Simultaneous Forced Convective Heat and Mass Transfer of Hot Air Flow Across a Humid‐Packed Bed

ABSTRACT The design of Packed Beds (PBs) presents significant technical challenges and has prompted extensive investigation. The present study experimentally investigates simultaneous heat and mass transfer through a Humid Packed Bed (HPB). A Packing Material (PM) of equal‐sized wetted spherical beads made from commercially available non‐hygroscopic porous white brick, with ambient air serving as the Heat Transfer Fluid (HTF). The influence of inlet air temperature (30°C–60°C), inlet air velocity (1.0–5.0 m/s), and bed profundity (5–20 cm) is analyzed for the characterization of the HPB system. Dimensionless parameters, including Nusselt number (Nu), Sherwood number (Sh), Stefan number (St), and Lewis number (Le), are systematically analyzed. Results demonstrate that both Nu and Sh are significantly enhanced by increased air velocity, driven by enhanced turbulence and thinner boundary layers, but decrease with greater bed profundity owing to declining temperature and concentration gradients. Higher inlet temperature enhances Sh by accelerating vapor diffusion, while concurrently limiting Nu due to cooling effects and the influence of temperature‐dependent properties. A direct relationship was observed between St and both air velocity and temperature, but demonstrated negligible sensitivity to bed profundity. Conversely, Le revealed an inverse relationship with rising air velocity and input temperature but increments with profundity. These findings illustrate the complicated interplay between heat and mass transfer mechanisms in HPB systems and provide valuable insights for system design optimization.