THE SURFACE CHARGE IN ELECTROSPRAYING: ITS NATURE AND ITS UNIVERSAL SCALING LAWS

The electrospraying of liquids in steady cone-jet mode follows a well-defined EHD mechanism described and quantified in this work using a hybrid experimental–numerical technique: a collection of emitted microjet shapes corresponding to several liquids and different flow rates have been digitized and introduced in a quasi-one-dimensional analytical model. A universal value of the surface charge on the liquid microjet and the resulting charged droplets, independent of their size and of the liquid permittivity, has been found. The surface charge is shown to be always in equilibrium, being the liquid bulk quasi-neutral. From these findings, we finally present a consistent general scaling of all EHD variables involved which is experimentally verified. In this scaling, the electric current I and the characteristic microjet radius R_o are both proportional to the square root of the emitted flow rate, Q^1/2, and independent of the liquid permittivity ε_i.     

The effects of compression and gas diffusion layers on the performance of a PEM fuel cell

Changes in the performance of a PEM fuel cell are presented as a function of the compression pressure resulting from torque on the bolts that clamp the fuel cell. Three types of gas diffusion layers were studied at 202 kPa and 353°K. An optimum bolt torque was observed when ELAT® or a combination of CARBEL® and TORAY™ gas diffusion media were used as diffusion layers. The optimum is related to the gasket thickness and the measured compression pressure on the diffusion layer. The performance changes may also be related to changes in the porosity, the electrical contact resistance, and the excluded water at the membrane.     

Potential application of solar thermal systems for hot water production in Hong Kong

This paper presents the evaluation results of conventional solar water heater (SWH) systems and solar assisted heat pump (SAHP) systems for hot water production in Hong Kong. An economic comparison and global warming impact analysis are conducted among the two kinds of solar thermal systems and traditional water heating systems (i.e. electric water heaters and towngas water heaters). The economic comparison results show that solar thermal systems have greater economic benefits than traditional water heating systems. In addition, conventional SWH systems are comparable with the SAHP systems when solar fractions are above 50%. Besides, analysis on the sensitivity of the total equivalent warming impact (TEWI) indicates that the towngas boosted SWH system has the greatest potential in greenhouse gas emission reduction with various solar collector areas and the electricity boosted SWH system has the comparative TEWI with the SAHP systems if its solar fraction is above 50%. As for SAHP systems, the solar assisted air source heat pump (SA-ASHP) system has the least global warming impact. Based on all investigation results, suggestions are given on the selection of solar thermal systems for applications in Hong Kong.     

Novel fabrication of silica nanotube by selective photoetching of CdS nanorod template

CdS/silica core–shell nanorod was prepared by silica coating over the CdS nanorod template of which the surface was initially capped by (3-mercaptopropyl)trimethoxysilane. The silica nanotube with both ends closed was fabricated from the core–shell nanorod by selective photoetching of the core CdS nanorod template with controlled photon energy in the oxygen-saturated aqueous solution including methyl viologen.     

Sulfur distribution within coal pyrolysis products

The pyrolysis of coal leads to distribution of sulfur compounds in pyrolysis gas, char and tar generated during the process. The effect of the process parameters of autothermal coal pyrolysis in the circulating fluidized bed reactor on total sulfur distribution has been investigated. Several experimental tests were performed at the temperature of 920°C. Non-coking coal from the Wieczorek Mine (Upper Silesian Coal Basin) and brown coal from the Bełchatów Mine were examined for sulfur distribution. It was found that distribution of total sulfur in coal pyrolysis products is basically affected by coal to air ratio and addition of steam or acceptor to the pyrolysis process.     

燃煤烟气全流程CCUS系统的技术经济分析

燃煤电站全流程CO₂捕集、利用与封存（CCUS）装置各个环节选用合适的技术决定其经济性,采用逐项比较的方法,确定出在不同条件下CO₂捕集、压缩、输送及驱油各个不同工段应采用的工艺技术,然后分别从建设投资与运行成本角度分析了各个工段的影响因素并有针对性地提出优化措施,并对3个100万t/a相同规模的不同地址燃煤电厂与不同位置油田驱块的组合方案进行了经济性评价。结果表明,CO₂输送距离是建设总成本的主要影响因素,而中长期CO₂公用输送管网的规划完善将弥补CO₂平均输送距离带来的成本增加。     

烟气CO2捕集工艺过程关键问题分析

CO2的减排越来越受到国际社会的关注,应用于火电厂的烟气CO2捕集技术是实现大规模降低火电厂CO2排放的主要手段之一,而捕集工艺是CO2捕集技术的基础。从工艺设计角度出发,简述了胺基吸收法的烟气预处理与捕集吸收工艺,分析了精脱硫、烟气冷却、吸收速率、电厂适应性、运行控制及节能工艺等因素对CO2捕集系统性能的影响,为火电厂烟气CO2大规模捕集的了工艺设计提供参考。     

低温洗涤法烟气脱硫脱碳工艺模拟研究

本文提出了一种通过低温戊烷液体洗涤烟气将CO2和SO2同时冷凝脱除的烟气处理工艺.该工艺采用2塔喷淋冷却方式冷却烟气,第1个喷淋塔采用冷冻水喷淋降温至接近冰点,第2个喷淋塔采用低温正戊烷液体喷淋降温至SO2和CO2的凝华温度,洗涤冷凝得到的SO2、CO2和H2O等组分不溶于正戊烷,故而从洗涤液分离出来.本文基于ASPE...     

1177t/h循环流化床锅炉燃烧优化调整试验及结果分析

对1 177t/h循环流化床(CFB)锅炉进行的燃烧优化调整试验结果表明,经燃烧优化调整,锅炉热效率平均为92.232%,比调整前提高约1.5%～2.0%,每年可节约燃料成本约840万元;稀相区烟气速度由调整前的4.22m/s降至3.87m/s,可减少磨损量约25%。     

Co2 +-exchanged MOR and 5A zeolites as efficient solid catalysts for the epoxidation of styrene with air

Selective oxidation of alkenes with air to corresponding epoxides was performed over simple ion-exchanged Co-MOR and Co-5A. Among all transition metal ions-exchanged M-zeolites, both Co-MOR and Co-5A exhibited the highest activity at 363 K. Notably, for the epoxidation of styrene, α-pinene, α-methyl styrene and cyclooctene, Co-MOR obtained higher conversions than Co-5A, in agreement with the difference of pore sizes of both zeolitic materials. Recycling and control tests showed high durability of Co-MOR as a heterogeneous catalyst in our catalytic system.