ASHRAE F32-2009 (SI)

Sorption refers to the binding of one substance to another. Sorbents are materials that have an ability to attract and hold other gases or liquids. They can be used to attract gases or liquids other than water vapor, which makes them very useful in chemical separation processes. Desiccants are a subset of sorbents; they have a particular affinity for water.

Virtually all materials are desiccants; that is, they attract and hold water vapor. Wood, natural fibers, clays, and many synthetic materials attract and release moisture as commercial desiccants do, but they lack holding capacity. For example, woolen carpet fibers attract up to 23% of their dry weight in water vapor, and nylon can take up almost 6% of its weight in water. In contrast, a commercial desiccant takes up between 10 and 1100% of its dry weight in water vapor, depending on its type and on the moisture available in the environment. Furthermore, commercial desiccants continue to attract moisture even when the surrounding air is quite dry, a characteristic that other materials do not share.

Chapter Table of Contents

Desiccant Applications
Desiccant Cycle
Types of Desiccants
Desiccant Isotherms
Desiccant Life
Cosorption of Water Vapor and Indoor Air Contaminants

ISBN: 978-1-933742-55-7
ISSN: 1523-7282

Units: SI

Citation: 2009 ASHRAE Handbook -- Fundamentals: Chapter 32, Sorbents and Desiccants



Product Code(s): D-F322009SI