Investigation of Thermal–Hydraulic Behavior of Natural Cooling‐Based Pillow‐Plate Heat Exchangers

ABSTRACT Pillow‐plate heat exchangers (PPHEs) represent an innovative, completely bonded plate‐type heat exchanger. The current research focuses on the thermohydraulic behavior of natural cooling‐based PPHE, in which the spacing of the plate is differentiated with 100 and 150 mm spacings. The methodology of this research combined theoretical modeling with rigorous experimental testing. The efficiency of PPHE is evaluated in terms of minimum, medium, and maximum flow rates. It is observed that the medium flow rate of the fluid in the module is more stable. Henceforth, pressure drop analysis, heat transfer analysis, expected and experimental power, and temperature validation are performed for 100 and 150 mm spacing PPHE at a medium flow rate. The flow regime delineation based on the Grashof number for 100 and 150 mm spacing is greater and follows a turbulent flow regime. The Grashof number increases with temperature for both spacings, boosting natural convection and the heat transfer efficiency of pillow plates. The of the outlet of 100 mm spacing varies from 879 to 1429, leading to a wide range of thermal resistance across the outlet channels. The significant application of pressure drop is processed with the computational area and hydraulic diameter, from which the importance of accuracy and the pattern of PPHE are explored. The simulated discharged heat and power trends closely match the experimental results, with a maximum error of 2% and average deviations of 0.42% and 0.46% for the 100 and 150 mm spacings, respectively. Moreover, the minimum deviation in power and temperature, respectively, validated the application of the 100 mm spacing pattern with enhanced thermohydraulic performance. Finally, the numerical results closely match the experimental data, with an error of only 3.16%, confirming the validity of the experimental model.