Humidity control of liquid desiccant membrane ceiling and displacement ventilation system

The liquid desiccant membrane cooled ceiling (LDMC-C) and displacement ventilation (DV) system removes humidity directly from the space. However, LDMC-C/DV system does not control humidity in the lower occupied zone. In this work, a method for humidity control is proposed where fraction of the dehumidified cool dry air adjacent to the LDMC ceiling is extracted from the exhaust stream and mixed with the DV supply air stream. This leads to re-establishing of the thermal comfort; reducing the DV cooling requirements, and saving energy. A time-dependent mathematical model of the LDMC-C was developed and validated experimentally. The LDMC-C transient model was then integrated to the mixed DV space model and was applied to a case study. When mixing strategy was applied, the relative humidity dropped by an average of 8.72% in the occupied zone within 12 min and energy saving of 24% was achieved compared to in-duct conventional dehumidification.