An experimental investigation on drying for five kinds of materials such as concrete admixture in a fluidized bed dryer with inert particles was carried out and a correlation to calculate volumetric heat transfer coefficient was established.The experimental result showed that the presence of inert particles could enhance heat transfer and mass transfer to incease the volumetric heat transfer coefficient to 3000 W·m~(-3)·K(-1)

but the bed pressure drop was comparatively high.The drying capacity(as water evaporated)and heat efficency could reach 50—60kg·m-30·h-1and 30％—43％ respectively

and furthermore would continue to increase with the entrance temperature of hot air.