Simulation Of Temperature Distribution Research Articles

CFD Analysis to Optimize Air Quality in Aeroponic Tower Garden

Aeroponic tower gardens represent an innovative approach to urban agriculture, utilizing vertical structures to cultivate plants without soil. Research highlights the efficiency of this method in optimizing resource usage, such as water and space, compared to traditional farming. Studies emphasize increased crop yields, faster growth rates, and reduced environmental impact. Additionally, aeroponic systems enable precise nutrient delivery to plants, fostering optimal growth conditions. While the technology shows promise, further investigations are needed to address potential challenges and optimize its application in diverse agricultural settings. The study presents the simulation of air temperature and humidity distribution in a closed chamber of the vertical farm for optimization purposes. The environmental conditions inside the chamber are optimized for plant growth, to maintain the temperature at a range of 18-24 °C temperature and the relative humidity at a range of 75-85 %. The paper also discusses the challenges, limitations, and future recommendations for improving the system. Simulation of the system, on the other hand, is crucial not only for prototype fabrication but also for the optimization of sensor locations. The simulation of the tower garden system was performed using ANSYS-FLUENT to portray how the airflow inside the tower garden's enclosed environment was distributed. The system parameters such as humidity and temperature were set to meet the plants' growth requirements, and the system was treated as the steady state with an adiabatic boundary. Based on the simulation results, the best design recommended is to use two humidity and temperature sensors, one at the top and the other at the core of the prototype. Hence, a complete mapping of temperature and humidity distribution that is critical for plant growth would be occurred.

Simulation of ambient temperature and humidity distribution in eight-span greenhouse under different wind conditions and corn height

The greenhouse environment suitable for crop growth usually depends on reasonable ventilation, and outdoor air flow state and indoor crop height are important factors affecting the ventilation effect. This study conducted simulation and experimental research on corn cultivation in an eight-span plastic greenhouse, analyzing the effects of outdoor wind speed, wind direction, and indoor crop height variations on the uniformity of temperature and relative humidity distribution as well as the air flow dynamics within the greenhouse. The study shows that as outdoor wind speed increases from 0.5 m/s to 2.5 m/s, for every 1 m/s increment, temperatures decrease by 2.2 °C and 0.9 °C, respectively. The increase in outdoor wind speed resulted in uniformity of greenhouse temperature and humidity along the vertical height, but exacerbated the degree of inhomogeneity in the east-west direction. The change in outdoor wind direction leads to differences in airflow direction and ventilation volume. On the south side of the greenhouse, while temperature is lower, the relative humidity is higher, with maximum differences in temperature and humidity between the north and south sides being 0.6 °C and 1.5 %, respectively, when the northeast wind blows. The east wind has the best cooling effect. The uneven degree of temperature and humidity distribution in the east and west direction of the greenhouse is positively correlated with crop height. This study can provide valuable insights for adjusting and optimizing natural ventilation strategies in large multi-span greenhouses.

Analysis of micro-hole formation in titanium nanofilms using a low power CW laser

This study investigates the mechanisms and dynamics governing microhole formation in titanium nanofilms under the influence of a continuous-wave low-power laser emitting at 1070 nm. Two distinct configurations were explored: one in which the laser interacted with the titanium film in an air environment (referred to as configuration AM), and the other in which the laser beam passed through glass before reaching the titanium film (referred to as configuration SM). Our experiments demonstrated that microhole formation is possible in both configurations. However, the threshold powers, hole characteristics, and time scales involved differ significantly between AM and SM configurations. Temperature distribution simulations, based on a linear absorption model, revealed notable differences in peak temperatures between these two configurations, primarily attributed to variations in focal spot size and Fresnel losses. These temperature variations resulted in significantly different mechanisms of material removal in both configurations. In the AM configuration, the boiling temperature was not achieved, even at the highest power; however, a melting pool was formed at powers exceeding 50 mW. Thus, the primary driver of microhole formation was the Marangoni effect, which caused molten material to flow tangentially towards the edges of the molten pool. Furthermore, titanium oxidation was identified as a competing process contributing to changes in optical transparency and potentially inhibiting the complete formation of holes. Conversely, within the SM configuration, boiling temperatures are easily achieved, leading to localized boiling and the formation of gas bubbles near the glass–titanium interface. As a result, the rupture of the bubble through the capping molten layer led to a vigorous expulsion of both gas and material, allowing for the creation of microholes even at remarkably low laser power levels (10 mW). Notably, in this configuration, the influence of titanium oxidation is negligible due to the relatively short time scale involved (hundreds of microseconds).

Integrating Numerical Simulation and Experimental Validation to Analyze Temperature Distribution in Friction Stir Welding of Dissimilar Aluminum Alloy

This study explores the temperature distribution in Aluminum alloys, specifically AA2024 T351 and AA6351 T6, during friction stir welding (FSW). Utilizing COMSOL Multiphysics software, the research investigates FSW at rotational speeds of 800, 1200, and 1600 rpm, while maintaining a constant welding speed (35 mm/min) and axial force (3 kN). The simulation incorporates temperature-dependent material properties. The findings reveal that the maximum temperature occurs at the upper part of the stir zone for both alloys. Experimental validation demonstrates excellent agreement with the simulated temperature distribution, reaffirming the accuracy of the COMSOL Multiphysics model.

New model improves simulation of pressure and temperature distribution around the Mars Rover

New model improves simulation of pressure and temperature distribution around the Mars Rover

Thermal Analysis of Power Transformer Using 2D and 3D Finite Element Method

An accurate simulation and computational analysis of temperature distribution in large power transformers used in power plants is crucial during both the design and operational phases. This study introduces a thermal modeling analysis encompassing two- and three-dimensional (2D and 3D) approaches for power transformers. The mathematical model for heat diffusion follows the Finite Element Method (FEM) approach. Validation of the computed results involves comparing them against measurements from Hyundai’s test report for both 2D and 3D models, aiming to identify the most effective solution. Additionally, the thermal dynamics of power transformers under diverse operational conditions, specifically oil-immersed ones, are examined. The efficacy of this model is confirmed through testing on a step-up transformer at Kureimat station in Egypt, with specifications including three-phase, 50 Hz, 16.5/240 KV, nine taps, and cooling type (ONAN/ONAF1/ONAF2).

Surface temperature field real-time reconstruction of hot forging die based on 1DCNN

Accurate reconstruction of the die surface temperature field during the hot forging process is crucial for ensuring optimal control of die temperature and high-quality metal forgings. In this study, we propose a novel method that combines hot forging process parameters with a deep neural network to reconstruct the temperature field on the die surface in real-time. Firstly, a high-fidelity finite element model of the hot forging process is created and validated with a forging experiment. Secondly, temperature observation points are initially selected based on the simulated temperature distribution of the forging die, and the correlation coefficient method is used to optimize the layout of observation points to improve reconstruction accuracy and efficiency. Subsequently, multiple high-quality simulations with varying process parameters are conducted, generating a comprehensive dataset. The 1DCNN algorithm is then presented to produce a mapping from the input to the surface temperature field. Finally, the effectiveness of the surface temperature field reconstruction method is verified. The results indicate that the overall performance of the proposed 1DCNN algorithm is better than the traditional regression algorithms. In terms of reconstruction accuracy, it achieves a prediction accuracy within an absolute error of 3 °C for the outer surface points and within a relative error of 5 % for the cavity region. Regarding reconstruction efficiency, it requires an approximate execution time of 0.064 s for predicting a new sample. This paper presents a method for real-time reconstruction of the die surface temperature field, leveraging hot forging process parameters and temperature data from observation points. This approach enables reliable online monitoring of transient temperature variations on the hot forging die surface, offering valuable support for operational control and maintenance.

Modelling the fire resistance of cross‐laminated timber rib panels

AbstractA cross‐laminated timber rib panel is a floor system comprising cross‐laminated timber plates rigidly bonded to glued‐laminated timber ‘rib’ beams. A design method was developed to estimate the fire resistance of cross‐laminated timber rib panels, based on a bending load‐carrying model. The bending load‐carrying model calculates the bending load‐carrying capacity of cross‐laminated timber rib panels based on simulated temperature distributions of numerical models. The numerical models were validated against the experimental results of full‐scale fire resistance tests. The proposed design method is based on the overall approach of the current revised draft of EN 1995‐1‐2:2004, that is, prEN 1995‐1‐2:2023, and provides conservative estimates of the bending load‐carrying capacity. The effective width is one of the most important design parameters and its influence was studied in detail. A limit value of 60% of the effective width according to prEN 1995‐1‐1:2023 is proposed as effective width in fire.

Thermo-Fluid–Structural Coupled Analysis of a Mechanical Seal in Extended Loss of AC Power of a Reactor Coolant Pump

We proposed a numerical method to investigate the thermo-fluid–structural coupled characteristics of a mechanical seal of a reactor coolant pump (RCP), especially during extended loss of AC power (ELAP) operation. We developed a finite element program for the general Reynolds equation, including the turbulence effect to calculate the pressure, opening force, and leakage rate of fluid lubricant and the two-dimensional energy equation to calculate the temperature distribution of the fluid lubricant. We verified the accuracy of the developed program by comparing the simulated temperature distribution and leakage rate of this study with those of previous research. Heat conduction and elastic deformation due to pressure and temperature changes at the seal structure were analyzed using an ANSYS program. The results showed that temperature more significantly affected the elastic deformation of the seal structure near clearance than pressure both under normal and ELAP operating conditions. High temperature and pressure of the coolant under ELAP operating conditions deform the seal structure, resulting in a much smaller clearance of the fluid film than normal operating condition. However, even with a small clearance under ELAP operation, the leakage rate slightly increases due to the high internal pressure of the coolant. This research will contribute to the development of robust mechanical seals for RCPs by accurately predicting the characteristics of mechanical seals, especially when the RCP is operating under ELAP.

HVAC Design Optimization for Pharmaceutical Facilities with BIM and CFD

Building Information Modeling (BIM) has been widely used in the past decade to enhance the design quality of Heating, Ventilation, and Air Conditioning (HVAC) systems. However, in specialized areas such as pharmaceutical facilities, HVAC design has traditionally relied on Computer-Aided Design (CAD) drawings. This conventional approach does not allow for the simulation of temperature distribution or the verification of system efficiency, which may lead to design failures. To address these challenges in pharmaceutical facilities, this study proposed a BIM-based approach for optimizing HVAC design with Computational Fluid Dynamics (CFD). By employing CFD to simulate the dynamic airflow conditions of pharmaceutical clean rooms, the effectiveness of HVAC systems can be verified. A case study of a clean room HVAC design is presented to demonstrate the workflow. The results of the case study indicated that the pharmaceutical temperature requirements were met within 1 °C during the design optimization simulation, and there was a 95% match in the 72 h temperature mapping test during site validation. The results confirmed that using CFD with BIM not only successfully simulates the design intentions of indoor air quality but also suggests HVAC system optimization for the required clean room design. The findings of this paper contribute to the body of knowledge on overcoming the limitations of the traditional CAD-based HVAC design process and provide valuable insights on optimizing HVAC design with BIM and CFD technologies.

Numerical simulation and experimental investigation of temperature distribution during the wire arc additive manufacturing (WAAM) process

Numerical simulation and experimental investigation of temperature distribution during the wire arc additive manufacturing (WAAM) process

Transient Heat Transfer Analysis in Metal Plates with Variable Thickness

Nonlinear transient heat transfer via conduction–radiation is a dynamic topic of long-standing interest with applications ranging from aeronautical and mechanical engineering to industrial and civil security. To gain a better understanding of the performances of materials having thermal proprieties that change during nonlinear heat transfer, several studies using the finite element method (FEM) have been conducted. Such studies apply nonlinear thermal material characteristics to describe the complete system under different loading conditions in each region by adjusting the temperature values for the other three edges and the thickness parameter with Dirichlet boundary conditions. As a result, while modeling and simulating temperature distributions for such situations, nonlinearities generated by temperature-dependent thermal conductivity must be considered. In this work, we focus on the analysis of coupled transient heat transfer through two metal plates with temperature-dependent thermal characteristics in which the temperature is fixed along the bottom edge and heat is transferred from both the top and bottom faces of the two plates. FEM is employed to solve the nonlinear heat equation and compute the temperature as a function of time for variable thickness. The study examines the effect of modifying the thickness parameter values on the temperature distribution over time for various edge values over 5,000 s.

Numerical Simulation of Airflow Velocity and Temperature Distribution in an Aircraft Cabin

In this work, a computational fluid dynamics (CFD) model is established to calculate the airflow distribution in the cabin of a single-channel Boeing 737-800 airplane. The RNG k-ε model, considering the calculation of turbulence kinetic energy and its rate of dissipation, is adopted to solve turbulence problems in physical field simulation. The proposed three-dimensional model is able to consider the particular physical factors and spatial structures, which can simulate the detailed distributions of complex physical fields, compared with the one-dimensional lumped parameter model. The velocity and temperature fields under different air supply velocities are then numerically investigated. The calculation results show that when the air velocity at the top air supply inlet is 1.4 m/s, the velocity and temperature distribution inside the cabin can both meet the comfort requirements of humans in the airworthiness standards. The results from this work can help to design an aircraft environmental control system.

High Intensity Focused Ultrasound (20MHz) and Cryotherapy as Therapeutic Options for Granuloma Annulare and Other Inflammatory Skin Conditions.

In dermatology, inflammatory skin conditions impose a substantial burden worldwide, with existing therapies showing limited efficacy and side effects. This report aims to compare a novel immunological activation induced by hyperthermic 20MHz high intensity focused ultrasound (HIFU) with conventional cryotherapy. The bioeffects from the two methods are initially investigated by numerical models, and subsequently compared to clinical observations after treatment of a patient with the inflammatory disease granuloma annulare (GA). Clinical responses to moderate energy HIFU and cryotherapy were analysed using numerical models. HIFU-induced pressure and heat transfer were calculated, and a three-layer finite element model simulated temperature distribution and necrotic volume in the skin. Model output was compared to 22 lesions treated with HIFU and 10 with cryotherapy in a patient with GA. Cryotherapy produced a necrotic volume of 138.5mm3 at - 92.7°C. HIFU at 0.3-0.6J/exposure and focal depths of 0.8 or 1.3mm generated necrotic volumes up to only 15.99mm3 at temperatures of 68.3-81.2°C. HIFU achieved full or partial resolution in all treated areas, confirming its hyperthermic immunological activation effect, while cryotherapy also resolved lesions but led to scarring and dyspigmentation. Hyperthermic immunological activation of 20MHz HIFU shows promise for treating inflammatory skin conditions as exemplified by GA. Numerical models demonstrate minimal skin necrosis compared to cryotherapy. Suggested optimal HIFU parameters are 1.3mm focal depth, 0.4-0.5J/exposure, 1mm spacing, and 1mm margin. Further studies on GA and other inflammatory diseases are recommended.

Analysis of Anthropogenic Waste Heat Emission from an Academic Data Center

The rapid growth in computing and data transmission has significant energy and environmental implications. While there is considerable interest in waste heat emission and reuse in commercial data centers, opportunities in academic data centers remain largely unexplored. In this study, real-time onsite waste heat data were collected from a typical academic data center and an analysis framework was developed to determine the quality and quantity of waste heat that can be contained for reuse. In the absence of a comprehensive computer room monitoring system, real-time thermal data were collected from the data center using two arrays of thermometers and thermo-anemometers in the server room. Additionally, a computational fluid dynamics model was used to simulate temperature distribution and identify “hot spots” in the server room. By simulating modification of the server room with a hot air containment system, the return air temperature increased from 23 to 46 °C and the annual waste heat energy increased from 377 to 2004 MWh. Our study emphasizes the importance of containing waste heat so that it can be available for reuse, and also, that reusing the waste heat has value in not releasing it to the environment.

Effect of flow pulsation on heat transfer performance of biomimetic bark microchannel heat sink

Pumping coolant or using pulse flow through microchannels with novel structures on microelectronic devices is suitable for high heat flux dissipation and sensor development. This study proposes a novel microchannel designed as a series of biomimetic bark channel networks. Simulation and experimental testing of temperature distribution and heat transfer performance are conducted under different working conditions, including various fluid parameters. The results show that combining biomimetic bar microchannel and pulsation flow can improve heat transfer performance. The effect of pulsating flow frequency on the temperature is only evident outside the range of 10 mm from the inlet. Compared with non-slip boundaries, the boundary slip of pulsating flow slightly enhances heat transfer. Pulsating flow has an optimal frequency, minimizing thermal resistance for different inlet temperatures.

Simulation and experimental study of temperature and mass distributions of indium metal in vacuum evaporation

The temperature field and spatial distribution of metal vapor (i.e., flow field) are critical for the purity and direct yield of metals. However, it is impossible to accurately determine the temperature field and distribution of the metal vapor in a vacuum furnace. This study developed a surface-to-surface thermal radiation and volume of fluid multiphase flow coupling model. The temperature distribution and mass distribution of indium vapor in the vertical vacuum furnace at different temperatures from 1423 to 1573 K under the condition of 1 Pa were obtained. The reliability of the model was verified by experimental data obtained under the same conditions as the simulation. The temperature difference between the inside and outside of the condensing plate was 30–45 K in the temperature interval of 1423–1573 K. The temperature difference between the inside wall and the center of the condensing plate was 10 K. The simulation results of indium vapor mass distribution match with the experimental values; the overall temperature error is 5%, and the volatility error is less than 15%. The model developed in this study can be used to predict the temperature field and metal vapor distribution in a vacuum furnace, which will significantly reduce experimental exploration and accurately guide the production practice of vacuum metallurgy. This will expand the application of vacuum metallurgy technology in metal purification, material preparation, waste recycling, and other industries. This can effectively reduce exploratory experiments in the process of vacuum distillation to prepare high-purity metals, reduce the consumption of resources and energy in the experiment and production process, and achieve clean production.

Molecular dynamics simulation of temperature and concentration distribution at liquid-gas interface during liquid air storage process

To address global challenge of climate changes, renewable energy has been fully developed in recent years. However, renewable energy is usually intermittent which makes it challenging for application. Liquid air energy storage can effectively store intermittent energy with promising prospects. Liquid air is a mixture composed of N2, O2 and Ar with different evaporation temperatures. It is assumed to form temperature and concentration stratification during storage and thus causes safety challenge. To address this issue, molecular dynamics (MD) simulation method is used to study the temperature and concentration distribution characteristics in liquid air. The results show that the system temperature remains constant at 94 K with no temperature stratification during storage. However, the concentration of liquid air changes along vertical direction (z axis): the oxygen concentration remains stable around 21% as z is 0-60 Å, rises to 22.1% as z is from 60-70 Å and drops to 0% as z is above 80 Å. The thin and short stratification phenomenon occurs at the gas-liquid interface region. In addition, a higher heat flux leads to a higher evaporation rate and a larger oxygen concentration. As the heat flux increases from 0.0 to 2.4 W/m2, evaporation rate rises from 0.13 to 0.2% and the oxygen concentration at the liquid-gas interface reaches 22.3%. Thus, concentration stratification exists during liquid air storage and should be treated carefully. This paper provides an insight into the temperature and concentration distribution of liquid air during storage and is significant for safety improvement and development of liquid air energy storage.

An accelerated lattice Boltzmann method for natural convection coupled with convolutional neural network

A novel approach is proposed in the present study, which combines the lattice Boltzmann method (LBM) with convolutional neural networks and is suitable for square cavity natural convection and conjugate natural convection problems, exhibiting remarkable acceleration capabilities and potentials. The density distribution function obtained from LBM at time t and the temperature distribution function at time t+Δt under different Rayleigh numbers (Ra) are, respectively, utilized as input and output datasets for training and comparison in three convolutional neural networks, aiming to select the optimal coupling model, namely, half-Res-Unet. The coupling model can accurately simulate the natural convection in a square cavity within six times the upper limit of the Ra under the training condition, which can save the central processing unit (CPU) calculation time and the iteration steps by up to 29.2% and 30.3%, respectively. The coupling model is further extended in the current study to incorporate conjugate natural convection, enabling the accurate simulation of temperature distribution under training conditions with a thermal conductivity ratio (Ka) of 25 and an upper limit of Ra increased by 20 times. The corresponding maximum relative errors for the average Nusselt numbers (Nu) are found to be 1.8% and 0.7%, respectively, providing strong evidence for the generalization capability of the coupling model. Furthermore, the coupling model demonstrates a remarkable acceleration performance, as evidenced by its ability to reduce the CPU calculation time by up to 39.6% and iteration steps in the simulation process by 36.5%. It offers valuable insights into the integration of LBM with machine learning techniques, thereby enhancing the computational efficiency of LBM.

Development of a microwave chemical cell coupled with post-wall waveguide for in situ/operando soft x-ray absorbance spectroscopy under microwave irradiation

In this study, we developed a microwave chemical cell for total electron yield soft x-ray absorption spectroscopy (XAS) using synchrotron radiation under microwave irradiation. In addition, in situ XAS measurements of ammonia borane were performed using the device developed. The device comprises a post-wall waveguide housing a sample holder formed within it. Electrons emitted from the sample during soft x-ray irradiation pass through the metal plates of the waveguide and are measured using a picoammeter. Integration of the microwave irradiation structure into a synchrotron radiation beamline, which is a challenge in soft x-ray analysis requiring measurements in a high-vacuum atmosphere, was achieved by miniaturizing the device using 24.125 GHz ISM band microwaves, instead of the typical 2.45 GHz microwaves. Performance of the device was thoroughly assessed through temperature distribution simulation, temperature measurement of water, and evaluation of frequency characteristics. When the sample holder was filled with water and irradiated with 3 W microwaves, the temperature increased to 97 °C, which is close to the boiling point. The in situ XAS measurements performed using this device with ammonia borane/graphite (2:1) powder at the B-K edge during microwave irradiation showed that peaks associated with hydrogen desorption intensified with prolonged microwave exposure. This result indicates that microwave heating in a vacuum and soft x-ray analysis during microwave heating were achieved. The developed microwave chemical cell emerges as a powerful tool, facilitating advancements in our understanding of elementary chemical processes and elucidating microwave-specific effects such as local heating during microwave irradiation.