Reduced modeling of liquid desiccant falling film absorbers

Abstract

Liquid desiccant falling film absorbers are an energy-efficient solution for humidity control and dehumidification in buildings and cold stores. This work presents a reduced one-dimensional physics-based modeling approach for this technology and compares it to a high-fidelity three-dimensional computational fluid dynamics (CFD) model. Both models capture the complex heat and mass transfer mechanisms of vertical falling films on two opposing walls and a horizontal crossflow of air. Additionally, both models were verified against experimental data from previous work, and the results showed good agreement within the uncertainties of the measurement equipment. A parameter variation study was also performed, comparing the results of both models under conditions relevant to cold store applications. The reduced model was found to be over 400 times faster than the high-fidelity model, while still achieving an average difference of less than ±0.14K, ±1.3%, and ±3.9% for the calculated air outlet temperature, absorbed water vapor mass flow rate, and air-side pressure drop, respectively. The reduced model is suitable for optimization studies and easy to implement in system simulations, making it a valuable tool for the design and optimization of liquid desiccant systems.