Dynamic Modeling of Liquid Desiccant Dehumidification Processes

摘要

This paper develops a dynamic heat and mass transfer model and its numerical solution for an adiabatic counter-flow dehumidifier. Dynamic characteristics include parameter distributions along the vertical flow path and outlet parameters of the air are analyzed. The dynamic responses of the outlet air temperature and humidity ratio and two indices of the dehumidifier efficiency (dehumidification rate and dehumidification effectiveness) to the step changes of the process air inlet temperature and humidity ratio and the solution inlet temperature are tested using the model developed. The results show that the variation of the air inlet temperature does not cause significant variation of the dehumidification performance of dehumidifier. A positive step change of the air inlet humidity ratio leads to a significant and rapid increase of the dehumidification rate. An increase of the solution inlet temperature results in a lower dehumidification rate. The step response results also indicate that the variation of inlet parameters has small influence on the steady state dehumidification effectiveness in the step response process. The numerical solution of the proposed dynamic model in steady state conditions is validated by steady state experimental results and the maximum difference is less than 10%. The results of aforementioned parameters analysis can be used for optimal design of liquid desiccant based air conditioning system.