Comprehensive analysis of geometric and thermohydraulic characteristics in single-embossed channels of pillow-plate heat exchangers

• Novel structural parameters in flat- and curve-type single-embossed pillow plates. • Novel correlations for mean hydraulic diameters in single-embossed pillow plates. • Determining optimum mean hydraulic diameters in single-embossed pillow plates. • Importance of wall temperature distributions in single-embossed pillow plates. • Establishing optimized artificial neural networks for single-embossed pillow plates. This study investigated the geometric and thermohydraulic characteristics of flat- and curve-type single-embossed pillow-plate channels (SEPPCs) elaborately for the first time. These examinations revealed that estimating mean hydraulic diameters (MHDs) in various SEPPCs remains a significant challenge, primarily due to the intricate channel structures. Additionally, assuming identical constant wall temperatures for the thinner and thicker plates of SEPPCs causes thermal uncertainties regarding the influence of conduction heat transfer in these plates. This research addresses these challenges in stainless steel, aluminum, and copper SEPPCs. A procedure for hydroforming simulation based on the finite element method was established to model the structure of SEPPCs reliably. By defining novel dimensionless parameters, improved MHD correlations were developed with estimation errors of 13.54 % and −8.68 % for flat- and curve-type SEPPCs, respectively, compared to simulation results. Compared to existing methods, these correlations improved MHD estimations and identified the MHD extremums. Conjugate heat transfer simulations were applied to study heat transfer in the plates of SEPPCs, revealing how material properties, geometric configurations, and fluid convection shaped temperature distributions. Analysis of the periodic-bulk-temperature ratio revealed that simulations using constant wall temperatures were insufficient to accurately represent the behavior of SEPPCs. Moreover, the development of optimized artificial neural networks facilitated the evaluation of the contributing parameters and resulted in accurate predictions of MHDs in both flat- and curve-type SEPPCs, as well as the average channel plate temperatures in flat-type SEPPCs. The findings of this study on MHD estimations and the critical role of channel wall temperatures offer a solid foundation for advancing research across diverse SEPPC configurations in the future.