技术中心

摘 要： 建立了洋白菜差压预冷实验台，设计了五种不同外部开孔方式，分别为28个孔、32个非均匀孔、32个均匀孔、40个孔和50个孔。分别对洋白菜在上述不同开孔方式下进行差压预冷实验，测试洋白菜中心及1/2R处温度降温过程，计算了洋白菜中心温度在预冷降温到6h时的均匀性。结果表明：在初始阶段，周转箱外部不同开孔方式对洋白菜中心及1/2R处温度影响不大，且降温速度均较缓慢。但随预冷时间增加，降温速度加快且降温速度之间开始有明显差距，其中外部开孔为40个孔的洋白菜中心温度和1/2R处温度均降低最快；通过计算知外部开孔为40个孔的降温均匀度最小，均匀性最好，故此种底部开孔孔径小，上部开孔孔径大的开孔方式在果蔬差压预冷应优先考虑采用。 关键词： 差压预冷；外部开孔方式；降温速度；冷却均匀性 The Study Of The Influence Of Different External Opening Models To The Effect Of Forced Air Pre-Cooling To Cabbage Niu Jianhui1 Liu Bin2 Chen Zhonghai1 Ge Jiyuan1 Bai Zhigang3 1. Department of Urban Construction, Hebei Institute of Architecture and Civil Engineering, Zhangjiakou, China; 2. School of Mechanical Engineering, Tianjin University of Commerce, Tianjin, China; 3.State Nuclear Electric Power Planning Design nbsp; Abstract: An experimental device had been set up to test the forced air pre-cooling to cabbage. Five different models of external openings were designed, including 28 holes, 32 non-uniform holes, 32 evenly holes, 40 holes and 50 holes. Forced air pre-cooling experiments had been carried out in the above different opening models to cabbage respectively. The core temperatures and 1/2R temperatures of cabbage were tested in the whole experiment, and the cabbage core temperature uniformity after 6 hours pre-cooling was calculated. The results showed that: in the initial stage, the external different opening models had little effect on cabbage center and 1/2R temperature, and all of the cooling rates were slow. However, with pre-cooling time increasing, the cooling rates speeded up and the gap between the cooling rates began to increase significantly. The temperatures of cabbage core and 1/2R were decreased fastest in the external openings for the 40 holes and through the calculation, the cooling uniformity of the external openings for the 40 holes was the smallest and the cooling uniformity was the best. So the external openings for the 40 holes in which of the hole diameter is smaller at the bottom than the upper ones should be adopted firstly. Keywords: Forced Air Pre-Cooling; External Opening Models; Cooling Rate; Cooling Uniformity 参考文献 [1]杨州，黄燕娟，赵春娥.果蔬通风预冷技术研究进展[J].中国农学通报.2006,22(9):471-474. [2]刘凤珍,王强.草莓差压通风预冷过程中影响参数的研究[J].制冷学报,2001,4:49-53. [3]王强,刘凤珍,连添达.葡萄差压通风预冷实验研究[J].制冷技术,2004,4:33-35. [4]左藤良二.果实日本[J].国外农业.1985,85(1):40-45. [5]HJELMFELT A T.Nonlinear flow through an isotropic porous media [J].Transactions of the ASAE,1995,38(3):234-240. [6]魏季瑄.数理统计基础及应用[M].成都:四川大学出版社,1991. [7]王强，陈焕新，董德发.黄金梨差压预冷送风速度的选择[J].制冷学报.2008.29(4):59-62.