scholarly journals Influence of thermal and flow conditions on the temperature distribution in the evaporator tubes

2019 ◽  
Vol 128 ◽  
pp. 01024 ◽  
Author(s):  
Marek Majdak
Keyword(s):  
Temperature Distribution ◽  
Numerical Model ◽  
Working Conditions ◽  
Thermal Stresses ◽  
Flow Analysis ◽  
Effect Of Temperature ◽  
Flow Conditions ◽  
Time Step ◽  
Thermophysical Parameters

The article presents the results of thermal and flow analysis of the working conditions of neighbouring waterwall tubes, loaded with heat streams of different values. The numerical model used for the analysis, allowing to calculate the temperature distribution of the tubes and the fluid flowing throughthem at each time step depending on the thermophysical parameters of the fluid and the material from which the tubes were made. By using the algorithm it is possible to precisely determine the temperaturedistribution for tubes, allowing to determine the places where the most divergent temperatures occur and in which thermal stresses of the highest value may occur. Analysis for several adjacent tubes willallow for the effect of temperature differences in the tubes to the temperature of the fin which is connecting them and to collect data that may be used for the determination of stress distribution in the tubes and fins.

scholarly journals Determination of temperature and thermal stresses distribution in power boiler elements with use inverse heat conduction method

2011 ◽  
Vol 32 (3) ◽  
pp. 191-200 ◽  
Author(s):  
sławomir Grądziel
Keyword(s):  
Boundary Condition ◽  
Heat Conduction ◽  
Temperature Distribution ◽  
Thermal Stresses ◽  
Thermal Boundary Condition ◽  
Transient Temperature ◽  
Inverse Heat Conduction ◽  
Transient Temperature Distribution ◽  
Power Boiler

Determination of temperature and thermal stresses distribution in power boiler elements with use inverse heat conduction method The following paper presents the method for solving one-dimensional inverse boundary heat conduction problems. The method is used to estimate the unknown thermal boundary condition on inner surface of a thick-walled Y-branch. Solution is based on measured temperature transients at two points inside the element's wall thickness. Y-branch is installed in a fresh steam pipeline in a power plant in Poland. Determination of an unknown boundary condition allows for the calculation of transient temperature distribution in the whole element. Next, stresses caused by non-uniform transient temperature distribution and by steam pressure inside a Y-branch are calculated using the finite element method. The proposed algorithm can be used for thermal-strength state monitoring in similar elements, when it is not possible to determine a 3-D thermal boundary condition. The calculated temperature and stress transients can be used for the calculation of element durability. More accurate temperature and stress monitoring will contribute to a substantial decrease of maximal stresses that occur during transient start-up and shut-down processes.

scholarly journals Influence of flow conditions on the distribution of thermal stresses in the waterwall tubes connected by fins

2021 ◽  
Vol 323 ◽  
pp. 00025
Author(s):  
Marek Majdak
Keyword(s):  
Temperature Distribution ◽  
Thermodynamic Parameters ◽  
Thermal Stresses ◽  
Thermal Conditions ◽  
Working Fluid ◽  
Control Element ◽  
Flow Conditions ◽  
Online Mode ◽  
Supercritical Parameters ◽  
Mass Flows

In this study are presented results of numerical analysis of the thermal conditions of smooth waterwall tubes connected by fins and heated with equal heat flux. Inside tubes flows the water at supercritical parameters. The thermodynamic parameters at the inlet to each tube are similar but the mass flow of the fluid differs in each tube. Numerical model used for analysis allows to determine the temperature distribution, in online mode, in every control element of the analysed tubes and in the finite elements of the working fluid depending on the current thermodynamic parameters of the fluid and tubes. After calculation of the temperature distribution field, it can be used to determine the thermal stresses distribution in tubes and fins and determine the parts of elements, where the maximum values of the thermal stresses occur. The presented analysis was carried out for comparison of the thermal stresses distribution in small fragment of the combustion chamber wall in case of changing the fluid mass flows in neighbouring waterwall tubes.

Thermoelastic Effects in Lubricated Rolling/Sliding Line Contacts

1991 ◽  
Vol 113 (1) ◽  
pp. 174-181 ◽  
Author(s):  
P. C. Sui ◽  
F. Sadeghi
Keyword(s):  
Temperature Distribution ◽  
Numerical Model ◽  
Film Thickness ◽  
Thermal Stresses ◽  
Shear Stresses ◽  
Ehd Lubrication ◽  
Line Contacts ◽  
Thermoelastic Effects ◽  
Machine Elements ◽  
Thermoelastic Displacement

A numerical model was developed to investigate the subsurface mechanical and thermal stresses in rolling/sliding machine elements operating under elasto-hydrodynamic (EHD) lubrication of line contacts. A thermal non-Newtonian EHD lubrication model was modified to include the thermoelastic displacement of the solids. The pressure, film thickness, and temperature distribution obtained from the model were used to calculate the subsurface mechanical and thermal stresses within the rolling/sliding machine elements. The thermoelastic effects on the magnitude and location of the maximum shear stresses are presented.

Analysis of Infrared Thermography during Tensile Test of GFRP

2008 ◽  
Vol 47-50 ◽  
pp. 1129-1132
Author(s):  
Jin Woo Kim ◽  
Dong Gi Lee ◽  
Jae Ki Sim ◽  
Jae Yeol Kim ◽  
Seung Hyun Choi
Keyword(s):  
Temperature Distribution ◽  
Crack Propagation ◽  
Tensile Test ◽  
Fiber Orientation ◽  
Effect Of Temperature ◽  
Maximum Temperature ◽  
Ir Thermography ◽  
Lower Maximum ◽  
Lock In

Property of GFRP is naturally dependent on the property of matrix, but receives of temperature effects by external force. Therefore, determination of mechanical property by effect of temperature in GFRP is most crucial factor. In this paper, temperature distribution during crack propagation from temperature change under tensile test was proposed through IR thermography camera. Lock-in thermography method, which is one of technique in IR thermography camera to measure minute change in temperature, was utilized to monitor temperature distribution and change during crack propagation. Method to analyze temperature distribution during crack propagation under tensile test of GFRP via IR thermography camera was suggested. Anisotropy in fiber orientation showed longer fracture time and lower maximum temperature.

Numerical Modelling of Net Motion in Waves and Current Using CFD

2019 ◽  
Author(s):  
Tobias Martin ◽  
Arun Kamath ◽  
Hans Bihs
Keyword(s):  
Fluid Dynamics ◽  
Numerical Model ◽  
Cfd Model ◽  
Time Step ◽  
Two Phase ◽  
Fluid Forces ◽  
Open Sea ◽  
Geometrical Constraints ◽  
Static Approach

Abstract The structural and environmental challenges in the operation of marine fish cage structures, in particular in the open sea, can accurately be determined if the fluid dynamics in and around the whole system is studied. An important part of the system represents the porous net which encloses the fish. In this paper, a numerical model for the determination of the deformed shape of nets under consideration of hydrodynamic loads and elastic twines is elaborated. It is a quasi-static approach based on force equilibria at the knots and geometrical constraints. The missing time step restriction leads to an overall less costly computation. The fluid around the net is calculated using a two-phase CFD model. The focus of the research is on the calculation of fluid forces on the net and the analyses of the nets motion in current and waves.

A Novel Energy Flow Model for High-Frequency Vibration Analysis of Beams in a Thermal Environment

2013 ◽  
Author(s):  
Wenbo Zhang ◽  
Hualing Chen ◽  
Danhui Zhu ◽  
Xiangjie Kong
Keyword(s):  
High Frequency ◽  
Thermal Effects ◽  
Energy Flow ◽  
Thermal Stresses ◽  
Thermal Environment ◽  
Flow Analysis ◽  
Effect Of Temperature ◽  
Stress Effect ◽  
High Frequency Response ◽  
Acoustic Community

As an exceedingly important issue in vibro-acoustic community, the thermal effects can significantly affect the dynamic behaviors of the structures. The previous studies are mainly performed using the deterministic methods which are infeasible at high frequencies. Energy flow analysis (EFA) is a recent method for high-frequency structural analysis. However, until now the thermal effects are neglected in EFA studies. In this paper, a novel EFA model is developed to predict the high-frequency response of beams in a thermal environment. The wavenumber related with the axial membrane force arising from thermal stresses is considered in the derivation, and then the thermal stress effect is incorporated in the EFA governing equation in terms of effective damping loss factor. In addition, the effect of temperature-dependent material properties is included in the EFA formulation. The proposed EFA model is validated against the modal analysis for a simply supported beam for various frequencies and damping loss factors, and good agreements are found. The results indicate that the thermal effects can affect spatial distributions and levels of the energy density, and the vibrational response of beam increases with temperature.

A study of the diffusion analogy technique for the photoelastic determination of transient thermal stresses

1988 ◽  
Vol 23 (1) ◽  
pp. 33-45
Author(s):  
P Stanley ◽  
Y J Yip
Keyword(s):  
Heat Conduction ◽  
Temperature Distribution ◽  
Isotropic Material ◽  
Heat Conduction Equation ◽  
Thermal Stresses ◽  
Conduction Equation ◽  
Formal Similarity ◽  
Photoelastic Study ◽  
Transient Thermal

The formal similarity between the equation governing the diffusion of a substance through a “porous” isotropic material and the heat conduction equation for the temperature distribution in an isotropic homogeneous solid is examined, and its use as a basis for the photoelastic study of transient thermal stresses is explored.

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