基于差示扫描量热法和热力学模型的生物柴油结晶行为分析

棕榈酸甲酯(C16:0)、硬脂酸甲酯(C18:0)和油酸甲酯(C18:1)是生物柴油的主要组成部分。为了深入探究生物柴油的结晶行为,该文基于差示扫描量热法(differential scanning calorimetry,DSC)分析了这3种脂肪酸酯的物性参数,研究发现饱和脂肪酸甲酯C16:0和C18:0的熔点和熔化焓远远高出不饱和脂肪酸甲酯C18:1的值,C16:0和C18:0的熔点分别为301.57、310.92 K,C18:1的熔点为255.01 K。对脂肪酸酯组成的二元溶液进行DSC扫描,DSC曲线出现了2个放热峰,并且溶液的结晶点要低于首先析出的饱和脂肪酸酯纯物质时的熔点;随着饱和脂肪酸酯质量分数的增加溶液的结晶点温度也相应提高。将生物柴油当作由多元脂肪酸甲酯的混合溶液时,C16:0和C18:0等饱和脂肪酸甲酯作为溶质,C18:1等不饱和脂肪酸甲酯作为溶剂,建立了热力学模型计算溶液的结晶点温度。将脂肪酸甲酯的混合溶液近似为理想溶液时对此模型进一步简化,并利用简化模型计算得到4种生物柴油的结晶温度,与实测值进行比较得到了很好的验证效果。该研究可为优化生物柴油低温流动性的技术措施提供参考。     

木材干燥过程含水率和温度变化的数学模型研究

木材干燥过程存在着热质互换和能量的转移,这为从热力学的角度研究木材干燥过程提供了前提条件,因此提出利用热力学原理分析木材干燥过程含水率和温度变化规律的数学模型.首先建立描述含水率和温度变化的高阶非线性偏微分方程组,然后采用有限元分析原理将方程组离散化,再经过一系列数学运算得到方程的收敛解,具体方法为牛顿迭代法,最后通过对木材含水率和温度变化情况仿真结果的分析,验证该方法的可行性及数学模型的准确性.     

大数据的特征解

大数据当数据的一个量趋向于无穷大时,这个数据称作为大数据。微分方程的数据都是大数据,微分方程的数据一定有一个量趋向于无穷大。微分方程中的本征函数和本征值是微分方程的特征解,当算符作用于一个函数其微分方程的特征解是微分方程的本征函数和本征值。     

植物单宁改性树脂吸附机理的研究

该文在静态条件下,研究了植物单宁改性树脂对碱性橙的吸附动力学和热力学特性.动力学研究表明,植物单宁改性树脂对碱性橙的吸附脱色过程符合Langmuir等温式;由动力学速率方程可知,该过程符合二级反应动力学,同时伴有吸附剂内的粒子扩散.热力学研究表明,吸附过程是放热吸附,温度升高不利于吸附,这与实验结果相符合;此外,吸附过程为自发的物理吸附.      

Study on the Dearsenization of Hot Metal Using CaO Basis Fluxes

There is plenty of iron ore with arsenic in China. Because a proven dearsenization technique does not come into existence in now iron making and steel making processes and it is necessary for developing the dearsenization of hot metal technologics. A serial of dearsenization experiments are carried out on electric resistance heated furnace, it's found that arsenic in hot metal can be removed by CaO basis fluxes. X ray qualitative analysis of CaO basis slag after dearsenization revealed that the product of hot metal dearsenization with CaO slag is Ca 3As 2 and the dearsenization reaction is a reducing one. The thermodynamic conditions of dearsenization of hot metal using CaO basis fluxes are that the lower of oxygen fraction pressure of the system and [s] in hot metal, the higher of temperature of the system and basically of the slag, the dearsenization efficiency is better.     

Thermodynamics analysis on the carbochlorination of flyash

Because of the high altitude of Qinghai, its air pressure is 0.77 atm which is lower than the atmospheric pressure. Therefore, an analysis is done for carbochlorination reaction of flyash for the extraction of aluminum in such an environment. The phase diagrams and predominance area diagram on chlorides are calculated and drawn and the equilibrium compositions of complex system composed of multi-components are simulated by Factsage software. Results show that, carbochlorination reaction converts Al2O3 and SiO2 which can not directly react with chlorine gas originally to chloride completely, and this demonstrates the thermodynamics feasibility of carbochlorination process. The ratio of FeCl3(Fe2Cl6) to FeCl2 changes with the amount of carbon and chlorine gas. The catalysts like Na2CO3, CaCO3 and B2O3 have some side effects in the aspect of thermodynamics such as consuming chlorine gas and carbon. The volatility of AlCl3(Al2Cl6) is affected by other chlorides. Compared with the normal pressure region, there are advantages and disadvantages to carbochlorination reaction under the pressure below the normal. The work provides thermodynamic data for the process.     

两性修饰剂修饰红壤对镉离子吸附的影响

采用不同比例的八烷基氨基酸表面修饰剂修饰红壤，研究了在单一Cd^2＋和苯酚混合条件下供试土样对Cd^2＋的吸附和热力学特征．目的在于探讨两性修饰剂修饰可变电荷土壤以增强对重金属离子吸附的效果。结果表明，除20℃混合条件下100％A A-8处理外．同一温度下不同修饰比例的供试土样对Cd^2＋的吸附量顺序均为CK〉50％A A-8〉100％A A-8，但差异并不显著。Cd^2＋的吸附具有化学吸附的升温正效应特征。苯酚的共存对Cd^2＋的吸附具有减弱作用。Langmuir模型是描述Cd^2＋吸附等温线的最佳模型。热力学研究结果表明供试土样对Cd^2＋的吸附为熵增控制的自发性反应，表面修饰剂羧基上的负电荷点位和土壤表面上的正电荷点位的结合可能是主要的修饰机理，八烷基碳链的疏水性则是Cd^2＋在供试土样表面上吸附阻力的主要形式。八烷基氨基酸不是一种较好的增强红壤吸附重金属能力的有机修饰剂。     

Thermodynamical analysis and simulation of smelting reduction process in magnesium production

In order to improve the response speed of materials in silicothermic reduction process for magnesium production, a new technology-smelting reduction process is presented. Adding an appropriate amount of Al2O3 and SiO2 can make slag completely melt in whole reduction process, thus the reaction rate can be sped up. Through software simulation, thermodynamic analysis and experimental verification, it’s found that completely molten CaO-MgO-Al2O3-SiO2 slag can be got at 1 600 ℃ with appropriate material component. The new reduction process is thermodynamically analyzed, and the results show that in equilibrium state, when the reduction temperature is 1 600 ℃, the dew-point temperature of the magnesium vapor is 870 ℃. It suggests that the new technology is feasible.     

湿法处理铜合金屑工艺过程的物理化学探讨

本文着重讨论了化学—机械法处理普通黄铜屑,制备纯铜粉末工艺的关键部分—酸浸过程的物理化学问题,解释了"镀铜"现象.热力学分析指出,本工艺适合于处理各种铜合金尾料,尤其适合于黄铜类铜合金尾料.     

利用热力学相平衡分析生物柴油晶体析出规律

生物柴油主要是由饱和脂肪酸甲酯和不饱和脂肪酸甲酯组成的混合溶液,从热力学角度分析,生物柴油的蜡晶析出是溶液由液相向固相转变的相平衡过程。该文建立将液相组成作为理想溶液且固相成分不互溶的理想溶液模型（模型一）和基于活度系数模型与正规溶液理论的正规溶液模型(模型二),分别计算了蜡晶的析出温度,并且通过模型二计算出在给定的温度下的析蜡量与石蜡的组成。两模型在计算析蜡点的温度精确性方面还是比较理想的误差在5 K左右。研究发现石蜡沉积量与饱和脂肪酸酯的量成一定的比例关系,而且石蜡沉积并不是按照脂肪酸酯熔点高低的顺序进行析出,析出的石蜡中同时包含了低熔点脂肪酸酯。固液平衡常数是表征物质在溶液中析出能力的决定性因素,在一定温度下,不饱和脂肪酸酯的固液平衡常数一般在0.1以下,而饱和脂肪酸酯的固液平衡常数却大得多。该研究阐明的晶体析出规律,可为优化生物柴油低温流动性技术措施,推动生物柴油在低温环境下的应用提供参考。