XPS study of the surface chemistry of L-CVD SnO2 thin films after oxidation

In this paper we present the results of XPS study of the surface chemistry of L-CVD SnO₂ thin films onto Si(100) before and after subsequent additional oxidation. Moreover, the ageing effect was also studied in order to check the influence of ambient oxidation. As-deposited L-CVD SnO₂ thin films exhibit evident nonstoichiometry with the relative concentration [O]/[Sn] equal to 1.29 ± 0.1. After in situ oxidation at high temperature (800 K) the relative concentration [O]/[Sn] increases to 1.95 ± 0.05 which corresponds to the almost stoichiometric SnO₂. Almost the same relative concentration [O]/[Sn] of L-CVD SnO₂ thin films has been obtained after long term exposure to air. The oxidation states of L-CVD SnO₂ thin films in both cases were confirmed by the shape analysis of corresponding XPS O1s and Sn3d_5/2 peaks using the decomposition procedure. For the as-deposited L-CVD SnO₂ thin films a mixture of SnO and SnO₂ was observed, while for the oxidized L-CVD SnO₂ thin films the domination of SnO₂ was determined.     

Transcritical CO2 refrigeration cycle with ejector-expansion device

An ejector expansion transcritical CO₂ refrigeration cycle is proposed to improve the COP of the basic transcritical CO₂ cycle by reducing the expansion process losses. A constant pressure mixing model for the ejector was established to perform the thermodynamic analysis of the ejector expansion transcritical CO₂ cycle. The effect of the entrainment ratio and the pressure drop in the receiving section of the ejector on the relative performance of the ejector expansion transcritical CO₂ cycle was investigated for typical air conditioning operation conditions. The effect of different operating conditions on the relative performance of the ejector expansion transcritical CO₂ cycle was also investigated using assumed values for the entrainment ratio and pressure drop in the receiving section of the ejector. It was found that the COP of the ejector expansion transcritical CO₂ cycle can be improved by more than 16% over the basic transcritical CO₂ cycle for typical air conditioning operation conditions.     

CO2用于自然复叠制冷系统的理论分析

对采用CO2和烷烃(R290、R600a、R600)组成的混合工质的自然复叠制冷系统应用于普冷领域进行了理论分析。研究了在CO2作为低沸点工质时，高沸点工质和中沸点工质对系统压比和性能系数COP的影响，以及这些性能参数随系统中CO2摩尔含量的变化情况。     

Flash gas bypass for improving the performance of transcritical R744 systems that use microchannel evaporators

The performance of transcritical R744 systems with direct expansion (DX) can be significantly improved by implementing a Flash Gas Bypass (FGB). The idea behind the concept is to bypass refrigerant vapor, created during the isenthalpic expansion process, around the evaporator. By feeding the evaporator with liquid refrigerant, pressure drop is reduced and refrigerant distribution is improved. With R744 as the working fluid, increased refrigerant-side heat transfer coefficients are expected as well. In addition, the FGB concept proves to be beneficial in terms of system design, in particular for combined air-conditioning and heat pumping applications. An experimental comparison to a conventional DX-system reveals that FGB increases the cooling capacity and COP at the same time by up to 9 and 7%, respectively. Even larger improvements are possible in case a variable speed compressor is utilized to match the performance of the conventional DX-system. A simulation model helps to separate the individual improvement mechanisms. It was found that the reduction of refrigerant-side pressure drop is the dominant improvement mechanism of FGB.     

硫酸法生产钛白粉水洗工艺真空系统设计改造方案与思路

讨论了水洗真空度对水洗工艺的影响，提出水洗真空系统的改造原则，并对真空系统改造设计思路和方案进行了详细的探讨。通过改进和优化能够提高设备的使用率，最终达到缩短水洗时间，提高本工序产能的目的。     

X-Ray absorption study of CeO2 and Ce/V mixed oxide thin films obtained by sol-gel deposition

CeO₂ and Ce/V mixed oxide thin films prepared by sol-gel deposition and annealed in an air or argon atmosphere have been studied by chronocoulometry and by XAFS (X-ray absorption fine structure). Multielectron photoexcitations (MPE), well known to pervade XAFS spectra of Ce making the analysis of structural parameters unreliable, are removed with the help of the atomic absorption background, determined on simple Ce compounds. Distinct MPE estimates for Ce³⁺ and Ce⁴⁺ ions are used. In the analysis of the recovered pure XAFS signal, the degree of disorder is found to depend on the Ce/V molar ratio and on the heating atmosphere. The disorder correlates with charge capacity of films, both increasing with vanadium content and V⁴⁺/V⁵⁺ molar ratio.     

二氧化氯杀藻特性研究

富营养化造成藻类大量繁殖 ,给饮用水生产带来诸多危害 .以ClO2 作为杀藻剂 ,对其杀藻效能及杀藻后水样的致突变性进行了系统研究 ,并对其杀藻机理进行了探讨 .结果表明 :①在同一投药速度下 ,随反应时间延长 ,叶绿素a(Chla)去除率随之提高 ,但提高的幅度随投药速度提高而趋于缓慢 ;同一反应时间下 ,随ClO2 投加速度的提高 ,叶绿素a(Chla)去除率显著升高 ,当反应时间小于 1 0min时 ,去除率随投药量增加而提高的幅度更为明显 .当ClO2 投加量为 38～ 85mgClO2 /mgChla时 ,叶绿素a(Chla)去除率可以达到 4 5 %～ 89.30 %.②ClO2 杀藻不会增加水样中有机浓集物的致突变性 .③藻类细胞的细胞壁结构与叶绿素a(Chla)的去除率有很大关系 ;ClO2 首先穿透细胞壁、细胞膜 ,进入细胞内部 ,在没有破坏藻细胞外部结构的情况下 ,将藻细胞中的叶绿素氧化 .     

Preparation and characterisation of titanium dioxide films for catalytic applications generated by anodic spark deposition

The advanced plasma electrochemical process of anodic spark deposition (ASD) was used to generate photoactive titanium dioxide films on titanium metal substrates. A shift to easier-to-machine substrates was demonstrated by the deposition of a titanium film with physical vapour deposition onto different materials such as glass, silicon, and stainless steel prior to ASD. Obtained films were characterised by scanning electron microscopy, surface area measurement (Brunnauer-Emmett-Teller method, BET), X-ray diffraction, electron-probe microanalysis, and glow discharge spectroscopy. Additionally, film thickness was determined by eddy current measurements. Standard ASD conditions were defined as 180 V applied voltage over a 180 s hold time, a voltage ramp of 20 V/s, a duty cycle of 0.5 and a frequency of 1500 Hz. Most prominent characteristics of the titanium films produced under these standard conditions are a film thickness of ≤80 μm, a surface area of approximately 51 m²/g (BET) and an anatase content of approximately 30% and rutile content of approximately 70%. Furthermore, the film formation process is elucidated and the dependence of film thickness on deposition time and the dependence of the anatase and rutile content on the deposited mass are shown for varying ASD conditions.     

结合清洁生产谈目前氯化法钛白生产的污染治理

结合实例说明,搞好清洁生产对氯化法钛白企业治理环境污染,提高企业的经济效益和今后长远发展起着举足轻重的作用和重要的指导意义.