Review of the advances in open-cycle absorption air-conditioning systems

A large percentage of building energy consumption is for the maintenance of indoor thermal comfort conditions in different climatic conditions, particularly in hot and humid climates. Typical heating, ventilating and air-conditioning systems present an expensive source of energy or electric energy consumption. However, these processes have possible alternatives, materials and energy sources that are more economical and environmental friendly to support the building’s indoor thermal environment. The application of hydrophilic liquid desiccant materials or absorbents can potentially support the maintenance of a comfortable and healthy indoor environment by controlling the air temperature, humidity and air quality. Many absorbent materials are being developed, tested and applied for absorbent-based heating, ventilating and air-conditioning systems. The design of these systems depends on the application and situation. Hence, the systems installed in actual buildings in different climates show their applicability and viability. Because buildings today require an increasing amount of energy for heating, ventilating and air-conditioning, the application of absorbent-based heating, ventilating and air-conditioning systems presents a potential alternative to costly traditional systems. These absorbent-based systems can lessen the building’s energy consumption for the maintenance of its indoor environment. These systems also eliminate chemical contents in the air, such as VOCs, and biological microorganisms, such as bacteria and viruses. Hence, absorbent-based air handling systems are a potential alternative to typical air handling systems. These systems have several advantages: they are cheaper, smaller, require simpler maintenance and can operate on available energy sources. Therefore, further research and studies are needed to address the above issues and simultaneously educate the public (ordinary users) and developing countries on the benefits and advantages of using absorbent-based air-conditioning systems as alternatives to the widely used and established systems.