Simulated Temperature Values Research Articles

Assessment of predicting temperature distribution of friction stir welded AA6061 induced by pin profiles for developing sustainable industry

Nowadays, the aspects of energy and environmental pollution have been becoming a big challenge in developing sustainable industries. Using green technology is considered as priority solution for any manufacturing process. Friction stir welding (FSW) is invented as green technology applied widely in many field industries. To evaluate its applicability, this study focused on the prediction of temperature distribution of FSWed AA6061 induced by various pin profiles. Research efforts are being made to gain a better understanding of FSW process, to explore different tool configurations, and their influence on the heat generation. The numerical model was developed in Abaqus software, utilizing the coupled Eulerian Lagrangian method, the Johnson-Cook material model, and the mass scaling technique. The model’s accuracy is verified by comparing its simulated temperature values with experimental data in Stir zone (SZ) and Heat-affected zone (HAZ). The numerical results show the high correlation with the experimental study, with the deviation around 10%. It is shown that tool pin profiles with the combination of thread and flat features generated the highest temperature.

Research on indoor dynamic temperature based on circulating water heating

During the heating season, cities in northeast China primarily emphasize the implementation of large-scale CHP central heating systems. However, the heat-electricity constraints associated with these heating units hinder the integration of clean energy sources such as wind power, photovoltaic, and other renewable energies. Despite efforts to reduce carbon emissions and address concerns related to urban haze formation, energy conservation, and emission reduction, coal remains the predominant energy source for heating.In light of these challenges, this paper aims to investigate the heat transfer characteristics of buildings during the heating season. It also examines the feasibility of implementing heating regulations and provides a theoretical foundation for establishing a regional heat model that incorporates low-carbon energy islands. The proposed model combines wind power, photovoltaic power generation, and other renewable energy sources supplemented with coal power.By employing the concentrated heat capacity method, this study develops a mathematical model to simulate the dynamic thermal process involved in heating buildings. The model encompasses various components, including the dynamic heat transfer model of the building’s envelope structure, which considers its heat storage characteristics, as well as the radiator model and the indoor air heat balance equation. Furthermore, the model comprehensively accounts for the influence of different indoor and outdoor disturbances on the heat transfer process, including the effects of solar radiation.To validate the model, a simulation program is implemented using Matlab. This program is capable of hourly calculations to determine the indoor temperature. By comparing the simulated temperature values with the measured ones, the rationality and accuracy of the model are verified.

Simulation Study on Sunshine Temperature Field of a Concrete Box Girder of the Cable-Stayed Bridge

This paper investigates the distribution of the sunshine temperature field in bridge structures. To implement thermodynamic boundary conditions on the structure under the influence of sunshine, this study utilized the FILM and DFLUX subroutines provided by ABAQUS. Based on this method, the sunshine temperature field of the concrete box girder of a cable-stayed bridge was analyzed. The results showed that the simulated temperature values were in good agreement with the measured values. The temperature difference between the internal and external surfaces of the box girder under the influence of sunshine was significant, with the maximum negative temperature difference appearing around 6:00 a.m. and the maximum positive temperature difference appearing around 2:00 p.m. The temperature gradient of the box girder section calculated by the method presented a C-shaped distribution pattern, which differs from the double-line distribution pattern specified in the current “General Specifications for Design of Highway Bridges and Culverts” in China (JTG D60-2015). Furthermore, a sensitivity analysis of thermal parameters using the proposed simulation method for the sunshine temperature field of the concrete box girder was conducted, and the results indicated that the solar radiation absorption coefficient had a significant impact on the temperature field. A 30% increase or decrease in the solar radiation absorption coefficient caused the maximum temperature change on the surface of the structure to exceed 10 °C. This paper provides an accurate simulation of the sunshine temperature field of the concrete box girder of a cable-stayed bridge, and the research results are significant for controlling bridge alignment and stress state during the construction period, ensuring the reasonable initial operating state of the bridge, and enhancing the sustainability of the structure.

Understanding temperature characteristics during microwave cladding through process modeling and experimental investigation

• A FEM model with rotating turntable was developed to simulate microwave cladding. • Susceptor heating, clad heating and clad-substrate system heating discussed. • Simulated temperature profile of clad can predict critical temperature of the clad. • Substrate dilution increases with microwave power. Knowing temperature in the clad layer during microwave cladding is essential to identify microwave exposure duration. Localized arcing due to microwave interaction with metallic thermocouples make it difficult to measure real temperature of the clad layer. Hence, simulation was carried out to analyse thermal profile of clad layer. Temperature dependent dielectric properties resulted in prediction of temperature with a error of 3.95%. Simulation results revealed critical temperature of clad to be 419 °C with only 4.7% error. Furthermore, microstructure of the clad layer has been also correlated with experimental and simulated temperature values of the cladding process. Hence, present simulation model can be used to optimize microwave exposure duration and power for development of the clads.

“The contribution of double skin roof coupled with thermo reflective paint to improve thermal and energy performance for the ‘Mozabit’ houses: Case of Beni Isguen’s Ksar in southern Algeria”

In traditional cities of hot and arid climate regions, roofs are usually the surfaces most exposed to intense sunlight in summer. This leads to high temperatures inside the houses and forces the inhabitants to escape to the terraces at night. On the other hand, some residents use air conditioning and therefore increase energy consumption. This work aims to study the contribution of a double skin roof coupled with a thermo-reflective paint on the reduction of indoor temperature and energy consumption in house located in the Ksar of Beni Isguen in southern Algeria. Firstly, the problem of overheating was identified through temperature and humidity measurements for traditional dwelling in hot season. Secondly, a model of double skin roof coupled with thermo-reflective paint was developed and numerically simulated using TRNSYS software. The obtained results showed that in summer, the temperatures in traditional houses are high compared to the comfort zone. The average indoor operating temperatures exceeded 37 °C during different hours of the day, over the investigation period of three representative days of hot season. Nevertheless, the proposed model reduces the indoor operative temperature by 5 °C. Also, the model was validated against in situ measurements, whose results showed a consistency between the measured and simulated temperature values. In addition, thermal simulation results performed over a period of one year indicate that the overall energy consumption required for cooling loads is reduced by 572 kWh i.e. 66% when optimizing the roof thermal performance.

Determination of thermal material properties for the numerical simulation of cutting processes

Thermal properties of machined materials, which depend significantly on the change in cutting temperature, have a considerable effect on thermal machining characteristics. Therefore, the thermal properties used for the numerical simulation of the cutting process should be determined depending on the cutting temperature. To determine the thermal properties of the machined materials, a methodology and a software-implemented algorithm were developed for their calculation. This methodology is based on analytical models for the determination of tangential stress in the primary cutting zone. Based on this stress and experimentally or analytically determined cutting temperatures, thermal properties of the machined material were calculated, namely the coefficient of the heat capacity as well as the coefficient of thermal conductivity. Three variants were provided for determining the tangential stress: based on the yield stress calculated using the Johnson-Cook constitutive equation, based on the experimentally determined cutting and thrust forces as well as by directly calculating the tangential stress. The thermal properties were determined using the example of three different materials: AISI 1045 and AISI 4140 steel as well as Ti10V2Fe3Al titanium alloy (Ti-1023). With the developed FE cutting model, the deviation between experimental and simulated temperature values ranged from approx. 7.5 to 14.4%.

Modeling of Fundus Laser Exposure for Estimating Safe Laser Coagulation Parameters in the Treatment of Diabetic Retinopathy

A personalized medical approach can make diabetic retinopathy treatment more effective. To select effective methods of treatment, deep analysis and diagnostic data of a patient’s fundus are required. For this purpose, flat optical coherence tomography images are used to restore the three-dimensional structure of the fundus. Heat propagation through this structure is simulated via numerical methods. The article proposes algorithms for smooth segmentation of the retina for 3D model reconstruction and mathematical modeling of laser exposure while considering various parameters. The experiment was based on a two-fold improvement in the number of intervals and the calculation of the root mean square deviation between the modeled temperature values and the corresponding coordinates shown for the convergence of the integro-interpolation method (balance method). By doubling the number of intervals for a specific spatial or temporal coordinate, a decrease in the root mean square deviation takes place between the simulated temperature values by a factor of 1.7–5.9. This modeling allows us to estimate the basic parameters required for the actual practice of diabetic retinopathy treatment while optimizing for efficiency and safety. Mathematical modeling is used to estimate retina heating caused by the spread of heat from the vascular layer, where the temperature rose to 45 °C in 0.2 ms. It was identified that the formation of two coagulates is possible when they are located at least 180 μm from each other. Moreover, the distance can be reduced to 160 μm with a 15 ms delay between imaging.

CFD simulation and investigation on flow field characteristics and temperature predictions of an electric generator unit

In order to evaluate the cooling performance and thermal characteristics of an electrical generator unit, a three-dimensional model with and without fluid–solid temperature coupling is established and the model reliability is verified by temperature experiments. Results show that the air quantity distribution of each cooling air duct of the engine in original electric generator is uneven and there is a zero-velocity zone in the local area of the muffler. After structural improvement, the uniformity of air quantity distribution improves significantly and the surface velocity of muffler cover increases. The simulated temperature values of magneto surface and muffler front cover obtained are in good agreement with the experimental values, having the relative error of 5.8% and 4.9%, respectively. The maximum temperature of engine body, winding coil of magneto, and inverter is 200 ℃, 137.13 ℃, and 91.66 ℃, respectively. The research results can be used to quantitatively evaluate the cooling characteristics of electric generator.

Calculating the temperature and degree of cross‐linking for liquid silicone rubber processing in injection molding

AbstractProcessing of liquid silicone rubber (LSR) in the injection molding process has a high economic potential. Since there are some fundamental differences compared to classical thermoplastic injection molding, up to now there is a lack of well‐founded knowledge of the process which allows an estimation of the cycle time. Because, in addition to reverse temperature control, LSR processing also involves an irreversible temperature‐ and time‐dependent chemical reaction. In this paper, the complex cross‐linking reaction is first modelled phenomenologically using dynamic differential scanning calorimetry (DSC) measurements and the well‐fitting Kamal‐Sourour model. Afterwards, a temperature and cross‐linking simulation is set up, which reliably simulates the time‐ and travel‐dependent temperature profile and degree of cross‐linking in the mold. Therefore, the released exothermic cross‐linking heat is also taken into account. The simulated temperature values are verified with measurements in the cavity during the injection molding process. The measured values correspond very well with the simulated values at different mold temperatures. It is shown that the influence of the cross‐linking heat on the overall temperature profile in the LSR component during the injection molding process is relatively low. Nevertheless, the model is necessary to determine the degree of cross‐linking ‐ it can be used to calculate the cycle time at which the component of a certain cross‐section can be ejected at a known tool temperature and is fully cross‐linked. With this knowledge, existing processes can be optimized in terms of mold temperature and curing time, but also new components can be calculated economically.

An integrated numerical study for using minimum quantity lubrication (MQL) when machining austempered ductile iron (ADI)

Machining difficult-to-cut materials is still an ongoing area of research because of the promising advantages of these materials in different industrial applications. Austempered Ductile Iron (ADI) is among the difficult-to-cut materials as it is usually associated with short tool life and poor surface integrity and quality. Flood coolant is an effective approach to eliminate the high generated heat when machining ADI. However, the use of conventional flood coolant is not a sustainable approach. Minimum quantity lubrication (MQL) is one of the environmentally friendly cooling approaches, which has been demonstrated to be an effective near dry machining technique. There is a gap in the open literature in the area of numerical modelling of the thermal and heat transfer behavior when machining ADI. Thus, this research focuses on simulating the cutting heat distribution on the cutting tool during machining of ADI by developing an integrated numerical model (finite element & computational fluid dynamics). Two cooling techniques were used in this work namely; dry and MQL. In terms of dry cutting, the simulated temperature values were in good agreement with the experimental results with an error of 5.74%. Regarding the MQL, there was a 10.74% margin of error between the results from the experimental and the integrated numerical model.

Building energy model calibration: A detailed case study using sub-hourly measured data

This paper details a manual calibration of a 132 zones, highly monitored 5 434 m2 office building located in France. The calibration is conducted over one year of simulation at a five minute time-step. The model is mostly fed with input files containing measured data for each simulation time-step. First simulation results show that the model cannot be considered as being calibrated considering usual guidelines based on statistical indicators calculated on monthly energy consumption. Instead of going through a classical tuning process to match measured and simulated monthly energy consumption data, the choice was made to focus on explaining those discrepancies using available building information and monitoring data. A first dynamical heating and cooling powers analysis has been made, resulting in good correlation with measured values and explaining most of the discrepancies previously noticed, followed by a dynamical temperature analysis performed at the zone scale, and completed by a global statistical analysis at the building scale for the 132 zones of the building. Results showed very good agreement between measured and simulated temperature values with 90% of data points ranging between −1.72 °C and 2.02 °C of error. This demonstrate that a model that at first glance does not perform well considering particular statistical indicators can show an accurate dynamical behavior and a good performance when other variables and performance criteria are considered. This is followed by a discussion of the possible model improvements along with the limitations of statistical analysis compared to dynamic physical analysis for calibration performance assessment. The paper concludes with several proposals to improve the guidelines for calibration procedures involving the use of detailed monitoring data.

Measured and simulated temperature values in the chosen wall of a wooden building considering cardinal direction

Abstract The lightweight timber-framed walls were built in a climate chamber at the pavilion type laboratory which is part of the Department of Building Engineering and Urban Planning Faculty of Civil Engineering, University of Zilina. There are different walls, for example with blown thermal insulation, ventilated external facing, massive wooden beams or a sandwich structure. Orientation of these two walls is to the south and to the east. Sensors of temperature and humidity are situated in every wall compositions. Measurements are going on the stationary internal conditions and the real outside conditions in Zilina. Latter internal conditions are going to change into the non-steady thermal state. This article is focused on a comparison of experimental measurements and simulations of the selected sandwich wall. One fragment of the wall is oriented on the south and another on the east. At the end of the research, there will be the analysis of coupled transport of heat and water in sandwich walls of a wooden building. This research could lead to the recommendations for the design of low energy wooden building.

Water exchange of a standing column well with aquifer: A numerical study

Part of groundwater circulating in the well conduct mass exchange with the aquifer. This part of exchange (the raw water exchange) is indicated the groundwater flow and heat transfer in a typical standing column well. In order to study the water exchange between the standing column well and the aquifer quantitatively, a mathematic model of flow in a standing column well and coupled heat transfer of well pipe, well hole and aquifer was developed. The model was verified by the field test of a standing column well, and results show that the simulated temper ature values of drawing water were in good agreement with the measured values both in the cooling and heating condition with the deviation less than 10% and the correlation coefficient up to 0.998. The raw water exchange of a standing column well was studied quantitatively by defining the raw water exchange ratio and the raw water exchange load ratio. For the typical example, the exchange ratio of raw water and the load ratio by raw water exchange were almost constant with the data of 29.6% and 23.4%, respectively.

Method for modifying convective heat transfer coefficients used in the thermal simulation of a feed drive system based on the response surface methodology

ABSTRACTThis paper presents a method based on response surface methodology (RSM) to calculate the convective heat transfer coefficients (CHTCs) of a feed drive system. First, the temperature values at thermal-critical points and ball screw thermal elongation of a feed drive system were obtained by experimental and finite element (FE) methods. Second, the relationship between the CHTCs and simulated temperature values was established using RSM, and the CHTCs were calculated using the designed 25 tests. Finally, the effectiveness of the proposed method was proved using steady-state and transient-state simulation of the feed drive system.

Calculation method of convective heat transfer coefficients for thermal simulation of a spindle system based on RBF neural network

Results from the temperature field and thermal deformation simulation of a spindle system are greatly affected by the accuracy of convective heat transfer coefficients (CHTCs). This paper presents a new method based on radial basis function (RBF) neural network to calculate CHTCs. First, the temperature field and thermal deformations of a spindle system were obtained by experimental and finite-element (FE) methods. However, the simulation results are significantly different from the experimental results because boundary conditions used for the FE model were derived empirically. Second, the relationship between the simulated temperature values and CHTCs were established by a RBF neural network. Using the experimental temperature values as an input vector of the RBF neural network, CHTCs of the spindle system can be predicted through an iterative calculation taking 14 cycles. Finally, the effectiveness of the proposed method was proved using steady-state and transient-state analyses of the spindle system. Results from the steady-state simulation show that temperature errors were less than 4 % at the seven thermal-critical points and deformation errors in the three directions were less than 6 %. Results from the transient-state simulation of the spindle system show that the variations for each of the thermal characteristics are in good agreement with the experimental results. The method provides guidance for modifying boundary conditions of a FE model.

Analysis and modelling of water and near water temperatures in flooded rice ( Oryza sativa L.)

The knowledge of micrometeorological conditions in flooded rice fields is crucial for better modelling the behaviour of the crop in mid and high latitudes, where the thermal mitigation provided by water layer is significant against the climatic risk of low temperatures in spring and early summer. Two micrometeorological models (a mechanistic and an empirical one) for the simulation of thermal profile related to water and near water temperatures were calibrated and validated with data gauged in some rice fields located near Milano, Italy. The mechanistic model is based on the solution of the equation of the surface energy balance; the empirical one is funded on Gaussian filters. Both the models need as input data only daily values of maximum and minimum temperatures and therefore are suitable for agroecological operational purposes. The results show that the models could improve the performances of crop simulation models physically based, currently used for crop growth, development and production analysis. In fact, the comparison between measured and simulated temperature values indicates that both the presented models are able to reproduce the effect of water on temperature (average RRMSE = 14% for the mechanistic model and 7% for the empirical one; modelling efficiency always positive).