Model Of Temperature Distribution Research Articles

Predicting smoke temperature distribution beneath ceiling for a large subway station fire

Fire accident seriously threatens the stable operation and personnel security in the subway station, and clarifying the smoke temperature distribution is conducive to arranging reasonably fire alarm. In this study, model experiments and numerical simulations are conducted to investigate the ceiling temperature profiles, mainly altering the heat release rate (HRR) and fire locations in a large subway station. The repeatability of the experimental data is confirmed, and the numerical model is validated by the measurement data. During a fire happening in a large-wide space, the smoke movement beneath the ceiling can be divided into radial and one-dimensional flow, whose prediction models are proposed under fire source located at the center. On this basis, it can be found that the radial temperature profile is independent of fire source location. While, the one-dimensional temperature distribution model is modified by introducing the effects of transvers and longitudinal fire locations respectively. This work could provide data support and theoretical reference for clarifying the smoke movement for large subway station fire.

On the analytical solution of the one-dimensional convection–conduction equation for packed-bed thermal energy storage systems

Temperature distribution modeling within packed-bed thermal energy storage (PBTES) systems is crucial to simulate its integration into heat sources and perform techno-economic analyses to assess the actual benefits associated with its use. This article proposes a one-dimensional convection–conduction equation to model a fluid–solid system by assuming volume-averaged properties for the energy balance and determines the analytic solution through Integral Transforms. The present study analyzes the applicability of this analytic solution considering different operational conditions of PBTES systems. The article revealed that the Péclet number (Pe) and the fluid-to-solid capacity ratio (κ) must be limited to obtain stable solutions, while the dimensionless time τ cannot be arbitrary despite computing an analytic solution. A sensitivity study of the solution for parameter a=κPe/2 defined the minimum dimensionless time required for the solution to be stable. This stability was assessed with existing experimental setups, indicating the solution’s feasibility for air–solid PBTES systems.

Study on the maximum ceiling temperature and downstream temperature distribution in inclined tunnel fire

Constrained by various factors, including terrain, tunnels frequently exhibit slopes. While existing research on fires in inclined tunnels predominantly focuses on the characteristics of smoke flow in large slope tunnels, there is a notable lack of attention given to the study of micro-slope tunnels and important factors such as induced air inflow. Therefore, in this paper, the numerical simulation method is used to study the maximum ceiling temperature rise and downstream temperature distribution in inclined tunnel fire under the conditions of micro-slope and large slope. The results show that the main factors affecting the ceiling temperature rise are not only the tunnel slope, but also the HRR and the downstream length. These effects can be expressed by the stack effect intensity. When the inclined tunnel fire occurs, the maximum ceiling temperature and the downstream temperature distribution characteristics show two states. When the stack effect in the tunnel is diminished, there is no significant alteration in the maximum ceiling temperature and temperature distribution within the tunnel when compared to a horizontal tunnel. In a tunnel with a strong stack effect, the maximum temperature decreases as the stack effect increases, and the temperature distribution differs greatly from a horizontal tunnel. The theoretical analysis of this paper identifies the demarcation point of the two state changes as the dimensionless induced air inflow velocity of 0.1. On this basis, a piecewise prediction model for the maximum ceiling temperature of the inclined tunnel fire is established. Because the temperature distribution between the fire source and the maximum temperature position is not regular. Thus, using the maximum ceiling temperature as a reference point, an accurate segmented prediction model of temperature distribution is proposed for downstream Region 1. This study offers guidance for designing tunnel structures with high-temperature resistance and assessing safety conditions within the tunnel.

Modelling for Temperature Distribution Calculation using Surface Scattering of Free Electrons in Finite Metal Solid

This study generalizes the temperature distribution equation for finite metal solid, unifying previous separate models for thick and thin plates. Effects of surface scattering of free electrons on heat conduction is taken account. As plate thickness decreases, these scattering events increase, leading to elevated temperatures due to reduction in mean free paths. We propose a prediction model for temperature distribution incorporating these effects onto the existing Rosenthal solution. It exhibits excellent agreement with finite element analysis results across all thicknesses. Furthermore, from an engineering standpoint, two examples of how heat concentration occurs in material with geometry that promotes multiple surface scattering are presented.

Investigation on activation performance of adhesive bonding connection between Fe-SMA and steel plates

Steel structures are extensively utilized in civil engineering because of their advantageous characteristics. However, cyclic loading can induce cracks in steel structures, resulting in a decline in mechanical properties and increased life cycle costs. In recent times, iron-based shape memory alloys (Fe-SMAs) have gained recognition as promising materials for structural reinforcement due to their distinct shape memory effect. The adhesive bonding connection between Fe-SMA and steel offers an efficient solution for reinforcing steel structures, enabling uniform stress transfer without introducing defects. This study investigates the influence of the geometric dimensions of Fe-SMA plates and the structural adhesive on the stress of steel plates through activation tests and finite element simulations. A multiple regression model has been proposed to describe the relationship between the size of Fe-SMA plates, structural adhesive, and the stress of steel plates. In addition, the temperature of the adhesive during activation is determined through activation tests. According to test results, a temperature distribution model for the adhesive has been developed, allowing for an accurate theoretical calculation of the adhesive softening length. The adhesive softening significantly impacts the stress distribution of the steel plate, making this model considerably valuable. This study provides valuable experimental data and a theoretical basis for the practical implementation of Fe-SMA in metal structural reinforcement.

Analytical model of the steady state temperature distribution in a single and multi-layer brake disc

This article focuses on the modeling and analyzing effort for the thermal analysis and design of disc brake for endurance braking scenario. Test cases of bike disc brake rotor are chosen as its unique double layered architecture has been recently proposed for thermal optimization especially. This work aims at the evaluation of the steady state temperature distribution during braking to be studied considering a constant rotation speed and localized heat sources at the brake pad area. The problem is solved analytically using variable separation and a double Fourier - Hankel transforms.The modelling strategy is developed for a single layered rotor as reference cases for various rotation speed and rotor thicknesses. The effect of the rotation speed is underlined using a representative constant heat exchange coefficient. For high rotation speed (greater than 50 rad s-1 for the studied geometry), an effective surface layer can be observed which limits the influence of the rotor thickness on the temperature level. The model is extended to a multi-layered material rotor architecture. The potential advantages of this composite structure for different layer thicknesses and materials are evaluated and discussed. It appears that the aluminium core provides the better results, yet the relative reduction of the temperature compared to a plain stainless steel disc is of about 1 % only.

Calculation method for the dynamic temperature distribution of winding area in dry-type on-board traction transformer

Dry-type on-board traction transformers have attracted considerable attention because of their lightweight and flameproof characteristics. The temperature distribution of winding areas is a critical indicator for representing operation performance. This study developed a calculation model for the dynamic temperature distribution of winding areas in dry-type on-board traction transformers under time-varying environments. First, a dynamic temperature calculation model was proposed based on the principle of thermoelectric analogy. Next, for addressing the transient outlet temperature of air ducts in the model, the influences of environment parameters and air duct size on heat dissipation were investigated, and a calculation model for the transient outlet temperature was proposed. Finally, the validity of the proposed dynamic temperature calculation method was verified experimentally, and the method was compared with conventional computational fluid dynamics numerical simulation using line data. The results revealed that for various structural parameters and time-varying operation scenarios, the proposed method could accurately obtain the temperature distribution in the winding area and could save more than 99% of the time cost compared with the conventional method.© 2017 Elsevier Inc. All rights reserved.

Thermodynamic Study on the Vortex Teeth of Electric Scroll Compressors Based on Gradient Tooth Height

Through the analysis of the adhesion between the tooth head and axial clearance leakage attributed to vortex tooth shape deformation, an innovative tooth shape design concept has been introduced entitled “progressive change tooth high vortex tooth”. This unique design includes a gradual change in tooth height and an elevated vortex tooth profile, using temperature-sensitive materials to enhance the resolution of temperature loading on the vortex disc. By refining the process of resolving the temperature loading on the vortex disc, the mean temperature function of the fluid domain along the wall of the vortex tooth is calculated, and a steady-state temperature distribution model for the solid domain of the vortex tooth is formulated. Subsequently, a finite element model for the high eddy current disc is constructed using Abaqus 2021 finite element software, which facilitates the calculation of stress–strain distribution within the high eddy current disc under both gas pressure and temperature field loads. The results show that, especially under conditions of low speed and low exhaust pressure, the temperature load mainly influences the maximum deformation and stress distribution of the vortex tooth. Specifically, under the influence of heat-solid coupling, the maximum deformation of the progressive change tooth high vortex tooth occurs in close proximity to the central compression cavity, reaching up to 13 microns. These results provide a crucial theoretical basis for the structural design and performance optimization of the compressor.

Large-scale experimental study on the average temperature distribution model of fire smoke under mechanical ventilation in the flat space

Mechanical ventilation is essential to ensure the safety of persons, equipment, and structures in cruise ship fire incidents. The mass loss rate, smoke temperature, and comprehensive heat transfer coefficient during large-scale fire experiments are researched in cruise ship flat space. The results indicate that the mass loss rate of four pool fires with different sizes presents different rules in mechanical ventilation conditions compared with open conditions. In addition, the vertical distribution of temperature appears to be stratification, which aligns with the “dual-zone model”. The horizontal distribution of the temperature has a “mutation point”. With the mutation point as the boundary, the temperature drops rapidly from the fire source to the mutation point and decreases more slowly. Furthermore, the distribution model of comprehensive heat transfer coefficient and average temperature are established. The comprehensive heat transfer coefficient is in direct proportion to the 1.00 power of heat release rate and inversely in proportion to the 0.69 power of the number of mechanical ventilation. However, the average temperature is in direct proportion to the 0.52 power of heat release rate and inversely in proportion to the 1.40 power of the number of mechanical ventilation.

Computer modeling of temperature distribution in the course of sintering of glass microspheres

Composite materials obtained by sintering glass microspheres are considered the promising ones for the underwater technology. The high indicators of the hydrostatic strength combined with the heat and sound insulation properties are due to the microspheres maintaining their shapes as close to the spherical as possible. The computer model of the temperature distribution is developed based on the physical and chemical conceptions of the glass composites structure formation by sintering the glass microspheres of sodium borosilicate composition and processing the experimental results of the temperature measurements. The modeling methodology is based on the principles of decomposition of the task by the researcher and ranking the temperature and time parameters. The ratio of the hydrostatic strength to the density of the samples is taken as a functional criterion and the software application is written in the Python language. The experimental setup that is used for sintering the glass microspheres enables to study the temperature fields and thermal deformation processes in real-time conditions. The coefficients of thermal conductivity of sintering are determined by the regular mode method. The results obtained are aimed at solving one of the most important scientific and practical issues of developing technologies for manufacturing glass composites for strategic purpose.

Framework for assessing the performance of overhead transmission lines under wind-temperature effects

This paper presents a framework for evaluating the wind-induced resistance of overhead transmission lines (OTLs), aiming to overcome the limitations associated with disregarding temperature effects and relying on a single metric for failure assessment. The proposed framework factors in temperature influence, carefully considers applied loads and structural characteristics, and accurately calculates failure probability based on a specific case study. Meteorological data is initially collected to create a probabilistic model of wind speed and temperature distribution, accounting for correlation. Components and systems are graded based on structural characteristics and damage modes. The neural network surrogate model is trained with finite element computations for load-structural response sample sets. The surrogate model, in conjunction with logistic regression, generates samples to determine fragility. Finally, the total structural failure probability and monthly failure likelihood are computed by integrating the joint probability model and fragility. Analyses highlight temperature's significant impact on conductor-ground line safety, validating the proposed framework's rationale.

Restoration of high-pressure turbine blade combs using a concentrated energy flow

A useful model of temperature distribution in the deposited layer of ВЖ159 powder and in the zone of its connection with the base material — ЖС6У alloy, during laser cladding is developed. The optimal modes of laser cladding of powder onto alloy blades are determined. The properties of the deposited layer and the quality of its bonding with the base material are studied. It is shown that there are no defects such as pores, cracks and discontinuities in the deposited layer and the interface zone. Keywords:restoration, laser cladding, blades, high-pressure turbine, temperature distribution, microstructure, microhardness, X-ray spectral microanalysis

Analyzing Temperature Distributions and Gradient Behaviors for Early-Stage Tumor Lesions in 3D Computational Model of Breast

The computational modelling and analysis of internal and external temperature distributions and their gradients, associated with the first stage of mammary tumors, was performed to relate thermal parameters to relevant tumor characteristics. A realistic 3D geometric model of breast anatomy was used to simulate tumor cases that were characterized in real life at their primary clinical stage. The thermophysical parameters of three tumors were extracted to implement the models; a fourth case without a tumor was used as a reference to provide quantitative measurements of temperature increases and gradient changes. The analysis considered superficial and internal temperature distributions and gradients, computed throughout specific paths. Finally, an evaluation was made of the ability of the thermometric technologies available today to detect the changes estimated in simulations. Maximum temperature increments in the range of 2.30 to 3.20 °C and in the range of 0.15 to 0.30 °C were found on internal and superficial paths, respectively. Internal gradient peak magnitudes fluctuated within the range of 0.34 to 1.14 °C/mm. Thermal results indicated a direct correlation between tumor size and temperature rise. Nevertheless, gradient results showed that the heat generation rate, an indicator of tumor malignancy, was directly proportional to internal gradient maximum peaks, which were related to tumor boundaries regardless of tumor size.

Imaging performance prediction of a hypersonic target in a geosynchronous orbit based on multi-dimensional information correlation of radiation, multi-spectral, and polarization

Hypersonic target detection based on infrared intensity characteristics is easily disturbed by sea surface and cloud flares when detected by space-based optical systems, which results in a low detection rate, high false alarm, and difficulty in stable detection. This paper explores a method to improve target detection performance based on the correlation of infrared radiation, multi-spectral and polarization. Firstly, the comprehensive factors that influence complex ambient illumination, atmospheric transmission, and clutter background on spectral-polarization characteristics of hypersonic targets are analyzed. Based on the global radiation scattering theory, the temperature distribution model of the hypersonic target is established by using FLUENT. The polarization emission and pBRDF model of the target is established, and the radiation polarization transfer model is generated. Secondly, the sea surface temperature distribution is obtained by inversion of Landsat8 remote sensing data. The radiation polarization transfer model of the sea surface is established based on the Cox-Munk model combined with pBRDF and the polarization emission model. Thirdly, the polarization scattering effect of atmospheric particles on the upward radiation of the interaction of the target with the sunlight is considered comprehensively, and the 6SV radiative transfer model is used to calculate the polarization effect of atmospheric particles on the upward radiation transmission of the target and the background. Then, combined with the point diffusion of the optical system and the photoelectric conversion of the detector, the multi-dimensional full-chain imaging prediction model of the hypersonic target-sea background-ambient atmosphere-optical system-detector is established. The imaging characteristics and detection performance of the target in different imaging dimensions are simulated and analyzed with the signal-to-clutter ratio (SCR). The research shows that in the direction of reflected sunlight from the sea surface, the sea surface glare is suppressed and the target is highlighted through a target detection method of multi-dimensional information. This method has better detection results than the infrared multi-spectral detection method.

Modeling of temperature distribution and clad geometry of the molten pool during laser cladding of CoCrCuFeNi alloys

Modeling of temperature distribution and clad geometry of the molten pool during laser cladding of CoCrCuFeNi alloys

A two-dimensional semi-analytic thermal model for global temperature distribution predicting and hot spot monitoring in interior permanent magnet synchronous motor

A two-dimensional semi-analytical thermal model (SATM) is presented, aiming to quickly and accurately achieve global temperature distribution predicting and hot spot monitoring for interior permanent magnet synchronous motor (IPMSM). Thereby, it provides a reliable analysis tool for thermal behavior evaluation and prevents undesired consequences induced by excessive temperature rise, which is of great worth and significance in promoting the flourishing of IPMSM. SATM combines the analytical method, lumped parameter thermal network, and finite element analysis to obtain an analytical solution for thermal behavior through mathematical derivation by considering the complicated configuration, heat source distribution, heat dissipation condition, and material thermal dependence. Through SATM, it is possible to observe the global temperature distribution as well as the location and size of hot spots in each element. The temperature distribution gradient on the static is more pronounced than that on the dynamic; secondly, the area with the most severe heating is mainly found on the winding; furthermore, the hot spot on the winding is mainly located a little bit inside the center. Moreover, the thermal behavior of IPMSM at rated load is investigated by numerical analysis and experiments. A comprehensive comparison with SATM is done. The computational deviations between SATM and numerical analysis regarding the hot spot, minimum, and average temperatures on each element are all within 4.06 %. However, SATM consumes only 20.92 % of the time and 68.29 % of the storage of the numerical analysis. The measured data also fully prove the reliability and validity of the comparison. It is certain that SATM can well break through the limitation of the existing non-numerical technique to quickly and accurately achieve global temperature distribution predicting and hot spot monitoring of IPMSM. It provides researchers and engineers engaged in thermal behavior evaluation with good analysis means, design guidance, and optimization direction.

A mathematical model of temperature distribution along the length of the oil production well

The paper gives a systems analysis in the field of heat transfer and temperature distribution (TD) along the length of oil production wells (OPW). The analysis shows that the existing mathematical models are suitable only for determining TD along the length of casing string (CS) and are not suitable for determining TD along the length of the tubing run, since the existence of the interfacial (between the CS and the tubing) annulus of the fluid and gas layers with heat capacity and thermal conductivity that differ significantly from the heat capacity and thermal conductivity of rocks surrounding the CS. Given the above, mathematical models taking into account the impact of the fluid and gas layers in the annulus on the heat transfer from the upward fluid flow to the tubing wall and from the wall to the interfacial annulus are developed. To ensure the technological effectiveness of the obtained model, formulas for quantitative estimation of the heat transfer of the fluid flow into the surrounding environment are given.

Time-dependent model of temperature distribution in continuous flow pulsed electric field treatment chambers

A key component of a continuous flow pulsed electric field (PEF) system is the treatment chamber, where the product is exposed to electric pulses. Determination of the temperature distribution in the chamber during PEF treatment is important since high local increases in temperatures can affect the quality of the product. Coupled simulations of electric field, fluid flow, and heating in the existing literature do not model each individual electric pulse, but rather employ a “duty cycle” approach, which does not account for transient variations in treatment intensity and temperature changes in the medium. We present a time-dependent approach to modelling PEF treatment in continuous flow treatment chambers, which can model each pulse separately, and thus enables a more accurate study of temporal and spatial distributions of electric field and temperature. The model has been validated on laboratory scale treatment chambers of parallel plate or colinear design and using realistic protocols. Industrial relevance textThe paper is relevant to all pulsed electric field (PEF) applications either on laboratory or industrial scale that implement a continuous flow treatment chamber. It presents an improved modelling approach which allows for an analysis of the electrical current, electric field, and temperature distribution in the chamber during, at the end, and in between application of electrical pulses. The model can be used to predict the peak temperature at the end of each pulse in the hot spots, which if large enough could potentially lead to thermal damage of the product or in extreme cases even potential local boiling of the medium, resulting not only in degradation of the treated product, but also in accelerated electrode fouling, oxidation, and dissolution (etching), as well as arcing. This would not only affect the quality of the treated product but would also affect the wear and lifetime of electrodes/chambers, and of the pulse generator. The model can also be used to avoid expensive trial-and-error optimization of the PEF protocols and chamber geometries in situ.

Quantification of geometrical errors and thermal effects during wire EDM of thin wall structures—A numerical study

Machining thin-walled structures with a high aspect ratio using Wire EDM can lead to geometrical errors, primarily of two types; overcut error due to kerf formation and thermal deformation of the entire wall section. To understand the driving mechanisms behind these errors three distinct numerical models were developed. Initially, a model based on a moving heat source was created, employing the apparent heat capacity approach to predict kerf width and the associated overcut error. These insights were then utilized to formulate a transient temperature distribution model with a redesigned geometry, considering time-dependent evolution of the kerf and corresponding changes in the material properties of the sub-domains. Finally, a thermo-mechanical coupled model was developed to predict geometrical errors caused by the deflection of the wall, considering the varying stiffness of the part. A series of experiments were conducted to gain insight into the effect of the designed wall thickness on wall deflection. For the selected design profile and machine parameters, the model predicts a 62.4% reduction in thickness and a corresponding over-cut error of 188μm. Similarly, the model predicts wall deformation in the range of 6μm to 312μm for various wall thickness levels and these findings were validated with experimental observations.

Gas turbine circumferential temperature distribution model for the combustion system fault detection

The gas turbine combustion system operates under harsh conditions, and any faults such as nozzle clogging, cracks, etc. can endanger the downstream components and cause catastrophic accidents. Thus, monitoring the combustion system status and detecting its performance degradation timely are crucial for gas turbine safety. The current predominant method for monitoring involves analyzing exhaust gas temperature (EGT) dispersion, utilizing thermocouples placed at the turbine outlet to indirectly assess combustion system performance. However, the EGT is affected not only by faults but also by various non-fault disturbances, such as operational conditions, atmospheric variations, compressor performance degradation, and uneven hot gas mixing and rotating. To improve the sensitivity of fault detection, it is necessary to investigate how various factors affect the EGT dispersion and differentiate between EGT changes due to interference and those due to combustion system faults. However, using actual operational data from gas turbines to analyze and reveal these impact mechanisms is challenging. Therefore, this paper develops a gas turbine model for combustion system fault detection that accurately reflects the uneven circumferential distribution of EGT. The model incorporates a multi-combustor burner, a multi-channel turbine, and a module for simulating the mixing and rotating of the hot gas. Using this model, simulations are conducted to study the effects of non-fault interference factors, such as variations in ambient temperature, fuel flow changes, and compressor performance degradation, on EGT distribution. Additionally, simulations are conducted to analyze the effects of faults, including combustor cracks, uneven fuel distribution, and the coupling of interferences with faults, on EGT distribution. By comparing the normal and abnormal modes, the study reveals the different EGT responses due to non-fault interferences and combustion system faults. Based on these findings, a fault detection method for coupled conditions is proposed. The research results provide a basis for the fault detection of combustion system, enabling practitioners to reduce interference in fault detection and to increase the detection sensitivity.