Heat Transfer Performance Evaluation of Pillow-plate Exchangers for Waste Heat Recovery from Hot and Humid Air

In industrial processes that recover waste heat for energy reuse, the heat source is often polluted air. When the surface temperature drops below the dew point, condensate can form during the heat recovery process. Pillow-plate heat exchangers are advantageous due to their high resistance to fouling, easy maintenance, and excellent heat transfer performance, as they facilitate heat exchange between two fluids through a single plate rather than an extended surface. Their straightforward design also promotes efficient condensate drainage. Despite numerous experimental studies on pillow-plate heat exchangers, research evaluating their performance in hot and humid conditions is still scarce. This study presents an experimental setup designed to assess the performance of a pillow-plate heat exchanger under such conditions, analyzing heat transfer performance across various operating scenarios. When varying the parameters on the water side, the heat transfer rate changed by approximately 10–20%. In contrast, altering the parameters on the air side resulted in changes of about 25–60%. Overall, it was found that the influence of air-side parameters was approximately 28.2% greater within the tested range. Notably, the heat transfer rate showed significant sensitivity to changes in parameters that affect the absolute humidity of the air.