ABSTRACT
The process of dehumidification by conventional processes accounts for higher energy loads and operating costs. In recent years, the use of innovative porous hollow fiber membrane contactor technology for air dehumidification has proven to be an energy efficient alternative worldwide. The hydrophobic porous membrane acts as an interface separating the liquid desiccant and air stream by effectively taking away water vapor from air. The performance of the membrane contactor system primarily depends on membrane selection, type of absorbent or desiccant, module design, and working conditions such as temperature, flow rate, humidity and pressure of air, and the liquid desiccant. This chapter discusses the fundamental and design aspects of hydrophobic hollow fiber membrane contactors equipped with a porous membrane structure for air dehumidification. An emphasis on surface / cross-sectional morphology, pore diameter, pore size distribution, and hydrophobic characteristics of the hollow fiber membrane is of considerable importance for determining the separation performance of the contactor. Fundamental concepts relevant to solute transport phenomena through non-wetted membranes with relevant mathematical correlations for determination of mass and heat transfer coefficients are discussed. Dehydration studies pertaining to gaseous mixtures, including natural gas and flue gas are also presented. Additionally, future recommendations in research and development of membrane contactors are also discussed in the context of their design and scale-up for dehumidification on a commercial scale.
