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针对苜蓿干燥存在的处理量小、耗能高、叶片损失率高的问题,该文将紫花苜蓿的干燥过程分为高温和常温两个干燥段,设计了气体射流冲击联合常温通风干燥装备,包括基于狭缝型气体射流冲击管的气体射流冲带式干燥机和基于环境条件自动控制的常温通风箱式干燥机。利用计算流体动力学软件Fluent对狭缝型气流冲击管内部的流场进行数值模拟。结果显示增设扰流板可以改善狭缝型气体射流冲击管喷嘴出口气流速度分布的均匀性,速度变异系数由不设扰流板情况下的51.1%降为7.7%;利用单片机控制系统进行信息采集并控制通风的进行,解决夜间物料吸湿回潮、发热的问题。以紫花苜蓿作为原料对干燥装备的性能进行试验验证,结果表明:气体射流冲击联合常温通风干燥的苜蓿具有批次处理量大(150 kg/h)、叶片损失率小(干草的叶片损失率为1.5%)、能耗低(单位去水能耗3 408 k J/kg)的优点。研究结果为低能耗、低叶片损失率的苜蓿干燥技术与装备提供参考。
Aiming at the problems of small amount of treatment, high energy consumption and high loss rate of leaves, this paper divided the drying process of alfalfa into high temperature and normal temperature drying section, and designed the gas jet impact and normal temperature ventilation and drying equipment, including A gas jet punch belt dryer based on a slit-type gas jet impact tube and a room temperature blower box dryer controlled automatically based on environmental conditions. The computational fluid dynamics software Fluent was used to numerically simulate the flow field inside the slotted impingement tube. The results show that the addition of spoiler can improve the uniformity of air velocity distribution at the outlet of the nozzle of the gas jet with slit gas jet. The coefficient of variation of speed is reduced from 51.1% to 7.7% without spoiler. The single chip control system is used to collect information And control the ventilation, to solve the problem of hygroscopic moisture and fever at night. The experiment of alfalfa drying with the equipment of alfalfa was carried out. The results showed that gas jet impact combined with room temperature ventilation and drying alfalfa has the advantages of large batch processing capacity (150 kg / h), low leaf loss rate (hay leaf loss rate 1.5%), low energy consumption (unit energy consumption of 3 408 k J / kg). The results provide a reference for the technology and equipment of alfalfa drying with low energy consumption and low leaf loss rate.