A MATHEMATICAL MODEL FOR A FIXED DESICCANT BED DEHUMIDIFIER CONCERNING ACKERMANN CORRECTION FACTOR.

Solid desiccants have long been used in dehumidification and cooling systems. Many investigators have presented mathematical work on it, but there is a considerable discrepancy between published values and experimental values. A mathematical model has been derived to show the dehumidification trend of a desiccant dehumidifier with no rotation. In this model, variation of several parameters such as air humidity ratio , air temperature, water content of desiccant bed and temperature of desiccant as a function of the length of the bed and time were investigated. The mathematical model was validated by experimental results on a fixed solid desiccant bed filled with silica gel. The results indicated that the dehumidification rate along the length of the desiccant bed depends mostly on input humidity ratio, air stream velocity, heat and mass transfer from the air stream to the bed and the Ackermann heat transfer correction factor. By increasing input air relative humidity and temperature more than 50% and 95°C, respectively, the Ackermann factor corrected the heat transfer coefficient up to 4%. The results also showed that air stream velocity was one of the most effective parameters on the dehumidification rate of the wheel.