The state of the art in energy saving techniques for garment/textile drying

Drying is a ubiquitous process in a wide range of applications and industries, including residential and commercial textile drying, agriculture, chemical processing, and the pharmaceutical industry. Thermal drying is energy intensive due to the unavoidable thermodynamic constraint of supplying sufficient energy to provide the latent heat of evaporation (> 2000 kJ kg(-1)) for the removal of water vapor. There is a critical need to reduce the overall energy consumption in drying, and several methods to do so have been explored. Most energy saving approaches for convective drying are based on heat recovery from the exhaust stream, because a significant amount of heat used in drying appears in the exhaust stream. Different techniques have been attempted to reduce energy consumption in different types of dryers (gas-fired, electrical, and heat pump dryers). This paper focuses on the literature addressing drying theory and the underlying mass, species, and heat transfer phenomena, identification of the most energy-consuming steps in the process, assessment of the potential for energy savings, and the energy saving techniques considered in the literature. Insights gained from this study are used to identify the optimal techniques to minimize energy consumption and drying time for a variety of drying scenarios.