scholarly journals Analysis of the possibility of determining the internal structure of composite material by estimating its thermal diffusivity

2014 ◽  
Vol 35 (1) ◽  
pp. 3-15
Author(s):  
Stanisław Kucypera
Keyword(s):  
Composite Material ◽  
Heat Conduction ◽  
Thermal Diffusivity ◽  
Internal Structure ◽  
Fibrous Composite ◽  
Electric Heater ◽  
Transient Temperature ◽  
Inverse Heat Conduction ◽  
Filtration Method ◽  
Fibrous Composite Material

Abstract The aim of this paper is analysis of the possibility of determining the internal structure of the fibrous composite material by estimating its thermal diffusivity. A thermal diffusivity of the composite material was determined by applying inverse heat conduction method and measurement data. The idea of the proposed method depends on measuring the timedependent temperature distribution at selected points of the sample and identification of the thermal diffusivity by solving a transient inverse heat conduction problem. The investigated system which was used for the identification of thermal parameters consists of two cylindrical samples, in which transient temperature field is forced by the electric heater located between them. The temperature response of the system is measured in the chosen point of sample. One dimensional discrete mathematical model of the transient heat conduction within the investigated sample has been formulated based on the control volume method. The optimal dynamic filtration method as solution of the inverse problem has been applied to identify unknown diffusivity of multi-layered fibrous composite material. Next using this thermal diffusivity of the composite material its internal structure was determined. The chosen results have been presented in the paper.

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.

Sign in / Sign up

Export Citation Format

Share Document