A heat exchanger or heat recovery wheel is an energy-saving device that recovers and reutilizes energy lost in ventilation of buildings and factories. As latent heat (humidity) as well as sensible heat (temperature) can be recovered in exchange, it has a high energy-saving effect, and different types of products have been manufactured in various countries. In order to give it a latent heat (humidity) exchanging function, desiccants are used as silica gel, alumina, and synthesized zeolite. However, because these materials absorb odors as well as humidity, they have become the cause of claims against offensive odor generation due to odor transfer. This problems occurs because of preferential adsorption when outdoor air humidity increases supply air cross-contamination.
