Heat Temperature Field Research Articles

Mechanical response of long-span CFST arch bridges based on the hydration heat temperature effect

As the span of concrete-filled steel tube (CFST) arch bridges increases, the hydration heat temperature effect of concrete inside steel tube becomes more severe, which increases the safety risk during the construction process. Therefore, a numerical simulation of the mechanical response of a long-span CFST arch bridge under the influence of hydration heat was carried out. First, based on the hydration heat conduction theory, a finite element model of the transient temperature field of a CFST arch rib was established. The temperature distribution of the CFST arch rib and its variation with time were revealed, and an approximate formula for the distribution of the hydration heat temperature along the radial direction of the CFST was provided. Subsequently, the variation law of the thermal stress of a CFST during hydration heat release was investigated. Finally, based on the principle of temperature equivalence, a finite element model of the overall CFST arch rib was established to examine the effect of hydration heat on the deformation of the arch rib. The results reveal that the hydration heat temperature field of the CFST arch rib exhibits nonlinear and axisymmetric characteristics. The maximum temperature of the section and the maximum temperature difference can reach 73.5 °C and 33.2 °C, respectively. Because of the influence of the hydration heat, there is a significant stress gradient in the cross section of the arch rib. A maximum radial stress of 2.08 MPa is attained, indicating a risk of concrete cracking. Additionally, the displacement along the transverse and vertical directions of the chord tube exhibits an initial increase, followed by a decrease over time. The maximum transverse displacement of the chord tube reaches 70.6 mm, while the vertical displacement reaches 117.8 mm.

An analysis of temperature control for electromagnetic induction heating of CFRP based on sparrow search algorithm

Accurate temperature control during the induction heating process of carbon fiber reinforced polymer (CFRP) is crucial for the curing effect of the material. This paper first builds a finite element model of induction heating, which combines the actual fiber structure and resin matrix, and systematically analyzes the heating mechanism and temperature field distribution of CFRP during the heating process. Based on the temperature distribution and variation observed in the material heating process, a PID control method optimized by sparrow search algorithm is proposed, which effectively reduces the temperature overshoot and improves the response speed. The experiment verifies the effectiveness of the algorithm in controlling the temperature of CFRP plate during the induction heating process. This study provides an effective control strategy and research method to improve the accuracy of temperature control in the induction heating process of CFRP, which helps to improve the results in this field.

High‐Temperature Thermal Conductivity of Fiber Hybrid Ceramic Matrix Composites with Different Modes

Thermal conductivity (TC) is one of the important thermal property evaluation parameters for high‐temperature‐resistant fiber‐reinforced composites. Herein, based on the flexible‐oriented three‐dimensional (3D) woven technology, fiber hybrid ceramic matrix composites (FH‐CMCs) with different hybrid modes are designed and fabricated by using carbon fiber and silicon carbide fiber. The representative volume element (RVE) models of fiber bundle and matrix with mesoscopic characteristics and the macroscopic RVE models with hybrid structure characteristics are established. The heat flux distribution and effective TCs of FH‐CMCs in the thickness and in‐plane directions at different temperatures are obtained by finite element analysis (FEA) and experimental tests. The results show that the FEA and experimental results of the TCs of different FH‐CMCs are in good agreement. In the range of 25–1000 °C, the effective TCs of FH‐CMC gradually decrease with the increase in temperature. The TCs in the thickness direction of different FH‐CMCs are directly proportional to the hybrid ratio, and the TCs in the in‐plane direction are inversely proportional to the hybrid ratio. The heat flux and temperature field distributions of the FH‐CMCs are mainly affected by the TCs of the components, fiber hybrid ratio, and orientation, and the distribution along different directions are obviously different. The research results are helpful to provide theoretical and experimental reference for the structural design and performance improvement of hybrid composites.

Discrete element analysis of heating transfer characteristics of airport pavements by using electro thermal method for snow melting and deicing

This study presents a discrete element investigation on the internal temperature change characteristic and heat transfer efficiency in airport concrete pavement by using the carbon fiber electrothermal method for snow melting and deicing. A discrete element model for snow melting and deicing of airport concrete pavement by using the carbon fiber electrothermal method was generated. The temperature evolution on the surface of the pavement was captured and compared with the indoor experimental results. The numerical simulation results were in good agreement with the experimental results, which verified the applicability of the numerical model. On this basis, the effects of the heating temperature and heating paths on the internal heat conduction and temperature field distribution were investigated. The results showed that the temperature of the pavement surface and the temperature rise gradient are linearly related to the temperature of the carbon fiber heating wire. The initial heating time has little influence on the temperature rise path of the road surface layer after stopping heating and reheating. The temperature of the road surface layer rises slowly after the heating is stopped, and then decreases linearly at a rate of 0.4 °C/h not corresponding to the initial heating time.

Integrated novel modeling approaches for non-uniform heat source and temperature field in gear profile grinding

Integrated novel modeling approaches for non-uniform heat source and temperature field in gear profile grinding

Inverse estimation of heat flux and temperature field for a nonlinear heat transfer system using step-renewed two-stage Kalman filter

Inverse estimation of the thermal input and states is a useful tool for the monitoring of a thermal system. Nonlinear heat transfer is a quite common issue in this kind of problem. As the thermal properties are temperature-dependent, it is difficult to inversely estimate the input and temperature field. To deal with this problem, a step-renewed scheme is adopted into the weighted optimal two-stage Kalman filter (WOTSKF), forming step-renewed WOTSKF (SR-WOTSKF). This strategy is a marching method, without solving the Jacobian matrix in extended Kalman filter. The feasibility of dealing with the nonlinear inverse heat transfer problem is implemented by comparing WOTSKF and SR-WOTSKF. Then, the weighting factor, initial guess of the input heat flux and measurement noise are changed to investigate their effects on the simultaneous estimation results of heat flux and temperature field. It is found that when the weighting factor is 0.95, the relative error of the estimated heat flux using SR-WOTSKF is approximately 2.73% which is much lower than that using WOTSKF. Results using SR-WOTSKF demonstrate that the estimation results are independent of the initial guess and the estimated heat flux can track the exact one in a short period. An incorrect initial guess causes the initial estimation error of the temperature and heat flux and it makes no sense to following period. When the standard deviations of the measurement noise are adopted as 0.01, 0.10, 0.50 and 1.00, the mean relative error of the heat flux is 2.73%, 4.79%, 7.71% and 9.43%, demonstrating the strong robustness of SR-WOTSKF to resist the measurement noise.

Effect of flow maldistribution on heat transfer performance and temperature field of plate-fin heat exchangers

Plate-fin heat exchangers (PFHEs) are widely utilized in aviation precoolers, emphasizing not only heat transfer performance but also the outlet temperature distribution, with flow maldistribution impacting both parameters. This study developed a numerical model of crossflow PFHE and a two-dimensional flow distribution model under the condition of flow maldistribution. Experimental validation shows a standard deviation of 6.9%. This investigation delves into the effects of flow distribution offset (ξ) and non-uniformity (ε) on heat transfer performance and outlet temperature distribution. With large temperature differences, variations in fluid properties due to temperature lead to changes in the surface heat transfer coefficient (SHTC). The combined effects of SHTC and temperature difference determine the heat transfer performance. The results indicate optimal heat transfer performance and outlet cross-sectional temperature distribution at ξ= − 0.67 and 1, respectively. For a given ξ, increased non-uniformity deteriorates heat transfer efficiency and outlet cross-sectional temperature distribution. At ε=0.66, relative to the uniform flow, the heat transfer performance and standard deviation of outlet temperature distribution decrease by 10.3% and 45.1%, respectively.

Numerical simulation of abrasive cutoff operation based on ALE adaptive meshing technique

Metal cutting is one of the most important and commonly used manufacturing processes in industry and has been studied for years; however, accurate simulation of cutoff operation is still a big challenge because of the complexity of the material removal process. The main challenge for the classical simulation method is computational difficulties during the material removal process, and furthermore, the material deletion criterion has to be somehow empirical. To conquer these problems, a more robust and efficient simulation technique for the cutoff process is proposed herein, in which the material removal is achieved through continuously adjusting mesh nodes on contact surfaces based on ALE adaptive meshing technique, instead of deleting elements. Finally, this new simulation technique is used to predict the heat partition and temperature field evolution during the cutoff operation of the steel plate. It is found that the obtained simulation results agree well with those by the analytical approach, demonstrating its effectiveness.

Research on one-dimensional digital twin algorithm of plate heat exchanger

Based on the differential idea, this article establishes two segmented algorithms which are the linear equations method and iterative method for solving the one-dimensional digital twin of the temperature field and pressure field of plate heat exchanger (PHE). The segmented algorithms are to consider the change of the physical properties of the fluid along the flow direction, which makes the solution of the temperature field and pressure field more accurate than that without segmentation. It can still get other important parameters besides temperature and is easy to converge with a few iterative steps. When the boundary conditions are known, it can accurately solve the heat transfer, wall temperature, convective heat transfer coefficient, temperature field and pressure field of fluid. Under six groups of test conditions, the heat exchange, temperature and pressure calculated by the two algorithms are compared with the commercial software Flownex, when the number of segments is 100, the average maximum error of each segment is not more than −0.39%, −0.97%, and 0.18%, respectively. To balance accuracy and calculation speed, this article also explores the impact of the number of segments on accuracy. It is found that when the number of segments increases to 10, the impact on the calculation accuracy can be ignored. Compared with Flownex, these two algorithms have smaller errors, and the solution speed of solving linear equations method is faster than that of iteration. It provides application value for emerging digital twin technology, data center chilled water system and other projects and industries that need to accurately control the outlet temperature and wall temperature of PHE.

Research on the heating rate of induction heating CFRP and temperature field based on image entropy

The electromagnetic induction heating technology has the advantages of fast heating speed and cleanness, and can realize the rapid temperature curing of carbon fiber reinforced polymer (CFRP). In order to improve production efficiency and curing quality, a finite element model of induction heating CFRP was established, and the temperature field distribution and heating mechanism during induction heating of CFRP were analyzed. The correctness of the model and conclusion is verified by experiments. On this basis, the influence of current, diameter, frequency and distance on the heating rate is analyzed, and it is found that frequency has the greatest influence on the heating rate. In addition, the mathematical relationship between temperature field uniformity and entropy value is established, which provides a quantitative analysis method for the temperature field uniformity of induction heating CFRP. Through optimization analysis, it is obtained that for the CFRP mentioned in the article, the coil size is selected between 65 mm and 95 mm, and the spacing is between 3.5 mm and 6.5 mm, so that the temperature field has the best uniformity.

Simulation Analysis and Optimization of Temperature Field for Hot In-Place Asphalt Pavement Recycling

The heating temperature field of asphalt pavement is a key factor affecting the quality of pavement heat-in-place recycling (HIR). Using the heat transfer characteristics of HIR, a three-dimensional heat transfer model was simplified into a one-dimensional heat transfer model along the depth direction. A temperature sensor was installed on the site to monitor the temperature change of the asphalt pavement at different depths under different heating powers, and the actual temperature and heat transfer model were highly compatible. Through this model, the influence of heater running speed and heater heat flux density on the temperature field of the asphalt pavement heated by infrared radiation (IR) was calculated by the finite differential method, and an optimal combination of heating is proposed. In accordance with construction continuity and minimum energy consumption principles, at the 3.0–3.5 m/min recommended running speed of the heating machine, the asphalt at a depth of 4 cm satisfied the temperature demand, but the asphalt on the road surface was prone to heat aging. The heating effect of the constant temperature variable power heating (CTVP) is ideal, but the continuous change in heating power increases the difficulty of construction. Constant temperature discrete power heating (CTDP) divides the ideal heat flux density curve into several stages according to the length of the heating plate in the heater, increasing the feasibility of constant temperature heating in engineering and reducing energy consumption.

Numerical Study of Ti6Al4V Alloy Tube Heated by Super-Frequency Induction Heating.

Ti6Al4V alloys have a narrow processing window, which complicates temperature control, especially during large-scale production. Therefore, a numerical simulation and experimental study on the ultrasonic induction heating process of a Ti6Al4V titanium alloy tube were conducted to obtain stable heating. The electromagnetic and thermal fields in the process of ultrasonic frequency induction heating were calculated. The effects of the current frequency and current value on the thermal and current fields were numerically analyzed. The increase in current frequency enhances the skin and edge effects, but heat permeability was achieved in the super audio frequency range, and the temperature difference between the interior and exterior of the tube was less than 1%. An increase in the applied current value and current frequency caused an increase in the tube's temperature, but the influence of current was more prominent. Therefore, the influence of stepwise feeding, reciprocating motion, and stepwise feeding superimposed motion on the heating temperature field of the tube blank was evaluated. The coil reciprocating with the roll can maintain the temperature of the tube within the target temperature range during the deformation stage. The simulation results were validated experimentally, which demonstrated good agreement between the results. The numerical simulation method can be used to monitor the temperature distribution of Ti6Al4V alloy tubes during the super-frequency induction heating process. This is an economical and effective tool for predicting the induction heating process of Ti6Al4V alloy tubes. Moreover, online induction heating in the form of reciprocating motion is a feasible strategy for processing Ti6Al4V alloy tubes.

A Review of Numerical Simulation of Laser-Arc Hybrid Welding.

Laser-arc hybrid welding (LAHW) is known to achieve more stable processes, better mechanical properties, and greater adaptability through the synergy of a laser and an arc. Numerical simulations play a crucial role in deepening our understanding of this interaction mechanism. In this paper, we review the current work on numerical simulations of LAHW, including heat source selection laws, temperature field, flow field, and stress field results. We also discuss the influence of laser-arc interaction on weld defects and mechanical properties and provide suggestions for the development of numerical simulations of LAHW.

Thermal stability model of power coupler niobium tube for accelerator based on multi-field coupling analysis

The power coupler is the key component of superconducting accelerator, and its thermal stability will seriously affect the stable operation of the superconducting cavity. The niobium (Nb) tube at the end of the power coupler directly connected to the superconducting cavity is taken as the research object, and a one-dimensional thermal stability model based on multi-field coupling analysis is established. The coupling relationship between the electromagnetic field, liquid helium boiling heat transfer and temperature field is considered. The finite difference method was used to discretize the control equations of the model, and the Newton-Raphson method was used to handle the influence of material parameters and internal heat sources nonlinearity on the accuracy and stability of the discrete equations. The results show that the thermal stability of the Nb tube can be improved by controlling the upstream heat leakage and maintaining the upstream temperature below 9.2 K. Under transient conditions, timely recovery of the upstream cooling capacity can stop the quench caused by the decrease of cooling capacity and restore the superconducting state. The maximum quench propagation speed caused by the increase of magnetic field is 0.188 m/s, which is higher than that caused by the decrease of cooling capacity. When the local region of the liquid helium contact enters the film boiling 0.0034 s, the entire region will enter the film boiling, and the maximum temperature will reach 11.3 K, which will cause the thermal quench of the superconducting cavity. The model can accurately analyze the factors affecting the thermal stability of Nb tube and provide a reliable theoretical basis for the thermal design and stable operation of this type of power coupler.

Early hydration heat temperature field of precast concrete T-beam under steam curing：Experiment and simulation

Precast concrete T-beam steam curing can improve production efficiency, realize large-scale production of T-beams, and achieve better economic benefits. We performed tests and numerical simulations on a 30-meter-long full-size precast concrete T-beam to study the economical and reasonable steam curing scheme. The study found that in the early stages of steam curing, the temperature at the mid-span section increases faster than that at the end-span section. The highest temperatures of the tested beams were found in end-span section., and the core-surface temperature difference increased and then decreased, with the maximum temperature difference occurring at the junction of the top and web slabs of the concrete T-beam. To meet initial prestress tensioning requirements, the steam curing of increasing the temperature for 2 h to 50 ℃, keeping the temperature constant for 7 h, and cooling the temperature for 1 h is the most economical scheme, as seen from the comparison and analysis of the development law of concrete hydration heat temperature and the results of concrete test blocks under the same curing. Under this steaming scheme, the end-span section of the concrete T-beam reached a peak temperature of 68.5 °C at 14 h, and the core-surface temperature difference reached a maximum of 8.6 °C at 4.5 h; the peak temperature of the mid-span section was 60.2 °C, with a maximum temperature difference of 8.3 °C. In order to accurately predict the law of T-beam concrete temperature development under steam curing, two subprograms, HETVAL and UMATHT, were compiled on the ABAQUS secondary development platform. When calculating by natural age t, the maximum differences between the measured peak values and the peak values calculated by HETVAL and UMATHT were 30.0% and 27.7%, respectively. After considering the equivalent age te of concrete, the maximum differences between the measured peak values and the peak values calculated by HETVAL and UMATHT were 8.2% and 1.9%, respectively. Therefore, the UMATHT subprogram, considering equivalent age and hydration degree, can accurately predict the development of the concrete hydration heat temperature field under the steam curing process.

Simulation of Temperature Field in FSW of 6061T6 Aluminum Alloy IGBT Liquid Cooled Radiator Panel

Heat input and temperature field distribution in the welding process are crucial to welding quality. The parameters in the FSW process are optimized to study the influence of the temperature field on a car Insulated Gate Bipolar Transistor(IGBT) liquid cooled radiator panel 6061T6 aluminum alloy under friction stir welding. This paper established the liquid cooled radiator panel with friction stir welding fully coupled thermo-mechanical model, and explored the thermal physical parameters of 6061T6 aluminum alloy based on JMATPRO. Then, the temperature field distribution rules of friction stir welding at the inlet of liquid cooling plate and the weld joint under different welding time are explored by using ABAQUS. The effects of different rotational and welding speeds on the temperature field of the welded joint are also studied. Results show that most of the heat in the FSW process is generated by the shaft shoulder of the tool, and the heat at the welding position is a conical shape. Under the assumption that other technological parameters remain unchanged, the rotational speed of the pin is the most important factor affecting the temperature field of the FSW process.

Study on Optimization of Cooling System for Mass Pier Column of Shenzhong Passage Non-navigable Bridge

In this paper, the optimization layout of cooling pipes and the measured temperature field of the mass pier column for the Shenzhong Passage non-navigable bridge are carried out, and the finite element modeling software is utilized to simulate the whole construction process, and the temperature time and process model is established for simulation analysis. The results show that the measured hydration heat temperature field in the field construction meets good agreement with the simulation results. The optimized cooling pipe layout scheme saves more raw materials and elbows, and shorts the project construction period; It can realize more effective internal lowering and external protection for the construction of mass concrete structures of piers and columns, which is especially suitable for the maintenance of sea-crossing bridges in windy environmental conditions; The temperature-induced cracks are effectively controlled, which can provide a reference for similar projects.

Temperature Control for Mass Concrete of Bridge Cap in Summer Construction

In order to realize the accurate calculation of the temperature field of concrete hydration heat, the paper takes the concrete hydration heat temperature field of the pile cap of Liexi Bridge as a case for simulation analysis. Firstly, a three-dimensional finite element model of concrete hydration heat temperature field is established; Then, the temperature field of the hydration heat of the concrete cushion cap of the Liexi Bridge is simulated. The experimental results show that the maximum actual measured temperature of the core point of concrete hydration heat temperature is 63.1 °C, and the corresponding calculated temperature is 62.2 °C. The maximum actual measured temperature of the surface point is 54.8 °C, and the corresponding calculated temperature is 53.8 °C. The maximum temperature difference between inside and outside is 18.9 °C, and the corresponding calculated temperature is 13.4 °C. The research results show that the calculation model has high accuracy

Temperature Control for Mass Concrete Construction of Wentang Bridge 5# Pier Pile Cap in Winter Construction

In order to ensure the construction quality of mass concrete structures in winter, and avoid and prevent harmful temperature cracks of mass concrete, a calculation method of temperature field of hydration heat in winter based on finite element method is proposed in this paper. First, the three-dimensional finite element model of the temperature field of hydration heat is established; Then, the temperature variation of winter hydration heat temperature field of Wentang Bridge is calculated through experiments. The results show that the maximum measured temperature of the core point is 44.2 °C, and the corresponding calculated temperature is 53.7 °C. The maximum internal and external temperature difference measured is 24.7 °C, and the corresponding calculated temperature is 22.4°C. The research results prove that the calculation model can better simulate the concrete hydration process.

Simultaneous estimation of heat flux and temperature field using optimal two-stage Kalman filters

Inverse estimation of unknown input heat flux and temperature field plays an important role in thermal state monitoring. Optimal two-stage Kalman filter (OTSKF) is introduced into the inverse estimation of thermal state in this work. To further improve its performance, a new method weighted optimal two-stage Kalman filter (WOTSKF) algorithm is developed, in which a forgetting factor is used to modify OTSKF. The estimation performances of OTSKF and WOTSKF are compared in a two-dimensional heat transfer system. They are employed to estimate the state with heat flux of temporal, spatial, and spatiotemporal variation. Additionally, the effects of forgetting factor and measurement noises on the estimation accuracy of heat flux and temperature are investigated. Though decreasing the forgetting factor can improve the tracking ability and estimation accuracy of WOTSKF, it should not be too low due to the reason that low α causes fluctuation of estimation results. When the standard deviation of measurement noises σr increases from 0.05 to 2.00, the mean relative error of estimated heat flux ηq using OTSKF rises from 4.03% to 10.67% and it climbs from 2.76% to 7.07% using WOTSKF. That demonstrates proposed WOTSKF has stronger robustness than OTSKF.