稻谷薄层干燥及其颗粒内部传质过程的试验研究

将稻谷颗粒视为圆柱体,利用Ｆｉｃｋ第二定律,建立了稻谷干燥过程中水分扩散模型,分析了稻谷干燥特性和介质温度与含水率对扩散系数的影响,并进行了薄层干燥试验。结果表明４：稻谷干燥过程中水分比呈指数曲线变化,风温越高,曲线越陡。稻谷在干燥的初始和最后阶段,水分比对水分扩散系数影响较大。     

玉米热风和真空干燥特性与干燥模型分析

通过对初始含水率分别为28.8%、24.8%和19.9%的玉米进行热风和真空干燥,研究了热风及真空干燥条件下玉米的干燥特性和模型.结果表明:玉米初始含水率越高,同温度下平均干燥速率越大,且真空干燥平均干燥速率大于热风干燥平均干燥速率;热风和真空干燥在干燥的前20 min干燥速率出现最大值;干燥过程中无明显的恒速干燥段,玉米干燥的数学模型符合Page方程.     

稻谷薄层干燥及其颗粒内部传质过程的试验研究

将稻谷颗粒视为圆柱体 ,利用Fick第二定律 ,建立了稻谷干燥过程中水分扩散模型 ,分析了稻谷干燥特性和介质温度与含水率对扩散系数的影响 ,并进行了薄层干燥试验 .结果表明 :稻谷干燥过程中水分比呈指数曲线变化 ,风温越高 ,曲线越陡 .稻谷在干燥的初始和最后阶段 ,水分比对水分扩散系数影响较大 .     

胭脂萝卜热风对流干燥过程的优化实验研究

本文对胭脂萝卜的热风干燥过程进行了优化实验研究,发现恒速干燥期的出现与否与干燥条件有关,考察了在相对湿度RH=8.2%下,风温风速对干燥后胭脂红获得的影响,得出了在本实验范围内干燥过程的最佳干燥条件,风温40～50℃。风速2.27m/s.这一结论可直接或间接用于工业生产。     

真空冷冻与热风联合干燥草莓

应用真空冷冻干燥与热风干燥(FAD)联合的方式做不同转换点试验，将得到的产品分别与完全的热风干燥(AD)和真空冷冻干燥(FD)的产品比较总的能量消耗和物化特性，确定了FAD联合干燥的方式和较佳转换点．FAD联合干燥的产品极大地改善了完全热风干燥草莓的品质，其质量较接近完全真空冷冻干燥的产品．     

胡萝卜热风干燥特性及其品质的研究

为保持胡萝卜的干燥品质,采用热风干燥对胡萝卜丁的干燥特性进行了研究,并对不同干燥条件下胡萝卜色泽和胡萝卜素含量进行了比较.结果表明,温度越高,干燥时间越短,胡萝卜色泽越差,胡萝卜素含量越低,温度越低则趋势相反.对干燥曲线进行对数变换以及线性拟合,确定胡萝卜热风干燥模型为Page方程.试验值和计算值拟合较好,此模型能够预测胡萝卜热风干燥过程.试验表明,50℃热风干燥条件下,干燥时间较短,胡萝卜色泽较好,并能较好地保持胡萝卜素,可选用50℃对胡萝卜进行干燥.     

真空冷冻与热风联合干燥毛竹笋

对毛竹笋进行真空冷冻与热风联合干燥研究，将得到的产品，分别与热风干燥和真空冷冻干燥的产品比较总的能量消耗和物化特性，确定了真空冷冻与热风联合干燥为较佳的联合干燥方式，较佳转换点为：真空冷冻干燥10．5h后，转为热风干燥4h，转换水分质量分数20％，真空冷冻与热风联合干燥的产品在感官、营养、复水比和细胞结构方面明显优于热风干燥的脱水笋片，较接近真空冷冻干燥的产品；同时，真空冷冻与热风联合干燥比真空冷冻干燥节省能耗约21％。     

热风和微波干燥生产草莓粉工艺比较研究

以新鲜草莓为原料,采用热风干燥和微波干燥对不同厚度的草莓片进行干燥生产草莓粉．结果表明;选用厚度为5mm的草莓薄片在60℃条件下热风干燥,制得的草莓粉色泽为暗红色;选用厚度为3mm的草莓薄片在“中火”条件下微波干燥,制得的草莓粉色泽为红色,且微波干燥对草莓中维生素C的影响较小．     

草鱼鱼片热风干燥特性的研究

以草鱼为研究对象对其热风干燥特性进行了研究.以不同厚度的新鲜草鱼鱼片和解冻草鱼鱼片分别在40℃、50℃和60℃热风温度下进行干燥.试验结果表明,温度和厚度对鱼片的干燥速率影响非常显著.热风干燥温度与干燥速度呈显著正相关性,鱼片厚度与干燥速度呈显著负相关性.冷冻处理对鱼片热风干燥速度的影响不显著.解冻鱼片在加热前期比新鲜鱼片干燥速率稍快,但其达到平衡水分所需的时间要比新鲜鱼片长.通过试验结果建立了草鱼鱼片热风干燥的数学模型.     

甘薯全粉的营养成分及其挤压食品特性分析研究

主要分析了由两种不同甘薯制得的甘薯全粉的营养成分,研究结果表明,黄石产白薯全粉的淀粉含量明显高于红安产红心薯全粉,但两者在氨基酸组成方面无明显差异,且必须氨基酸的含量都很丰富,红安产红心薯全粉还含有丰富的胡萝卜素。对所制得的两种甘薯全粉经挤压蒸煮后,淀粉发生降解,蛋白质变性,不溶性膳食纤维变构,导致了淀粉和蛋白质含量的下降,以及可溶性膳食纤维含量的上升,提高了甘薯全粉的消化率。     

Non-classical diffusion model for heat and mass transfer in laser drying

A numerical analysis of the laser drying process by employing a generalized, Maxwell-Cattaneo equation to treat both heat and mass transfer was presented. Calculations were performed to illustrate the non-classical transport of heat and moisture. The effect of the heat flux density and the initial moisture content on water removal was also investigated. The results indicate that the nonequilibrium mass diffusion plays an important role during the very early stages of moisture removal, especially at the surface of the medium. Away from the surface, the non-Fickian model shows a delay in the reduction of the moisture content. The calculation resuits also show that the initial moisture content of the medium has a considerable effect on water removal.     

Rheological properties of sweet potato starch before and after denaturalization

Based on the sweet potato starch,cationic starch,acetic starch and cationic-acetic compoundedly modified starch were made through chemical denaturalization.The above three kinds of static rheological parameter and dynamic rheological parameter were measured,respectively.The experimental result reveals that the thermal stability of starchy viscosity increases after chemical denaturalization.Under the condition of identical shearing rate,the shear stress of cationic-acetic ester compoundedly modified sweet po...     

Study of Kinetic Characteristics for Drying Rice Husk

Rice husk (biomass fuel) samples have been dried in drying oven and a series of drying curve for illustrating moisture migration of rice husk have been obtained. It is first research for rice husk drying, and it can provide reference of fuel processing for different boilers which require rice husk with various water contents. In this paper, we apply Page equation to reflect the drying process and obtain drying characteristic curve, then analyze the drying law. Kinetic analysis of the results of moisture migration test has been done, after which, effective moisture diffusion coefficient, activation energy and drying kinetic equation of rice husk samples are obtained in test temperature range (80-130 ℃). And these results show specific influence law of temperature for effective moisture diffusion coefficient.     

原子吸收法测定甘薯中的微量铜镁

研究了用原子吸收分子光光度法测定甘薯中的微量铜镁的方法,采用高温灰化法对样品进行处理,并对不同品种和不同种植地区的甘薯40多种进行了实样测定和含量差异进行比较。测定回收率Cu91．3％－102．7％;Mg92．2％－105．7％之间,相对标准偏差RSD分别为3．8％、6．6％。取得了满意的结果。     

连铸坯红送热装应用效果分析

对加热炉用连铸坯红送热装效果的分析结果表明，该技术的应用可节能降耗，提高产量和加热质量。     

Energy efficiency performance of multi-energy district heating and hot water supply system

A district heating and hot water supply system is presented which synthetically utilizes geothermal energy, solar thermal energy and natural gas thermal energy. The multi-energy utilization system has been set at the new campus of Tianjin Polytechnic University (TPU). A couple of deep geothermal wells which are 2 300 m in depth were dug. Deep geothermal energy cascade utilization is achieved by two stages of plate heat exchangers (PHE) and two stages of water source heat pumps (WSHP). Shallow geothermal energy is used in assistant heating by two ground coupled heat pumps (GCHPs) with 580 vertical ground wells which are 120 m in depth. Solar thermal energy collected by vacuum tube arrays (VTAs) and geothermal energy are complementarily utilized to make domestic hot water. Superfluous solar energy can be stored in shallow soil for the GCHP utilization. The system can use fossil fuel thermal energy by two natural gas boilers (NGB) to assist in heating and making hot water. The heating energy efficiency was measured in the winter of 2010-2011. The coefficients of performance (COP) under different heating conditions are discussed. The performance of hot water production is tested in a local typical winter day and the solar thermal energy utilization factor is presented. The rusults show that the average system COP is 5.75 or 4.96 under different working conditions, and the typical solar energy utilization factor is 0.324.     

甘薯荧光碳点的合成及其对Fe3+的灵敏检测

以甘薯为碳源,采用水热法制备了蓝色荧光水溶性碳点(CDs),并通过傅里叶变换红外光谱、紫外可见光谱和荧光光谱法对该碳点的性质进行了研究.研究结果显示,碳点溶液具有良好的稳定性,CDs表面存在羟基、羧基等亲水性官能团.碳点的最大激发波长和发射波长分别为390 nm和486 nm,且碳点具有典型的激发波长依赖性.考察pH对CDs荧光强度的影响显示,CDs荧光强度在pH为2.0～6.8范围内无明显变化.基于Fe³⁺能够选择性地猝灭CDs荧光的特性,建立了一种利用CDs检测实际水样品中Fe³⁺的方法.该方法的线性范围为10～1 670 μmol/L,相关系数(R²)为0.994 4,检出限为5.64 μmol/L; 在加标样品中, Fe³⁺的加标回收率为94%～104%, RSD <2.4%.     

空气流量及用水量对空气源热泵热水机组性能影响的试验研究

空气源热泵机组在较低的环境温度时,会出现结霜、制热量下降等问题.而余热空气源热泵系统以40℃低温余热作为低温热源,不仅避免了结霜、制热量下降等问题,而且回收了低温余热资源.通过构建空气源热泵系统的数学模型,揭示余热流量、温度及冷水温度对系统性能的影响规律,并搭建试验平台验证数学模型的结果.结果显示,在热风温度为45℃、风量为4 500 m³/h时,系统的各项性能指标参数达到最佳值;随冷水温度的升高,系统性能系数（coefficient of performance,COP）的变化不明显;在冷水温度为10℃时,压比的偏差最大值为12.5%.回收余热的空气源热泵系统的性能模拟结果为低温余热的回收利用提供了一定的理论指导.