不同干燥方法下枸杞干燥特性及气流床厚层干燥的压降特性  

Drying characteristics of Chinese wolfberry under different drying methods and pressure drop characteristics of airflow thick-layer drying

作　　者：张牧心 尹少武[1,2] 刘传平[1,2] 童莉葛[1,2] 王立[1,2] 

机构地区：[1]北京科技大学能源与环境工程学院,北京100083 [2]北京科技大学冶金工业节能减排北京市重点实验室,北京100083

出　　处：《食品工业科技》2017年第12期103-108,共6页Science and Technology of Food Industry

基　　金：北京青年英才计划项目(YETP0360);国家重点研发计划(2016YFB0601101);中央高校基本科研业务费(FRF-BD-15-009A)

摘　　要：对枸杞采用自然晾晒、烘箱薄层和气流床厚层三种不同方法进行干燥实验,考察干燥温度、是否碱水处理等因素对枸杞的干燥速率和干燥特性的影响,同时模拟气流床内的床层压降,探究不同因素对干燥过程中压降的影响。实验结果表明,将新鲜枸杞干燥至含水率13%以下,采用26℃的自然晾晒干燥时,经碱水处理和未经碱水处理的样品分别耗时103、350 h;而采用温度为50、60、70℃的烘箱薄层干燥法,经碱水处理的样品,耗时分别为14、10.5、6.5 h;温度对枸杞的干燥速率起决定性作用;枸杞喷洒碱水后干燥速度显著增加,且枸杞干品表面色泽明亮。气流床厚层干燥结果表明,气流速度和孔隙率对压降影响显著,气流温度对压降影响不显著;在雷诺数(Re)较小的情况下,Ergun方程所预测的压降值与实验值吻合较好,本模拟方法可以准确预测气流床厚层干燥的床层压降。The drying experiments of Chinese wolfberry were performed at natural drying, oven thin-layer drying and airflow thick-layer drying conditions. The influences of drying temperature and spraying alkali water on Chinese wolfberry were studied,the drying rate curves and drying characteristics were obtained.At the same time, the pressure drop in the airflow hed was simulated to investigate the influence of different factors on the pressure drop during drying process. The results showed that,the fresh Chinese wolfberry were dried to moisture content below 13% under 26 ~C natural drying conditions,it needed 103 h and 350 h for the wolfberry with spraying alkali water and without alkali water, respectively. When the fresh Chinese wolfberry were dried under oven thin-layer drying conditions, it needed 14,10.5,6.5 h for the wolfberry with spraying alkali water at 50,60,70 ℃ ,respectively.The temperature played a decisive role in drying rate of Chinese wolfberry.The drying rate increased significantly after spraying alkali water, and the surface of wolfberry was bright.The results of airflow thick-layer drying showed that the air velocity and porosity had significant influence on the pressure, air temperature on the pressure drop was not significant.In Re small, the Ergun equation predicted pressure drop values agreed well with experimental values.This simulation method could accurately predicted the pressure drop of airflow thick-layer drying conditions.

关 键 词：枸杞 干燥 干燥特性 压降 

分 类 号：TS255.1[轻工技术与工程—农产品加工及贮藏工程]