Study On Heat And Mass Transfer Of Dehumidification By Falling Film On Corrugated Surface

Attention to the liquid desiccant air conditioning system has been greatly intensified in recent times.The advantages of this technology are plentiful:it requires minimal energy,is free of pollution,has adjustable humidity levels,and offers solar energy and low-grade heat energy for solution regeneration.Liquid film flow pattern is crucial for heat and mass transfer performance of falling film liquid desiccant dehumidifier.Corrugated plate is effective on modifying the liquid film pattern and then enhancing the dehumidification effectiveness.This investigation endeavors to analyze the gas-liquid flow,heat and mass transfer performance of the falling film liquid desiccant dehumidification process on corrugated plates.By means of the volume of fluid technique,the turbulent regime was addressed through the utilization of the RNG k-εturbulence model,and the phase interface was monitored.Using the two-film theory and penetration theory,the dynamic liquid film flow characteristics,gas-liquid flow field,and the mechanism of enhanced dehumidification on a corrugated surface were analyzed.The impact of different physical properties of air and liquid desiccant on the heat and mass transfer performance was studied.The main conclusion of this study are as follows:The corrugated surface significantly enhances the wave motion of the liquid film,thereby improving the dehumidification performance.When the inlet air velocity is 0.2m·s^-1 and the Li Cl solution concentration is 30%,the dehumidification effectiveness,absolute dehumidification rate,interfacial heat and mass transfer area,and mass transfer coefficient of the corrugated plate were improved by 16.6%,16.8%,2.4%,and 13.7%,respectively,compared to the flat plate.The main reasons why the corrugated surface can significantly improve dehumidification performance include the enhancement of interfacial mass transfer area due to liquid film wave motion and the generation of eddies near the gas-liquid interface.When the inlet air velocity is low and the inlet desiccant solution concentration is high,the dehumidification effect is particularly evident.A univariate methodology is utilized in this research to explore the effect of geometric parameters（λ,A）of the corrugated surface on the dehumidification rate and effectiveness.The corrugated plate with a wavelength of 5 mm and an amplitude of 0.5mm exhibited the highest dehumidification rate.By employing the univariate technique,the effect of inlet parameters of air（Reynolds number,temperature,and humidity）and inlet parameters of solution（Reynolds number,temperature）can be determined.An analysis was conducted to assess the effectiveness of dehumidifiers,with particular focus on their performance.As solution inlet concentration,Reynolds number,air humidity,and air inlet velocity rose,the dehumidification rate rose,yet it declined as solution temperature and air inlet temperature increased.Based on the present computational results,the predictive correlations for Nu and Sh have been proposed.The fitted correlations show excellent consistency with the calculated results.