Drying models of rice milk in a verticle spray dryer

Abstract

The objective of this research is to study on drying models of rice-milk powder produced by using a verticle spray dryer. Two mathematical models, diffusion theory and Ranz&Marshall models, were used to determine the moisture content of rice-milk powder in falling-rate drying period and to compare with experimental results. Rice-milk powder was produced by using the small spray
dryer at process optimum condition i.e. drying air temperature of 193 °e, volumetric air flow rate of 35 m3/h and rice-milk feed rate of 738 mllh. Effective diffusivity was estimated from diffusion theory based on a thin slab and its value was 3.36X 10,12 m2/s. The diffusion model showed better results than Ranz&Marshall model. However, product moisture content predicted from the diffusion model gave a lower value of 45 % when it was compared to the experimental result.