Performance Characteristics of a Drying Heat Pump Using Superheated Steam

A complete mathematicalhumerical model is proposed, in order to simulate the performance characteristics of a novel concept of a drying heat pump based on the theory of minimum energy cyclcs. The drying heat pump involvcs vapour condensation in a Lava1 nozzle. removal of the liquid phase in a supersonic separator as well as compression of the working medium. which is superheared vapour.     

担载型含稀土三组份体系在二氧化碳甲烷化反应中的催化性能

用浸渍法制备了一系列氧化锆担载的含稀土Ⅷ族金属催化剂，对其在二氧化碳甲烷化过程中的催化活性作了研究，并用漫反射紫外可见光谱，ＦＴＩＲ等手段对催化剂作了表征。结果表明，含稀土新型催化剂具有催化活性高，目标产物选择性好等优点；稀土主要以氧化物形式存在于催化剂表面，参与对氢及表面含碳物种的吸附及活化；含稀土三组份催化剂的活性与所添加稀土三价离子的４ｆ电子数有关。     

Screening model for assessing ‘cost’ of minimum flow requirements in the Svartå River,Sweden

The minimum flow requirements in the Svartå River in Sweden are directed at maintaining fishlife and providing suitable dilution for waste flows. The implications of varying the minimum flow requirements in the river are examined using a mixed integer optimisation model. The model is formulated as a modified method-of-weights technique with the economic issues of hydro-electricity generation, irrigation and urban water supply placed in the objective function and the minimum flows specified within the constraint set. The integer component of the model is required to model the operating policy at the major flow regulation facility in the system and the restricted validity of the irrigation permits. Application of the model shows that in dry years where competition between minimum flow levels and the other economic uses, is most intense, the levels achieved by the various economic objectives are only slightly reduced even with significant increases in the minimum flow requirements. Variations in minimum flow requirements of up to 45% only produce changes of 10% or less in the economic objectives. The lack of sensitivity of the objective levels is due primarily to the level of control exerted indirectly on the whole system in dry years by the release regulation policy and the restricted validity of the irrigation permits. In normal to wet years these policies are not as restrictive and more choice is available. In such years, however, there is generally sufficient water to satisfy all requirements and allocation is not a critical issue. The model itself is formulated generally so that a range of scenarios beyond those examined specifically in the paper can be considered.     

铸造用CO2硬化冷芯盒材料及工艺的发展

铸造用CO2硬化粘结剂系统具有气硬冷芯盒的优点,同时又具有环保方面的优势。主要介绍了水玻璃-CO2法、聚丙烯酸钠-CO2法、酚醛树脂-CO2法三种工艺。这些工艺方法近年来国内外研究较多,并且取得了很大进展。     

碳纳米管及稀土元素钇(Y)对高Ni含量Ti(C,N)基金属陶瓷组织与性能的影响

研究了不同含量的碳纳米管及0.8%稀土Y对高Ni含量Ti(C,N)基金属陶瓷组织性能的影响.将不同成分的试样分别于1400℃、1410 ℃、1420℃真空烧结,测试抗弯强度、洛氏硬度,观察背散射电子形貌、断口形貌并做能谱分析.结果表明,加入质量分数(下同)为0.8%Y及0.3%～1.0%的碳纳米管时,碳纳米管含量为0.5%的组织较均匀,芯壳结构明显,抗弯强度及硬度均较高.     

不同活化剂对石油焦基活性炭孔结构的影响

以石油焦为原料 ,Na OH,KOH和 Na2 CO3 为活化剂制备活性炭 ,采用氮气吸附考察了不同活化剂对活性炭的比表面积、中孔和微孔孔径分布、孔容积及平均孔径等孔结构的影响 .结果表明 :KOH活化制备的活性炭包含 1 nm的微孔和 4nm的中孔 ,总孔容 0 .648cm3 /g,比表面积大 ;Na OH制备的活性炭以 1 nm的微孔为主 ,占总孔容 ( 0 .1 65 cm3 /g)的 98% ,平均孔径 1 .83nm;Na2 CO3 制备的活性炭以 4nm的中孔为主 ,占总孔容 ( 0 .1 43cm3 /g)的 68.5 % ,平均孔径 3.42 nm,比表面积小 .3种样品的孔径都呈现出多峰分布特征 .KOH和 Na2 CO3 活化制备的活性炭的 N2 吸附脱附曲线属于 型 ,Na OH活化制备的活性炭吸附脱附曲线属于 型 .     

Influence of volatile matter and deposited carbon on coke yield from coals

The relations between coke yields and the volatile matter content of 30 individual and 30 blended coals were investigated. Coke yields and deposited carbon related to volatile matter content can be expressed in the following equations: CY (%) = 97.89?0.86 VMch+VMc; and DC (%)= ?2.24+0.16 VMch; where: CY=real coke yield; VMch = volatile matter content of charging coal; VMc=volatile matter content of coke, and in the case of <2%; DC = deposited carbon. The test results show excellent correlation with practice.     

High resolution XPS characterization of chemical functionalised MWCNTs and SWCNTs

High resolution XPS analysis of chemical functionalised multi-wall carbon nanotubes (MWCNTs) and single wall carbon nanotubes (SWCNT) was done with ESCA300 (overall instrument resolution of 0.35 eV). Information to the degree of functionalisation was ascertained by argon ion bombardment of the samples followed by XPS analysis to detect the functional groups, the percentage atomic concentration of various elements present and whether or not the detected functional groups imposed a chemical shift on the CNT atoms. The results show that true chemical functionalisation was achieved and by argon ion bombardment these functional groups can be altered relative to the C 1s carbon atoms of the CNT. The choice of chemicals used for functionalisation, the techniques employed and the types of nanotubes treated are important factors in chemical characterisation. The carbon atom on the nanotube ring to which the functional group (atom) is bonded, the chirality of the CNT, the electronegativity of the functional group, the bond type and whether the CNT is single-wall or multi-wall, or cut (short) could play a role in determining the chemical shift on the CNTs atoms. These investigations are relevant to chemical functionalisation of carbon nanotubes for various applications for example DNA sensors and other biomedical sensors.     

Kinetics of the methanation of carbon dioxide over a supported Ni-La2O3 catalyst

The kinetics of the methanation of carbon dioxide was investigated using an alumina supported Ni-La₂O₂ catalyst in a differential and integral reactor. In the differential reactor the molar ratio of H₂ to CO₂ was varied from 0.6 to 30. In the integral reactor the rates were measured with up to 90% conversion. Both reactor tests were carried out at temperatures between 513 and 593 K. The experimental results were described by a Langmuir-Hinshelwood type equation. The kinetics can be explained by assuming equilibrium of dissociative carbon dioxide and hydrogen adsorption, and assuming hydrogenation of surface carbon as the rate determining step.     

Carbon Aerogels as Electrode Material in Supercapacitors

Due to their large specific surface area and their high electrical conductivity carbon aerogels are promising materials for electrodes in electrochemical double-layer capacitors (supercapacitor). The carbon aerogels were made via pyrolysis of resorcinol formaldehyde aerogels. The latter were prepared by supercritical and subcritical drying as well. The important findings of our investigation were, that the highest capacities of 46 F/cm³ were measured for samples with a density of about 800 kg/m³ pyrolyzed at 800°C. Also it was shown that RF-gels with molar resorcinol/catalyst ratios 1000 or higher can be dried subcritically without cracking or significant shrinkage. Carbon aerogels derived from these RF-aerogels have a small mesopore surface area, however an especially large micropore area. They provide electrical capacities which are most suitable for their use in supercapacitors.