采用蒙特卡罗方法模拟过饱和液相体系内的析出-长大行为，其中针对溶质扩散、溶质析出以及颗粒溶解等微观过程分别制定模拟规则，并在分析模拟数据时引入临界晶核，考虑液相析出浓度与临界形核尺寸之间的关联性。模拟结果表明，随着模...采用蒙特卡罗方法模拟过饱和液相体系内的析出-长大行为，其中针对溶质扩散、溶质析出以及颗粒溶解等微观过程分别制定模拟规则，并在分析模拟数据时引入临界晶核，考虑液相析出浓度与临界形核尺寸之间的关联性。模拟结果表明，随着模拟时间延长，液相浓度和过饱和度均呈现出急剧下降、缓慢下降、最后趋于平衡稳定的变化趋势。模拟温度越低，则平衡浓度越低，达到平衡浓度所需时间越长，并且在图形模拟结果中形成更多、更小的溶质格点聚集析出微区。在延长模拟时间的过程中，会发生Ostwald熟化长大，并且平均析出颗粒半径呈抛物线增加，提高模拟温度则会引起更快的析出长大行为，各种模拟温度下得到的颗粒长大指数在0.320~0.332之间，不随模拟温度变化发生较大波动。上述模拟结果与NiFe 2 O 4-KCl熔盐体系和SrMoO 4过饱和溶液体系在降低温度和延长保温时间过程中的实验现象以及在扩散过程控制下的Ostwald熟化长大理论较为吻合。展开更多
Based on the model of hard--sphere molecules and weak molecular attraction the reaction equation of molecular aggregation is derived by statistical mechanical method in thispaper. And from the reaction equation the j-...Based on the model of hard--sphere molecules and weak molecular attraction the reaction equation of molecular aggregation is derived by statistical mechanical method in thispaper. And from the reaction equation the j-function describing phenomena of molecularaggregation is developed and then applied to modify the van der Waals equation of state.The modified equation of state is tested through the PVT data the calculated results showthat this equation is well suited to calculate the volume data of saturated vapors and liquidsfor substances, including some strongly polar, and associated compounds, such as methanol,ethanol, acetic acid and water etc.展开更多
The gas and dispersed phase holdups and mass transfer coefficients of liquid-iquid were determined for gas-liquid-liquid three phase system in a screen plate column. The flow pattern of gas-liquid-liquid three phase s...The gas and dispersed phase holdups and mass transfer coefficients of liquid-iquid were determined for gas-liquid-liquid three phase system in a screen plate column. The flow pattern of gas-liquid-liquid three phase system was studied under different gas velocities. The shape factors showed the geometric properties of screen plates and the corrected drop characteristic velocities were introduced. The phase holdup in two phases was correlated. The research results indicated that mass transfer coefficient for liquid-liquid system in a column with screen plates and gas agitation was found to increase apparently.展开更多
This paper study stability of saturated salt solutions cells at 25 ℃. These cells were prepared and measured at National Institute for Standard （NIS-Egypt） to study the stability of the saturated salt solutions. Th...This paper study stability of saturated salt solutions cells at 25 ℃. These cells were prepared and measured at National Institute for Standard （NIS-Egypt） to study the stability of the saturated salt solutions. The study was carried out using three saturated salt solutions, which are Potassium Acetate 22.5%, Potassium Iodide 68.9% and Potassium Sulphate 97.3% to cover low, medium and high relative humidity. The study was carried out using different shapes and volumes half liter spherical, liter spherical and liter conical per each salt which was prepared. The apparatus which used in measurement system in the first time are the same which used after ten years. The results show that the change of relative humidity value after ten years ranged from 0.1% to 0.7%. This value is suitable within uncertainty ＋ 2%. The period of stability for each run for all cells was found to be more than five hours and this period enough for calibration. The measurements show that the cells are stable for more than ten years with accepted value.展开更多
文摘采用蒙特卡罗方法模拟过饱和液相体系内的析出-长大行为，其中针对溶质扩散、溶质析出以及颗粒溶解等微观过程分别制定模拟规则，并在分析模拟数据时引入临界晶核，考虑液相析出浓度与临界形核尺寸之间的关联性。模拟结果表明，随着模拟时间延长，液相浓度和过饱和度均呈现出急剧下降、缓慢下降、最后趋于平衡稳定的变化趋势。模拟温度越低，则平衡浓度越低，达到平衡浓度所需时间越长，并且在图形模拟结果中形成更多、更小的溶质格点聚集析出微区。在延长模拟时间的过程中，会发生Ostwald熟化长大，并且平均析出颗粒半径呈抛物线增加，提高模拟温度则会引起更快的析出长大行为，各种模拟温度下得到的颗粒长大指数在0.320~0.332之间，不随模拟温度变化发生较大波动。上述模拟结果与NiFe 2 O 4-KCl熔盐体系和SrMoO 4过饱和溶液体系在降低温度和延长保温时间过程中的实验现象以及在扩散过程控制下的Ostwald熟化长大理论较为吻合。
文摘Based on the model of hard--sphere molecules and weak molecular attraction the reaction equation of molecular aggregation is derived by statistical mechanical method in thispaper. And from the reaction equation the j-function describing phenomena of molecularaggregation is developed and then applied to modify the van der Waals equation of state.The modified equation of state is tested through the PVT data the calculated results showthat this equation is well suited to calculate the volume data of saturated vapors and liquidsfor substances, including some strongly polar, and associated compounds, such as methanol,ethanol, acetic acid and water etc.
文摘The gas and dispersed phase holdups and mass transfer coefficients of liquid-iquid were determined for gas-liquid-liquid three phase system in a screen plate column. The flow pattern of gas-liquid-liquid three phase system was studied under different gas velocities. The shape factors showed the geometric properties of screen plates and the corrected drop characteristic velocities were introduced. The phase holdup in two phases was correlated. The research results indicated that mass transfer coefficient for liquid-liquid system in a column with screen plates and gas agitation was found to increase apparently.
文摘This paper study stability of saturated salt solutions cells at 25 ℃. These cells were prepared and measured at National Institute for Standard （NIS-Egypt） to study the stability of the saturated salt solutions. The study was carried out using three saturated salt solutions, which are Potassium Acetate 22.5%, Potassium Iodide 68.9% and Potassium Sulphate 97.3% to cover low, medium and high relative humidity. The study was carried out using different shapes and volumes half liter spherical, liter spherical and liter conical per each salt which was prepared. The apparatus which used in measurement system in the first time are the same which used after ten years. The results show that the change of relative humidity value after ten years ranged from 0.1% to 0.7%. This value is suitable within uncertainty ＋ 2%. The period of stability for each run for all cells was found to be more than five hours and this period enough for calibration. The measurements show that the cells are stable for more than ten years with accepted value.
