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排序方式: 共有1410条查询结果,搜索用时 15 毫秒
971.
PENG YaPing TAN ManZhi GUO Liang LIU FaFa LI Hua GUO YingNan 《科学通报(英文版)》2007,52(19):2731-2736
In this paper the ethanol homogeneous charge compression ignition (HCCI) is achieved in a modified single cylinder engine by means of a self-developed fast thermal management system (FTMS), and the ethanol SI/HCCI operation regions are defined. It can be concluded that the thermal efficiency is higher and the NOx emission is lower in the HCCI operation region. In addition, the maximum NOx emission drops by 98%. The ethanol SI/HCCI combustion mode transition is conducted in different conditions near the SI/HCCI operation boundaries. It is likely to realize the transition by the utilization of FTMS. However, it is impossible to complete the transition within one operating cycle under current operation conditions. There are fluctuations in engine speed and brake mean effective pressure during the transition process. In order to reduce the fluctuations during the transition, the initial work concerning the effects of the spark ignition on the transition smoothness is carried out and the investigation indicates that the engine speed and brake mean effective pressure fluctuations cannot be eradicated only through spark ignition. Therefore, the control strategies combined with other factors should be further optimized. 相似文献
972.
The operational characterization of a fluidized-bed bioreactor for ethanol fermentation using Ca-alginate immobilized yeast
cells is described. An additional air stream is supplied to the fermenter to ensure and maintain satisfactory fluidization
behavior of beads and to avoid slug formation. The influence of physical properties such as bead density and liquid density
on the fluidization quality and stability are discussed. 相似文献
973.
乙醇-柴油在线混合燃料的燃烧排放特性 总被引:7,自引:0,他引:7
为了改善柴油机在不同工况时的排放,建立了超声波乙醇柴油在线混合装置,以实现适时混合不同比例的乙醇柴油燃料。在一台柴油机上试验研究了这种在线混合燃料的燃烧与排放特性,结果表明:随着混合燃料中乙醇体积分数的增加,碳烟排放明显降低,其最大降幅达74%,而且燃烧持续期缩短;但在中、高负荷工况NOx排放明显增多,因此尚需采取措施降低乙醇柴油混合燃料燃烧时的NOx排放。在一台可视化发动机上的研究结果表明:随着乙醇体积分数的增加,燃烧持续期也缩短,而且火焰亮度降低,碳烟形成得到了抑制。 相似文献
974.
975.
Excess volumes of binary mixtures of water with methanol, ethanol and 1-propanol were obtained from density measurements at 5 degree intervals from 15 to 35°C over the entire composition range. Excess thermal expansion coefficients, partial molar excess volumes, and expansibilities at 25°C were derived from the results. The significance of these values is discussed in relation to hypothesized structural changes in the mixtures. 相似文献
976.
977.
本工作利用体外灌输技术,观察了三种不同浓度的乙醇(1%,2.5%、5%)对妊娠早期人工流产新鲜胎盘绒毛分泌雌二醇的影响。结果表明,乙醇具有促进雌二醇分泌的作用,但在乙醇剂量和雌二醇水平之间不存在正相关性。提示妊娠妇女经常饮酒或酗酒可能通过破坏胎盘激素内分泌的平衡,从而影响胎儿的正常生长和发育。 相似文献
978.
The methylation of heavy-metal compounds (e.g. mercury, lead, tin) in the environment has great significance owing to the much higher toxicity of their methyl derivatives in comparison with inorganic metal species. In this paper abiological methylation of inorganic tin is described. Ethanol, acetic acid and propionic acid abiologically methylated inorganic tin, and the highest yield of methyltin was observed in the reaction between inorganic tin(II) and ethanol. Furthermore, environmental factors for the methylation, such as pH, temperature, added ethanol, concentration of sodium chloride and photoirradiation, were investigated in this reaction. Methyltin production increased at low pH, and decreased at higher concentrations of sodium chloride. Photoirradiation accelerated the reaction rate, and a shorter wavelength showed a higher rate. Inorganic tin(II) was converted rapidly into monomethyltin, and gradually transformed into dimethyltin and trimethyltin with the course time. 相似文献
979.
《天然气化学杂志》1995,(1)
The influence of VOCl2 additive in the supported Rh catalysts derived from both Rh2 (CO )4 Cl2 and RhCl3 on CO hydrogenation was investigated. The VOCl2 additive as a promoter can effectively enhance the CO conversion and catalytic selectivity to ethanol. This effect is caused by the interaction of Rh with vanadium promoter. It is found that the Rh centers on which the gem- adsorbed CO could be formed are main active sites. The Rh2(CO)4Cl2 complex is better than the RhCl3 salt as the precursor of the Rh catalyst for the CO hydrogenation to ethanol. 相似文献
980.
利用新型泵式沸点仪,在101.3kPa下测定了乙醇-甲基三乙氧基硅烷二元体系汽液相平衡数据,并对甲基三乙氧基硅烷的临界性质进行了估算,分别用Wilson,NRTL,Margules,Van Laar四种模型进行了关联。 相似文献