Temperature Distribution Curve Research Articles

Farklı Denge Sıcaklıkları İçin Isıtma ve Soğutma Derece-Saatlerinin Değişimi: Bandırma Örneği

Data on exterior temperature constitute one of the most important parameters in the calculation of energy needs in buildings. This study obtained the temperature distribution curves by analyzing the outdoor air temperature in Bandırma. Heating Degree Hour (HDH) and Cooling Degree Hour (CDH) for three different base temperatures were calculated. A 21-year data set between 2000-2020 obtained from the General Directorate of Meteorology was used. The incidence (%) of outdoor air temperature according to months was determined. In the calculation of the HDH and CDH values, base temperatures of (15, 18 and 20 °C) and (20, 22 and 24 °C) were considered respectively. The results of the analysis showed that the number of HDH changed between 31357 and 53037, while CDH numbers ranged between 10433 and 2669. The increase in the average outdoor air temperature with the effects of global warming was determined for heating and cooling season in a 21-year period according to year. It was determined that there was an increase of 1.68 °C in the heating season in the 21-year period and 1.80 °C in the cooling season in the 21-year period. In this study, the necessity of determining energy needs for heating and cooling purposes in a clear and up-to-date manner was emphasized once again. This is highly important to not only achieve energy savings but also reduce the air pollution effects of energy consumption. It is believed that this study will make a contribution to the literature in this sense.

Experimental Study on Manned/Unmanned Thermal Environment in Radar Electronic Shelter Based on Different Air Supply Conditions

Studies on the thermal environment of the electronic radar shelter have been mainly focused on the simulation of the unmanned thermal environment, and there have been few studies on experiments in the thermal environment. Additionally, a comparative study of the experimental results from manned and unmanned shelters has been missing. In this paper, we experimented in thermal environments of manned/unmanned shelter under different air supply conditions. The experiment was divided into cooled, ventilated, and heated trials analyzing three aspects: (1) The average temperature distributions of walls, air inlet points, air outlet points, and surfaces were measured over time under different conditions in an unmanned shelter. The temperature distribution curve was fitted into the function. (2) Based on different working conditions, the temperature distribution experiments were carried out in three different areas for subjects wearing short or long clothing respectively. (3) The wind speed was measured at each measuring point in the air supply pipeline under different working conditions. The wind speed distribution was detected on the setting surfaces. The experimental results show that: (1) The air does not gradually tend to steady state with the time, and under different conditions, the air temperature obviously differs. (2) The clothing selection, air supply conditions, and locations of measuring points have significant influences on human body temperature distribution and left–right difference. (3) The mixing of the thermal plume caused by the vertical temperature difference of the human body and the jet generated by the mechanical air supply will reduce the wind speed of the airflow in the cabin, the adsorption of the jet to the bulkhead, and the stability of the airflow. The experimental data can provide the initial and boundary conditions for the simulation of the shelter. The results can provide a reference for the study of fluid control methods, the setting of thermal boundary conditions, and the simulation of the influence of thermal plumes on the airflow distribution. The experimental study in this paper has filled in the blanks regarding experimental study in electronic radar shelters. It has important research value and practical significance.

Метод визначення положення і форми пластичної зони в доменній печі з використанням показників розподілу температури газового потоку

The purpose of the work is the development of analytical and indirect methods for determining the shape and position of the plastic zone of a column of blast furnace charge materials. It is shown that the development of new mathematical models and methods for operational determination of the parameters of the cohezive zone for installation on blast furnaces of various means of controlling the distribution of the charge and gas flow has the greatest potential for further use in solving the problems of effective control of blast furnace melting. A new method for determining the parameters of the plastic zone (shape, thickness, and position) in the blast furnace is proposed, which is a combination of known and improved mathematical models as a result of research: loading of charge materials into the blast furnace, determination of melting temperatures and softening of iron-containing components of the charge in its various zones, determination parameters of the charge column in the dry zone of the blast furnace, determination of the area of the melting surface and a new method of determining the position of the softening and melting lines in the blast furnace using information on the means of controlling the temperature distribution of the gas flow and the surface of the charge backfill. The configuration of the melting line (surface) is determined on the basis of the similarity of this line to the temperature distribution curve of the gas flow (filling surface) on the furnace surface, as well as the equality of the area of the side surface of the figure of rotation of the forming line around the axis of the furnace and the calculated melting area. The calculation of the coordinates of the points of the softening line is based on the results of mathematical modeling of loading processes and the distribution of charge components along the radius of the blast furnace top, which provides the possibility of determining the component composition of iron ore layers of charge materials in a given zone of the furnace and forecasting the formation of melts and their properties with the help of high-temperature transformation models. Unlike the known approach, according to which when determining the area of the melting surface, the amount of heat in the lower part of the furnace is set as a constant, the proposed method implies the calculation of this value taking into account the current technological conditions of blast furnace melting.

Influence of the location of drilling fluid loss on wellbore temperature distribution during drilling

Circulation loss can occur at different positions during drilling, which has different effects on the wellbore temperature distribution. To ensure the safety and effectiveness of the drilling process, it is necessary to study the influence of circulation loss at different positions on the wellbore temperature distribution. In this study, we established mathematical models of wellbore temperature distribution corresponding to different situations in which circulation loss occurred and obtained the wellbore temperature distribution for each situation. When circulation loss occurred in the one-dimensional region, the annulus drilling fluid temperature at the circulation loss position changed suddenly; when it occurred in the two-dimensional region, the wellbore temperature at the circulation loss position was significantly disturbed. Under other conditions unchanged, as the circulation loss occurred closer to the bottom hole, the lower the wellbore temperature became at the same well depth. After circulation loss occurred, the formation temperature in the circulation loss area decreased significantly. The difference between the wellbore temperature distribution curve after circulation loss occurs and the wellbore temperature distribution curve when no circulation loss occurred can be used to monitor the location of the circulation loss in real time.

Wellbore temperature distribution during drilling of natural gas hydrate formation in South China sea

The natural gas hydrate resources in the South China Sea alone are about 85 trillion cubic meters. In the drilling process of marine gas hydrate, the natural gas hydrate will decompose and produce gas, as the rising of temperature and dropping of the pressure in the annulus. This process will have a significant impact on drilling safety. Therefore, it is necessary to study the wellbore temperature distribution during the drilling of marine hydrate layer. In this paper, the wellbore temperature distribution of safe drilling in hydrated formation is taken as the research goal, and the research status of relevant domestic and international wellbore temperatures was investigated. According to the characteristics of the marine environment and reservoir-forming characteristics of hydrate reservoirs in the South China Sea, the wellbore temperature distribution model of offshore drilling wellbore under the condition of hydrate decomposition was established. The temperature distribution curve of drilling straight wellbore in hydrate layer of South China Sea was obtained. When drilling the hydrate reservoir, the distribution regularity of the wellbore temperature is similar to that of the conventional offshore drilling wellbore. However, the temperature of the wellbore annulus near the hydrate decomposition site is lower than the ambient temperature, mainly due to the hydrate decomposition endothermic. In this paper, the sensitivity analysis of several main parameters of the wellbore temperature distribution of drilling straight wellbore in hydrate layer of South China Sea was carried out. Through the conduction of experiment and numerical simulation, we have get some new findings: (1) The hydrate saturation has little effect on the wellbore temperature; (2) As the drilling fluid displacement increases, the annulus temperature of the wellbore above the mudline increases, and the temperature of the wellbore below the mudline decreases continuously; (3) As the density of the drilling fluid increases, the temperature at the wellhead decreases, and the temperature at the bottom of the well increases slightly; (4) The greater the rate of penetration of the well, the temperature at the upper part of the wellbore decreases, and the temperature at the bottom of the wellbore increases; Among them, the penetration rate has the most obvious effect on the annular temperature. The results are expected to be helpful to guide the drilling process of marine gas hydrate and offer some references.

POWER CABLE INSULATION PRODUCTION LINE CONTROL

The paper considers the problem of control the cable insulation continuous vulcanization line. The axisymmetric mathematical model of the power cable rubber insulation vulcanization technological process has been developed. The model describes the heat transfer process inside the vulcanization pipe and the vulcanization process kinetics inside the insulation. The mathematical model is based on the energy conservation equation and it is presented in the form of a differential equations system closed by boundary conditions The mathematical model makes it possible to estimate the influence of various technological and design parameters on the temperature distribution along the radius and length of the cable. Based on the temperature distribution curves, the cable insulation vulcanization degree is calculated The study of the raw rubber compositions vulcanization properties was carried out by rotary rheometer, where the samples of the material were subjected to an oscillating load at different temperatures. As a result of the experiment, the curves family of the torque dependence on the curing time at different temperatures was obtained. To describe the vulcanization process kinetics, a parametric expression is used based on the experimentally obtained torque dependences. The obtained temperature dependence of the parametric expression coefficients makes it possible to describe the vulcanization process taking into account the uneven temperature distribution along the cable radius and length. The developed model makes it possible to calculate the speed at which the vulcanization degree reaches a given value. Algorithms for calculating and correcting line speed and extruder flow rate are proposed on the basis of a mathematical model. It allows us to determine the speed and flow rate of the extruder for various: cable designs, insulation materials, abnormal operating conditions of the production line. The results can be used at enterprises engaged in the production of cable and wire products with cross linked insulation. In cases where it is required to quickly calculate a new technological mode, make changes to the cable design, change the insulation material, and also take into account possible pressure drops inside the vulcanization pipe and deviations in the cable properties during the production process.

Thermal Performance of Finned Heat Sinks Embedded with Form-Stable Myristic Acid Phase Change Material in Photovoltaic Cooling for Green Energy Storage

Photovoltaic (PV) panels must be equipped with a cooling system to increase their electrical output generation. Despite numerous publications on the fabrication of form-stable phase change material (FSPCM) for thermal energy storage application, studies on the usage of FSPCM for PV cooling are incredibly limited. In this work, the cooling performance of myristic acid FSPCM encapsulated with cross-linked nitrile rubber (NBR) was investigated. A fin heat sink (FHS) was employed to hold the FSPCM. The thermal performance of the FHS embedded with FSPCM (FHS-FSPCM) was preliminarily tested in an indoor setup. Results show that the FHS-FSPCM has a lower temperature distribution curve than the bare FHS, highlighting the increase in cooling capability of fabricated FSPCM. Field-testing of PV panels integrated with an FHS-FSPCM displayed that FSPCM manages to reduce the operating temperature of the panel by 4 to 15 °C and increase power output generation by 38.61%.

Analysis of influence of ripple parameters of heat storage elements on flow and heat transfer performance

In order to study the influence of the corrugated angle and width of enamel heat storage element on the flow and heat transfer performance, a certain enamel heat storage element was numerically simulated by FLUENT software, and the variation curves of internal flow field velocity, temperature distribution, Nusselt number and drag coefficient with Reynolds number were obtained when the corrugated angle and width of the heat storage element were different. Thesimulation results show that when the ripple inclination increases from 20° to 60°, the resistance coefficient of the heat storage element increases, and the Nusselt number increases, and the increase of the resistance coefficient is greater than that of the Nusselt number; when the ripple width increases from 6 mm to 10 mm, the increase of resistance coefficient is small, and the increase of Nusselt number is large.

Design of adaptive weld quality monitoring for multiple‐conditioned robotic welding tasks

AbstractMultiple‐conditioned welding monitoring is a challenging issue in complex robotic welding tasks. In practice, the monitoring system has to be sensitive to different welding conditions (WCs) and weld quality changes. In this paper, a swing high temperature sensor system is used in order to obtain the temperature distribution curve under different WCs. A sigmoid feature extraction (SFE) method is proposed to obtain the geometric features of the temperature distribution curve, and a weld monitoring algorithm is proposed for multiple‐conditioned welding tasks using multi‐layer perceptron (MLP) classifier and Kalman filter‐based Gaussian probability density function (PDF) prediction for the probabilistic weld quality estimation. When there are unknown WCs, the proposed method uses an efficient incremental learning for the MLP and an online maximum likelihood estimation for the Gaussian models of the unknown WCs. The experimental results show that the proposed framework can accurately reflect the weld quality changing in both single‐WC and multiple‐WC tasks. In addition, the proposed adaptive updating methodology can achieve comparable performance with unknown WCs, as compared to the results with knowing all the WCs.

Effect of lateral smoke extraction on transverse temperature distribution and smoke maximum temperature under ceiling in tunnel fires

This paper studied the effect of lateral smoke extraction on the transverse temperature distribution and maximum smoke temperature beneath the ceiling. The experiments were conducted in a reduced model tunnel (1:8). In the experimental study of optimal aspect ratio of the smoke extraction vent, a series of experimental conditions were considered. Keeping the same area of vents, four kind aspect ratios were set (n = 1, 2, 3, and 4). In experiment investigation of ceiling maximum smoke temperature, under the best vent aspect ratio n = 3, four fire heat release (50 kW, 60 kW, 70 kW, and 80 kW) rates were considered. The experimental results showed that the lateral smoke extraction system will affect the transverse temperature distribution, the transverse temperature distribution curve shows good stratification phenomenon, and the maximum temperature point will offset to the direction of the lateral extraction vent. The data of the maximum temperature under different test conditions were analyzed, and the influence factors of lateral smoke extraction were considered. Finally, the correlation of the maximum smoke temperature under the influence of lateral smoke extraction was proposed.

Dynamic measurement and correction of infrared radiation temperature for rocket motor exhaust plume

The dynamic measurement and correction of infrared radiation temperature for rocket motor exhaust plume was established based on Stefan-Boltzmann formula under the assumption that the colorimetric temperature is regarded as the real value. The relationship between the spectral emissivity of the exhaust plume and time is obtained, and the temperature distribution measured by the infrared thermal imager is corrected in real time. During the stable working period of the rocket motor, the maximum value of the infrared radiation temperature distribution curve and the average value corresponding to the time are used to represent the maximum and average infrared radiation temperature of the motor exhaust plume field. This method is applicable to the real-time determination of the spectral emissivity of the exhaust plume and the accurate measurement of the infrared radiation temperature distribution at static or rocket sled flight state, and is of great significance to the development of the low-signature rocket motor and propellant charge.

Experimental and numerical studies on gas tungsten arc welding of Ti–6Al–4V tailor-welded blank

The effect of gas tungsten arc welding (GTAW) process parameters and its impact on the titanium TWB was studied experimentally as well as using numerical simulation. Bead characteristics of BoP trials (bead on plate) were analyzed based on Taguchi L27 orthogonal array by taking welding current (115 A, 125 A, 135 A), welding speed (4.1 mm/s, 5.8 mm/s, 7.5 mm/s) and arc length (3 mm, 4 mm, 5 mm) as process parameters. The bead width and depth of penetration for all trials were measured by using the weld expert system. Based on the bead characteristics, optimized GTAW process parameters (135 A, 4.1 mm/s and 3 mm) were identified for making the TWB by joining 2–1.6-mm-thick Ti–6Al–4V sheets. The tensile test of the prepared Ti–6Al–4V TWB was conducted in the universal testing machine. The COMSOL and ABAQUS software packages were used for the numerical simulation of TWB to assess the bead profile and tensile properties. The prediction made from the temperature distribution curve related to phase change near weld zone, exactly matched with the experimental work. The joint strength of TWB observed to be around 982 MPa and 1005 MPa was evaluated experimentally and conducting ABAQUS simulation work. The tensile test results were comparable with each other within the acceptable error level.

Two-channel time-optimal control of induction heating process with maximum temperature constraint

The formulation and method of solution of the problem of time-optimal control of induction heating process of an unlimited plate with two control actions on the value of internal heat sources with technological constraint in relation to a one-dimensional model of the temperature field are proposed. The problem is solved under the conditions of a given accuracy of uniform approximation of the final temperature distribution over the thickness of the plate to the required. The method of finite integral transformations is used to search for the input-output characteristics of an object with distributed parameters with two control actions. The preliminary parameterization of control actions based on analytical optimality conditions in the form of the Pontryagin maximum principle is used. At the next stage reduction is performed to the problem of semi-infinite optimization, the solution of which is found using the alternance method. The alternance properties of the final resulting temperature state at the end of the optimal process lead to a basic system of relations, which, if there is additional information about the shape of the temperature distribution curve, is reduced to a system of equations that can be solved. An example of solving the problem of time-optimal control of temperature field of an unlimited plate with two offices is carried out in two stages. At first stage the case of induction heating without maximum temperature constraints is considered, at the second stage is carried out on the basis of the results of the first stage to obtain the solution subject to the limitation on the maximum temperature of the heated billet.

Finite Element Analysis of Thermal Stress of GIS Shell in Sunlight Environment

In order to study the thermal stress of the GIS shell under normal internal pressure in the sunshine environment, First, the 24-hour temperature field on the surface of the GIS shell of a substation is detected for and the temperature change curve is plotted. Then the ANSYS software is used to carry out finite element stress analysis including temperature field on GIS shell. During the analysis, select the highest temperature and lowest temperature periods, fit the temperature distribution curve of the cross section of the shell varying with the angle under the two conditions, and apply the corresponding temperature load of the two conditions to obtain the stress distribution and stress amplitude distribution. The results show that under normal sunlight environment, the stress of the shell without stress concentration is less than 30Mpa, and the stress variation value caused by diurnal temperature difference in most areas of the shell is within 5MPa, and it can reach about 10Mpa at the top where the stress concentration occurs. This study analyzes the stress distribution and fluctuation range of the GIS shell under the solar radiation, which provides important data support for the safety evaluation of the GIS shell.

Investigation of numerical modelling of TIG welding of austenitic stainless steel (304L)

Welding is one of the most commonly joining processes used in industry at widespread. Austenitic stainless steel are application in fabrication pressure vessels. Thin sheets of 304L can be welded by pulsed Tungsten Inert Gas (TIG) joining process. The current study investigates the numerical modelling of pulsed TIG welding of austenitic stainless steel using ANSY APDL. Double ellipsoidal heat source have been used for modelling the pulsed TIG welding. The objective of the present investigation is to study the effect of varying welding current on the temperature distribution curve. Temperature profile affects the microstructure, mechanical properties and the residual stresses developed in the welded joint during TIG welding. It has been observed that the peak temperature increases with increasing welding current.

Measurement of in-plane thermal conductivity of self-suspended thin films

A method for in-plane thermal conductivity measurement of self-suspended thin films by steady-state infrared thermal thermography is introduced. Based on the one-dimensional heat conduction equation, a theoretical model of temperature distribution on the surface of thin film at steady state is established. The simulation results show that the error between in-plane thermal conductivity and theoretical value is less than 3% when the temperature rise of the film is less than 5K. By measuring the boundary temperature and thickness of the film, the in-plane thermal conductivity and emissivity can be obtained simultaneously without measuring the absorption of visible light by the film. Polyimide film with the thickness of 550 nm is experimentally investigated by this method. We find that the in-plane thermal conductivity is 2.15W/mK and emissivity is 0.93 by fitting temperature distribution curve. These results validate the method developed.

Development of a wellbore heat transfer model considering circulation loss

Well loss is a common and complex accident in drilling engineering. The wellbore temperature under lost circulation plays a very important role on safe drilling and affects rheology of fluid, wellbore pressure, well-wall stability, etc. At present, the study on wellbore temperature profile under lost condition is quite limited. And, factors that have obvious impact on the wellbore temperature distribution are neglected in the existing heat transfer model under lost circulation, which reduces the accuracy of simulated results. In this paper, a wellbore heat transfer model is developed to predict the wellbore temperature profile under the condition of lost circulation. The effects of drilling fluid lost into zone, complex casing programs, and heat sources on wellbore temperature under the condition of lost circulation are fully considered in the model. And, the model is solved by iterative method. Then, the model is validated by the measured temperature data and the existing model. Comparison results show that the simulated results by the model in this paper are more consistent with the true value after considering these factors. Last, case study is conducted under lost circulation condition. Some meaningful conclusions are listed below: (a) The annular fluid temperature near the wellhead is less than the fluid temperature inside the drill pipe under lost circulation; (b) Different from normal circulation, there is an inflection point on the temperature difference curve under lost circulation; (c) The number of inflection points on the annular fluid temperature distribution curve increases with the increase of loss zone number; (d) Under the same change of loss rate, flow rate, thermal conductivity of formation, and heat capacity of fluid, the variation range of fluid temperature at bottom-hole is greater than the variation range of fluid temperature at wellhead.

Application of Thermal Image Data to Detect Rebar Corrosion in Concrete Structures

Rebar corrosion monitoring techniques have been used in studies involving embedded sensors that can detect changes in the corrosion currents and the polarization resistance of rebars in large structures. Defect detection methods that employ infrared cameras are useful non-destructive testing methods to detect defects in concrete structures. However, the measurement results from these methods would vary depending upon several factors that affect thermography. Because of these reasons, they have not been able to provide sufficient reliability. The goal of this study is to develop a technique that uses infrared cameras to quantitatively measure rebar corrosion rates. To examine the impact of the cover thickness, the experiment variables were set at cover thicknesses of 10, 20, and 30 mm and rebar corrosion ratios of 0%, 1%, 3%, 5%, 7%, and 10%. Each variable was tested and a total of 60 specimens were created (i.e., 54 specimens and 6 preliminary specimens). In this study, corrosion was applied using an electrochemical corrosion method that employs Faraday’s law, i.e., the law of conservation of electric charge. The test results of height, width, and area of temperature distribution curve were analyzed, the height of temperature distribution curve was increased as the heating time was grown. In addition, the area of temperature distribution was varied dependent upon the corrosion rate and cover thickness.

Molten Steel Level Identification Based on Temperature Field Distribution Sensed by a Refractory Bar

Molten steel level is difficult to measure as a result of high-temperature medium and the covering flux. The crux of molten steel level measurement is to distinguish between the molten steel and the covering flux. The characteristic of the steelmaking process is that a strong stratification of the temperature gradients is formed between the flux and the molten steel. Thus, sequential clustering (SC) by using the temperature gradients is introduced to identify the flux–steel interface. But considering that temperature gradients are sensitive to noise in the temperature field distributions, piecewise linear regression (PLR) by using temperature field distribution is also proposed to look for the flux–steel interface. The two approaches, SC and PLR, are investigated and compared to each other mathematically without loss of generality. It is found that the two approaches cannot predict the same flux–steel interface and the differences of the prediction results decrease with the increase of the slope changes of the temperature distribution curve. Consequently, the two approaches are applied to the temperature field distributions and gradients of the refractory bar obtained from numerical analyses. The findings demonstrate that, overall, SC predicts a result with a smaller error compared with PLR. However, SC may fail with a high noise level while PLR still behaves robustly. Then, thermal images obtained from actual on-site applications are used to validate the two approaches. Finally, the two approaches are both adopted and the prediction results by them are fused for practical applications.

A Feasibility Study of Transformer Winding Temperature and Strain Detection Based on Distributed Optical Fibre Sensors.

The temperature distribution and deformation of the transformer windings cannot be measured in a distributed manner by the traditional method and failure location cannot be performed. To solve these problems, we present a transformer winding temperature and strain based on a distributed optical fibre sensing detection method. The design of the optical fibre winding composite model is developed and simulated winding temperature rise test and local deformation test distinguish between measuring the winding temperature and the strain curve. The test results show that the distributed optical fibre can transmit wire strain efficiently. Optical fibres, in the process of winding, have a certain pre-stress. Using the Brillouin–Raman joint measuring method, one can effectively extract the optical fibre temperature and strain information and measure the length of the winding direction of the temperature and strain distribution curve to a temperature measurement precision of ±2 °C and strain detection accuracy of ±50 με. The system can carry out local hot spot and deformation localisation, providing new ideas for the transformer winding state monitoring technology.