Performance analysis of liquid desiccant dehumidifier system for various packing density. (1st February 2023) - Sonowal, Juri
Graphical abstract: Highlights: Packing density of packed bed influences the dehumidifier performance. The effectiveness varies non-linearly with packing density. Higher rate of condensation is obtained for higher packing density. Air pressure drop decreases with packing density at higher air and solution flow rates. Abstract: Due to rising environmental concerns and decreasing fossil fuels, renewable energy-driven liquid desiccant packed bed dehumidifiers are fast developing as a viable alternative for air dehumidification. In this article, the effect due to the material of packing as well as the packing density of an individual packing on dehumidifier performance is numerically investigated by coupled heat and mass transfer analysis through two sets of case studies. A parametric study using less corrosive potassium formate (KCOOH) solution is conducted for the set of design variables at the inlet viz. air flow rate m ̇ a, desiccant flow rate m ̇ s, desiccant concentration ξ, inlet air specific humidity ω a, desiccant temperature T s and ambient temperature T a . The numerical model is validated with literature and in-house experiments. As the packing density increases, moisture removal rate (MRR) and pressure drop (PD) non-linearly vary with air velocity due to material properties. Further, numerical analysis shows an overall improvement in dehumidification performance in terms of MRR, moisture effectiveness ε abs, latent heat ratio (LHR) and PD when packing density of Mellapak 250Y is varied in the range 100–700 m 2 /m 3 . Performance of the dehumidifier increases with ω a, ξ, m ̇ s and m ̇ a but decreases with T s . An improvement of 52 % in MRR is found with higher ξ which is further improved by 97 % at higher packing density. PD increases by 99 % with m ̇ a and packing density but decreases under higher humid conditions. An optimal packing density and m ̇ a with higher ξ and m ̇ s (based on limitations in the pump capacity) guarantee maximum dehumidifier performance.