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

Marek Majdak,M Rerak,M Majdak

doi:10.1051/e3sconf/202132300025

Abstract

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.

Highlights

Due to necessity of development of more efficient and environmental-friendly technologies of energy production in huge power plants were introduced the supercritical boilers
In this paper will be presented the method of calculations of temperature distribution in multiple waterwall tubes connected by fins in case of the equal heating of each tube and different mass flows of fluid inside the tubes
After calculations performed using MATLAB code, the temperature distribution field has been exported into the worksheet and used as a input data for the CFD model, which allows to calculate the thermal stress distribution

Summary

Introduction

Due to necessity of development of more efficient and environmental-friendly technologies of energy production in huge power plants were introduced the supercritical boilers. The thermal conditions occurring in the combustion chambers of supercritical boilers are much more complicated than in the subcritical boilers. The heat flux and mass flow of the working fluid (working fluid is generally a supercritical steam) varies in the width of the combustion chamber wall. It is necessary to develop algorithms that allows to determine temperature and thermal stresses distribution in cross-sections of the waterwall tubes and fins between them. In this paper will be presented the method of calculations of temperature distribution in multiple waterwall tubes connected by fins in case of the equal heating of each tube and different mass flows of fluid inside the tubes. The temperature field obtained by using this algorithm can be used to calculation of the thermal stresses distribution in cross-sections of the analysed system

Problem analysis

Results and discussion

Conclusions