Effects of liquid-desiccant air conditioning processes on the presence of inhalable particles in the air

Abstract

Liquid desiccant is a new means of controlling air humidity with significant energy-saving potential. However, direct contact between the salt solution and the treated air may cause carryover droplets that degrade the indoor air quality, and this is a major obstacle to widespread application. This paper experimentally investigates how dehumidification and regeneration using LiCl solution affect the mass concentration of micro-particles in the treated air. The results show that dehumidification tends to remove micro-particles with sizes of 0–2.5 μm rather than carryover droplets, especially for PM2.5 by 7.73%. However, larger micro-particles with sizes of 2.5–10 μm are generated during regeneration of the liquid desiccant, which indicates that the change in the amount of micro-particles depends on the direction of moisture migration. Increasing the rate of air or solution flow increases moisture migration during regeneration to release more micro-particles. Additionally, the amount of micro-particles released during counter flow is less than that during parallel flow, because the larger particles settle down during the former. This investigation should help to understand the behavior of carryover droplets in liquid-desiccant air-conditioning systems and inspire new methods for controlling humidity and particles.