NUMERICAL ANALYTIC APPROACH TO A CALCULATION OF A THERMAL STRESS STATE OF SHELL AND TUBE HEAT EXCHANGERS

摘要

Nowadays, a stress calculation of shell and tube heat exchangers' elements is based either on analytic methods described in ASME, TEMA, EN, GOST and other standards or on numerical modeling using FEA. The main disadvantage of the analytic methods is that they can be applied only to certain apparatuses' designs and it is very difficult or even impossible to use them with non-typical constructions. Otherwise, such a calculation is easy to perform with modeling by FEA. However, a direct finite element simulation of several thousands of tubes, which can be designed in one heat exchanger, makes the task very time-consuming and the resulting model very big and computation-intensive. This paper examines a typical model, which includes 3.5 million nodes and more than 3 million elements. We offer a numerical analytic solution of this task, which consists in modeling of a tube bundle by an orthotropic continuum with equivalent properties. The comparison of the results of a temperature distribution calculation and the stress-strain distribution calculation using direct numerical modeling of the tubes in the tube bundle by shell elements from one hand, and of the suggested numerical analytic solution from another, shows that these results do match closely enough to practice.