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2D thermal radiation distribution together with I–V and L–I characteristics has been measured and analyzed in forward and reverse biased p–n heterostructures based on InAs0.9Sb0.1 and grown onto n-InAs substrates. The measurements revealed a sufficient difference in the temperature distribution onto the sample surface at forward and reverse bias, which is explained by an impact of heat pump operation initiated by an electron–phonon interaction at the p–n junction and diode contacts at U < 0. [ABSTRACT FROM AUTHOR]

X-ray self-heating is a common by-product of X-ray Free Electron Laser (XFEL) techniques that can affect targets, optics, and other irradiated materials. Diagnosis of heating and induced changes in samples may be performed using the x-ray beam itself as a probe. However, the relationship between conditions created by and inferred from x-ray irradiation is unclear and may be highly dependent on the material system under consideration. Here, we report on a simple case study of a titanium foil irradiated, heated, and probed by a MHz XFEL pulse train at 18.1 keV delivered by the European XFEL using measured x-ray diffraction to determine temperature and finite element analysis to interpret the experimental data. We find a complex relationship between apparent temperatures and sample temperature distributions that must be accounted for to adequately interpret the data, including beam averaging effects, multivalued temperatures due to sample phase transitions, and jumps and gaps in the observable temperature near phase transformations. The results have implications for studies employing x-ray probing of systems with large temperature gradients, particularly where these gradients are produced by the beam itself. Finally, this study shows the potential complexity of studying nonlinear sample behavior, such as phase transformations, where biasing effects of temperature gradients can become paramount, precluding clear observation of true transformation conditions. [ABSTRACT FROM AUTHOR]

One of the main methods for obtaining information about the generation of sound pulses in metals is to measure the reflection coefficient of a probe wave. Various theoretical models are used to interpret the results of measuring the contribution to reflection coefficient Δ R (t) due to sound-generated displacements of lattice atoms. The purpose of this paper is to establish the degree of accuracy of models used in the case of sound generation in thin films exposed to a femtosecond pulse. It is shown below that the assumption of uniform heating used for thin films is justified if the film thickness is less than the film heating depth and for thicker films at times greater than the film heating time over the entire thickness. For optically thick films, a relatively simple expression for the field can be used. If the film thickness is less than the skin layer depth of the pump field, then it is necessary to consider the field reflection from a substrate. In this case, depending on the optical properties of the metal and the substrate, taking into account reflection can lead to either an increase or a decrease in Δ R (t). It has been established that if the skin layer at the frequency of probe radiation is less than the film heating depth, then taking into account temperature gradients in the equation for the displacement of lattice atoms leads to small changes in Δ R (t). This makes it possible to significantly simplify calculations of the displacement of lattice atoms. [ABSTRACT FROM AUTHOR]

Purpose: To measure the surface temperature distribution after using a CO2 laser to heat titanium dental implants via different power settings, application intervals, and irradiation times. Materials and Methods: A total of 10 tissue-level titanium implants (Screw-Line Promote Plus, Camlog; 4.3 × 11 mm) were placed (EpoFix, Struers) and irradiated with a CO2 laser (Denta 2, Lutronic) with a wavelength of 10.6 µm at power levels of 4 watts (Group 1), 6 watts (Group 2), 8 watts (Group 3), and 10 watts (Group 4). A continuous beam mode (setting I) and noncontinuous beam modes with 5-second (setting II) and 10-second (setting III) pause intervals were used. For each setting, a total irradiation time of 50 seconds was used and repeated 10 times. The temperature was measured using external thermocouple (Testo) in contact with the implant surface at the implant shoulder, middle, and apex. A linear regression model was used to analyze the data (P = .05). Results: Setting I demonstrated the most rapid increase in implant surface temperature in all three test sites as well as the greatest total temperature at 50 seconds of irradiation time. The greater the pause interval (settings II and III) during the 50 seconds of irradiation, the lower the rate of temperature increase as well as the total temperature in all three test sites and with all power levels. The average temperature difference between the apex and shoulder site was significant for setting III for all groups, but not for any groups in settings I and II. Conclusions: Heating the internal aspect of an implant with a CO2 laser produces different temperature distribution profiles depending on the laser power level and the application interval. Laser-beam irradiation leads to a temperature gradient, which is greatest at the implant apex and smallest at the implant shoulder. [ABSTRACT FROM AUTHOR]

Magnetic and magnetocaloric properties of L a 0.85 S r 0.15 M n 0.99 F e 0.01 O 3 perovskite oxides are investigated in the framework of the mean-field theory with a goal to develop a comprehensive model with parameters that can be used to optimize the caloric performances for cooling applications. Using the experimental magnetic isotherms M(H,T), we estimate and compare the exchange parameter (λ) , the saturation magnetization (M 0) , the total angular momentum (J) , and the gyromagnetic factor (g) for two different samples annealed at 1170 and 1250 °C. These parameters are used, in turn, in the simulation of the magnetic and the magnetocaloric properties of these L a 0.85 S r 0.15 M n 0.99 F e 0.01 O 3 compounds assuming imperfect samples with compositional and/or magnetic inhomogeneities. For this purpose, a Gaussian distribution of the Curie temperature is assumed. The temperature dependence of the magnetic entropy change, − Δ S M (T) , resulting from an applied field variation is simulated for both samples. The selected distribution captures the rounding of the − Δ S M (T) peak at its maximum and its broadening with growth conditions, features that are constantly observed in many bulk polycrystalline compounds. [ABSTRACT FROM AUTHOR]

Numerical methods for analyzing diffusion phenomena involving strong discontinuities and complicated interfaces are of great scientific and technical importance. In this paper, we extend the existing step-balanced random walk, which overcomes the problem of detailed balance of a random walker in three-dimensional (3D), diffusion-tensor discontinuous systems, to particle density (ρ) discontinuous systems, and introduce volumetric heat capacity C and temperature T by considering ρ as heat density, i.e., ρ = C T , to apply it to thermal problems. Two types of thermophysical simulations are demonstrated: one is steady-state heat flow due to a temperature difference at the end surfaces on a two-phase slab model unit cell with periodic boundary conditions; the other is the time variation of temperature distribution due to heat diffusion from a point heat source in a repeated two-phase slab model with no periodic boundary conditions. We see the correct behavior of heat and temperature expected in 3D discontinuous systems composed of two phases with anisotropic thermal conductivity. The applicability to problems other than pure diffusion and the limitations of the method are also discussed. [ABSTRACT FROM AUTHOR]

We report the development of a novel variant of cavity ringdown polarimetry using a continuous-wave laser operating at 532 nm for highly precise chiroptical activity and magnetometry measurements. The key methodology of the apparatus relies upon the external modulation of the laser frequency at the frequency splitting between non-degenerate left- and right-circularly polarized cavity modes. The method is demonstrated by the evaluation of the Verdet constants of crystalline CeF3 and fused silica, in addition to the observation of gas- and solution-phase optical rotations of selected chiral molecules. Specifically, optical rotations of (i) vapors of α-pinene and R-(+)-limonene, (ii) mutarotating D-glucose in water, and (iii) acidified L-histidine solutions are determined. The detection sensitivities for the gas- and solution-phase chiral activity measurements are ∼ 30 and ∼ 120 μdeg over a 30 s detection period per cavity round trip pass, respectively. Furthermore, the measured optical rotations for R-(+)-limonene are compared with computations performed using the TURBOMOLE quantum chemistry package. The experimentally observed optically rotatory dispersion of this cyclic monoterpene was thus rationalized via a consideration of its room temperature conformer distribution as determined by the aforementioned single-point energy calculations. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations have been widely used in exploring the nucleation behavior of many systems, including gas hydrates. Gas hydrates are ice-like solids in which gas molecules are trapped in water cages. During hydrate formation, a considerable amount of heat is released, and previous work has reported that the choice of temperature control scheme may affect the behavior of hydrate formation. The origins of this effect have remained an open question. To address this question, extensive NVE simulations and thermostatted (NPT and NVT) simulations with different temperature coupling strengths have been performed and compared for systems where a water nanodroplet is immersed in a H2S liquid. Detailed analysis of the hydrate structures and their mechanisms of formation has been carried out. Slower nucleation rates in NVE simulations in comparison to NPT simulations have been observed in agreement with previous studies. Probability distributions for various temperature measures along with their spatial distributions have been examined. Interestingly, a comparison of these temperature distributions reveals a small yet noticeable difference in the widths of the distributions for water. The somewhat reduced fluctuations in the temperature for the water species in the NVE simulations appear to be responsible for reducing the hydrate nucleation rate. We further conjecture that the NVE-impeded nucleation rate may be the result of the finite size of the surroundings (here the liquid H2S portion of the system). Additionally, a local spatial temperature gradient arising from the heat released during hydrate formation could not be detected. [ABSTRACT FROM AUTHOR]

In water-guided laser technology, the stability of water jets is crucial to ensure the efficient transmission of laser energy. However, the thermal effects generated when high-power lasers are coupled with water jets are bound to impact the stability of the water jets, thus becoming a critical issue that restricts the development of high-power water-guided laser technology. In addressing this issue, this paper establishes a temperature model for coupling high-power lasers with water jets. Subsequently, with validation of the model's effectiveness through experimental data, simulations are conducted to analyze the temperature distribution within the water jet. During the simulation process, lasers with different parameters were coupled with water jets to analyze the temperature variation law of the water jets. Additionally, the maximum laser power coupled with water jets of different lengths was solved. Based on the calculated temperature values of the water jet, simulate the evolution of its profile over time when it has an initial temperature gradient. Simultaneously, perform a three-dimensional reconstruction of the obtained perturbed profile and conduct ray tracing to analyze the laser's transmission losses within the perturbed profile. Finally, high-speed cameras are utilized to capture the profile of the water jet, validating the laser-induced fragmentation behavior in the water jet. The research findings will provide a significant reference value for selecting laser parameters and controlling thermal effects in water-guided high-power technology. [ABSTRACT FROM AUTHOR]

With the wide application of thermoelastic structures in industries such as the aerospace field, the problem of topology optimization of thermoelastic structures has become a very common and important research topic. It is well known that the thermal environment has a non‐negligible influence on the dynamic performance of structures. However, few people consider the influence of the thermal environment on structural stiffness in thermoelastic dynamic topology optimization. In practical engineering applications, the influence of the environment on the structure performance should be considered to obtain the optimal structure. In this paper, we focus on the problem of dynamic topology optimization considering the effect of non‐uniform temperature fields on structural stiffness. The influence of non‐uniform temperature fields adds on structural stiffness to the topology optimization of thermoelastic dynamic for the first time, thereby comprehensively addressing its effects on structural stiffness in the context of dynamic topology optimization under harmonic vibration and transient load. The proposed method begins by computing the distribution of the non‐uniform temperature field within the structure. Subsequently, thermal stresses in the structure are determined through the application of thermoelastic theory. The geometric stiffness matrix of the structure is then calculated using finite element theory. The dynamic topology optimization model, employing a variable density approach, is established in conjunction with the dynamic compliance design objective. Sensitivity analysis is conducted through the adjoint method, and the design variables are updated utilizing the method of moving asymptotes. Numerical examples are presented to validate the efficacy of the proposed method and obtain the influence of different factors on the optimization results. The results show that the dynamic compliance of the optimized structure increases with increasing heat flux. For the optimization under harmonic vibration, the optimization results obtained by different external excitation frequencies are significantly different. For transient optimization, the study discovers that the optimization present transient effect. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the analysis of Oldroyd 8-constant fluid flow with nanoparticle suspension via a porous media during the coating of wire is carried out. A constant magnetic field and electrically conducting fluid are considered. The governing equations thus obtained for the present model are converted to nonlinear differential equations using variables in dimensionless form. These equations are analytically solved. The influence of some parameters, like magnetic field parameter, porosity parameter, dilatant constant, pseudo-plastic constant and Brinkman number on velocity and temperature distributions are discussed graphically. For fluctuating viscosity, two models, Reynold's and Vogel's are considered. It is observed that the magnetic parameter and the Brinkman number increase, both temperature and velocity profiles show a retarding effect in both Reynold's and Vogel's models. [ABSTRACT FROM AUTHOR]

Insufficient handling of spontaneous combustion in coal piles arises from the influence of natural wind during the piling process, resulting in the displacement of the heat source. To investigate the impact of wind flow on heat source movement in simulated coal piles under varying wind velocities, an experimental stage was established. The research findings elucidate that both normal and tangential winds exert an influence on the heat source position, with normal winds exhibiting a greater effect than tangential winds. The relationship between heat source position speed and wind speed magnitude follows a common fitting function under both wind conditions. Specifically, the speed of the heat source at the edge position demonstrates a linear correlation with the magnitude of wind speed, while the speed of the heat source at the center position conforms to a quadratic function with the wind speed magnitude. The heat source moves at a distance of 0.8 cm to 5.3 cm on the Y = 0 tangent, corresponding to a moving speed of 0.03 cm/min to 0.18 cm/min. On theY = −20 tangent, the heat source moves at a distance of 2.1 cm to 8.1 cm, corresponding to a moving speed of 0.07 cm/min to 0.27 cm/min. Moreover, the study reveals that the influence on heat source movement at the center of the simulated coal pile diminishes as wind speed decreases under both wind conditions. These research findings provide a theoretical foundation for managing spontaneous combustion in coal piles and offer insights into precise management of heat source positions within coal piles. [ABSTRACT FROM AUTHOR]

The implementation of third order shear deformation theory using finite element method is presented in the current article to analyze the stability characteristics of porous magneto-electro-elastic (MEE) plates. This study aims to present the obscure behavior of FGMEE plate considering the loading to be hygrothermal in nature for buckling. Several temperature and porosity distribution are involved in this study in order to understand their influence on the buckling characteristics. The material properties of the porous MEE plate are assumed to vary continuously throughout its thickness according to rule of mixture. The porosity is considered as a locally distributed density estimated using the modified power law. The effect of temperature and moisture on buckling of MEE plates is of interest in this study. Skewness is incorporated through a transformation matrix to account for the angle. The stability characteristics of the porous FGMEE plate are examined under thermal, hygrothermal, electric, and magnetic loads to determine the critical buckling temperature. The influence of various variables, such as porosity, porosity distribution, and porosity volume, on the buckling behavior is extensively studied to realize that as porosity increases, the critical buckling temperature decreases in both load forms and noticed to be highest in Vo and Vx porosity distribution. Skew angle directly influenced the critical buckling temperature and was seen to be increasing with increase in skew angle between the plates. The study is also extended to assess the effect of geometrical parameters, such as aspect ratio, thickness ratio, and boundary conditions, on the stability characteristics that established an inverse relation between the parameters. [ABSTRACT FROM AUTHOR]

Microwave energy is based on creating heat in the structure by creating vibrations in the moisture in the product used. In drying processes, drying kinetics, energy consumption, quality, and so on features are evaluated based on the temperature equivalent of the heat created by the heat source in the product. For this reason, the temperature value formed in the product in microwave drying processes is important. In this study, the effects of microwave drying powers (180, 540, 720, and 900 W) on the surface temperature profile, drying kinetics, thermophysical properties, and color values of peach slices were investigated. For drying processes performed at 180, 540, 720, and 900 W microwave powers, the surface temperatures of peach slices were 34.5–83.40, 49.60–89.60, 55.90–94.06, and 68.20–145.20°C, respectively. Effective diffusion values varied between 1.01 × 10−7 and 2.12 × 10−7, and the activation energy value was measured as 20.73 kJ/mol. Specific heat values varied between 871.62 and 838.21 J/kg K, density values varied between 839.41 and 697.93 kg/m3, thermal diffusivity values varied between 5.69 × 10−7 and 2.344 × 10−7 m2/s and thermal conductance values ranged between 0.44 and 0.08 W/m K. As compared to the fresh fruits, the best color values of dried material were achieved at 720 W microwave power. It is recommended to determine the microwave drying power value well and to determine the drying kinetic properties of each agricultural product specifically for the product. [ABSTRACT FROM AUTHOR]

A proton exchange membrane electrolysis cell (PEMEC) is a promising method for hydrogen production. However, the flow-field structure of PEMEC presently has the disadvantages of poor fluidity and uneven heat distribution. A titanium mesh flow field was, therefore, proposed to replace the traditional parallel channel structure. A single-cell test platform was set up in this study, and a new in situ temperature measurement method was proposed. The temperature variation and electrolysis performance of titanium mesh structures were studied experimentally. The results demonstrated that the polarization performance of the titanium mesh structure was enhanced compared to that of the parallel structure. In situ measurements showed that the temperature increased and the voltage decreased with an increase in the inlet temperature and flow rate, with the rate of change gradually decreasing. The temperature distribution in the titanium mesh structure was more uniform than that in the parallel structure. When the current density and inlet flow rate step were changed, the voltage stabilized within 12 s. After 100 h of operation, the voltage of the parallel structure and titanium mesh structure increased by 0.12 V and 0.07 V, respectively, indicating good dynamic and duration performance. • A novel PEMEC structure with a Ti mesh flow field structure is proposed. • 18 thermocouples are utilized to realize in situ temperature measurement. • The temperature distribution of the titanium mesh structure is more uniform. • The voltage dynamic response speed of PEMEC is within 12 s. • After 100 h of operation, the voltage of Ti mesh structure increased by 0.07 V. [ABSTRACT FROM AUTHOR]

This study investigates the effects of complete slip conditions on the peristaltic pumping of a Casson nanofluid with suction and injection in a vertical due to the crucial role that nano liquids play in a variety of technological and medical fields, particularly in peristalsis, a mechanism that transports liquids. The Casson fluid belongs to a class of non-Newtonian fluids that, through a particular stress threshold magnitude, exhibit elastic solid behavior before changing to liquid behavior. These fluids have several uses in engineering, food preparation, drilling and other fields. After establishing the governing conservation equations, the resulting flow model is effectively simulated using the realistic assumptions of a long wavelength and a low Reynolds number. The temperature distributions, velocity, pressure rate per wavelength and nanoparticle concentration of the resulting flow problem have been solved analytically. The effects of all physical factors on temperature, velocity, concentration fields, pressure rate, frictional force and pressure gradient are graphically examined using Wolfram MATHEMATICA software. There are a variety of biofluids that cannot be classified as liquids. For example, blood contains WBC, RBC and plasma. It is essential to model biofluids (blood) as nanofluids given the physical properties of these biofluids. According to reports, one of the finest yield stress models is the Casson model, and blood exhibits a similar behavior. We took these facts into consideration when thinking about Casson nanofluid flow in a vertical layer under peristalsis. Additionally, the suction and injection mechanisms can be used to represent the exchange of carbon dioxide in bold. In order to understand how blood flows through small blood vessels, this model must be examined. The obtained results show that the Newtonian case and those found in the literature have a very good agreement. Since the liquid moves faster and more effectively when the value is increased, it becomes clear that this increases the strength of the velocity.  In other words, nanoperistaltic pumps can maintain a pressure differential that increases or decreases at all operating flow rates with an increasing thermophoresis effect. Furthermore, it is obvious that the pressure reduction in a Casson fluid is greater than in a Newtonian fluid. [ABSTRACT FROM AUTHOR]

The temperature distribution has a significant influence on the performance and lifespan of proton exchange membrane fuel cell (PEMFC) stacks. However, analyzing the temperature distribution of large PEMFC stacks is challenging and has been rarely conducted. In this study, a simplified model of a large PEMFC stack is developed using computational fluid dynamics (CFD) methods, which includes 300 cells and 60 cooling plates. The influence of cooling parameters, including configurations, dimension and flow rate, is discussed. The study indicates that U-type stack exhibits better temperature uniformity than Z-type stack. Increasing the coolant flow rate can effectively reduce the stack temperature. The study proposes a modified cooling design, which effectively reduces the heat accumulation at the end of the stack. Lastly, a comparison between traditional serpentine channels and porous foam metal flow fields reveals that the porous foam metal flow field exhibits superior thermal management characteristics. The results can offer insights for thermal management of large-scale PEMFC stacks. • A simplified model of water-cooled large-scale PEMFC stack with 300 single cells is established. • The effects of cooling parameters, including configurations, dimension and flow rate, are discussed. • U-type stack exhibits better temperature uniformity than Z-type stack. • The modified cooling design with one cooling plate at both ends can reduce the heat accumulation at the end of the stack. [ABSTRACT FROM AUTHOR]

–High-temperature Solid Oxide Electrolysis Cell (SOEC) may generate excessive local temperature differences during transient operation, which can affect its electrochemical performance and thermal safety. Therefore, this study develops a localized temperature difference control strategy based on a temperature observer, which can avoid a series of issues such as sealing failure caused by the installation of thermocouples. Firstly, a discrete thermoelectric coupling model was developed, dividing SOEC along the flow direction into five nodes. This model was rigorously validated and refined using actual sensor data, including voltage and outlet temperature. Subsequently, a temperature observer for the SOEC's local temperature distribution was designed using a NARX neural network. Finally, an adaptive PID algorithm-based local temperature difference controller was developed, employing the local temperature data provided by the observer as the controlled variable. The effectiveness of the controller was verified under conditions such as excessive electrolysis current and air leakage. The test results show that the response time of the open-loop NARX observer is only 2 s, with the observation error controlled within 0.09K, providing a stable and reliable control variable for the local temperature difference controller. The local temperature difference control strategy effectively ensures that all thermal safety indicators remain within the specified range, demonstrating higher safety and reliability compared to traditional inlet and outlet temperature difference control methods. • A discrete thermoelectric coupling model for the SOEC was developed and subsequently validated by experiments. • A temperature observer based on NARX neural network was designed to eliminate the need for thermocouple. • A local temperature difference control strategy based on adaptive PID algorithm was proposed to enhance SOEC thermal safety. [ABSTRACT FROM AUTHOR]

Ammonia (NH 3) dissociation is of an initial and very important step during its combustion process. This study therefore systematically investigates the effect of reaction temperature (650–950 °C), fluidisation number (0.83–2.50) and static bed depth (0–25 mm) on NH 3 dissociation in a laboratory-scale Bubbling Fluidised Bed (BFB). By analysing the concentrations of H 2 and N 2 in the effluent using gas chromatography, results show that the conversion ratio of NH 3 in BFB was merely 0.26%–0.29% at 650 °C but increased significantly to 18.1%–25.3% at 950 °C. This highlights the importance of temperature in promoting NH 3 dissociation. However, as fluidisation number increased from 1.0 to 2.5, attributing to a decrease in gas – solid contact time, the conversion ratio of NH 3 decreased correspondingly from the highest 20.7%–5.7%. Moreover, as static bed depth increased from 15 mm to 25 mm, the conversion ratio of NH 3 increased slightly from 21.5% to 26.8%, both of which were found to be higher than that without bed particles. Clearly, NH 3 dissociation is enhanced by the bed material depth but is also dependent on the gas – solid contact time. In addition, by measuring the temperature distribution in the BFB reactor, a temperature drop of ca. 20 °C near the distributor was confirmed, showing a strong effect of endothermicity during NH 3 dissociation. These would provide an improved comprehension on the mechanisms of NH 3 dissociation and offer theoretical guidance for optimising the combustion processes in BFB burning NH 3. [Display omitted] • NH 3 dissociation at different temperatures and fluidisation numbers in BFB studied. • NH 3 conversion increased with temperature due to enhanced kinetic and heat transfer. • Increasing bed depth promotes NH 3 dissociation by increasing gas-solid contact time. • NH 3 conversion was the highest at incipient fluidisation but decreased at higher FN. • The endothermic NH 3 dissociation decreases bed temperature and hinders conversion. [ABSTRACT FROM AUTHOR]

Respiratory infections are currently understood to be caused by pathogens released through the nose or mouth of an infected individual, and subsequently transmitted to susceptible hosts. These pathogens are enclosed in liquid particles that are aerosolized from the respiratory tract during activities such as breathing, speaking, sneezing, and coughing. These particles vary widely in size, ranging from submicron to several microns. While past research has largely overlooked the human respiratory system, recent analysis has revealed that the actual structure of the nasal cavity significantly influences the prediction of aerosol transmission during exhalation. In this study, computational fluid dynamics (CFD) simulations were conducted to analyze the aerosol transmission generated during exhalation from the nasal and oral cavities. Realistic nasal and oral cavity structures were taken into account, and authentic temperature distributions were applied to the surfaces. Additionally, inhalation conditions for susceptible individuals were established to evaluate the risk of inhalation-generated exposure. Through various simulation scenarios, we separately discussed the impact of environmental wind speed, separation distance, and exhalation flow rate. The simulation results indicate that environmental wind amplifies the complexity of the flow field and the transmission and deposition of particles between two individuals. Under ambient wind velocities of 0.5 m/s and 1 m/s, it was observed that over 80% of the particles with a diameter of 1 µm inhaled through the nasal cavity accounted for the total deposition on the infected individual. Furthermore, high exhalation flow rates exhibited higher deposition ratios at close distances, in line with our expectations. Therefore, it is advisable to minimize close contact as much as possible during periods of frequent respiratory infections, and to wear masks in order to reduce the risk of inhalation exposure. Implications: During the activities such as breathing, speaking, sneezing, and coughing, liquid particles containing pathogens are aerosolized from the respiratory tract and are released from nose or mouth through the nebulization. In this study, we investigated the transmission of aerosols from human exhalation in the outdoor environment, innovatively taking the real oral-nasal structure and the active inhalation of vulnerable people into consideration, and explored the human-to-human transmission of respiratory viruses. The results are beneficial for public health assessment and policy development. [ABSTRACT FROM AUTHOR]

The solution of one-dimensional nonlinear problem of stationary heat conduction in a dielectric layer with volumetric energy release at a constant difference in electric potentials on the curvilinear heat transfer surfaces, bounding the layer, is presented in a closed analytical form. The analytical form of the solution, being a set of integral relations, allows to conduct a quantitative analysis of the influence of governing parameters on temperature state of the layer, including the one preceding the occurrence of thermal dielectric breakdown. Such form of solution can be used to test the results of numerical solution of this problem. An example of quantitative analysis of the presented integral relations is given. Approximate formulas that make it possible to find estimates of the parameters of temperature state of dielectric layer and the maximum difference in electrical potentials, preceding the thermal breakdown of the layer, are obtained. [ABSTRACT FROM AUTHOR]

This article examines the bioconvection impact on Marangoni convection flow of nanofluid past a stretching cylinder. The effects of Brownian motion and thermophoresis are considered. The impact of temperature-based thermal conductivity and diffusivity is taken into account. A multitude of nanofluid technologies was used in areas of electronics, automobile, and atomic science, effective heat dispersion and increased heat evaporation have been identified. Thermal transmission is necessary. The heat transfer rate can be increased due to the thermal conductivity of nanofluid. Due to the property of nanofluid, it uses in many applications in manufacturing, medical, and nanoelectromechanical systems. The system of PDEs is converted to ODEs by using similarities transformation. Resultant ODEs are solved by the bvp4c approach in MATLAB. Velocity field, temperature distribution, concentration and microorganism profiles are affected by flow controlling parameters. The graphical and numerical results are elaborated. The results of the current analysis designates that the velocity of a fluid is reduced for the magnetic parameter. The microorganism field shrinks when the Peclet parameter and the bio convectional Lewis parameter are increased. Furthermore, the microorganism profile is reduced by raising the Marangoni number and Marangoni ratio parameter. [ABSTRACT FROM AUTHOR]

The Lamb-type waves in the homogeneous isotropic thermally conducting porous plate immersed in the inviscid fluid in the context of the Lord and Shulman theory of thermoelasticity are studied. To seek out solutions, the Helmholtz decomposition technique is used. Plugging the solutions in the appropriate boundary conditions, a secular equation is derived for the symmetric and anti-symmetric family of wave modes. It is found that shear horizontal wave mode uncouples itself from the coupled system of waves. Particular cases of the secular equation have also been deduced in the absence of fluid or certain energy fields such as thermal field and/or volume fractional field. Different regions of the secular equation are obtained. Furthermore, these regions have been led to peculiar cases such as short-wavelength, and long-wavelength waves. The amplitude of displacement, change in volume fraction field, and temperature distribution is computed and compared with prior accomplished research work. The numerical computations are carried out for a porous magnesium plate immersed in water to understand the behavioral pattern of waves, and the various graphs are plotted to defend the analytical findings. [ABSTRACT FROM AUTHOR]

In this study, a developed two-dimensional microwave-cutting Al2O3 ceramics model along with the thermodynamic and thermal stress is presented, considering the thermal conduction, convection, and radiation effects. The extended finite element method (XFEM) is innovatively proposed to evaluate the temperature field and stress field distribution. The temperature and stress distributions under different time, power, and scanning velocity are obtained by simulation. The results indicate that there is a positive correlation between temperature and microwave power. Nevertheless, the temperature registers a negative relationship with the scanning velocity. As for the higher velocity, the highest temperatures of microwave-cutting Al2O3 ceramics are nearly the same, and the higher velocity is not an indispensable factor in the temperature profiles of microwave-cutting ceramics. Notably, compressive stress is the primary interaction that induces crack propagation. At the front of the crack is the compressive stress and the location where the crack grows is the tensile stress. The location of the compressive stress is the direction of its crack propagation and the tensile stress causes it to crack. Finally, the study would not only provide a theoretical reference, but also pave the way for the national defense, aerospace, and semiconductor industries in the near future. [ABSTRACT FROM AUTHOR]

The pursuit of energy-efficient and uniform processing drives ongoing research in microwave-assisted freeze drying (MWFD). While microwave application is acknowledged for its potential to reduce energy consumption of freeze drying applications, it introduces new challenges to gentle processing, particularly in achieving uniformity of processing due to the inherent uneven microwave field distribution in the drying chamber. This study investigates the impact of maximum drying temperature (Tmax) and microwave power input on energy consumption and uniformity in temperature-controlled MWFD. Experimental results reveal that shorter equilibration times associated with higher Tmax significantly amplify the inhomogeneity of temperature distribution. Further, higher Tmax was associated with a significant reduction in total energy demand of MWFD. Despite noticeable trends, microwave power input did not yield statistically significant differences in energy consumption or uniformity. The limited range of explored values, combined with the temperature-controlled nature of the process, may have rendered a potential influence of microwave power input negligible. This research elucidates the extent of inhomogeneity in MWFD, with implications for achieving uniform, gentle drying. It highlights the critical role of temperature control in MWFD. The study contributes to advancing the understanding of optimal processing in temperature-controlled MWFD. [ABSTRACT FROM AUTHOR]

Understanding the thermal conditions inside a burning cigarette is a top priority for controlling chemical emissions and cigarette design. Since experimental methods are difficult to observe in depth, this paper starts from the perspective of numerical simulation and models the structure of the tobacco distribution of the cigarette, integrating the end surface ignition model, puffing model, chemical reaction model, heat and mass transfer and diffusion model have established a three-dimensional comprehensive model that can represent the changes in combustion cone morphology during cigarette combustion. The model covers chemical reaction and mass transfer as well as generation, flow and reaction mechanism. The simulation results show that the model can better predict the temperature distribution, component distribution and combustion cone morphology changes during cigarette smoking and combustion. It provides an effective means for in-depth research on cigarette combustion. [ABSTRACT FROM AUTHOR]

Electric vehicles encounter significant challenges in colder climates due to reduced battery efficiency at low temperatures and increased electricity demand for cabin heating, which impacts vehicle propulsion. This study aims to address these challenges by implementing a thermal management system utilizing Phase Change Materials (PCMs) and validating the performance of a Multilayer Perceptron (MLP) model in predicting PCMs behavior and battery temperature distributions. The study employs an MLP model trained with 160 samples of diverse heat inputs, including pulsating, constant, wiener, discharging, and random temperatures. The model uses these temperatures as inputs and liquid fractions as target values. Performance evaluation is conducted using the MATLAB platform and is benchmarked against existing approaches, such as Long Short‐term Memory (LSTM), spatiotemporal convolutional neural network (CNN), and pooled CNN‐LSTM. The MLP model's accuracy in predicting PCMs phase transitions is validated by comparing predicted liquid fractions with numerically obtained values. Additionally, this study forecasts temperature distributions within a standard battery pack under various discharge scenarios, considering the performance of commercial lithium‐ion batteries. The proposed MLP model demonstrates high efficacy, achieving a correlation of up to 0.999 and root mean squared error below 0.013 compared with numerical results. [ABSTRACT FROM AUTHOR]

This study explores the dynamics of unsteady magnetohydrodynamics (MHD) parabolic flow along an infinite vertical plate, emphasizing the effects of thermal and mass stratification in a porous medium subjected to periodic temperature variation and exponential mass diffusion. Utilizing the Laplace transform technique to obtain precise solutions, this study effectively integrates the impacts of both thermal and mass stratification without dependence on approximations. The main goal is to assess how thermal and mass stratification impact MHD flow dynamics, temperature, and concentration profiles under varying conditions. The study provides a thorough comparison of these findings with traditional nonstratified scenarios, presenting a comprehensive analysis of fluid behavior under diverse conditions. The conclusions reveal that thermal and mass stratifications considerably diminish velocity and stabilize temperature distributions, which suggests a damping influence on fluid movement and improved management of diffusion processes. Enhanced Grashof numbers improve heat and mass transfer efficiency, while magnetic and Darcy parameters significantly influence flow resistance and heat transfer characteristics. These conditions also result in higher Nusselt and Sherwood numbers, indicating increased efficiency in heat and mass transfer. In contrast, scenarios without stratification display higher velocities and more unstable temperature and concentration profiles. The findings highlight the critical role of stratification in improving fluid dynamics and increasing the efficiency of heat and mass transfer processes, offering valuable insights for engineering and environmental applications in similar conditions. The main novelty of the research is being the first to use the Laplace transform for exact solutions on combined thermal and mass stratification in MHD flows, enhancing prediction accuracy and process control. [ABSTRACT FROM AUTHOR]

For industries like the cement industry, switching to a carbon-neutral production process is impossible. They must rely on carbon capture, utilization and storage (CCUS) technologies to reduce their production processes' inevitable carbon dioxide ( CO 2 ) emissions. For transporting continuously large amounts of CO 2 , utilizing a pipeline network is the most effective solution; however, building such a network is expensive. Therefore minimizing the cost of the pipelines to be built is extremely important to make the operation financially feasible. In this context, we investigate the problem of finding optimal pipeline diameters from a discrete set of diameters for a tree-shaped network transporting captured CO 2 from multiple sources to a single sink. The general problem of optimizing arc capacities in potential-based fluid networks is already a challenging mixed-integer nonlinear optimization problem. The problem becomes even more complex when adding the highly sensitive nonlinear behavior of CO 2 regarding temperature and pressure changes. We propose an iterative algorithm splitting the problem into two parts: (a) the pipe-sizing problem under a fixed supply scenario and temperature distribution and (b) the thermophysical modeling, including mixing effects, the Joule–Thomson effect, and heat exchange with the surrounding environment. We demonstrate the effectiveness of our approach by applying our algorithm to a real-world network planning problem for a CO 2 network in Western Germany. Further, we show the robustness of the algorithm by solving a large artificially created set of network instances. [ABSTRACT FROM AUTHOR]

In order to determine the damaging effect of different fire temperatures on a segment, experimental research was carried out on the structural performance of segments subjected to different fire temperatures. A temperature plateau occurred when the temperature reached 100°C. There were two temperature layers across the 300 mm thickness of the segment due to heating on one side only, and the temperature gradient within 0–50 mm was much more significant than that within 50–300 mm. The concrete spalling and the cracking initiated on the fired surface of the segment were severe; the maximum depth of concrete spalling on the fired surface of the segment at different fire temperatures was 600°C: 15 mm; 800°C: 45 mm; and 1,000°C: 67 mm; further, the main reinforcement was exposed or even softened. Cracking was also initiated on the unfired surface, and even penetrating cracks developed on the side surface. The damage at both ends of the segment was more severe than that in the center. The fire temperatures were 600°C, 800°C, and 1,000°C, the maximum midspan deflections were 5.27, 7.83, and 11.79 mm, the maximum midspan axial forces were 65.58, 208.41, and 333.63 kN, and the maximum reinforcement stresses were 22.49, 35.08, and 52.63 MPa, respectively. The mechanical parameters of the segment increased during the firing process and recovered during the cooling process, which is equivalent to a loading and unloading cycle for the segment. This study advances the understanding of the structural performance of shield tunnel segments subjected to different fire temperatures. [ABSTRACT FROM AUTHOR]

In modern applications, demand for the rotor shafts made of FGM has increased in aerospace, gas turbine and turbo jet engines due to its improved dynamic characteristics at elevated temperatures. The dynamic vibration response of a functionally graded Jeffcott rotor-bearing system with induced porosities has been studied for non-uniform porosity distributions. The functionally graded (FG) shaft's radial direction exhibits continuous variation in the material qualities. The FG rotor's cross-sectional material properties have been graded using the exponential law. The temperature gradients have been considered to be varied across the cross-section based on exponential temperature distribution. For the first time, using the FE method, it has been possible to study the impact of induced porosities on the free vibration frequencies and steady-state vibration responses of the functionally graded rotor-bearing system. This has led to the development of a two-node porous functionally graded rotor element with uneven porosity distributions using the Timoshenko beam theory. It has been observed that the free vibration frequencies and the FG rotor-bearing system critical speeds are affected by increased porosity and thermal gradients. The frequency responses demonstrate that as temperature gradient and volume fraction of porosity rise, the FG rotor-bearing system's critical speeds shift to the left. [ABSTRACT FROM AUTHOR]

Magnetic texture in a chiral material is touted as one of the next-generation nonvolatile computing elements. Thermal manipulation of magnetic textures attracts considerable attention and has promising applications. Here, the temperature-dependent magnetic properties of Ta/CoFeB/MgO thin film are studied experimentally and theoretically. We report the controllable spin texture distribution with a temperature gradient in the Ta/CoFeB/MgO thin film. The nucleation area could be generated at a certain location through the cooperation of heat and magnetic field. This method offers a way to realize spin texture injection at specific positions in magnetic thin films and devices. This work provides useful guidelines for the thermal control of the spintronic device operation. [ABSTRACT FROM AUTHOR]

In this research, friction stir processing (FSP) was carried out on Al0.3CoCrFeNi high-entropy alloys (HEAs) using two different tool geometries (cylindrical and square-shaped pin) at different tool rotational speed (TRS) of 800 and 1000 rpm. Phase analysis exhibited BCC phase in both casted and friction stir processed (FSPed) HEAs. FSP of HEAs with a square-pin tool produced more refined grains in the stir zone than the cylindrical-pin tool. It was also discovered that as the TRS increased, it produced more refined grain size in the stir zone. FSP with a square-pin tool generated a processed zone having highest hardness, ultimate tensile strength, and % elongation due to the evolution of more refined microstructure. Further, a numerical study was performed using ABAQUS/Explicit finite element software to understand the complex thermo-mechanical process and to study the stress distribution, temperature distribution, and material flow behaviour during FSP. The numerical study involved the Johnson-Cook models for defining material flow behaviour during FSP. A coupled Lagrangian-Eulerian technique was used to control mesh distortion while simulating excessive deformation. The peak temperature of the FSPed zone got enhanced as the TRS increased, and the temperature enhancement was higher with a square-pin tool than a cylindrical-pin due to pulsating motion. [ABSTRACT FROM AUTHOR]

The temperature field variation of overhead conductors in the operating environment of the Qinghai-Tibet Plateau is significant, causing the stress on the conductor wires to fluctuate with climate changes, leading to fatigue and wire breakage. Conducting numerical simulation and analysis of the temperature field of overhead conductors in this environment is crucial for enhancing the safety of transmission lines. This paper establishes a numerical algorithm for solving the radial temperature distribution of overhead conductors in operation based on the two-dimensional steady-state heat balance theory. This method is applied to the numerical simulation of the temperature field of the heat-resistant aluminum alloy conductor NRLH58GJ630-55 in the Qinghai-Tibet Plateau environment, analyzing the effects of current load, wind speed, and ambient temperature on the radial temperature distribution of the overhead conductor. [ABSTRACT FROM AUTHOR]

The aim of this work was to determine quantitatively the temperature uniformity of steel slab in high-temperature heating process under non-contact measuring conditions. Specifically, the temperature distribution of steel slab in heating process was obtained by infrared thermal imager, steel slab analog, and industrial image acquisition. The image isoline method was utilized to extract the non-uniform temperature region and temperature gradient of the steel slab. The local discrepancy function was used to measure the temperature uniformity of steel slab surface. Results showed that the problem of internal thermal conductivity of the steel slabs was reflected on the surface. The temperature of the cross section raised more slowly than that of the surface, but the temperature distribution was more uniform. More attention should be paid to the temperature distribution of the smaller surface and cross section rather than larger ones. The temperature uniformity degree of the surface of the steel slab samples from open literature was quantified respectively by 0.95, 0.92, 0.91, and 0.98. The steel slab with better quality would be obtained since the non-uniform heating could be adjusted according to the understanding of the distribution characteristics of the temperature field of the steel slab. This work was probably of great significance to increase the qualified steel slab, reduce scrap rate, and improve economic efficiency. [ABSTRACT FROM AUTHOR]

In this study, full-scale fire experiments and numerical simulations of the underground powerhouse of a hydropower station during the construction stage were performed to investigate the temperature distribution and smoke propagation. The characteristic of inverse ambient temperature in the vertical direction was discovered, resulting in the vertical movement of smoke differing from that in a uniform temperature environment. The maximum temperature increase appeared at non-highest points. Smoke characteristic parameters such as smoke settlement height and temperature increase were discussed at different heat release rates (HRRs) of fire sources to determine the fire risk distribution of the powerhouse. Two ventilation modes were proposed, and their smoke control effects were compared. The optimal ventilation mode and volume in different fire scenarios were proposed. The findings offer scenario and data support for fire smoke control and emergency plan design in powerhouses of hydropower stations. [ABSTRACT FROM AUTHOR]

Development of improved drying strategies is necessary to enhance qualitative characteristics of food powders. This study aimed to investigate impact of egg white (ovalbumin) concentrations on properties of banana powder produced using foam-mat drying. Increase in ovalbumin concentrations reduced foam density and bulk density of powders and increased overrun, porosity and stability of foams as well as absolute density, intra-granular porosity and water solubility of powders. Field-emission scanning electron microscopy showed that increase in ovalbumin concentrations from 1 to 2% decreased surface shrinkage and increased sticking of particles to one another. At a moisture content of 0.04 (dry basis) and ovalbumin concentrations of 1, 2 and 3%, glass transition temperature (Tg) of the powders were 60.60, 54.38 and 62.73 °C, respectively. Simulation results illustrated homogeneous distributions of moisture and temperature during drying. Overall, the results showed that banana powder could be produced with significant increase in various quality properties using foam-mat drying with a better product formulation. [ABSTRACT FROM AUTHOR]

In this study, a numerical simulation technique is employed to predicate the temperature distribution and velocity profile data of cold and hot nanofluids within a T-mixer was studied. The mixing of nanofluid flow with Al2O3 nanoparticles of 50 nm flows at Φ = 0.4 vol.% in a T-shaped mixer. The present numerical problem has been solved using the COMSOL Multiphysics version 5.4. Six angle of inclination was studied (θ = 15, 30, 45, 60, 75, and 90°) of the gate and evaluated its effects on the temperatures and velocity contour in the T-junction. The study's findings indicated that the presence of a gate in a stationary, non-rotating flow regime has a noteworthy impact on the stationary vortex flow. Also, the mixing occurs more quickly at angles of 45 or 60°. Mixing at a 30° or 90° angle took longer. [ABSTRACT FROM AUTHOR]

Underfloor heating systems ensure maximum comfort through optimal vertical temperature distribution, and the possibility of exact control and programming of the indoor climate. Used as a total heating source, the underfloor heating system will provide all the heat requirements of the space to be heated, provided that the external walls are properly insulated. In the study, two underfloor heating systems were analyzed using the dynamic simulation feature of the HTflux software. Following these simulations, temperature differences will be observed in front of the floor finish depending on the type of system used. The wet screed system heats up significantly faster and reaches a higher temperature by approximately 4.5% compared to the dry screed system. [ABSTRACT FROM AUTHOR]

Thermal environment may affect sleep quality and sleeping thermal comfort at the same time. Up to now, there is no direct evidence or physiological theory can prove the idea that thermal comfort equal to good sleep quality, but how to balance the relationship between them is often ignored when designing thermal environment. This review took body temperature distribution as a bridge for the connection of sleep quality and sleeping thermal comfort. At first, we reviewed the quantitative relationships among thermal environment, body temperature, sleep quality and sleeping thermal comfort, and then based on the idea of reverse derivation, a recommended design process for bedroom thermal environment was proposed. Each step of the process corresponded to the impact mechanism described above. The review results showed that, body temperature distribution was closely related to both sleep quality and thermal comfort, and thus it was suitable to be used as a bridge between them; body temperatures fluctuated dynamically during sleep, and thus heat transfer and thermal regulation models should be used to describe them; most current sleep researches regarded skin temperature as the representative value of body temperature distribution, yet core body temperature needs to be paid more attention on in the future because it was more closely related to sleep rhythm; furthermore, in addition to young people, subjects of more age groups should be tested to enrich China's sleep research database. In general, it's theoretically possible to guarantee both sleep quality and sleeping thermal comfort, and this review can be used as a reliable reference for bedroom thermal environment design. [ABSTRACT FROM AUTHOR]

The exoplanet transit telescope uses high-precision CMOS image sensor for planet searching. This device operates at 233 K to reduce dark current and noise interference on the effective signal. This paper examines the effects of space proton radiation on the performance of high-precision CMOS image sensor through proton irradiation and post-irradiation testing at various temperatures. The results indicate that proton irradiation degrades parameters like dark current, dark signal, and fixed pattern noise, with dark current being the most sensitive. As the operating temperature increases, radiation-sensitive parameters degrade rapidly, significantly impairing sensor performance. This indicates that lower temperatures provide better performance. Notably, Dark signal distribution fluctuates with temperature. Compared to before irradiation, the Gaussian mean decreases at 233 K and increases between 243 and 273 K. At low temperature, the ionization damage caused by proton radiation mainly results in the decrease of Gaussian mean, while the displacement damage mainly results in the increase of this. The study concludes that proton-induced displacement damage, which leads to bulk defects, is the primary cause of performance degradation. This provides essential data and foundational support for radiation damage assessment and on-orbit applications. [ABSTRACT FROM AUTHOR]

The electrification of transportation has led to an increased emphasis on the thermal management of battery packs to ensure their safety, efficiency, and longevity. This study presents a comprehensive estimation of the C-rate through analytical and the thermal behavior of an electric two-wheeler battery pack (3.2kWh) under varying operational conditions through a combination of simulation and experimental testing. Numerical analysis was conducted using Celsius EC Solver (version 2023.2) software, with a specific focus on parameters such as C-rate and temperature distribution. Experimental validation was performed under controlled conditions, and key metrics such as ambient temperature, maximum temperature reached at various locations, heat generation rates, voltage, and current were measured. The findings of this study demonstrate that there is less than 4% error which is well agreed between simulation and experimental results. This indicates a significant congruence between the simulated and experimental data, underscoring the reliability of the proposed simulation model. This analysis provides valuable insights for optimizing thermal management strategies in battery packs. [ABSTRACT FROM AUTHOR]

The article focuses on the issue of efficiently recovering waste heat from low-exergy process gases, which poses a significant challenge for improving energy efficiency in many industrial sectors. To address this problem, the application of a thermoelectric generator (TEG) has been proposed, allowing for the direct conversion of thermal energy into electrical energy. In the course of the research, experimental measurements were conducted for process gases at temperatures of 240 °C and 300 °C, along with CFD (computational fluid dynamics) simulations using Ansys Fluent 2023 R2 software. These simulations enabled the analysis of the temperature distribution in the TEG and the determination of the safe operating range of the device for process gas temperatures of 350 °C, 400 °C and 450 °C. The results obtained from both experiments and simulations demonstrated the effectiveness of the TEG in recovering waste heat from low-exergy gases. Additionally, these findings suggest the potential for scaling the solution to larger industrial systems, making TEG a promising technology for long-term sustainable development efforts. The developed numerical model proved to be a valuable tool in the design of TEG systems, allowing for the analysis and optimization of heat recovery systems. The innovation of the solution lies in the use of TEG for efficiently utilising waste heat from low-temperature gases, which holds significant potential for improving energy efficiency in processes where traditional energy recovery technologies are not effective. [ABSTRACT FROM AUTHOR]

The present article provides a theoretical investigation into the thermoelastic behavior of functionally graded materials (FGMs) using modified thermoelastic conduction models. These enhanced models have potential applications in various engineering fields, including aerospace, pressure vessels, and structural engineering. The research delves into examining a thermoelastic scenario concerning an infinite FGM with a spherical cavity exposed to thermal shock. This analysis is framed within the dual‐phase‐lag (DPL) thermoelasticity theory and incorporates higher‐order fractional derivatives. The analysis employs the Laplace transform method to address the problem, utilizing the Taylor series expansion of higher‐order fractional derivatives as proposed by Caputo and Fabrizio. This approach enables advanced approximations of heat flux, temperature gradients, and thermal displacements. The study assumes that the thermal and mechanical properties of the FGM vary as a power function of the radial coordinate. The results are presented graphically, showing temperature distributions, stress fields, and displacement profiles. Additionally, the study explores how variations in the gradation parameter and the coefficient of fractional derivatives impact the thermoelastic behavior of the material. [ABSTRACT FROM AUTHOR]

The aim of this numerical study is to investigate the heat transfer characteristics of the air flowing in the triangular photovoltaic thermal (PV/T) array/system at variable velocities. The PV/T array in the present analysis is composed of seven photovoltaic (PV) panels connected in series along with a triangular duct throughout its length. The heat transfer analysis in the PV panel (solid component) and visualization of temperature distribution in the PV/T system has been simulated by the use of system coupling of steady state thermal and CFX tools in ANSYS 18.2. Experiment was initially performed at velocity of 1.5 m/s inside the duct by the use of ANSYS software to predict the glass temperature, outlet air temperature, and tedlar temperature of triangular PV/T system. Further, the velocity has been incremented by 1 m/s up to 6.5 m/s to see the overall performance of the system. The validation of simulation results showed a good agreement with the experimental results under reasonable limit. The gain in temperature with the increase in velocity becomes marginal (only 7%) after 4.5 m/s. The temperature contours from the numerical simulation also revealed that cooling up to the last panel is not significant beyond 4.5 m/s. Similar tendency is documented in the overall exergy efficiency which significantly increased to 4.5 m/s and became marginal with further increment in velocity. It can be inferred that the optimum velocity which can fulfill the requirement of cooling of all PV panels along with reasonable thermal output is 4.5 m/s. The thermal energy gain gradually increases as the day progresses and becomes maximum at 2:00 PM. The average thermal energy gain being 9.6% higher than that in the morning (10:00 AM) indicates its suitability for applications requiring moderately high temperature. The present numerical investigation focuses on improving the overall performance of the system without the involvement of any additional cost. The system can be used in various applications like crop drying, space heating, etc. Owing to different outlet air temperatures during the day, the applications can either be utilized independently or can be combined to be used at different times according to the temperature requirement. [ABSTRACT FROM AUTHOR]

The energy-intensive nature of hydrogen liquefaction underscores the critical need for efficiency improvements. This study presents an approach to enhance the design and performance of hydrogen heat exchangers by optimizing the cold-to-hot fluid mass flowrate ratios across various temperature ranges, leading to substantial improvements in the Continuous Conversion Proximity Index (CCPI). A dynamic simulation model is developed to explore the complex interactions between temperature distribution, mass flowrate ratio, inlet conversion rate, and the heat transfer and catalytic efficiency in cryogenic hydrogen heat exchangers. Optimal cold-to-hot fluid mass flowrate ratios, ranging from 3.31 to 8.44 across the 80-33 K temperature range, are identified. In particular, a 23.0% improvement in CCPI is observed in the 40-33 K range, significantly optimizing the continuous catalytic conversion process. The results show that inlet conversion rates between 96% and 94% ensure effective heat transfer and high ortho-para hydrogen conversion efficiency, whereas rates below 94% lead to rapid conversion but insufficient cooling. These findings provide a theoretical foundation for the design of highly efficient hydrogen heat exchangers and demonstrate that optimizing the mass flowrate ratio can enhance the process within the exchanger, bringing it closer to an ideal continuous conversion form. [Display omitted] • The CCPI index is introduced to evaluate deviation from ideal continuous conversion. • The optimal fluid flowrate ratios across various temperature ranges are determined. • The dynamic model reveals the impact of inlet conversion rates on heat transfer efficiency. • A 23% increase in CCPI is achieved with optimal flowrate in the 40-33 K temperature range. • The validated model supports improved design of cryogenic hydrogen heat exchangers. [ABSTRACT FROM AUTHOR]