| Abstract A mathematic formula for calculating heat transfer coefficient in swirl pneumatic flash dryer has been derived basing on the heat balance principle of a differential unit, which is a ring of swirl mass current in the dryer. The experimental relationship of Nusselt number Nu, Reynold number Re and the ratio of gas and solid loading B has also been correlated. Experiments have been performed according to orthogonalizing experimental process in a small scale swirl flash installation(Φ150mm)using corn starch as experimental material. The plots of particle size and moisture content of starch as well as the heat transfer coefficient between starch particles and hot air stream versus the height of dryer have been obtained. The data obtained have been regressed nonlinearly with electron brain and a regression equation is established asNu=-0.937+0.133Re~(0.662)-0.042Re~(-1.285)B~(-0.790)Heat transfer in the swirl pneumatic flash dryer is very uniform andthe heat transfer coefficient is greater than that in the straight flash dryer. It is affected significantly by temperature. |
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1992, Vol. 9 
