Fluidization Study in the Fluidized Bed Drying of Naked and Husked Barley

쌀보리와 겉보리의 유동층 건조에서의 유동화 연구

To keep up with urgent need of continuous, effective and rapid drying unit, a fluidized bed drying system with computer controlling air temperature, velocity and relative humidity was designed. This study was attempted to determine physical properties and some basic experiments of fluidized bed d교ing of barley. Also experimental data of the designed fluidized bed drying system using the barely were compared with those of published equations to confirm the reliability of the system and the following results were obtained. The physical dimension husked barley were shown larger than that of naked barley from the experiment. When air temperature. relative humidity and charged amount were $35^{\circ}C$, 30% and 300g respectively, the minimum fluidization velocity of naked and husked barley were found 1.5 m/s and 1.7 m/s. And the optimum fluidization velocity was shown as 3.0 m/s from the experiment. The empirical equation of $U_{mf}$ in this fluidized system was obtained as follow; $U_{mf}^2= \frac{{\phi_s}\;d_p}{Hk}\;{\cdot}\;\frac{(\rho_s-\rho_g)g\;{{\varepsilon}_{mf}^3}} {\rho_g}(Re_p>1,000)$ Where HK=0.4881 for naked barley, 0.6649 for husked barley.

보리를 초기의 고수분 상태에서 연속적이고 효과적인 인공건조를 실시하기 위하여 보리의 물리적 특성을 구하였으며, 또 유동층 건조장치를 제작하여 유동화 특성을 실험하여 이론식과 비교 검토하였다. 공기의 온도 및 상대습도가 각각 $35^{\circ}C$, 30%이고 충전량이 300g일 때 쌀보리와 겉보리의 최소 유동화 속도는 1.5m/s 및 1.7m/s였으며, 최적 유동화 속도는 3.0m/s였다. 본 실험에서 실험한 쌀보리와 겉보리의 $U_{mf}$는 1.5m/s 및 1.7m/s였으며, Leva식에 의한 계산치는 각각 1.06m/s 및 1.07m/s로 실험치와 계산치는 잘 일치하지 않았다. 또한 쌀보리와 겉보리의 유동층 건조에서 실험치와 일치하는 다음과 같은 최소 유동화 속도에 관한 실험식을 얻었다. $U_{mf}^2= \frac{{\phi_s}\;d_p}{Hk}\;{\cdot}\;\frac{(\rho_s-\rho_g)g\;{{\varepsilon}_{mf}^3}} {\rho_g}(Re_p>1,000)$ 이 실험의 상수 Hk는 쌀보리 및 겉보리가 각각 0.4881, 0.6649였다.