Drying Homogeneity of Grass Mixture Components in a Rotary Drum

A test of drying homogeneity of a mixture of white clover and ryegrass dried in a rotary drum was performed. The tests were conducted at 40, 60, and 80°C with drum speeds of 15, 20, and 30 rpm; flat and square flights were used, and the amount of material was 10% of the drum volume. The size of the flights was used to handle this volume of dry material. It was found that all of the drying curves were fit to a single exponential model, and some regression was obtained to predict the moisture content of every part, changing the temperature and the drum speed. The results showed that the geometry of the flights has no effect on the homogeneity of the final moisture content. The best results were reached at 80°C and 30 rpm, when the differences in time to reach 0.1 kg water/kg dry matter were less than 1 h.