Study of the method of reducing temperature stresses in shell-and-tube heat exchangers

Аuthors

Perov V. A., Glebov S. E.^*, Basharina T. A.^**, Shmatov D. P.^***

LLC SPE "InterPolaris", Pervomayskaya str., 2, Novovoronezh, Voronezh Region, Russia, 396073

*e-mail: glebovse@interpolyaris.ru, se_glebov@mail.ru
**e-mail: ta@interpolyaris.ru
***e-mail: shmatov@inlerpolyaris.ru

Abstract

Shell-and-tube heat exchangers are widely used in various industries for heating or cooling one of the heat carriers to the required temperature value. The key criterion for the performance of such heat exchangers is the ability to ensure continuous heat exchange between the heat carriers both in the absence of the possibility of heat carrier leaks into the external environment and in the absence of the possibility of mixing the heat carriers. One of the most common causes of failure of shell-and-tube heat exchangers during operation is a violation of the separation of the cooling and cooled media due to the destruction of the pipe wall due to mechanical and temperature stresses, which necessitates the study of methods aimed at reducing stresses caused by uneven temperature distribution in the structural elements. The paper considers a method for reducing stresses caused by uneven temperature distribution across the tube thickness in a heat exchanger by adding a smaller diameter tube into the main coil tube. Comparative analysis is performed for heat exchanger designs without an insert in the coil, as well as a design with the introduction of an internal tube of a smaller diameter at the initial section of the coil. During the comparative analysis, an assessment is made of the effect of the modified design on the heat exchange and strength characteristics of the heat exchanger. A theoretical description of the proposed method is given based on the fourth theory of strength, as well as a mathematical model of a computational experiment of the heat exchanger operation, including the Navier-Stokes equation and heat transfer equation and description of the behavior of a solid deformable body with a linear isotropic model of the material in the elastic zone. Based on the results of the computational experiment of the heat exchanger operation process, it is shown that the use of the flow separation method does not have a significant effect on the thermal-hydraulic characteristics of the heat exchanger, reducing the values of thermal expansion in the structure, and thereby reducing the stresses that arise in the inlet pipe of the coil, which increases the strength and service life of the structure, thereby increasing the service life of the heat exchanger.

Keywords:

recuperative heat exchanger, heat exchanger with a coil, numerical modeling of thermal-hydraulic processes, temperature stresses, strength characteristics

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