scholarly journals The Effect of Pallet Component Geometry on Temperature Gradient During Cooling

2015 ◽  
Vol 15 (1) ◽  
pp. 5-8 ◽  
Author(s):  
A. Bajwoluk ◽  
P. Gutowski
Keyword(s):  
Heat Treatment ◽  
Temperature Distribution ◽  
Temperature Gradient ◽  
Thermal Stresses ◽  
Rapid Cooling ◽  
The Impact

Abstract The paper discusses the impact of the geometry of foundry pallet components on the value of temperature gradient on the wall crosssection during heat treatment. The gradient is one of the most important factors determining the distribution of thermal stresses in these items. Analysis of quantitative simulation was carried out to detect possible effect of the type of connection between pallet walls and thickness of these walls (ribs) on the interior temperature distribution during rapid cooling. The analysis was performed for five basic designs of wall connections used in pallets. Basing on the results obtained, the conclusions were drawn on the best connection between the ribs in foundry pallets.

scholarly journals Thermal Stresses in the Wall Connections of Cast Grate Structures

2016 ◽  
Vol 16 (4) ◽  
pp. 11-16 ◽  
Author(s):  
A. Bajwoluk ◽  
P. Gutowski
Keyword(s):  
Heat Treatment ◽  
Cross Section ◽  
Hot Spots ◽  
Thermal Stresses ◽  
Cooling Process ◽  
Temperature Variations ◽  
Temperature Changes ◽  
Different Types ◽  
The Difference ◽  
The Impact

Abstract The purpose of this study was to establish a relationship between the type of wall connection used in the cast grates, which are part of the equipment operating in furnaces for heat treatment and thermal-chemical treatment, and stresses generated in these grates during the process of rapid cooling. The places where the grate walls are connected to each other are usually characterized by the thickness larger than the remaining parts of walls. Temperature variations in those places are responsible for the formation of hot spots, and in the hot spots temperature changes much more slowly. The type of wall connection shapes the temperature gradient in the joint cross-section, and hence also the value of thermal stresses generated during cooling. In this study, five different designs of the grates were compared; the difference in them was the type of the designed wall connection. The following design variants were adopted in the studies: X connections with and without holes, T connections with and without technological recesses, and R (ring) connection. Numerical analysis was performed to examine how the distribution of temperature changes in the initial phases of the cooling process. The obtained results served next as a tool in studies of the stress distribution in individual structures. The analysis were carried out by FEM in Midas NFX 2014 software. Based on the results obtained, the conclusions were drawn about the impact of different types of wall connections on the formation of thermal stresses in cast grates.

Influence of climate change on thermal stresses in concrete box girders

2021 ◽  
Author(s):  
Saad Saad ◽  
Rashid Bashir ◽  
Stavroula Pantazopoulou
Keyword(s):  
Climate Change ◽  
Temperature Distribution ◽  
Thermal Stresses ◽  
Structural Model ◽  
Meteorological Data ◽  
Structural Response ◽  
Box Girders ◽  
Box Girder ◽  
Compressive Stresses ◽  
The Impact

<p>The purpose of this study is to investigate the impact of climate change on the thermal and structural response of concrete box girders. An advanced finite element platform was used to model a concrete box girder and analyze the additional thermal stresses that result from climate change. Meteorological data for future climate scenarios in Toronto, Canada was used as input in a thermal model to simulate the temperature distribution within the bridge deck. The temperature distribution was then used as input in a structural model of the bridge, to determine the resulting thermal stresses. The results show increases in tensile and compressive stresses as well as increased bridge movements. This study highlights the importance of explicitly considering climate change to achieve more robust bridge codes, particularly when it comes to thermal effects.</p>

scholarly journals Effect of modified Ohm's and Fourier's laws on magneto thermoviscoelastic waves with Green-Naghdi theory in a homogeneous isotropic hollow cylinder

2021 ◽  
Vol 8 (6) ◽  
pp. 40-47
Author(s):  
Khamis et al. ◽  
Keyword(s):  
Magnetic Field ◽  
Temperature Gradient ◽  
Charge Density ◽  
Current Density ◽  
Thermal Stresses ◽  
Generalized Thermoelasticity ◽  
Solid Cylinder ◽  
Viscoelastic Solid ◽  
The Impact ◽  
Change System

This paper deals with the modified Ohm's law, including the temperature gradient and charge density effects, and the generalized Fourier's law, including the present current density impact, the problem of conveyance of thermal stresses and temperature in a generalized Magneto–Thermo-Viscoelastic Solid Cylinder of radius L. The formulation is applied to the generalized thermoelasticity dependent on the Green-Naghdi (G-N II) hypothesis. The Laplace change system is utilized to solve the problem. At last, the outcomes got are introduced graphically to show the impact of Magnetic Field and time and on the field variables.

Comparative Study on Different National Standards for Local Post Weld Heat Treatment of Pressure Vessels

2020 ◽  
Author(s):  
Fang Ji ◽  
Guide Deng ◽  
Linlin Duan ◽  
Cenfan Liu ◽  
Xiaonan Zhao
Keyword(s):  
Heat Treatment ◽  
Temperature Distribution ◽  
Temperature Gradient ◽  
Temperature Difference ◽  
Pressure Vessel ◽  
Post Weld Heat Treatment ◽  
National Standards ◽  
Butt Weld ◽  
Axial Temperature ◽  
Weld Heat

Abstract In order to eliminate these welding residual stress which produced in the process of pressure vessel manufacturing and assembling, post-weld heat treatment is required for the weld structure. The Large size and complex structure pressure vessel which cannot integral post-welding heat treatment always implement local post-welding heat treatment. The reasonable heated band and insulated band are particularly important in the procedures of local post-welding heat treatment to meet the requirements of pressure vessel heat treatment. The recommended heated band and insulated band are given in different national standards. But the recommended width of heated band and insulated band are different in different national standards. In the paper, numerical simulation was carried out to compare and study the difference of temperature distribution in the holding temperature period when post-welding heat treatment of pressure vessel barrel butt weld. The result show that the temperature distribution on sock band is very closed when the barrel butt weld implements post weld heat treatment with the heated and insulated band recommended in ASME BPVC-VIII-2017 and EN 13445-4:2014. The axial temperature gradient on sock band is very small and the temperature difference almost comes from the temperature difference through the thickness. Compared with this, the axial temperature gradient is larger and the temperature difference through thickness is smaller when post weld heat treatment with the max recommended heated and insulated band given in GB/T 30583-2014.

Study on Relevant Effects Concerning Heat Transfer of a Convection Cooled Gas Turbine Blade Under Realistic Engine Temperature Conditions

2013 ◽  
Author(s):  
Y. Mick ◽  
B. Wörz ◽  
E. Findeisen ◽  
P. Jeschke ◽  
V. Caspary
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Thermal Stresses ◽  
Cooling System ◽  
Gas Turbine Blade ◽  
Temperature Conditions ◽  
The Impact ◽  
Operating Points

This paper presents a study of the temperature distribution of a convection cooled gas turbine blade under realistic operating temperature conditions using experimental and numerical methods. The analysis is performed experimentally in a linear cascade with exhaust gas from a kerosene combustor. Detailed information at different operating points is taken from the experiments for which conjugate heat transfer (CHT) simulations with ANSYS CFX are carried out. By comparing the experimental and numerical results, the required complexity of the simulations is defined. The subject of this study is a gas turbine rotor blade equipped with a state-of-the-art internal convection cooling system. The test rig enables the examination of the blade at temperatures up to 1300K. The temperature distribution of the blade is measured using thermocouples. The calculations are carried out using the SST turbulence model, the Gamma Theta transition model and the discrete transfer radiation model. The influence of hot gas properties and radiation effects are analysed at three different operating points. This paper gives a quantitative overview of the impact of the mentioned parameters on temperature level and distribution as well as thermal stresses in a convection cooled blade under realistic engine temperature conditions.

scholarly journals Mathematical Model of Transient Temperature Distribution and Thermal Stresses in Large Steam Turbine Rotors

1982 ◽  
Author(s):  
J. Sasiadek ◽  
C. K. Kwok
Keyword(s):  
Mathematical Model ◽  
Temperature Distribution ◽  
Temperature Gradient ◽  
Thermal Stresses ◽  
Transient Temperature ◽  
Load Variation ◽  
Transient Temperature Distribution ◽  
Start Up ◽  
On Line ◽  
Turbine Rotors

The most important problems encountered in power plants are related to cold start-up, hot start-up, daily and seasonal variation in load. These problems are specially critical for high power units above 525°C and 10.5 MN/m2. As a result of higher thermal capacity of the thicker components in larger power units, the temperature gradient and thermal stresses assumed much higher values. It is, therefore, particularly important during transient operation conditions to know the temperature distribution and thermal stresses of rotors. One of the most common concerns is how fast can a turbine be started without significant damage. If the turbine is loaded very rapidly, high temperature gradient and excessive thermal stresses can easily damage the machine. A concept was developed whereby an on-line computer was used to control the start-up and load variation operations of the turbine. The feasibility of such concept depends upon the knowledge of the instantaneous temperature distribution and thermal stresses of the turbine rotors. This paper presents a 2-D mathematical model of the transient temperature distribution as well as thermal stresses of the rotor. The mathematical model was simulated in the computer and ADI method was used for the solution of the governing equations. Discussions will be made of the procedure of coupling this mathematical model with on-line computer for optimum control of start-up and load variation schedule.

scholarly journals Analysis of the occurrence of natural convection in a bed of bars in vertical temperature gradient conditions

2013 ◽  
Vol 34 (1) ◽  
pp. 71-83
Author(s):  
Rafał Wyczółkowski ◽  
Dorota Musiał
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Treatment ◽  
Natural Convection ◽  
Temperature Distribution ◽  
Temperature Gradient ◽  
Free Convection ◽  
Vertical Temperature Gradient ◽  
Vertical Temperature ◽  
Rayleigh Criterion

Abstract The reason for undertaking this study was to determine the possible involvement of natural convection in the global heat transfer, that occurs in the heated steel rods bed. This problem is related to the setting of the effective thermal conductivity of the bars bed. This value is one of the boundary conditions for heating modeling of steel rods bundles during heat treatment. The aim of this study was to determine for which geometry of the bed bars, there will be no free convection. To analyze the problem the Rayleigh criterion was used. It was assumed that for the value of the number Ra < 1700 convection in the bed bars does not occur. For analysis, the results of measurements of the temperature distribution in the unidirectionally heated beds of bars were used. It has been shown, that for obtained, during the test, differences of temperature between the surfaces of adjacent rods, convection can occur only when the diameter of the rod exceeds 18 mm.

Microstructural and Mechanical Behaviour Evaluation of Mg-Al-Zn Alloy Friction Stir Welded Joint

2020 ◽  
Vol 17 (3) ◽  
pp. 8150-8159
Author(s):  
Kulwant Singh ◽  
Gurbhinder Singh ◽  
Harmeet Singh
Keyword(s):  
Heat Treatment ◽  
Friction Stir Welding ◽  
Magnesium Alloys ◽  
Mechanical Performance ◽  
Fuel Efficiency ◽  
Research Work ◽  
Grain Structure ◽  
Tensile Fracture ◽  
Friction Stir ◽  
The Impact

The weight reduction concept is most effective to reduce the emissions of greenhouse gases from vehicles, which also improves fuel efficiency. Amongst lightweight materials, magnesium alloys are attractive to the automotive sector as a structural material. Welding feasibility of magnesium alloys acts as an influential role in its usage for lightweight prospects. Friction stir welding (FSW) is an appropriate technique as compared to other welding techniques to join magnesium alloys. Field of friction stir welding is emerging in the current scenario. The friction stir welding technique has been selected to weld AZ91 magnesium alloys in the current research work. The microstructure and mechanical characteristics of the produced FSW butt joints have been investigated. Further, the influence of post welding heat treatment (at 260 °C for 1 h) on these properties has also been examined. Post welding heat treatment (PWHT) resulted in the improvement of the grain structure of weld zones which affected the mechanical performance of the joints. After heat treatment, the tensile strength and elongation of the joint increased by 12.6 % and 31.9 % respectively. It is proven that after PWHT, the microhardness of the stir zone reduced and a comparatively smoothened microhardness profile of the FSW joint obtained. No considerable variation in the location of the tensile fracture was witnessed after PWHT. The results show that the impact toughness of the weld joints further decreases after post welding heat treatment.

scholarly journals Impact of the Simulated Gastric Digestion Methodology on the In Vitro Intestinal Proteolysis and Lipolysis of Emulsion Gels

Foods ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 321
Author(s):  
Camila Mella ◽  
Michelle Quilaqueo ◽  
Rommy N. Zúñiga ◽  
Elizabeth Troncoso
Keyword(s):  
Heat Treatment ◽  
Protein Isolate ◽  
Gastric Digestion ◽  
Human Gastrointestinal Tract ◽  
Gel Structure ◽  
Intestinal Digestion ◽  
Food Digestion ◽  
The Impact ◽  
Digestion Methods

The aim of this work was to study the impact of the methodology of in vitro gastric digestion (i.e., in terms of motility exerted and presence of gastric emptying) and gel structure on the degree of intestinal proteolysis and lipolysis of emulsion gels stabilized by whey protein isolate. Emulsions were prepared at pH 4.0 and 7.0 using two homogenization pressures (500 and 1000 bar) and then the emulsions were gelled by heat treatment. These gels were characterized in terms of texture analysis, and then were subjected to one of the following gastric digestion methods: in vitro mechanical gastric system (IMGS) or in vitro gastric digestion in a stirred beaker (SBg). After gastric digestion, the samples were subjected to in vitro intestinal digestion in a stirred beaker (SBi). Hardness, cohesiveness, and chewiness were significantly higher in gels at pH 7.0. The degree of proteolysis was higher in samples digested by IMGS–SBi (7–21%) than SBg–SBi (3–5%), regardless of the gel’s pH. For SBg–SBi, the degree of proteolysis was not affected by pH, but when operating the IMGS, higher hydrolysis values were obtained for gels at pH 7.0 (15–21%) than pH 4.0 (7–13%). Additionally, the percentage of free fatty acids (%FFA) released was reduced by 47.9% in samples digested in the IMGS–SBi. For the methodology SBg–SBi, the %FFA was not affected by the pH, but in the IMGS, higher values were obtained for gels at pH 4.0 (28–30%) than pH 7.0 (15–19%). Our findings demonstrate the importance of choosing representative methods to simulate food digestion in the human gastrointestinal tract and their subsequent impact on nutrient bioaccessibility.

Sign in / Sign up

Export Citation Format

Share Document