Topology Optimization of Two Fluid Heat Exchangers

TL;DR

This paper introduces a density-based topology optimization method for two-fluid heat exchangers, maximizing heat transfer while respecting pressure constraints, demonstrated through 2D and 3D examples with significant performance improvements.

Contribution

It presents a novel topology optimization approach for two-fluid heat exchangers using a single design variable and erosion-dilation techniques for fluid separation.

Findings

Optimized designs show improved heat transfer over baseline.

Performance improvements up to 113% in shell-and-tube heat exchangers.

Method verified with 2D and 3D case studies.

Abstract

A method for density-based topology optimization of heat exchangers with two fluids is proposed. The goal of the optimization process is to maximize the heat transfer from one fluid to the other, under maximum pressure drop constraints for each of the fluid flows. A single design variable is used to describe the physical fields. The solid interface and the fluid domains are generated using an erosion-dilation based identification technique, which guarantees well-separated fluids, as well as a minimum wall thickness between them. Under the assumption of laminar steady flow, the two fluids are modelled separately, but in the entire computational domain using the Brinkman penalization technique for ensuring negligible velocities outside of the respective fluid subdomains. The heat transfer is modelled using the convection-diffusion equation, where the convection is driven by both fluid flows. A stabilized finite element discretization is used to solve the governing equations. Results are presented for two different problems: a two-dimensional example illustrating and verifying the methodology; and a three-dimensional example inspired by shell-and-tube heat exchangers. The optimized designs for both cases show an improved heat transfer compared to the baseline designs. For the shell-and-tube case, the full freedom topology optimization approach is shown to yield performance improvements of up to 113% under the same pressure drop.