APPLYING THE BOUNDARY ELEMENT METHOD TO ANALYZE STEADY- STATE HEAT CONDUCTION IN GENERIC MULTIMATERIAL HEAT EXCHANGER TUBES

Resumo

The determination of the temperature distribution in exchanger tubes of arbitrary geometric
shapes, under different boundary conditions of temperature and normal fluxes, allows for their optimized
design. In this paper, we apply the Boundary Element Method (BEM) to carry out two-dimensional
analysis of steady-state heat transfer in exchanger tubes with cross sections of any shapes, and having
walls that may present any type of prescribed boundary values (temperature, normal flux or convective
condition). For simulating heat exchangers constituted of multimaterials, the generic boundary-element
subregion-by-subregion (BE SBS) technique is applied. In this technique, the global matrix resulting
from coupling the many domains available is not explicitly assembled. Instead of that, Krylov solvers
are applied to the iterative solution of the global system of equations by taking into account the separate
contributions of the systems stated for each independent subdomain. A very important step in this
strategy is the inclusion of discontinuous boundary elements, which are fundamental for the simulation
of sharp corners inside interface boundaries or at outer boundaries with prescribed temperature values.
To cope with the quasi-singular and singular integrals involved in the BE models, the Telles cubic
coordinate transformation is applied to derive efficient (low-order) quadratures. They are particularly
relevant for dealing with the quasi-singular integrals resulting from the use of discontinuous boundary
elements. Comparisons with the ANSYS software are considered in the validation/efficiency discussion
of the strategy proposed.