Measurements of effectiveness in a silica gel rotary exchanger

Desiccant air conditioning systems that incorporate rotary heat and mass ex changers are getting a closer look in view of the pressure on the industry to decrease the use of chlorofluorocarbons and for fuel economies. Heat and mass exchangers that utilize LiCl, silica gel and other desiccants have be en considered as possibilities. The performance features of a silica gel ro tary mass exchanger wheel, which is the primary component in a desiccant sy stem, has been measured. The process air flow velocities and temperatures r anged from 0.5 to 2.5 m/s, and 20 to 30 degrees C with 30 to 100% relative humidities. Similar velocity and relative humidity conditions were used for regeneration air. The desiccant data are compared to two different theorie s from the literature; the method of characteristics and a numerical approa ch. The method of characteristics appears to be good for only a small range of conditions, generally for low values of specific capacities. The numeri cal approach appears to predict the trends well, though sometimes with larg e errors. (C) 1999 Elsevier Science Ltd. All rights reserved.