Potentials and challenges for pillow-plate heat exchangers: State-of-the-art review

For a long time, shell-and-tube heat exchangers have been the most common choice in the industry. Despite some limitations, their main advantage is that they have been extensively investigated and reliable design tools are readily available. In other words, any alternative design should not only outperform shell-and-tube heat exchangers, but also be equipped with a comparably reliable and robust design platform for engineers. In recent years, a growing market share can be observed for plate heat exchangers, particularly for a special class known as pillow-plate heat exchangers. Recently, the research on pillow-plate heat exchangers has gained momentum primarily due to their relative low cost, compact design and structural integrity. However, a comprehensive literature review on the advancements so far and challenges ahead of their widespread application is missing. This study aims to fill this gap in the literature by systematically, critically and comprehensively surveying earlier studies on pillow-plate heat exchangers and providing an in-depth discussion regarding the achievements so far. The findings of this study are expected to help direct the forthcoming research on pillow-plate heat exchangers, especially towards more robust design tools. Overall, further investigation is needed on cost, plate material, flow configuration, heat transfer enhancement, correlation development, two-phase flow, etc.