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.

Analysis of Thermal Stresses in a Boiler Drum During Start-Up

1999 ◽  
Vol 121 (1) ◽  
pp. 84-93 ◽  
Author(s):  
J. Taler ◽  
B. We˛glowski ◽  
W. Zima ◽  
S. Gra˛dziel ◽  
M. Zborowski
Keyword(s):  
Heat Conduction ◽  
Temperature Distribution ◽  
Thermal Stresses ◽  
Heat Conduction Problem ◽  
Inverse Heat Conduction Problem ◽  
New Method ◽  
Transient Temperature ◽  
Fluid Temperature ◽  
Inverse Heat Conduction ◽  
Vessel Elements

The paper presents an analytical way of calculating thermal stress distributions in cylindrical vessels, nonuniformly heated on their circumference. In thick-walled vessel elements, simplified analytical formulas do not give satisfactory results. A new method for determining thermal stresses has been developed. On the basis of temperature history measurements at several points on the drum outer surface, a time-space temperature distribution in the component cross section is determined, and next, thermal stresses are calculated using the finite element method (FEM). The new method, proposed for the solution of the inverse heat conduction problem, is sufficiently accurate. Knowledge of the boundary conditions on the inner surface of the drum, i.e., fluid temperature and heat transfer coefficient, is not necessary because the transient temperature distribution in the component is obtained from the solution of the inverse heat conduction problem. Comparison of the thermal distributions from FEM versus the new method demonstrate the accuracy of the new method. An example application of the new method demonstrates its benefits over the solution of the boundary-initial problem obtained by FEM.

Monitoring of thermal stresses in pressure components using inverse heat conduction methods

2017 ◽  
Vol 27 (3) ◽  
pp. 740-756 ◽  
Author(s):  
Jan Taler ◽  
Bohdan Weglowski ◽  
Marcin Pilarczyk
Keyword(s):  
Heat Conduction ◽  
Temperature Distribution ◽  
Thermal Stresses ◽  
Heat Conduction Problem ◽  
Inverse Heat Conduction Problem ◽  
Transient Temperature ◽  
Measured Temperature ◽  
Inverse Heat Conduction ◽  
Content Type ◽  
Start Up

Purpose The purpose of this paper is to present a method for monitoring transient thermal stresses. This paper also presents the analysis of thermal stresses of boiler pressure element heating during the start-up in real conditions. The inverse methods are used to determine the wall temperature, whereas the commercial software ANSYS is used to determine the thermal stresses in the pressure component. Design/methodology/approach The method is based on the solution of the inverse heat conduction problem. Thermal stresses are determined indirectly taking into account the measured temperature values at selected points on the outer wall of a pressure component. First, the transient temperature distribution in the entire pressure element is calculated, and then, thermal stresses are determined by the finite element method. Measured pressure changes are used to determine the stresses resultant from the internal pressure. Findings The obtained stresses and temperature in the thick-walled pipe are illustrated and compared with experimental data. Satisfactory agreement was found between computational and experimental results. Originality/value The method can be used in the monitoring of thermal and mechanical stresses during the boiler’s start-up and shut-down. Because the temperature distribution at each time level is determined, it can be applied as a thermal load during the structural analysis.

The Transient Temperature Distribution in One-Dimensional Heat-Conduction Problems With Nonlinear Boundary Conditions

1969 ◽  
Vol 91 (1) ◽  
pp. 77-82 ◽  
Author(s):  
W. Z˙yszkowski
Keyword(s):  
Boundary Condition ◽  
Temperature Distribution ◽  
Nonlinear Boundary ◽  
Internal Heat ◽  
Nonlinear Boundary Conditions ◽  
Transient Temperature ◽  
One Dimensional ◽  
Parabolic Profile ◽  
Transient Temperature Distribution ◽  
Approximate Analytical Solutions

The transient, one-dimensional temperature distribution is determined for bodies with internal heat generation and nonlinear boundary condition in the form: k·e·gradθ+ε(θn−T0n)+ε1(θ−T0)=0 Approximate analytical solutions are derived with the aid of Biot’s variational method. The additional boundary condition introduced by Lardner is modified, and this modification makes it possible to solve the problem. The solution has been obtained assuming a parabolic profile of temperature distribution. Formulas are given for plates, cylinders, and spheres. Some results are illustrated with the graphs, and compared with the exact solution for the case of convective heat transfer.

Determination of Temperature Limits for Heat Exchanger Joint Assembled of Solid Stainless Tubesheet With Girth Flanges

2017 ◽  
Author(s):  
Bassel Y. Mohamed ◽  
Mohamed A. Hamdy ◽  
Tamer I. Eid
Keyword(s):  
Heat Exchanger ◽  
Temperature Distribution ◽  
Heat Exchangers ◽  
Transient Analysis ◽  
Transient Temperature ◽  
Heating Rates ◽  
Element Analysis ◽  
Transient Temperature Distribution ◽  
Steel Heat

Although heat exchangers are built according to international codes and proved to be leak tight by hydrotesting at ambient temperature, leak of stainless steel heat exchangers girth flanges at the tubesheet gaskets likely occurs during startup and operation at high temperatures. Accordingly, evaluation of the design to assure leak free operation considering anticipated thermal events is required. WRC 510 bulletin [4] introduces a simplified analytical method to address this issue and provides safe guarding against leakage. This study is performed on solid 300 series stainless stationary tubesheet flanged with girth flanges having the same or different material of construction. A thermal finite element analysis is performed to obtain the transient temperature distribution through a girth flanges and stationary tubesheet assembly of a heat exchanger using SOLIDWORKS® SIMULATION [7]. The model of the flanged joint consists of two girth flanges with a tubesheet and gaskets in between. Thermal time dependent transient analysis of the above model is conducted to compute the temperature distribution in the flanged joint assembly for different time steps. Further, these temperature distributions are used to compute the expansion, deflection and rotation for the flanged joint parts using WRC 510 bulletin [4] equations. The study determines both the permissible heating rates during startup and the temperature limits, for the example studied, which are suitable for using solid 300 series stainless tubesheet for both material types of the girth flanges to have the most leak tight & economical assembly when the minimum design metal temperature allows these materials.

Sign in / Sign up

Export Citation Format

Share Document