共查询到20条相似文献,搜索用时 171 毫秒
1.
A novel technique serves to monitor instantaneous rates of loss of a volatile solute from a suspended drop during drying. A highly sensitive electron capture detector is used to monitor concentrations of SF6 released into a flowing gas stream from a suspended, drying drop. Simultaneously, the appearance and morphological development of the drop are monitored with a video camera. This provides the wherewithal of relating instantaneous rates of loss of the volatile solute to particular events during the development of particle morphology.
Initial experiments have been carried out with drops of aqueous solutions of glucose, sucrose, maltodextrin and coffee extract. The results clearly display the onset of the volatiles-retentive selective diffusion phenomenon. There is also substantial loss of the volatile component later in the drying process, when the drops undergo repeated ex ansion, bursting and cratering due to the formation of internaf bubbles. These experiments appear to be the first quantitative demonstration of major losses accompanying changes in drop morphology. 相似文献
Initial experiments have been carried out with drops of aqueous solutions of glucose, sucrose, maltodextrin and coffee extract. The results clearly display the onset of the volatiles-retentive selective diffusion phenomenon. There is also substantial loss of the volatile component later in the drying process, when the drops undergo repeated ex ansion, bursting and cratering due to the formation of internaf bubbles. These experiments appear to be the first quantitative demonstration of major losses accompanying changes in drop morphology. 相似文献
2.
P. P. Budnikoff 《Journal of the American Ceramic Society》1924,7(11):817-820
The different analytical methods proposed for the evaluation of gypsum have been subjected to an experimental test. A combination method, consisting of a fusion with KHCO3 and determination of CaO by KMnO4 titration, the SO3 by Andrews method of titration of BaCrO4 has been found to give very reliable results with the least consumption of time. 相似文献
3.
ANALYSIS OF RECENT MEASUREMENTS OF THE VISCOSITY OF GLASSES 总被引:5,自引:0,他引:5
Viscosity of Simple Soda-Silicate 500° to 1400°C Comparison of the results given by English with those of Washburn, Shelton and Libman, indicates a discrepancy in the absolute values of log10 viscosity amounting to 0.6, those of Washburn et al., being relatively too high. If correction for this is made, the isothermal curves of log10 viscosity as a function of soda content are smooth up to 50% Na2O, showing no inflection. The observations as a function of temperature T are all represented within accidental error by an equation of the type where all three constants vary regularly with the composition. Change of Viscosity of Glass (6SiO2, 2Na2O) due to Molecular Substitution of CaO, MgO and Al2O3 for Na2O The effect is clearly brought out by plotting (from the results of English) the change of log10η due to the substitution as a function of temperature. The curves each show a sharp bend at a temperature between 840° and 1050°C, which is designated the aggregation temperature Ta. If we divide these curves by the corresponding percentage substituted, we get curves for each oxide which are straight and parallel below the aggregation temperatures, the slopes (increase of change of log10η per 100°C) being −0.056 (CaO), −0.055 (MgO), −0.018 (A12O3) per per cent oxide substituted. For substitution of 1/2 molecule the slopes are −0.325 (CaO), −0.23 (MgO) and −0.18 (Al2O3) per 100°. At the aggregation temperature the change of log10η per per cent is a minimum, 0.03 to 0.06 for CaO, 0.12 for MgO, 0.07 for Al2O3. Evidence of Aggregation in Glasses, from viscosity Measurements The sharp bends in the plots of change of log10η due to substitution of an oxide for Na2O, suggest the beginning of molecular aggregation at these temperatures. These aggregation temperatures are close to the devitrification temperatures, but the effect on the viscosity curves cannot be due to actual devitrification since it does not change with time. Taking the aggregation temperatures as equal to devitrification temperatures, additional isotherms are roughly sketched into the equilibrium triangle of the system Na2O-CaO-SiO2. Change of Viscosity of Glass (4SiO2, 2Na2O) due to of Substitution of B2O3 for SiO2 The change of log10η (from the results of English) is plotted as a function of temperature, and also the change of log10η per per cent B2O3. The curves are more complex than for the substitution for Na2O. 相似文献
4.
直链烷烃氯磺酰化反应的光催化动力学研究 总被引:3,自引:1,他引:3
本系统采用氯气和二氧化硫作为气相原料,C18-17直链烷烃为液相原料,在光作用下进行气相氯磺酰化反应。由于该反应过程机理复杂,本研究采秀工程研究方法,对过程进行合理简化,导得该反应的动力学速率模型,并采用非线性多响应常微分模型的参数估计方法求得模型参数。模型计算值与实验结果能较好吻合,该模型可用于反应器的设计计算。 相似文献
5.
硫酸钠盐结晶对混凝土破坏的影响 总被引:8,自引:2,他引:8
研究了Na2SO4盐结晶对干湿循环作用下混凝土剥蚀破坏、膨胀率和强度的影响,以及降温作用下Na2SO4溶液体积膨胀率和结晶压的变化.结果表明:Na2SO4盐结晶产生的混凝土膨胀和剥蚀破坏随着盐浓度和干湿循环次数的增加明显增大,且超过一定循环次数后,经干燥后的混凝土非但不收缩,反而继续膨胀.在降温作用下,Na2SO4溶液盐结晶体积膨胀率和结晶压随着盐浓度增加显著增大,且开始出现膨胀和结晶压的温度也提高,其产生的盐结晶压可超过7MPa,足以引起混凝土破坏. 相似文献
6.
Experiments were carried out to find the effects of dissolved gas pressure,liquid flow rateand nozzle geometry on the bubble generation when saturated water was depressurized through anozzle.A new method,high speed camera system was developed to measure the generated microbubblesdynamically.On the basis of the laws of ideal gas and solution,theoretical generated gas flow ratewas deduced,while the Smoluchowski′s equation was applied to describe the kinetics of bubblenucleation.It was found that the size distribution of nucleated bubbles was of skewed distribution.An explanation to this phenomenon was made and the Gamma function distribution was employedfor mathematical simulation.The results show good agreement between the experimental data and thepredictions by proposed model. 相似文献
7.
8.
An expression to predict the values of the latent heat of vaporization of pure compounds at their normal boiling point has been developed. A knowledge of the critical temperature, critical pressure, normal boiling point and acentric factor of the compound coupled with the use of generalized correlations for second virial coefficient and liquid molar volume allows to obtain good estimates, particularly for alcohols and ketones. Results for 71 various substances are compared with experimental values and with the results of eight other equations available in the literature. The possibility of using the calculated heats of vaporization at the normal boiling point to estimate values at other temperatures is discussed. 相似文献
9.
气化工艺特性对IGCC效率的影响 总被引:1,自引:1,他引:1
影响煤气化联合循环总效率的五个主要因素为煤转化率、燃气轮机循环,蒸汽循环,热旁路比率和发电效率。其中以煤转化率影响最大,它将包括产品气的显热和剩余蒸汽。在任何气化装置中气化炉是最主要单元并极大地影响气化性能。为改善气化效率,所有第二代气化方法均已引入加压操作。本文讨论了高温操作、生严能力放大、负荷跟踪能力、加煤方式、气化剂和煤气净化,同时提出仍待开发的某些值得注意的问题。 相似文献
10.
The lattice fluid (LF) equation of state derived by Sanchez and Lacombe from a lattice model is compared to the empirical Peng-Robinson (PR) equation for normal alkane fluids ranging from methane to heptadecane in molecular weight. With respect to vapor pressure predictions, the equations are both good. The LF equation is superior, especially for higher molecular weight fluids, to the Peng-Robinson equation in predicting saturated liquid densities. For carbon numbers less than 6, the PR equation predicts heats of vaporization more accurately, whereas for carbon numbers greater than 9 the LF equation is more accurate than the PR one for temperatures lower than about 95% of critical. 相似文献
11.
An expression to predict the values of the latent heat of vaporization of pure compounds at their normal boiling point has been developed. A knowledge of the critical temperature, critical pressure, normal boiling point and acentric factor of the compound coupled with the use of generalized correlations for second virial coefficient and liquid molar volume allows to obtain good estimates, particularly for alcohols and ketones. Results for 71 various substances are compared with experimental values and with the results of eight other equations available in the literature. The possibility of using the calculated heats of vaporization at the normal boiling point to estimate values at other temperatures is discussed. 相似文献
12.
13.
提出了有双官能团酸相对分子质量调节剂存在时己内酰胺水解聚合过程动力学模型 ,并进行了实验验证 .对不同温度下聚合产物组成和各影响因素对数均聚合度的影响进行了模拟 .结果表明 ,数均聚合度随进料中水、氨基己酸及相对分子质量调节剂浓度的增加而减小 ,其中水的浓度影响较显著 ,且在考察浓度范围内相对分子质量调节剂浓度 [R]0 ≤ 0 0 0 68mol·kg- 1 时数均聚合度基本不变 ,而 [R]0 >0 0 0 68mol·kg- 1 时数均聚合度则显著减小 .无氨基己酸及相对分子质量调节剂时数均聚合度亦随水浓度增加而减小 . 相似文献
14.
Onion of two varieties, i.e. Oporto and Blonska was dried by convection at 60°C and 2 m/s. Prior to drying sliced onion was subjected to following treatments: soaking in water, dipping in starch solution, dipping in starch solution supplemented either with ascorbic acid or CaCl2, and dewatering by osmosis in sucrose solution. Drying of raw onion was taken as a reference.
It has been found that both variety and pretreatment affect the course and rate of drying. Soaking in water and dipping in starch solution either increase rate of drying or have no effect on the kinetics of the process. Supplementing the starch solution with ascorbic acid or CaCl2 adversely affects the rate of drying. Unfavorable effect on the rate of drying has also osmotic dewatering preceding convective drying. 相似文献
It has been found that both variety and pretreatment affect the course and rate of drying. Soaking in water and dipping in starch solution either increase rate of drying or have no effect on the kinetics of the process. Supplementing the starch solution with ascorbic acid or CaCl2 adversely affects the rate of drying. Unfavorable effect on the rate of drying has also osmotic dewatering preceding convective drying. 相似文献
15.
微生物侵蚀会导致混凝土的严重破坏,尤其导致了城市污水收集和处理系统的过早破坏,使其需要提前修复。世界范围内的研究结果表明:处于污水和下水道污泥中的混凝土会遭受由硫酸盐、酸、CO2等导致的严重破坏。评述了混凝土处于利于细菌生长和生物降解环境中时的细菌、微生物侵蚀破坏过程。此外还分析了硫酸产生的机理(硫循环)、用于污水管道系统和农用工业的混凝土的受侵蚀破坏机理以及评价混凝土抵抗微生物侵蚀的方法。 相似文献
16.
17.
C. R. Amberg 《Journal of the American Ceramic Society》1944,27(11):324-326
Diopside was substituted for both talc and feldspar in a typical wall-tile body. It was found to lower the fusion temperature and to lower thermal expansion when compared with talc and to raise thermal expansion when compared with feldspar. Its effects on firing shrinkage, fired absorption, and moisture expansion were somewhat similar to those of talc. 相似文献
18.
聚合物的阻燃性能评价 总被引:3,自引:1,他引:2
田小锋 《现代塑料加工应用》2002,14(2):50-53
介绍了评价聚合物阻燃性能的基本方法,重点介绍了氧指数法、水平和垂直燃烧法、烟密度法,并指出了评价过程中应注意的有关问题。 相似文献
19.
20.
归纳了当今卫生陶瓷工业的发展现状和水平 ,对窑炉产业提出了的新要求 ,分析了某一新型窑炉的特点 ,对发展我国陶瓷窑炉产业提出了建议 相似文献