Design and optimization of membrane-based energy exchangers for less energy consumption and thermal comfort: A comprehensive analysis of hot climate

This paper investigates heat and mass transfer, design, and optimization of internally-cooled membrane-based energy exchangers for hot and dry weather. Fluid flows are assumed laminar and incompressible. Governing equations for airflow, desiccant solution, and a third fluid (refrigerant) are solved using finite difference method. Forced convection is the primary heat transfer mechanism. We compare efficiency and energy consumption of two configurations: three rectangular ducts ("three-duct" configuration) and a tube-in-duct design ("tube-duct" configuration). Results reveal the three-duct configuration offers higher sensible and latent efficiencies with less energy consumption. Optimization analyses, using response surface method, identify best operational and geometric parameters for maximizing this configuration's performance under extreme summer air conditions. Subsequently, we analyze these parameters across a range of inlet temperatures and humidity ratios to investigate sensitivity to variations. Findings suggest that for a target outlet temperature of 296.88 K, sensible effectiveness of 84 %, and maximum relative humidity constraint of 70 % (meeting comfort conditions), maximum latent effectiveness is 51 %. For this case, optimal values obtained with 99.6 % desirability are: solution concentration 0.14, solution temperature 298.2 K, water temperature 293.0 K, air duct hydraulic diameter 5.2 mm, and solution and water flow rates for each duct 0.551 g/s and 0.210 g/s respectively.