龙眼果实差压预冷过程中的阻力特性

Pressure Drop Characteristics in Forced-air Pre-cooling of Longan Fruits

建立了龙眼差压预冷试验台,测定了不同条件下龙眼果实的通风阻力特性。结果表明,风速与压降之间的关系可以用Ramsin方程来描述,压差与风速近似呈平方关系。研究了包装箱的开孔形状与开孔率对压力损失的影响,研究表明,在相同的风速和开孔率条件下,圆形开孔的压力损失较小,矩形开孔的压力损失较大,龙眼差压预冷包装箱的开孔率大于15.5%时,压力损失小而且能耗较低。

A forced-air pre-cooling experimental unit was established. The characteristic curves of Longan ventilation resistance in different experimental conditions were obtained. The relationship between airflow rate and pressure drop was found out. The pressure drop through Longans could be expressed through the Ramsim equation. The pressure drop was proportional to the square of the airflow rate approximately. The effects of shape and area of container venting hole on pressure drop were discussed. At the same airflow rate and venting area, pressure loss is smaller through round vent holes than through rectangular vent holes. When opening areas were bigger than 15.5% of the package surface, then it could meet low pressure loss and had small energy consumption. The results provide foundation and theoretical basis for design of forced-air pre-cooling system.