EXERGY ANALYSIS OF COMBINED FLUIDIZED-FIX BED DRYER

Exergy analysis is one method for studying of energy efficiency and optimization for systems and machines including dryers. Fluidized bed dryers despite widespread usage have low energy efficiency. Therefore a new method has been proposed that the fluid bed drying has been combined with thick (fix) bed dryer as outlet air from the fluidized bed section is conducted to the thick bed section for drying the other material or same kind material that existed in the first section. Experiments were performed in three temperatures, 50, 60 and 70 °C and three bed depth in down, fluidized bed drying, 4, 6 and 8 cm and two beds depth in up, batch bed drying, 6 and 8 cm. The results show that exergy loss of top floor is lower than down floor. And also increasing in bed depth of down floor causes increasing in exergy loss of top floor, but exergy loss of down floor decreases with increasing in bed depth of top floor.