Membrane distillation-liquid desiccant air-conditioning for thermal comfort in buildings

Increasing demand for thermal comfort in buildings together with the urgent need for reducing greenhouse gas emissions has resulted in significant technological advancement in the air-conditioning industry, most notably including the development of the liquid desiccant air-conditioning (LDAC) process. This innovative process involves two stages, namely air dehumidification and liquid desiccant solution regeneration, and its dehumidification capacity is regulated by the efficiency of liquid desiccant solution regeneration. Membrane distillation (MD) has been increasingly explored for regeneration of liquid desiccant solutions in LDAC systems owing to its notable advantages including excellent membrane rejection, resilience to hypersalinity, and effective incorporation of low-grade waste heat and solar thermal energy. Despite these advantages, MD regeneration of liquid desiccant solutions has been demonstrated only at the lab-scale level using direct contact membrane distillation (DCMD) and vacuum membrane distillation (VMD) configurations for manifestation of their technical feasibility. Although these lab-scale demonstrations have arguably paved the way for progress on the MD regeneration of liquid desiccant solutions, more studies at the pilot or large-scale level are required to realize this MD strategic application