关键词: 热交换器, 动态特性, 数学模型

Abstract:

This paper applies the concept of thermal resistors and capacitors to describe approximately the dynamic behavior of the section with the thickmess of the annular heat exchanger in axial direction, i.e. the section is converted to lumped thermal capacities connected by thermal resistors. The number and size of lumps are determined by the accuracy requirements of the problem and temperature gradients . Then, based on the principle of heat balance, the mathematical model is established. The dynamic performance is obtained by the finite-differences approach . It is possible to consider such problems as change of state, variable thermodynamic properties and arbitrary variable boundary condition. As an example, the paper analyze the dynamic performance of the annular heat exchanger of the environmental control system in the aircraft. It has shown that there is a good agreement between the numerical results with the flight test data. The paper also presents the steady performance and the core temperature distribution in the given condition.

Key words: Heat exchanger, Dynamic characteristics, Mathematical model