Optimization of a liquid desiccant based dedicated outdoor air-chilled ceiling system serving multi-zone spaces

A liquid desiccant based dedicated outdoor air-chilled ceiling (DOAS-CC) system is proposed to serve a multi-zone space. The outdoor airflow rate and the supply air humidity ratio are two crucial variables in such a system, which significantly influence indoor thermal comfort, indoor air quality and energy consumption. Two strategies are presented to optimize these two variables in the study. They are the demand-controlled ventilation (DCV) strategy and the supply air humidity ratio set-point reset strategy. To evaluate the performances of these two strategies, a basic control strategy, i.e., the strategy adopting constant ventilation flow rate and constant supply air humidity ratio, is selected as the benchmark. Performances of the two strategies in terms of indoor air temperature, relative humidity and CO₂ concentration as well as energy consumption are analyzed using simulation tests. The results show that the supply air humidity ratio set-point reset strategy is effective for the indoor air humidity control. It can save about 19.4% of total energy consumption during the whole year. The DCV-based ventilation strategy can further reduce about 10.0% of energy consumption.