Open Cycle Desiccant Air Conditioning Systems

The increasing concern with indoor air quality has led to air-quality standards with increased ventilation rates. Although increasing the volume flow rate of outside air is advisable from the perspective of air-quality, it is detrimental to energy consumption, since the outside air has to be brought to the comfort condition before it is insufflated to the conditioned ambient. Moreover, the humidity load carried within outside air has challenging HVAC engineers to design cooling units which are able to satisfactorily handle both sensible and latent contributions to the thermal load. This constitutes a favorable scenario for the use of solid desiccants to assist the cooling units. In fact, desiccant wheels have been increasingly applied by HVAC designers, allowing distinct processes for the air cooling and dehumidification. In fact, the ability of solid desiccants in moisture removal is effective enough to allow the use of evaporative coolers, in opposition to the traditional vapor-compression cycle, resulting in an ecologically sound system which uses only water as the refrigerant. Desiccant Assisted Cooling: Fundamentals and Applications presents different approaches to the mathematical modeling and simulation of desiccant wheels, as well as applications in thermal comfort and humidity controlled environments. Experts in the field discuss topics from enthalpy, lumped models for heat and mass transfer, and desiccant assisted radiant cooling systems, among others. Aimed at air-conditioning engineers and thermal engineering researchers, this book can also be used by graduate level students and lecturers in the field.

The ever-increasing demand for efficient, sustainable, and environmentally friendly cooling solutions has led to significant advancements in the field of HVAC technology. Among these innovations, desiccant cooling systems have emerged as a promising alternative to traditional air conditioning methods. By harnessing the principles of moisture absorption and evaporation, desiccant cooling systems offer precise control over indoor environments, reduced energy consumption, and minimized environmental impact. This comprehensive guide aims to explore the intricacies of desiccant cooling systems, providing readers with a deep understanding of the fundamental principles, diverse applications, challenges faced, and future trends in this field. Through detailed chapters, we delve into the psychrometric processes, types of desiccants, system components, configurations, performance evaluation, real-world applications, and the innovative solutions that shape the landscape of desiccant cooling technology. As the world grapples with the challenges of climate change and the imperative to reduce greenhouse gas emissions, the significance of sustainable cooling technologies cannot be overstated. Desiccant cooling systems stand at the forefront of this movement, offering a path toward energy efficiency, environmental responsibility, and enhanced indoor comfort. We invite readers, ranging from HVAC professionals and engineers to researchers and environmentally conscious individuals, to embark on this journey through the realms of desiccant cooling. By embracing the knowledge presented within these pages, we can collectively contribute to a greener and more sustainable future.

This paper has presented a review of the thermodynamics of three desiccant cooling cycles: the ventilation cycle, the recirculation cycle, and the Dunkle cycle. For the ventilation cycle the qualitative effects of changes in the effectiveness of individual components were analyzed. There are two possible paths to improved dehumidifier performance: changing the design of dehumidifiers using currently available desiccants so as to increase effectiveness without increasing parasitic losses, or developing new desiccants specifically tailored for solar cooling applications. The later part of this paper has considered the second option. A list of desirable desiccant properties was defined, properties of currently used solid and liquid desiccants were compared to this list, and a hypothetical desiccant type that would give improved system performance was discussed.

This book presents the necessary fundamental knowledge in the research, development, design, selection, and application of desiccant heating, ventilating, and air-conditioning systems. It covers the established installations in different climatic conditions and building types. In addition, advanced performance evaluation techniques are presented, covering thermodynamic, economic, and environmental aspects. Hence, the book is an important resource for undergraduate and graduate students, design and installation engineers, researchers and scientists, building owners and occupants, and energy and environmental policy makers.

Desiccant cooling systems process water vapor in the earth's atmosphere to produce cooling. Since mass transfer occurs between the system and its environment, they are commonly referred to as "open-cycle" systems. These systems all use a liquid or solid material called a desiccant to remove water vapor from the air. The process by which water is removed is most often adsorption of the solid desiccants and absorption in the liquid desiccants