Displacement ventilation with cooled liquid desiccant dehumidifier membrane at ceiling : modeling and design charts -

Abstract

A novel transport model is developed for a space conditioned by a cooled liquid desiccant dehumidification membrane ceiling (LDMC-C) and displacement ventilation DV in which the space is divided into three zones: an occupied cool with fresh air zone; an upper recirculation zone; and a ceiling adjacent boundary layer zone where the air is drawn at the exhaust grill. The adjacent air boundary layer at the ceiling membrane predicted the latent and sensible heat transfer to the desiccant solution. The boundary model was validated experimentally in a climatic chamber. The developed model predicted of the LDMC-C-DV system operational parameters such as the supply flow rate and temperature and the liquid desiccant concentration, flow rate, and inlet temperature that meet thermal comfort and air quality requirements. Extensive simulations were performed on a typical office load of 75 W-m2 to generate design charts of the system for three DV supply air temperatures of 18, 20, and 22°C to identify the appropriate DV flow rate and inlet desiccant (CaCl2) solution temperature that provides comfort and air quality and ensures that condensation is unlikely to occur. The LDMC sensible and latent load removal from the space load is directly read off the charts.