Investigation on solar assisted liquid desiccant dehumidifier and evaporative cooling system for fresh air treatment

Abstract

The widely used semi-centralized air conditioning (A/C) system consisting of independent fresh air system and fan coil system suffers from huge energy consumption, especially for fresh air treatment. Therefore, a liquid desiccant dehumidifier and regenerative indirect evaporative cooling (LDD-RIEC) system is proposed for fresh air treatment. The fresh air is handled by the LDD-RIEC system in which no electricity-intensive compressor involves. The hot and humid fresh air is firstly dehumidified by LDD and then sensibly cooled by RIEC. The thermal energy captured by solar collectors is used for desiccant solution regeneration. Indoor return air is cooled by fan coils of a mechanical cooling system. The system performance is analyzed by solving the heat and mass transfer equations of each component integrally in a closed loop. Focus is placed on discussing the influences of solar collector area and inlet air conditions, and optimizing the extraction air ratio of RIEC. The energy saving ratio is quantitatively evaluated with respect to a conventional A/C system. Results reveal that the optimal extraction ratio is 0.3 considering the interacted influence of dehumidifier, regenerator, RIEC and solar collector. The energy saving ratio ranges from 22.4% to 53.2% under various inlet air conditions.