Removal Efficiency for Airborne Particles and VOCs in Liquid Desiccant Dehumidifier

Abstract

This study investigated the removal effect for particles and volatile organic compounds (VOCs) in liquid desiccant dehumidifier through experiments. In liquid desiccant dehumidifier, outdoor air is dehumidified by directly sprayed lithium chloride solution. Removal efficiency was used to evaluate the ability to capture airborne particles and VOCs. Particles larger than PM 2.5 in ambient air and one representative VOCs, toluene were considered. The contaminants concentration was measured at inlet and outlet stream of liquid desiccant dehumidifier. The removal efficiency was calculated when the process air containing contaminants bypassed and passed through packed bed of liquid desiccant dehumidifier respectively. The flow speed was set to 1.9 m/s, acceptable airflow speed of ASHRAE standard 52.2. The condition of process air was constantly maintained at 28-31 degree Celsius of temperature and 52-53% of relative humidity during experiments. Particles were analyzed according to its size range: PM 2.5-5, PM 5-10, PM 10-. The results of experiments showed that the better capturing ability can be expected for larger particles. Overall particle removal efficiency represented 43.9%, 56.1% and 70.5% in size range of PM 2.5-5, PM 5-10, PM 10-25 respectively. Overall VOCs removal efficiency showed 23.9% for toluene. When particle removal efficiency is converted to MERV (Minimum efficiency reporting value), liquid desiccant has similar filtering efficiency to filter of MERV 8 which is typically applied to commercial buildings.