Моделирование процессов нестационарной теплопроводности в теплоизолированной цилиндрической стенке барабана котла

Abstract

Предложена модель процессов нестационарной осесимметричной теплопроводности в теплоизолированной цилиндрической стенке барабана котла. Рассмотрены случаи, отвечающие резкому изменению температуры, колебаниям температуры около заданного среднего значения, а также резкому изменению и последующим колебаниям температуры относительно нового среднего значения на внутренней поверхности барабана, которые охватывают типичные состояния, присущие установившимся и неустановившимся режимам эксплуатации котла.This scientific paper is devoted tothe investigation of nonstationary axisymmetric heat conductivity in the cylindrical heat-insulated wall of a boiler drum. Consideration was given to the cases of an abrupt change in the temperature of internal surface of the boiler, temperature fluctuations on the internal drum surface near the prescribed average value and also an abrupt change in the temperature of internal drum surface with subsequent fluctuations near a new average value embracing typical states peculiar for the stationary and nostationary boiler operating modes. The investigations carried out showed that abrupt changes in the temperature of internal drum surface during some seconds may result in temperature fields, in which the temperature difference of internal and external surfaces is equal to a change in the temperature of internal surface. It takes the drum wall of 16 mm thick 30 seconds to align the temperature field after an abrupt increase in the temperature of internal surface. Harmonic temperature fluctuations on the internal surface create the temperature field in the drum wall with the temperature difference between the internal surface and the external surface a little bit higher then the half amplitude of vibrations in temperature. In the future, we plan to study mechanical stresses in the boiler drum wall caused by the internal pressure and nonstationary temperature fields considered in this scientific paper. In addition, we will study the influence produced by the temperature relationship for heat conductivity properties of the structural material on the nonuniform distribution of temperature field in the drum wall thickness.