TA-23-C038 – Optimization of the Liquid Desiccant Cooling Systems in Hot and Humid Areas

An air-conditioning system in a commercial building (AC) consumes more than 50% of the building’s total energy use in hot and humid regions. The regional restriction of indirect evaporative cooling (IEC) used in wet areas can be overcome by integrating a liquid desiccant dehumidifier (LDD). This energy-saving and emission-reduction plan, known as the liquid desiccant cooling system (LDCS), is anticipated to replace traditional mechanical vapor compression refrigeration systems (MVCR) in hot and humid areas. This study developed a simulation-based empirical model for the LDCS and proposed an optimization strategy for its operating parameters. A newly developed internally cooled LDD applied the system exhaust air as a cooling source. Sensitive analysis and multifactor optimization were used in the optimization and assessment of the potential and performance of the system. An orthogonal test was employed for the sensitivity analysis in this study, and five critical parameters were optimized based on the response surface model (RSM). The system coefficient of performance (COP) is the optimization objective. Three cities in hot and humid regions were selected to be optimized, demonstrating the LDCS’ regional capability. The results illustrated that the COP of the newly proposed system increases from 4 to 6.03 w/w (0.96 to 1.45 Btu/Wh) compared to a traditional MVCR system. The system can significantly increase the COP (34.9%) of the primary air supply system and satisfy the dehumidification demand when operating with low airflow speed (6.56 ft/s or 2.0 m/s) and a high airflow rate of LDD (75%) during months with high humidity and temperature. The results will facilitate the application of the IEC and LDD technologies and guide the design and operation of the LDCS in hot and humid regions.