Convergent-divergent design of fins for improving the thermo-hydraulic performance of heat exchangers assisted by a dual-flow topology generator

• A novel design of fins with convergent-divergent distribution is acquired using a TG. • The thermo-hydraulic performance is enhanced under a wide range of Re numbers. • Underlying mechanisms between TG-results are analyzed based on field synergy principle. In this work, a density-based topology generator (TG) is used to maximize the effectiveness of a 2D periodic unit within the counter-flow Plate heat exchanger (PHE), resulting in a novel convergent–divergent fin arrangement. Due to the high sensitivity of the TG setting parameters, an investigation is conducted to study their effects on the acquired topologies. It is observed that the convergent-divergent distribution feature remains consistent regardless of the input parameter settings with a conspicuous variation of the acquired fins distribution. To assess the efficacy of this newly-proposed design guideline of fins, a simplified HX (heat exchanger) with convergent-divergent (C-D) rectangular fin distribution is introduced and compared with the TG-acquired structures and a conventional uniform fin design. The comparative analysis is performed by conducting a set of computational fluid dynamic (CFD) simulations on the five structures (three TG-obtained, one simplified and one conventional) under two different cases (case1: water-water, case2: water–oil as cold and hot working fluids respectively) that encompass a wide range of Reynolds numbers (300–3000). The results show a thermo-hydraulic improvement of the TG-acquired and simplified HXs compared to the conventional one with an enhancement in the performance evaluation criteria (PEC) number up to about 23% and 10% for case 1 and up to 36% and 16% for case 2, respectively. Eventually, a detailed physical interpretation of the generated topology is delivered. The current work provides a novel guideline for fin design inspired by topological features, which could be helpful to improve the performance of HXs.