基于数据驱动的纸浆洗涤过程优化控制

针对纸浆洗涤过程的残碱和黑液波美度不能直接在线测量、控制回路的动态特性难以用数学模型描述的问题，通过研究数据驱动操作模式的优化思想，提出了基于数据驱动的纸浆洗涤过程综合优化的方法。基于PCA-BP神经网络法和多元回归分析建立了残碱和黑液波美度的预测模型及工况综合评价模型。基于大量工业运行数据和工况评价模型对纸浆洗涤过程的操作模式进行优化，构建优化操作模式库。以高产、低成本、低耗为目标对优化模式库寻优，找出最优操作模式。通过实际应用，证实该方法能准确预测残碱和黑液波美度，并在满足洗涤质量的同时，使出浆量提高，清水加入量减少，达到优化生产的效果。     

啤酒糟含水率的软测量

啤酒糟的含水率是安全储存的重要指标，工艺上要求干燥后的啤酒糟含水率8%-10％。但啤酒糟含水率难以实现在线检测，为解决此问题，该文建立了啤酒糟旋转闪蒸干燥过程BP神经网络建模，并基于该模型建立了啤酒糟含水率的实时预测系统，实现啤酒糟含水率的软测量。该系统的预测值与离线分析平均相对误差小于2．5％，满足干燥工艺的要求，预测结果对实际干燥过程的操作具有指导作用。     

双干网多烘缸纸机纸页干燥过程建模研究

根据质量和能量守恒定律,结合干燥过程的传热传质特点,建立了双干网多烘缸纸机纸页干燥过程的数学模型。基于该模型对纸页干燥过程进行了模拟,通过模拟值与实测值的比较发现,模拟得到的纸页干度接近于实测值,纸页温度模拟值随干燥区的变化趋势也与实测值有较好的一致性,表明该模型具有较高的可靠性,可为纸页干燥过程的设计和操作优化提供参考。     

基于正交设计与BP网络优化人参真空冷冻干燥工艺参数

研究了人参真空冷冻干燥工艺参数对干燥速率的影响规律。运用正交试验方法研究了干燥室压力、物料厚度、加热温度对干燥速率的影响,得到了优化的工艺组合。在此基础上运用BP神经网络对试验数据进行分析处理,建立BP神经网络模型,并通过该模型进行预测和优选,得到最佳的方案,即加热温度为60℃、干燥室压力为80 Pa、物料厚度为5 mm,此时干燥速率为1.46 h-1,与网络预测值1.44 h-1相差1.38%。结果表明,经正交试验数据训练过的BP神经网络,能较好的反应工艺参数与优化指标之间的复杂非线性关系,对指导生产试验与降低经济成本具有一定的意义。     

五段通汽烘干过程的优化与控制(一)——烘干过程的优化控制方案

根据纸机烘干部五段通汽的工艺流程，确定烘干部干燥过程的优化控制方案，建立五段烘罐表面温度的不确定性模型，设计相应的鲁棒H∞控制器，并进行仿真实验研究。     

五段通汽烘干过程的优化与控制(二)——烘干表面温度的鲁棒H∞控制

根据纸机烘干部五段通汽的工艺流程，确定烘干部干燥过程的优化控制方案；建立五段烘缸表面温度的不确定性模型，设计相应的鲁棒H∞控制器，并进行仿真实验研究。     

农产品干燥过程数值模拟研究现状及进展

我国是农业大国，农产品种类丰富，产量也居世界前列。但目前产后加工贮藏环节较薄弱，常因产后干燥不及时致产品发生霉变，或干燥参数不合理影响农产品品质，造成巨大经济损失。随着计算机技术的发展，数值模拟方法已广泛应用于农产品干燥研究中，通过数值模拟方法对农产品干燥过程进行分析，可有效模拟其干燥过程温湿度变化，节约干燥工艺开发时间，降低生产成本。该文概括了农产品干燥经验模型、理论模型以及人工神经网络预测模型的研究进展，提出了农产品干燥过程数值模拟研究当前存在的问题，并对未来发展趋势进行了展望，以期为数值模拟技术在农产品干燥领域中的优化及应用提供参考。     

玉米籽粒缓苏干燥过程动力学分析

对玉米籽粒的缓苏干燥过程进行了理论分析,并假设玉米籽粒为轴对称结构、各向同性的均匀物质,建立了玉米籽粒的缓苏干燥数学模型,利用COMSOL Multiphysics模块进行了热质传递过程的模拟研究。结果表明,该模型可较好地模拟玉米籽粒的干燥过程。利用该模型模拟研究了不同干燥条件下玉米籽粒温度、干燥时间、缓苏时间、缓苏度的变化及其对干燥速度的影响。结果表明,玉米籽粒内外温度在3~5 min内即可达到热风温度,玉米籽粒内部最大水分梯度出现在热风干燥5~10 min后,不同干燥阶段不同初始含水率对缓苏度的影响很小,缓苏60 min水分梯度可以基本消除。利用该优化工艺参数对玉米籽粒交替进行热风干燥和缓苏干燥,可使总的热风干燥时间最少,实现节能目的。     

牛肉泠冻干燥过程优化及最佳工艺条件的确立

对熟牛肉进行冷冻干燥实验，确定了熟牛肉片冻干工艺条件。计算了冻结终点温度、冻结时间，建立了熟牛肉片冻干的传热传质模型，由模型计算出理论干燥时间，并与实验值进行了比较。探讨了原料、预冻速率、干燥室压强、升华温度、捕水器温度、压强对制品品质及干燥时间的影响。熟牛肉的冻干工艺条件为：预冻时间3h，预冻终点温度-24℃，干燥室真空度60Pa，捕水器压强45Pa，温度-40～-50℃，干燥时间4h。     

基于遗传算法优化带有密闭气罩造纸机干燥部送风温度

以降低带有密闭气罩造纸机干燥部干燥过程蒸汽消耗量为目的,针对造纸机干燥部吨纸蒸汽消耗而提出一种基于遗传算法优化干燥部送风温度的方法。首先分析送风温度对吨纸蒸汽消耗量的影响,然后建立纸机干燥部模型并利用遗传算法对送风温度进行优化。仿真实验表明,利用遗传算法对送风温度优化后,使带有密闭气罩造纸机干燥部蒸汽消耗量进一步降低。     

太阳能脱水车间湿差脱水技术研究

采用太阳能资源与西北干燥空气合理结合的方式,以娃娃菜为例进行脱水干燥实验研究。研究西北地区不同季节的气候条件,对娃娃菜实际脱水速度与理论空气脱水速度的影响。得出全年干燥参数。研究表明,干燥室满载脱水时,室外干空气绝对湿度显著低于室内,不论白天和夜间都可以有效辅助太阳能进行脱水,150kg娃娃菜全年干燥时间为28～72h,干燥效率保持在80%左右。夏季将最大节能79%,秋季最小节能47%。利用spss17.0软件对实验结果进行分析表明,Cubic模型拟合效果较理想。     

胡萝卜丁中维生素C在热风辅助射频干燥过程中降解的动力学模型

目的研究热风辅助射频(hot air-assisted radio frequency,HA-RF)干燥过程中维生素C随温度变化的降解动力学模型。方法在6.5 cm极板间距和60℃热风系统条件下进行HA-RF干燥,重点研究胡萝卜丁中维生素C在干燥过程中的降解动力学,包括脱氢抗坏血酸(dehydroascorbic acid,DHAA)和抗坏血酸(ascorbic acid,AA)。总维生素C含量采用2,4-硝基苯肼分光光度法测定,AA采用2,6-二氯吲哚酚滴定法测定。结果HA-RF干燥过程中维生素C的降解规律符合一级可逆模型,其降解活化能为40.54 kJ/mol。DHAA活化能为35.83 kJ/mol,表明DHAA的稳定性低于AA。结论本研究使用的干燥温度为62.5~77.5℃,较高的干燥温度下维生素C降解速率较高,较低处理温度下的降解过程具有更好的模型适应度(R2>0.98)。     

茎瘤芥的气体射流冲击干燥动力学及多酚降解动力学特征

为了阐明气体射流冲击干燥过程中茎瘤芥的干燥动力学和多酚降解动力学特征,分别在40、50 ℃和60 ℃下对茎瘤芥进行气体射流冲击干燥,利用8 个薄层干燥模型探究干燥动力学特征;利用4 个反应动力学模型探究茎瘤芥多酚单体的降解动力学特征。结果表明：与热风干燥相比,气体射流冲击干燥对茎瘤芥的干燥效率更高且所干燥茎瘤芥褐变程度更轻。茎瘤芥的干燥速率随着气体射流冲击干燥温度的升高而增加,该过程的茎瘤芥水分散失行为可以用Modified Page模型进行描述和预测。液相色谱-质谱联用分析发现气体射流冲击干燥会导致茎瘤芥中对香豆酸、阿魏酸、芸香柚皮苷、柚皮苷、橙皮苷、枸橘苷和橙皮素的降解。其中,橙皮苷、芸香柚皮苷、枸橘苷、柚皮苷、橙皮素和对香豆酸的降解符合二级反应动力学,且显著影响茎瘤芥的抗氧化活性。气体射流冲击干燥过程中,茎瘤芥多酚的降解是典型的非自发吸热反应。本研究为进一步改进茎瘤芥的气体射流冲击干燥品质提供了理论参考。     

Effect of ultrasound on banana cv Pacovan drying kinetics

The aim of this work was to study and to model the drying kinetics of fresh and ultrasonic pretreated banana cv Pacovan using the diffusional model (Fick’s second law) and an empirical two parameters model (Page model). The pretreatment was carried out in an ultrasonic bath at 30 °C. The drying process was carried out in a fixed bed dryer at two different temperatures (50 and 70 °C) and 3.0 m/s air velocity. Page empirical model provided the best simulation of the drying curves. The diffusional model was used to describe the moisture transfer and the effective diffusivities of water were determined and were in the order of 10⁻⁹ m²/s. These diffusivities increased with increasing temperature and with the application of ultrasound, while the process time reduced, which can represent an economy of energy, since air drying is cost intensive.     

龙眼间歇真空微波干燥动力学研究

针对龙眼原料受热不均匀和微波干燥速率过快与局部过焦的问题,采用间歇微波与变功率微波相结合的方式进行龙眼真空微波干燥,从功率密度、真空度、装载量三方面分析龙眼果肉在真空微波干燥过程中水分比及干燥速率的变化,并建立薄层拟合模型;以颜色、总酚含量、复水性为考察指标,建立功率密度、真空度、装载量三因素三水平的正交试验,优化最佳龙眼间歇真空微波干燥工艺。试验结果表明:龙眼间歇真空微波干燥有效扩散系数随着微波功率密度增加、真空度升高以及装载量减少呈上升趋势;7种数学模型中Two-term model模型拟合效果最好;功率密度12 W/g,真空度90kPa,装载量100g为龙眼间歇真空微波干燥的最佳干燥工艺。     

油菜籽微波预处理的干燥动力学及模型研究

为了探明油菜籽微波预处理过程中的水分变化情况,建立油菜籽微波预处理干燥模型,对油菜籽在料层厚度12 mm、不同微波功率（1.0、1.5、2.0 kW）以及微波功率1.5 kW、不同料层厚度（6、12、18 mm）下预处理后的含水率、水分比和失水速率的变化情况进行了研究,并以常用的3种干燥模型指数模型、单项扩散模型和Page模型进行了数据拟合。结果表明:微波功率越高、料层越薄,油菜籽水分流失越快,微波预处理时间越短;微波预处理过程中油菜籽水分变化情况与Page模型拟合度最好。     

Assessment of the Electrohydrodynamic Drying Process

Industries using energy-intensive processes are being forced to explore ways for reducing their energy consumption. In the food industry, air drying is one of the more energy-consuming processes. To reduce the energy consumption during this operation, alternative processes should be investigated. One promising alternative consists in the electrohydrodynamic (EHD) enhancement of heat and mass transfer. This paper analyses the literature and describes the great potential of this innovative process based on the generation of an electric wind by a corona discharge. The main aspects of this technique are discussed and special emphasis is given on its benefit for food processes. The main part of this paper concerns experimental investigations carried out to assess the EHD enhancement on the drying process. An experimental set-up was designed to measure the weight losses on a food product submitted to an electrostatic field and to a cross air flow. Present results confirm that, for a low cross air velocity, the ionic wind leads to an enhancement of the drying rate. The best results are obtained for the smaller distance between the food surface and the corona electrode. Nevertheless, the process is less efficient for a high air velocity. The last part deals with a numerical model that was developed to evaluate the electric parameters and the flow field in turbulent regime. This model provides useful information on the coupled phenomena and permits to explain the experimental observations and to help in designing EHD drying processes.     

Controlled Low-Temperature Vacuum Dehydration–A New Approach for Low-Temperature and Low-Pressure Food Drying

The processes of freeze-drying, vacuum drying and controlled low-temperature vacuum dehydration (CLTV) were used to dry clam paste and a gelatin-microcrystalline cellulose model food system. CLTV was carried out as cold as possible without freezing the product. Much less drying time was required for CLTV and vacuum drying than for freeze-drying. The mass transfer resistance for both freeze-drying and CLTV was less than that of vacuum drying. Functional properties were closer to those of freeze-drying than to vacuum drying. CLTV versus freeze-drying showed a 30% reduction in enthalpy change and 40% reduction in running cost. Microbiological analysis, used to monitor the safety of processing clam paste, showed that the process was satisfactory relative to common parameters.     

Evaluation of high pressure pretreatment for enhancing the drying rates of carrot,apple, and green bean

Preservation of fresh produce by drying dates back to ancient times and is still an indispensible technique. Conventional drying of fruits and vegetables is often accompanied by changes in color, texture, and taste. Suitable pretreatments can improve the drying process by reducing the drying time, yielding higher-quality products, and energy savings. In this study, two varieties of apples, Amasya and red delicious, green beans and carrots were pretreated with high hydrostatic pressure (HHP) at different pressure–time–temperature combinations (100–300 MPa for 5–45 min at 20 and 35 °C) prior to drying. The drying experiments were carried out by using a hot-air tunnel dryer at different temperatures (27–85 °C) and air velocities of 0.4 and 0.8 m/s with constant external conditions. Improving the drying conditions by increasing the drying temperature generally masked the effect of HHP pretreatment on drying rate. Generally, pressures of more than 100 MPa caused cell permeabilization resulting in higher drying rates. Among 14 models, the modified Page model was found to best explain the drying behaviors and model constants were evaluated accordingly. The Tukey multiple comparison test was applied on characteristic drying times to evaluate the relative effects of different pretreatments and drying conditions.     

Physical pre-treatment of plums (Prunus domestica). Part 1. Modelling the kinetics of drying

An alternative physical method for enhancing the drying rate of plums is proposed. It consists of the superficial abrasion of the plums’ peel using an inert abrasive material to remove the cuticular waxy layer, the limiting factor for moisture loss. The physical pre-treatment was compared with a chemical treatment in which the plums were dipped into a solution of ethyl oleate. The drying kinetics of the above samples, including the untreated one, were reconstructed by using a mathematical model. The drying process, carried out at 60 °C to reduce the prunes’ quality loss, showed the great capability of both pre-treatments to enhance water diffusivity in the plum peel with respect to the untreated samples. Moreover, it was found that the physical treatment was more effective than the chemical one.