The transformation to a truly sustainable energy system will require taking better advantage of the waste heat. Integrating heat exchangers with the triply periodic minimal surface (TPMS) is a promising and efficient way to build waste heat recovery systems that harness heat emissions from the low pitch thermal systems. This is mainly due to the low hydrodynamic resistance and pressure drop in the TPMS while securing good heat transfer at low-temperature gradient. This study establishes a computational design and analysis of heat and mass transfer inside a heat exchanger based on the TPMS structure and determine thermal effectiveness, heat transfer coefficient, and pressure drop inside the channel. The non-linearity dependence of results to several design variables makes obtaining the optimal design configuration solely using conventional CFD or experimental study nearly impossible. Hence, a multi-objective optimization workflow based on a Genetic Algorithm for laminar flow is employed to reveal the underlying relationships between design variables for the optimal configurations. The results illustrate the local sensitivity of important parameters such as the heat transfer coefficient, Nusselt number, and thermal performance of the heat exchanger against various design variables. It is shown that the pressure drop is directly affected by gas inlet velocity, viscosity, and density, from high to low, respectively. The Pareto frontiers for the optimal thermal performance are extracted, and the correlation between design objectives is determined. This methodology provides a promising framework for heat exchangers' design analysis, including multi-objective goals and design constraints.

Triply Periodic Minimal Surfaces (TPMS) have promising thermophysical properties, which makes them a suitable candidate in the production of low-temperature waste heat recovery systems. A TPMS thermal performance is connected to the complex flow patterns inside the pores and their interactions with the walls. Unfortunately, the experimental study's design analysis and optimization of TPMS heat exchangers are complicated due to the flow pattern complexity and visual limitations inside the TPMS. In this study, three-dimensional steady-state, conjugate heat transfer (CHT) simulations for laminar incompressible flow were carried out to quantify the performance of a TPMS based heat exchanger. TPMS Lattices based on Schwartz D architecture was modeled to elucidate the design parameters and establishing relationships between gas velocity, heat transfer, and thermal performance of TPMS at different wall thicknesses. In this study, four types of lattices from the same architectures with varying wall thickness were examined for a range of the gas velocity, with one design found to be the optimized lattice providing the highest thermal performance. The results and methodology presented here can facilitate improvements in TPMSheat exchangers' fabrication for recycling the waste heat in low pitch thermal systems.