Multi-Domain Analysis and Optimisation of Plate Heat Exchangers: Theory, Experiment, and CFD Integration

Anas F A Elbarghthi, Ph.D.

Doctoral thesis

Abstract:

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 optimize the performance of PHEs by improving their effectiveness, maximizing the heat transfer capabilities,and reducing the associated pressure drop. An in-depth literature review was carried out to discover the latest advancements in PHE design and optimization strategies. The optimization was performed for the geometrical parameters using the multi-objective technique, utilizing 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) integrated into this research captures complex flow behaviors inside the channels and analyzes the optimized shape. The result revealed that the strategy used in this research obtained an optimized design with superior thermal-hydraulic performance. Specifically, the optimized design exhibited a thermal effectiveness improvement of up to 13% higher than the original design while achieving a 30.49% increase in heat transfer rate. Remarkably, the optimized design achieved a substantial reduction in pressure dropup to 56.9%in contrast to the initial design, with respect to the mass flux passing through the channels. Moreover, the optimized design provided better uniformity and flow distribution, reducing the maldistribution by 25.2% in turbulent regions and 48.7% in laminar flow. The exergy metrics highlighted the preference for the optimized design to maintain higher exergy efficiency. Further, it indicated a 29% reduction in irreversibilities, making the optimized shape more energy-efficient and sustainable. The sensitivity analysis result recognized the channel gap as the key governing variable on pressure drop with more than 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.

Abstract:

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 optimize the performance of PHEs by improving their effectiveness, maximizing the heat transfer capabilities,and reducing the associated pressure drop. An in-depth literature review was carried out to discover the latest advancements in PHE design and optimization strategies. The optimization was performed for the geometrical parameters using the multi-objective technique, utilizing 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) integrated into this research captures complex flow behaviors inside the channels and analyzes the optimized shape. The result revealed that the strategy used in this research obtained an optimized design with superior thermal-hydraulic performance. Specifically, the optimized design exhibited a thermal effectiveness improvement of up to 13% higher than the original design while achieving a 30.49% increase in heat transfer rate. Remarkably, the optimized design achieved a substantial reduction in pressure dropup to 56.9%in contrast to the initial design, with respect to the mass flux passing through the channels. Moreover, the optimized design provided better uniformity and flow distribution, reducing the maldistribution by 25.2% in turbulent regions and 48.7% in laminar flow. The exergy metrics highlighted the preference for the optimized design to maintain higher exergy efficiency. Further, it indicated a 29% reduction in irreversibilities, making the optimized shape more energy-efficient and sustainable. The sensitivity analysis result recognized the channel gap as the key governing variable on pressure drop with more than 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.

Keywords

Thermal-hydraulic performance, Plate heat exchanger, Multi-objective optimisation, Computational fluid dynamics, Pressure drop, Exergy analysis, Maldistribution

Jazyk práce: English

Datum vytvoření / odevzdání či podání práce: 7. 7. 2025

Obhajoba závěrečné práce

• Vedúci: prof. Ing. Václav Dvořák, Ph.D.

Technical University of Liberec

Faculty of Mechanical Engineering

Doctoral programme / odbor:
Machines and Equipment Design / Machines and Equipment Design