Modification of analytical solutions of coupled heat and mass transfer processes in liquid desiccant dehumidifier for deep dehumidification

Abstract

The dehumidifier is the key component in a liquid desiccant air-conditioning system, and analytical solutions for predicting its performance have been proposed in the literature. The existing analytical solutions cannot be directly used in deep dehumidification circumstances, owing to the significant nonlinearity of the iso-relative humidity (φ) line of humid air under deep dehumidification circumstances (managing air humidity ratio to below 7 g/kg). A concise correction method for modifying the analytical solutions for deep dehumidification is proposed in this study, wherein the nonlinearity of the iso-φ line is taken into consideration. The results reveal that the modified analytical results show good agreement with available experimental data. The average absolute deviations between the modified analytical results and experimental results are within 10%. Moreover, based on the modified analytical solutions, it is illustrated that the enthalpy and moisture efficiencies of the dehumidifier are greater than those of the regenerator under the same solution and air flow rates, NTUm, and change amount of air humidity ratio. This study is beneficial to understand efficiency difference between the conventional dehumidification and deep dehumidification, and helps to illustrate performance difference between the dehumidifier and regenerator.