Process analysis for an alfalfa rotary dryer using an improved dimensional analysis method

All parameters in terms of wet alfalfa input capacity, dry alfalfa output capacity, alfalfa stem length, rotary speed, heated air temperature, air flow velocity and number of lifting flights fixed at the interior wall of rotary dryer were integrated and derived into four π terms based on Jiang’s principle. The drying temperature was a significant factor influencing the drying rate and the post-drying quality of alfalfa hay. An improved G. Murphy theorem with high confidence was used to design an experimental program for alfalfa drying in a rotary dryer. A πequation was derived by using the multiplication of component equations involving the drying parameters and most of its correlation coefficients were higher than 0.99. The validation results show that most of the relative errors of πterms were lower than 10% and are acceptable in engineering practice. This empirical equation may be used to investigate the parameter interactive effects on conveyor performance, which may be useful in the design and selection of rotary dryers for drying alfalfa hay. Keywords: alfalfa, drying, rotary dryer, dimensional analysis DOI: 10.3965/j.issn.1934-6344.2009.03.076-082