Thermal Distribution Research Articles

Numerical study of temperature distribution in a solar receiver with a focus on water heating in an internal helical tube

Solar energy is one of the clean energies that many researchers have focused on. This study used the Monte Carlo Ray Tracing (MCRT) method in MATLAB coding to calculate the water temperature inside a solar receiver containing a spiral coil through which water passes. To guess the amount of solar radiation that would hit the receiver and figure out the temperature of the water coming out, the Monte Carlo method was used. The three cases were: a change in the receiver's exposure time to solar radiation (t = 2, 4, 6, 8, 10 h); a change in the gas flow rate (Qg = 5, 10, 15, and 20 L/min); and a change in the water flow rate (from 2 to 20 with an increase of 2 L/min in each case. The study found that the gas volume flow rate (Qg) slightly affected the thermal distribution at Qg = 5 L/min, Tg = 358 C, and at Qg = 20 L/min, Tg = 352 C, while the water volume flow rate (Qw) and time directly affected the water temperature. The study showed that the thermal distribution was stable at 8 and 10 h. At 8 h, the water reached a maximum temperature of 153 °C at Qg = 5 and Qw = 2. When Qg = 5 L/min and Qw = 2 L/min, the receiver wall temperature reached 322 °C, the receiver backplate temperature (Tbp) reached 498 °C, and the gas temperature (Tg) reached 354 °C. At QG and Qw = 20, the water temperature dropped to 46 °C. This showed that the volume flow rate significantly affected the temperature.

Оценка эффективности технологических решений по обеспечению проветривания нефтяных шахт

Results of thermal calculation and air distribution among mining workings of an oil mine for the ventilation of an inclined block (mining area) in accordance with a new proposed method have been provided. The method implies that the open space of the drilling gallery of the inclined block upon well drilling and steam pipeline connection is divided by a longitudinal airtight heat-insulating partition. Thus, the fresh air supplied to the incline is divided into two flows: one flow moves between the heated wall and the heat-insulating partition and then is withdrawn through the ventilation well to the surface; the second flow under the general mine depression is supplied to the working area of drilling gallery. The calculations performed by the Aeroset software package for the entire mine (for three inclined blocks) have shown that for the suction ventilation method, there is a probability of a change of airflow movement in the vertical ventilation well. When the air-conditioning system is operated and the air cooled in the system evaporator is supplied to the working area, whereas the air heated in the system condenser is supplied to the area between the heat-insulating partition and the heated oil reservoir, the comfortable thermal regime will be maintained in the mining workings. At the same time, the air in all mining workings will move in the required direction. Another considered option that ensures comfortable working conditions in the working area is the change of oil mine ventilation method from suction to supply. For both cases, the efficiency of the proposed ventilation method for the inclined block and the oil mine as a whole has been established, and its advantages have been compared with the currently used solutions.

Thermal environment optimization and process product design of CNC grinding machine based on improved neural network

In the machining process of CNC grinding machine, the non-uniformity of heat source often leads to the deformation of the workpiece, the intensification of wear and the machining error, so the optimization of thermal energy environment has become an important research direction to improve the machining performance. The aim of this study is to optimize the thermal energy environment of CNC grinding machine by improving the neural network algorithm, so as to achieve the goal of improving the machining precision and surface quality. We hope that by establishing thermal environment model, we can deeply analyze the characteristics of thermal energy distribution and put forward effective optimization measures. The improved neural network model is used to model the heat energy distribution of CNC grinding machine. The accuracy of the model is improved by introducing multi-layer perceptron and convolutional neural network. At the same time, combined with the experimental data, training and testing are carried out to verify the effectiveness of the model. Genetic algorithm and fuzzy control are used to adjust the thermal energy environment and obtain the best process parameters. The experimental results show that the prediction accuracy of the improved neural network model is significantly improved, and the prediction error of the model is significantly reduced compared with the traditional method. After thermal optimization, the surface roughness of the workpiece is reduced, the dimensional accuracy is significantly improved, and the overall processing efficiency is significantly improved. By improving the neural network model, the thermal energy environment of CNC grinding machine is effectively optimized, and the machining precision and surface quality are successfully improved.

Research on a novel method of air distribution to create a uniform indoor environment in a long and narrow building

Because people work a long time in buildings, good indoor thermal environments and air distributions have attracted increased amounts of attention. To improve the indoor thermal environment and air quality, an effective ventilation strategy must be used. In the air conditioning of a building, the air distribution has been identified as a significant factor that affects the indoor thermal environment. A novel method for air distribution was presented to create a uniform indoor environment along the room length direction. In this study, numerical simulations were carried out to analyse the airflow pattern and performance of the sidewall air supply (SAS) and the sidewall air supply with deflector (SASD). Orthogonal experiments were conducted to study the airflow distribution law of the deflector. The ventilation performance of the two air supply modes was evaluated by air velocity distribution, temperature distribution, horizontal temperature difference, age of air, and other evaluation indicators. The results indicate that the horizontal air temperature differences in the SASD at three heights are 46.05%, 16.44%, and 26.51% lower than those in the SAS, which has a better energy-saving effect. Moreover, the indoor air distribution performance was obtained under three influencing factors: the gap width from the deflector to the ceiling, the horizontal position, and the length of the deflector. A better deflector optimization scheme was obtained. Experimental research was carried out to verify the indoor air distribution of the SASD. This research can provide a reference for the innovative design of indoor air supply systems

A High-Power, Flexible, and Magnetically Attachable Radiative Cooling Film

Radiative cooling is an environmentally friendly, passive cooling technology that operates without energy consumption. Current research primarily focuses on optimizing the optical properties of radiative cooling films to enhance their cooling performance. In practical applications, thermal contact between the radiative cooling film and the object significantly influences the ultimate cooling performance. However, achieving optimal thermal contact has received limited attention. In this study, we propose and experimentally demonstrate a high-power, flexible, and magnetically attachable and detachable radiative cooling film. This film consists of polymer metasurface structures on a flexible magnetic layer. The monolithic design allows for convenient attachment to and detachment from steel or iron surfaces, ensuring optimal thermal contact with minimal thermal resistance and uniform temperature distribution. Our magnetic radiative cooling film exhibits superior cooling performance compared to non-magnetic alternatives. It can reduce the temperature of stainless-steel plates under sunlight by 15.2 °C, which is 3.6 °C more than that achieved by non-magnetic radiative cooling films. The radiative cooling power can reach 259 W∙m−2 at a working temperature of 70 °C. Unlike other commonly used attachment methods, such as thermal grease or one-off tape, our approach allows for detachment and reusability of the cooling film according to practical needs. This method offers great simplicity, flexibility, and cost-effectiveness, making it promising for broad applications, particularly on non-horizontal irregular surfaces previously considered challenging.

On the role of non-equilibrium heat transfer in the filled fracture-rock matrix system

Understanding heat transfer processes in fractured porous media is critical for characterizing thermal behaviors and improving the operation efficiency of geothermal energy. The field observations have shown that many fractures are filled with sediment infilling rather than being fully open, but heat transfer in such a filled fracture-rock matrix system has received less attention to date. Since multiple domains are involved in such a system and the fracture is highly permeable even with sediment infilling, local thermal equilibrium may not be reached instantaneously. In this study, a fully coupled analytical model is proposed and developed to investigate the role of transient local heat transfer in the filled fracture-rock matrix system and analyze the spatiotemporal thermal distributions in each domain. The results indicate that multiple thermal properties of the rock matrix, such as average volumetric thermal capacity and thermal conductivity, have significant impacts on the spatiotemporal thermal distribution in the fracture. The temperatures of the pore water and sediment infilling in the fracture are sensitive to flow velocity, thermal conductivity of the rock matrix, and volumetric thermal capacities of the fluid and rock matrix. The thermal transfer coefficient has moderate interaction effects with other parameters according to the sensitivity analysis.

Simultaneous Proton and Electron Energization during Macroscale Magnetic Reconnection

The results of simulations of magnetic reconnection accompanied by electron and proton heating and energization in a macroscale system are presented. Both species form extended power-law distributions that extend nearly three decades in energy. The primary drive mechanism for the production of these nonthermal particles is Fermi reflection within evolving and coalescing magnetic flux ropes. While the power-law indices of the two species are comparable, the protons overall gain more energy than electrons, and their power law extends to higher energy. The power laws roll into a hot thermal distribution at low energy with the transition energy occurring at lower energy for electrons compared with protons. A strong guide field diminishes the production of nonthermal particles by reducing the Fermi drive mechanism. In solar flares, proton power laws should extend down to tens of keV, far below the energies that can be directly probed via gamma-ray emission. Thus, protons should carry much more of the released magnetic energy than expected from direct observations.

A study of the effects of welding parameters on macrostructure properties and heat distribution in FSW of aluminium metal matrix composite

Abstract The objective of this study is to present the effects of welding variables, specifically traverse speed and rotational speed, on the macrostructure of an aluminium metal matrix composite. This investigation includes comprehensive thermal monitoring and measurements within the weld joint area, utilizing infrared thermography to track the primary stages of friction stir welding (FSW). By examining different areas of the weld, to study aims to elucidate how temperature is distributed across the aluminium metal matrix composite in relation to the specific parameters of the FSW process, and to determine the subsequent impact on weld quality. Using infrared thermography, the researcher not only maps the thermal profile during welding, but also correlates these thermal variations with macrostructural changes in the aluminium metal matrix composite. This method allows for precise detection of temperature fluctuations and provides a detailed understanding of how traverse speed and rotational speed influence thermal distribution. Moreover, the study demonstrates the efficacy of thermography as a valuable tool for assessing weld quality. By capturing real-time thermal images, this technique enables the identification of potential defects and inconsistencies within the weld zone, facilitating a more thorough investigation into the integrity and performance of the welded joints. Ultimately, the findings aim to contribute to optimizing welding parameters on enhance the structural integrity and reliability of aluminium metal matrix composites in various applications.

Development of diesel combustion with low cooling loss and high dispersion spray using two-dimensional optical measurements

In this study, a novel, high-efficiency, and clean combustion concept utilizing low cooling loss and high dispersion spray is proposed. The research aims to validate the objectives of this concept through spatiotemporal analysis of phenomena when key variables such as combustion chamber shape, spray parameters, and swirl are modified. This new combustion approach focuses on achieving low heat loss by using smaller nozzle diameters, multi-hole nozzles, and reduced swirl compared to conventional combustion. The combustion chamber is designed with an increased cavity diameter and an expanded taper diameter to enhance upward spray dispersion, thereby reducing fuel spray penetration into the cavity and decreasing cooling loss. This configuration reduces the fuel spray penetration in cavity, achieving a reduction in cooling heat loss. Furthermore, to increase the volume in the lower part of the combustion chamber, a corner-bottom shape is employed. Additionally, by causing spray impingement through the corner bottom shape, the strategy aimed to prevent the return of the mail injections to the central part of the combustion chamber. These parameters were evaluated using two-dimensional optical measurements, which calculated thermal flux, temperature, velocity, and KL value distributions. The impact of cavity diameter on internal cooling loss is significant, and preventing flame stagnation from a smoke perspective is crucial. An increase in taper diameter reduces squish velocity, achieving heat losses reduction, while necessitating spray dispersion into the squish area. The influence of swirl ratio on heat losses is more pronounced in the squish and taper areas than inside the cavity, necessitating consideration of flame temperature reduction within the cavity when reducing swirl ratios. The implementation of double after injection influences low heat losses and avoids flame stagnation, enabling soot reduction. The corner bottom shape combustion chamber proved effective in reducing heat losses and particulate matter (PM) at medium and high loads.

Dynamics of urban development patterns on thermal distributions and their implications on water spread areas of Vellore, Tamil Nadu, India

Recent satellite maps have reported that India is experiencing extreme heat waves, surpassing even Middle Eastern countries. This study addresses a critical gap in understanding how land use land cover (LULC) changes impact land surface temperature (LST), urban heat intensity (UHI), and water spread area (WSA) in rapidly growing cities such as Vellore and Katpadi over three decades (1997–2024). We used Landsat thermal bands and the support vector machine (SVM) algorithm to investigate LULC and LST patterns, examining the effects of urbanization and water body reduction on local climate dynamics. The LULC results showed an increase in built-up lands from 5.89 to 25.89%, while zooming water areas shrank from 3.15 to 1.02%. LST showed a significant increasing trend, with temperatures for water bodies and vegetation ranging from 17.4°C to 26°C, and for barren and built-up areas from 28°C to 42.6°C. The results of the multivariate analysis revealed a positive correlation between LST and the Normalized Difference Built-up Index (NDBI) and negative correlations between LST and the Normalized Difference Vegetation Index (NDVI), the Normalized Difference Water Index (NDWI), and the Modified Normalized Difference Water Index (MNDWI). Moreover, spatial and time series analyses of WSAs indicated a significant increase in LST. Furthermore, a strong negative correlation was found between WSA and LST, with a 10% decrease in WSA potentially increasing LST by 0.12°C to 0.55°C in surrounding regions. This study offers important contributions to improving land use policy and water resource management in urban areas, while addressing environmental concerns related to rising temperatures. The findings underscore the urgency of mitigating heat impacts and managing water resources in rapidly expanding cities. Our results provide valuable insights for policymakers and practitioners aiming to develop more sustainable, resilient, and livable urban environments.

Cholesterol Conformational Structures in Phospholipid Membranes.

Cholesterol is a major component of biomembranes that impacts membrane order, permeability, and lateral organization, but the precise molecular mechanisms of cholesterol's actions are still under investigation. Density functional theory (DFT) calculations have opened the fingerprint vibration bands of large molecules to detailed spectral analysis. For cholesterol, Raman spectral interpretation for conformational structure and hydrogen bonding is now possible. Here, DFT calculations of cholesterol conformers identify 10 structure types that also have unique low-frequency Raman spectra. By fitting experimental spectra to these types, the distribution of cholesterol structures present in phospholipid (PL) membrane vesicles was measured. The distributions reveal that the cholesterol iso-octyl chain tends to align with saturated PL chains and shifts to a thermal distribution for unsaturated PL chains. The results agree with the templating effect of cholesterol on PL membranes and show that the top of the iso-octyl chain is rigid like the rings. It is also shown that the inclusion of water molecules hydrogen bonded to the cholesterol hydroxy group in the DFT calculations may improve the spectral fitting for future studies.

Multi-scale collaborative modeling and deep learning-based thermal prediction for air-cooled data centers: An innovative insight for thermal management

Investigating the data center (DC) thermal environment and temperature distribution is crucial to responding to unforeseen events such as equipment failure or environmental changes. However, building full-scale simulation models from DC room level to chip level faces significant challenges. In this paper, we propose a distinctive approach that combines multi-scale collaborative modeling with deep learning techniques for thermal prediction in air-cooled DCs. By taking the simulation results of the parent model as the boundary conditions of the child model, we constructed the DC multi-scale simulation model, which significantly reduces the model complexity and computational resources. Leveraging experimental data, the models at different scales were validated separately. The effects of different cooling strategies, air supply temperatures and air supply flow rates on multi-scale simulation models were investigated. Based on the parametric simulation approach, datasets for training data-driven models are constructed. Simultaneously, we propose the CNN-BiLSTM-Attention neural network model to predict the maximum CPU temperature and optimize the hyperparameters of the neural network through by Bayesian optimization. The prediction results of the coupled multi-scale model and the deep learning prediction model show that the absolute error is controlled within ±0.1 K, and the R2 value of the model evaluation metric is as high as 0.9899. Herein, the results provide valuable insights for enhancing thermal management in air-cooled DCs, paving the way for more efficient and resilient DC operations in the future.

Persistent Ground-State Planar Alignment of Iodine Molecule through Resonant Excitation.

We demonstrate the generation of a persistent planar molecular alignment by subjecting a relatively warm gas sample to a resonant femtosecond laser pulse. By optically probing I_{2} molecules in their vibronic ground states, we observe a persistent delocalization of their axes near the plane orthogonal to the field direction. This phenomenon is attributed to the one-photon resonant excitation, primarily removing molecules from the thermal ground-state distribution that are initially aligned along the field, i.e., those with small projection of their rotational angular momentum along the field.

A graph theory-based modelling method for multi-splitting-merging-channel refrigerant-cooled evaporator in battery thermal management

A multi-splitting-merging-channel refrigerant-cooled evaporator can provide non-uniform cooling capacity distribution to match a non-uniform distributed heat flux produced by a battery by properly arranged hierarchical refrigerant channel network, however the design of the refrigerant channels is extremely complex. The purpose of this study is to present a model to support the design of a multi-splitting-merging-channel refrigerant-cooled evaporator, and the model should have the functions of describing various channel network, predicting the refrigerant flow distribution in splitting and merging channels, and accurately presenting temperature distribution at unevenly distributed heat flux. In the model, the distributed parameter modelling approach is applied for predicting the thermal performance distribution; arbitrary kinds of control volumes are normalized into five standard types according to channel structures; the refrigerant flows with multiple splitting and merging are described by the calculation sequences of control volumes, which are generated based on the graph theory. Model validations are done on a small sized and a large sized evaporator samples by comparing the simulated results with the experiment data. It is shown show that, the average temperature deviations of the small sized and the large sized evaporator samples are 1.0 °C and 0.9 °C, respectively while their average pressure drop deviations are 2.8% and 2.1%, respectively. The validation result indicates that the accuracy of the proposed model is acceptable for engineering application.

Coupled Impact of Points of Interest and Thermal Environment on Outdoor Human Behavior Using Visual Intelligence

Although it is well established that thermal environments significantly influence travel behavior, the synergistic effects of points of interest (POI) and thermal environments on behavior remain unclear. This study developed a vision-based outdoor evaluation model aimed at uncovering the driving factors behind human behavior in outdoor spaces. First, Yolo v5 and questionnaires were employed to obtain crowd activity intensity and preference levels. Subsequently, target detection and clustering algorithms were used to derive variables such as POI attractiveness and POI distance, while a validated environmental simulator was utilized to simulate outdoor thermal comfort distributions across different times. Finally, multiple classification models were compared to establish the mapping relationships between POI, thermal environment variables, and crowd preferences, with SHAP analysis used to examine the contribution of each variable. The results indicate that XGBoost achieved the best predictive performance (accuracy = 0.95), with shadow proportion (|SHAP| = 0.24) and POI distance (|SHAP| = 0.12) identified as the most significant factors influencing crowd preferences. By extrapolation, this classification model can provide valuable insights for optimizing community environments and enhancing vitality in areas with similar climatic and cultural contexts.

Impact of non-thermal phase-space distributions on dark matter abundance in secluded sectors

Many new physics models include secluded sectors that interact little with the Standard Model and whose internal interactions control the dark matter abundance. If these same interactions are responsible for maintaining kinematic equilibrium within the secluded sector, it is possible that the phase-space distributions will differ considerably from their thermal values during freeze-out. This can potentially result in deviations of the dark matter abundance from that computed under the assumption of thermal distributions. In this paper, we revisit dark matter abundance computations for a benchmark secluded sector by numerically tracking the phase-space distributions. Namely, we show that the dark matter abundance can deviate considerably from standard results during the freeze-out process, but that a longer period of annihilation ultimately leaves only a slight excess.

Behaviors and mechanism of volatiles producing during coal pyrolysis with calcium oxide loading: Insights from model compounds analysis

Calcium is a highly effective catalyst for controlling the tar compounds produced during the pyrolysis of low-rank coal, forming valuable end products. However, the exact catalytic mechanism of calcium in coal pyrolysis remains unclear due to the complex nature of coal. In this study, the pyrolysis process and tar composition of lignite, both with and without the addition of calcium, were investigated across three distinct temperature intervals. The addition of calcium oxide increased the hydrocarbon content of tar by 16.39 % in the low-temperature range and 26.53 % in the intermediate-temperature range. Four model compounds containing different coal-related functional groups were selected to investigate the effects of calcium on pyrolysis performance and tar composition using thermogravimetric analysis, fixed bed reactor experiments, gas chromatography/mass spectrometry, in situ Fourier transform infrared spectroscopy, X-ray diffractometer, and X-ray photoelectron spectroscopy. The addition of calcium did not affect the thermal decomposition of polystyrene or polyethylene terephthalate; however, the primary pyrolysates underwent secondary reactions on the surface of calcium, which affected the composition of the liquid pyrolysis product. Meanwhile, calcium interacted with the carboxyl and phenolic hydroxyl groups in trimeric acid and phenolic resin to form carboxylates and phenates, which affected the thermal reaction and distribution of liquid products. The influence of calcium on the transformation mechanism of coal-related functional groups provides a theoretical basis for understanding the mechanism of calcium-catalyzed coal pyrolysis.

Physically accessible and inaccessible quantum correlations of Dirac fields in Schwarzschild spacetime

In this study, we investigate the influence of Hawking decoherence on the quantum correlations of Dirac fields between Alice and Bob. Initially, they share a Gisin state near the Schwarzschild black hole (SBH) in an asymptotically flat region. Then, Alice remains stationary in this region, while Bob hovers near the event horizon (EH) of the SBH. We expect that Bob, using his excited detector, will detect a thermal Fermi-Dirac particle distribution. We assess the quantum correlations in the evolved Gisin state using quantum consonance and uncertainty-induced non-locality across physically accessible, physically inaccessible, and spacetime regions. Our investigation examines how these measures vary with Hawking temperature, Dirac particle frequency, and the parameters of the initial Gisin state. Additionally, we analyze the distribution of these quantum correlation measures across all possible regions, noting a redistribution towards the physically inaccessible region. Our findings demonstrate that Hawking decoherence reduces the quantum correlations of Dirac fields in the physically accessible region, with the extent of reduction depending on the initial state parameters. Moreover, as Hawking decoherence intensifies in the physically inaccessible and spacetime regions, the quantum correlations of Dirac fields reemerge and ultimately converge to specific values at infinite Hawking temperature. These results contribute to our understanding of quantum correlation dynamics within the framework of relativistic quantum information (RQI).

Evaluation of the influence of climatic changes on the degradation of the historic buildings

While climatic change has been a widely studied topic, its impact on cultural heritage degradation remains a gap to overcome. The environment can contribute to the degradation of historic buildings and materials decay, especially temperature and humidity. So, characterizing the micro-climates of a landmark zone and understanding the influence of the recovery layers, building disposition, and street characteristics on environmental parameters are the first steps to investigating resilience strategies for heritage conservation and micro-climates. Thus, this paper presents a new approach to assess the influence of climatic warming on historic building degradation, combining multiscale experimental data and numerical modeling. The environmental parameters of the historic center of Aracati downtown, such as concentration of CO2, relative humidity, temperature, and air condition, were characterized and used together with urban volumetry to discuss the influence of on the urban microclimate and relate the data to the physical degradation of cultural heritage. An uncrewed aerial vehicle was used to register the volumetry of the historic center, and the data was used to simulate the wind conditions. Following this, numerical analysis was used to investigate the rising damp and thermal tension distributions under temperature variation over the years (from 2023 to 2100). The methodology’s applicability was demonstrated in recurrence with the Nosso Senhor do Bonfim Church, one of the most representative heritage constructions from Aracati downtown. Finally, the new methodology contributed to understanding how urban volumetry contributes to the climatic conditions of a historic area and demonstrates that the increase of the temperature can significantly affect the rising damps and the development of stress tension.

Geothermal distribution and evolution of fault-controlled Linyi geothermal system: Constrained from hydrogeochemical composition and numerical simulation

This study explores the Linyi geothermal field, located in Shandong Province, China, characterized by its non-magmatic, active fault-controlled geothermal system. Utilizing a combination of geochemical analyses, temperature measurements, and numerical simulations, a detailed genetic model of the geothermal system has been developed. The analysis included extensive water geochemical and isotopic characterization to determine reservoir temperature, depth, and origin of the geothermal waters. The thermal-hydro coupling model was integrated with these data to refine the thermal distribution and assess the evolutionary dynamics of the geothermal system. Our findings indicate that the geothermal anomalies in the Linyi field are predominantly controlled by hydrothermal convection within the Ordovician and Cambrian carbonate layers, facilitated by the high permeability of the Yishu Fault. The fault acts as a crucial conduit for meteoric water recharge, which undergoes significant heating due to the geothermal gradient in deeper rock formations. Isotopic analyses of hydrogen and oxygen revealed the meteoric origin of the geothermal waters, with recharge likely originating from the nearby Yimeng Mountains. Furthermore, the study established a conceptual evolutionary model to understand the mechanisms driving the geothermal resource development in the area. It was determined that the geothermal resources are typically fault-controlled, with significant potential for further exploration due to the identified hydrothermal anomalies at the fault's footwall. The model predicts the preservation of heated meteoric water in the reservoir rock for periods ranging from 10 to 50 thousand years, providing a sustainable source of geothermal energy. This comprehensive approach not only enhances the understanding of the heat accumulation mechanism but also highlights the potential for optimizing geothermal exploration strategies within fault-controlled geothermal systems.