Performance and optimization of a novel solar-driven liquid desiccant air conditioning system suitable for extremely hot and humid climates

Abstract

Extremely hot and humid climate has typical characteristics, such as high temperature, high humidity and lack conventional energy. It highly relies on the use of refrigeration and dehumidification equipment, which results in a large amount of conventional energy consumption. However, this contradicts the local energy system. Therefore, a novel solar-driven liquid desiccant air conditioning system is described and investigated in this study. It combines photovoltaic and thermal solar power, dehumidification, and active cooling. A mathematical model is first developed for each of components in the study: liquid-desiccant dehumidification/regeneration, photovoltaic system, solar collector, chiller, and auxiliary equipment. This study then analyzes, via numerical simulation, the entire system: the total cooling-capacity, the wasted condensation heat, and the regeneration-heat reduction-rate. Finally, the study investigates the system performance and optimize the ratio of photovoltaic/collector area, considering the building-area constrains typically associated with extreme heat and humidity. Using the proposed system, for every 2% increase in indoor air relative humidity, the regeneration temperature and regeneration heat quantity decrease by 2.8 °C and 62.08 kW respectively. For every 10 °C increase in condensation temperature, the wasted condensation waste heat quantity increases by 173.7 kW. Furthermore, when the heat humidity ratio and cold load index are constant, together with the decrease in installed roof-area, the ratio of photovoltaic/collector area required by the system decreases gradually.