electrospinning process did not require any organic solvent, and hence was eco-friendly, non-hazardous, and cost-effective. Therefore, it is suitable for large-scale thermal energy storage and environmental protection applications.

Dielectric waveguides have potential as transmission lines in subterahertz (sub-THz) applications due to their low-loss. A new application of a rectangular dielectric waveguide (RDW) for a THz superconducting receiver system for radio astronomy is investigated and demonstrated for the first time. The RDW can be used to transmit sub-THz local oscillator (LO) signals into the cryostat for driving the superconductor insulator superconductor mixer, with very low heat transfer. A series of RDWs with different lengths are fabricated. The measured average attenuation constants of the RDW are 0.034 and 0.069 dB/mm at 3.4 and 300 K measurement environments over 240–300 GHz, respectively. The double-sideband system noise temperature of the receiver system is also measured. With this LO signal feeding system, there is only 0.69 mW thermal transfer power from the 300 to the 3.4 K cold stage. Compared to traditional pumping signal feeding schemes, such as the horn-to-horn structure and beam splitter method, this approach outperforms the traditional schemes in terms of feeding flexibility, insertion loss, and thermal isolation for the cryostat. The proposed RDW can be widely applied to superconducting receivers for radio astronomy in the future.

Advanced solar thermal devices with a high performance/cost ratio is a major concern nowadays. In this paper, we investigate the energetic efficiency of a new concept based on a direct coupling of a solar water heater with a thermoelectric module, in order to exploit the maximum of the solar spectrum, produce heat and electricity at the same time and improve the normal solar collector efficiency. An unsteady-state mathematical model of the system is presented in details to describe the system behavior. Using state-of-the-art thermal transfer calculations, the differential equations of the global system were established and solved numerically. The system model is solved using MATLAB program, while the finite difference method is based. Our major finding shows that the new hybrid system significantly improves the storage process by controlling the flow rate according to the concentration ratio variation. This flow rate attains a capacity of 1200.453 L/day, for 0.92 × 1.9 × 0.05 m3 a collector tilted at 30° under 20 suns, and produces a significant additional electrical energy about 10.41 Watts, which is very promising for future thermal/electrical applications.

Plasmonic aluminum nanoparticles have emerged as an exciting new materials platform, due to the high natural abundance of aluminum, their ability to be synthesized in the solution phase, and the potential of these materials to be used for photocatalysis and sensing. However, the photothermal properties of solution-processed aluminum nanoparticles, particularly how phonon energy transfer depends on particle size and surface properties, are critical for practical applications and are currently unexplored. Here, we use transient absorption spectroscopy, in combination with simulations of phonon and thermal energy dissipation, to investigate the photoresponses of aluminum nanoparticles of various diameters (54, 85, 121, and 144 nm) suspended in 2-propanol. Fast thermal transfer rates to the solvent (170-280 ps) are observed for particles of all sizes and are facilitated by native oxide coverage, as verified with a two-interface thermal energy-transfer model. Size-dependent phonon “breathing”/vibrational modes...

In this work, we solved the differential equations of mass and energy balance describing the n-hexane adsorption and desorption process in 5A zeolite under non-isothermal and non-adiabatic conditions. The solution provided a theoretical model that may be used to determine the significance of the mass and thermal transfer effects applied to transient adsorption. We validated numerical results with experimental data from the literature, finding the n-hexane adsorption to be exothermic. Because the diffusion in the system is fast, the breakthrough curves showed the typical form of thermal limitation. We found desorption depends on the desorbent fluid and feed rate. We evaluated the stability of the numerical method using the eigenvalues of the matrix system. Hence, the computational code developed may be used to simulate real operating conditions for the adsorption/desorption process of gases with porous adsorbents once the process parameters are known.