Coupling complex microchannel heat exchanger CFD with plug flow and Poiseuille flow models

Abstract

Microchannel heat exchanger simulation provides a means to obtain design predictions at low cost and quick turnaround. Using computational fluid dynamics to solve the conjugate heat transfer problem, key output metrics such as overall pressure drop, heat exchanger effectiveness, and heat exchanger output can be obtained quickly for many different designs. For most microchannel heat exchangers, the problem can be simplified by solving the individual channel flow separately. By substituting plug flow and Poiseuille flow models for the individual channels, computational efficiency can be improved. This work presents the coupling of plug flow and Poiseuille flow models with ANSYS's computational fluid dynamics package, FLUENT. The coupling algorithm is implemented between User Defined Functions and boundaries within FLUENT's domains, eliminating the individual channel domain from the computational domain. Using the simplified model, full heat exchanger designs can be accurately represented with up to a 74% improvement in computational cost.