Multi-domain analysis and optimisation for plate heat exchangers: Integrating theory, Experiment, and CFD-based approaches

The compactness and the high thermal efficiency of plate heat exchangers (PHEs) are key attributes that make them crucial in various industrial applications. This research aims to optimise the performance of PHEs by improving their effectiveness, maximising the heat transfer capabilities, and reducing the associated pressure drop. The optimisation was performed for the geometrical parameters using the multi-objective technique, employing the Kriging model for the predictions. The study developed a complete representation of a 1D mathematical model to estimate the PHE performance and validate the result against experimental data. The computational fluid dynamic (CFD) model integrated into this research captured complex flow behaviours inside the channels and analysed the optimised shape. The result revealed that the strategy used in this research obtained an optimised design with superior thermal-hydraulic performance. Specifically, the optimised design exhibited a thermal effectiveness increase of up to 13% over the original design. Additionally, it achieved a 30.49% improvement in heat transfer rate. Remarkably, the optimised design achieved a substantial pressure drop reduction of up to 56.9% compared to the initial design, relative to the mass flux through the channels. Moreover, the optimised design provided improved flow uniformity and distribution, reducing maldistribution by 25.2% in turbulent flow and 48.7% in laminar flow. The exergy metrics highlighted the preference for the optimised design to maintain higher exergy efficiency. Furthermore, it indicated a 29% reduction in irreversibilities, making the optimised shape more energy efficient and sustainable. The sensitivity analysis identified the channel gap as the primary governing parameter for pressure drop, accounting for over half of the variability, while plate thickness had the most significant impact on the effectiveness of the heat exchanger and was responsible for 42.6% of the direct and interaction effects of variables.