涤纶织物热定型降耗优化算法

为有效降低热定型过程的能量消耗,针对热定型过程缺乏有效的理论模型、定型机烘房温度设置不合理等问题,提出一种热定型过程参数优化的方法。利用Fluent软件模拟了烘房的温度、空气压力的分布情况,验证了织物加工位置温度、压力的均匀性。分析了织物加工过程的热力学特性,采用机制建模的方法建立了织物的实时温度估算模型框架,利用实验数据辨识了关键参数,在此模型的基础上以能量最小为优化目标,运用粒子群算法对烘房温度的设定值进行寻优。涤纶织物的热定型实验结果表明,所提出的实时温度估算模型可较好地匹配织物的实时温度数据,且在满足工艺约束的条件下,优化后的温度设定值可有效地降低能耗。     

全自动恒温恒湿模拟太阳能自然风干咸腿实用技术

利用能够进行全自动恒温恒湿烘房设备,缩短了咸腿风干时间,降低了咸腿被二次污染的几率,保证了产品质量稳定性和均匀性。     

梭子烘房恒温控制的研制

我厂修梭间烘梭子烘房的温度,原来靠人工手动调节,稍有疏忽有时会烘坏梭子,严重时还会造成火警事故,用电也较多。为了解决这一问题,我厂研制了晶体管电路自动控制温度的烘梭子恒温烘房的电路图是:     

来稿摘登

对G142-180型浆纱机烘房和浆槽的改进 1.去掉烘房内全部喷嘴,保留下部鼓风机和散热器,在鼓风机出口处增加一排散热器,使散热器由原三排增至四排,总散热面积从390米~2增加到520米~2。 2.用隔板将烘房上部干区与下部湿区隔开。 3.在烘房上部增装5只φ570毫米不锈钢烘筒,烘筒采用高低形排列,烘筒中心高低差355毫米,二只烘筒间距25毫米。烘房穿纱路线重新设计,改后绕妙长度为23米。     

热风干燥烘房气流速度场均匀性优化

针对常规干燥烘房存在气流速度场不均匀,导致木材干燥不均、干燥效果差的问题,课题组在常规干燥烘房的基础上,设置风机引导送风罩,利用FLUENT对设置3种规格送风罩的烘房进行数值模拟,结果表明600 mm×300 mm矩形出风口的引导送风罩可以使气流速度场均匀性达到最佳;将其与常规干燥烘房进行对比,结果表明设置600 mm×300mm引导送风罩的干燥烘房能使气流速度更加均匀,气流均方差降低了2. 5%,变异系数降低了4. 0%。本研究可提高木材干燥的均匀性。     

挂面缓酥的原因及预防

挂面缓酥的主要原因,一是烘房二区温度未控制好,挂面降水未能达到预期值;二是烘房三区降温过快,或挂面出烘房时遇冷风袭击所致.前者主要靠烘房工正确、可靠的操作来保证;后者主要出现在冬天,可适当提高三区温、湿度并提高包装车间和仓库的温度,实行保温储藏1～2 d后再出仓销售.     

薄板烘丝工艺参数对卷烟焦油释放量的影响

通过设计不同的单因素试验,分别考察了筒壁温度、热风温度、热风风门开度、排潮风门开度和滚筒转速5个薄板烘丝工艺参数对卷烟焦油释放量的影响.通过均匀试验设计,建立了叶组样品烘丝工艺参数与对应焦油释放量之间的二次回归模型,根据模型得到叶组样品的理论最优烘丝工艺参数:筒壁温度135℃,热风温度130℃,热风风门开度100%,排潮风门开度50%,滚筒转速8 r/min.     

定形机喷风均匀性的探讨

拉幅定形机是印染后整理中必不可少的关键设备。织物定形质量的好坏受多种因素的影响，但重要的是取决于烘房温度的横向均匀性，而烘房温度的横向均匀又主要取决于喷风管喷风速度的均匀性。因此，设计结构合理的喷风管，是评价定形机内在质量的关键。一、喷风口形式及喷风均匀性机理热风机械中采用的喷风管喷口形式一般分为孔形及条缝形喷口，孔形喷口有圆孔形及方孔形喷口，条缝形喷口分为横向及纵向条缝形喷口。一般来说，孔形喷口喷风均匀性易保证，而纵向条缝形喷口喷风均匀性较难保证。事实上，气流由风机送到风管再从喷风口喷出的过程…     

烘房隔热门外表温度浅析

烘房是印染烘燥设备的必要组成部分,烘房的密封性能和隔热性能直接影响烘房的烘燥效率。隔热门是烘房的重要组成部分,由里板、面板和保温层组成,对生产过程中的热交换有较大的影响。介绍了隔热门外表温度的形成和设定,分析了烘房内工作温度、保温材料、隔热门结构和烘房周围环境对隔热门外表温度的影响。     

隧道式两排挂面烘房气流特征分析

为改进挂面干燥工艺,采用便携式微型气象仪研究了双排挂架隧道式挂面烘房风速和方向分布情况以及烘房挂面干燥过程的气流特征。结果表明,隧道式双排挂面烘房内风速呈波形分布,均值为0.82 m/s,绝大多数风速集中在0.00~2.00 m/s之间,侧风和逆风则集中在0.00~1.00 m/s区间内,烘房不同位置的风速具有不均匀性。风向受到风扇位置、排潮口位置以及烘房结构的影响,烘房左上、左中、左下部位主导风向集中在SW-NNW扇区,右上、右中、右下部位主导风向集中在NE-SSE扇区。     

不同形状尺寸冷冻牛肉的射频解冻均匀性探究

分别选取不同形状、厚度、底面积和放置方式的8种冷冻牛肉样品,采用频率为40.68 MHz的小型射频解冻炉进行解冻试验;基于试验数据,建立并求解计算机模型,预测样品的解冻升温速率和温度分布,并计算其解冻均匀性系数。结果表明,模拟计算得到的温度值与试验值契合度较高;所有牛肉样品的解冻速率整体上呈线性上升的趋势(相变温度区上升较缓慢)。厚度大的样品解冻速度快,但解冻均匀性较差;相同厚度的样品,底面积越大,解冻速度越慢,解冻均匀性较好;当样品垂直放置时,长方体样品出现严重过热现象,最高温度达到了55.2℃,解冻均匀性较差,而圆柱体样品的最高温度为36.6℃,解冻均匀性相对较好。     

Temperature programmed reduction for measurement of oxygen content in nanoscale zero-valent iron

Nanoscale zerovalent iron (nZVI) has increasingly been used for environmental remediation and in toxic waste treatment. Most applications exploit its large surface area and high reactivity, the latter being a function of zerovalent iron content. In this work, temperature programmed reduction was applied to measure oxygen in nZVI. Iron oxides in nZVI were reduced by hydrogen to form metallic iron and water, which was then measured with an online mass spectrometer to determine oxygen content of the sample. For fresh nZVI prepared by sodium borohydride reduction of iron salts, average oxygen content was 8.21%. Total iron content was approximately 90.35% by the method of acid digestion; Fe(III) content was estimated at 14.37%, and that of zerovalent iron [Fe(0)] at 75.98%. The oxygen content quickly increased to 26.14% after purging with oxygen for four hours. Several other techniques were also used to characterize the iron nanoparticles. High resolution TEM provided direct evidence of the oxide shell structure and indicated that the shell thickness was predominantly in the range of 2-4 nm. The surface elemental composition was determined from high-resolution X-ray photoelectron spectroscopy. The nZVI oxygen content results fill a knowledge gap on nZVI composition.     

汾酒关键酿造工艺节点控制及品温变化规律研究

通过长期生产实践跟踪,研究了汾酒某优秀班组在酿造过程中对入缸温度、入缸水份等关键工艺节点的控制及在制品品温变化规律,发现汾酒不同生产时期入缸温度和入缸水份参数需在工艺范围内进行适宜的变化和组合,各时期节点参数见结论部份。在制品品温变化方面,不同时期材料顶火用时及日升温幅度也有区别,在平季期和热季期,大米查顶火用时一般需5d~7d,日升温幅度介于2℃~3.6℃;二米查顶火用时为2d~4d,日升温幅度介于3℃~4℃。冷季期大米查顶火用时需8d~9d,日升温幅度介于1℃~1.5℃,二米查顶火用时需4d~5d,日升温幅度介于2℃~2.8℃范围内。     

Effect of different iron compounds on wheat and gluten‐free breads

BACKGROUND: Iron fortification of bread often results in sub‐optimal quality of the final product due to undesirable changes in the physical characteristics and sensory properties of the bread. In this study both the form of iron (soluble, insoluble or encapsulated) and the type of bread (wheat or gluten‐free) were varied in order to investigate the effect of iron and gluten on the product characteristics. RESULTS: The effect of iron on the quality characteristics of the breads investigated depended on iron type, but not on iron solubility. Colour, crust firmness, specific volume, cell number and uniformity as well as aroma were the attributes that were mainly affected in iron‐enriched wheat bread. In some cases, specific volume was 30% lower than that of the control sample, while cell uniformity was significantly lower, as low as 50% of the control sample in some fortified samples. In gluten‐free breads, differences between unfortified and fortified samples included colour, crust firmness, cell number, ‘moisture’ odour, metallic taste and stickiness. In some cases, the sensory scores were better for fortified samples. CONCLUSIONS: Differences due to iron fortification were less pronounced in gluten‐free compared to wheat breads. The choice of the appropriate iron compound which will not cause adverse quality changes is still a challenge. Copyright © 2010 Society of Chemical Industry     

Iron Bioavailability from Common Raisin-containing Foods Assessed with an In Vitro Digestion/Caco-2 Cell Culture Model: Effects of Raisins

The effects of raisins on iron bioavailability from wheat bran cereal, bread, rice pudding, and granola bars were studied. Iron bioavailability was assessed with an in vitro digestion/Caco‐2 cell culture model. Raisins reduced iron bioavailability from all foods except granola bars. Raisins also reduced iron bioavailability from samples of wheat bran cereal and bread fortified with elemental iron or ferrous sulfate, but this inhibitory effect was less pronounced in samples fortified with sodium iron ethylenediaminetetraacetate (NaFeEDTA). Iron bioavailability was markedly higher for samples fortified with NaFeEDTA, suggesting that iron in the form of NaFeEDTA is more bioavailable than elemental iron or ferrous sulfate in raisin‐containing foods.     

叶菜类蔬菜真空预冷模型的研究

为研究叶菜类蔬菜在真空预冷过程中温度场、水及水蒸气浓度场变化规律,利用Comsol软件建立真空预冷模型,模型包括多孔介质的扩散与传热耦合过程,由五部分联立求解。通过对结构简单的肉制类火腿的模拟,验证了真空预冷模型可靠性,进一步验证模型对叶菜类蔬菜的适用性。模拟与实验对比结果表明:肉制类表面最大温差3.1 ℃,中心最大温差4.3 ℃,整体趋势相同,模型具有可靠性;叶菜类中菠菜最大温差在3 ℃以内,菠菜、小白菜、菜心、芥兰温度变化趋势与模拟一致,模型适用于叶菜类蔬菜。预测表明:叶脉影响叶菜类蔬菜的参数分布,沿叶脉处温度、水及水蒸气浓度均较低,模拟对真空预冷中各参数设定有指导作用。     

热胁迫和培养温度对大肠杆菌抗热性的影响

研究大肠杆菌O157:H7 ATCC 43889经50、60 ℃和70 ℃反复多次热胁迫处理与在10、28、36 ℃和45 ℃的条件下生长培养后对其80 ℃抗热性的影响。分别对ATCC 43889进行50、60 ℃和70 ℃的热胁迫,研究在一定的热力致死温度条件下杀死某细菌数量90%所需要的时间（D值）的变化,观察ATCC 43889热胁迫前后菌落形态和个体形态的变化;将ATCC 43889置于10、28、36 ℃和45 ℃培养至稳定期,分别测定其在80 ℃的存活量,再利用Weibull模型拟合其在80 ℃的热致死曲线。结果表明,50、60 ℃和70 ℃热胁迫处理均可诱导ATCC 43889抗热性增加,经10 次热胁迫并传代培养后,其D值分别为第1次热胁迫处理后的1.88、2.38 倍和8.18 倍,D值随热处理次数的增加不断增大,说明胁迫温度越高,D值越大,其抗热性越强;经过60 ℃和70 ℃热胁迫后,ATCC 43889菌落形态和个体形态与对照组相比差异显著;在80 ℃,ATCC 43889的致死曲线表明,胁迫温度越高,其抗热性越强（P＜0.05）;在10～45 ℃培养,随培养温度的升高,ATCC 43889的抗热性显著增加（P＜0.05）。利用Weibull模型可以较好地拟合ATCC 43889经过50、60 ℃和70 ℃热胁迫处理10 次后与10、28、36 ℃和45 ℃培养后在80 ℃的抗热性曲线,随着胁迫温度和培养温度的升高,ATCC 43889的抗热性都呈增加趋势。综上,一定热处理与培养温度可胁迫诱导大肠杆菌ATCC 43889抗性热增强和形态的变化。     

热溶胶结合高温干燥降低琼脂溶胶温度的研究

琼脂在食品工业中具有重要的应用价值,将琼脂溶化温度降低至90℃以下有利于琼脂在乳制品中的应用.文章探究了加热溶胶后高温干燥对琼脂性质的影响,并探索琼脂与常用水溶性胶体复配后经加热溶胶、高温干燥制备低温溶解琼脂复配胶体的技术.研究发现琼脂在热处理时间1.5 h、热处理温度120℃条件下进行热处理并经高温烘干后其溶化温度最...     

Numerical Prediction of Temperature Distribution and Measurement of Temperature in a High Hydrostatic Pressure Food Processor

Numerical simulation of temperature distribution in the pressurizing medium (water) during high hydrostatic pressure processing was carried out at different initial temperatures. Numerically predicted variations of temperature with time within the pressurizing medium were compared with the experimental results. The experimental data were corrected for the lag between the true temperature and the temperature measured by the thermocouples. A good agreement between numerically predicted and corrected experimental data was obtained when pressurization was started at initial temperature of 298.15 K, whereas some disagreement was observed at higher initial temperatures. The disagreement was attributed to the water addition to the vessel during pressurization which was not included in numerical simulation. A simple enthalpy balance was used to correct the numerically predicted temperatures, which led to better agreement. The numerical simulation enabled us to evaluate the process in terms of temperature uniformity inside the vessel. The results showed that the conjugate conduction and the natural convection heat transfer at the vessel wall affected the temperature distribution. The temperature non-uniformity increased with increasing initial temperature. The understanding of temperature uniformity during the high pressure process is important for uniform inactivation of microorganisms, enzymes, and particularly spores for which high pressure–high temperature combination is needed. Based on the 2007 CIGR Section VI International Symposium on FOOD AND AGRICULTURAL PRODUCTS: PROCESSING AND INNOVATIONS, Naples, Italy, 24–26 September 2007.     

亚临界水温度对梭子蟹下脚料萃取物性质的影响

目的:为探究亚临界水对梭子蟹下脚料的萃取效果,考察了亚临界水温度对萃取物性质的影响。方法:利用140、170、200、230℃等不同温度的亚临界水提取梭子蟹下脚料萃取物(SCWE),采用凯氏定氮法、苯酚硫酸法和高效液相色谱法等对SCWE的性质进行分析。结果:当亚临界水温度从140℃上升至230℃,SCWE中的总糖和灰分含量分别从1.86%和9.23%下降至0.27%和6.35%,分子量分布为180~1000 u的组分占比从11.09%增加至74.88%,而蛋白含量却出现先上升后下降的趋势。氨基酸分析结果表明,140℃和170℃亚临界水下获得的SCWE氨基酸组成与蟹肉相比没有明显的差别,但进一步提高亚临界水温度,SCWE中的天门冬氨酸、丝氨酸、苏氨酸和精氨酸等氨基酸含量却出现下降趋势。而且,随着亚临界水温度的提高,必需氨基酸和非必需氨基酸的含量均出现先上升后下降的趋势,且在200℃时达到最高值。不管亚临界水的温度是多少,SCWE中的赖氨酸含量都比WHO/FAO模式高。根据蛋白溶解性的结果,发现140℃下提取的SCWE中蛋白存在等电点,而170℃提取的SCWE蛋白溶解度在任一pH下都比其他SCWE高。结论:利用170℃亚临界水萃取梭子蟹加工下脚料获得的SCWE氨基酸不会受到破坏,且蛋白溶解性最高。