WO3—SiO2复合薄膜制备、结构和气致变色性能

采用溶胶－凝胶法在玻璃衬底上成功制备了具有良好气致变色性能的透明,均匀,附着力强的WO3－SiO2复合薄膜,讨论了络合剂的量和乙醇与水的比例对溶胶稳定性的成膜均匀性的影响,用热重－差热,X射线衍射,红外光谱分析对薄膜在热处理过程中的结构变化特征进行分析,用扫描电镜对薄膜表面微观形貌进行观察,初步研究了镀铂薄膜的气致变色性能,研究结果表明,溶胶稳定性随着H2O2的增加而增加,但溶胶成膜均匀性降低,增加乙醇与水的比例,可提高溶胶的成均均匀性和溶胶稳定性,结构分析和性能测试的结果表明,360℃热处理的复合薄膜具有高浓度相界,氢原子迁移速率高,变色响应速率快,气致变色性能优于单一组分薄膜。     

光电致变色薄膜及其器件

光电致变色器件(Photoelectrochromic device)由染料电池和WO3电致变色薄膜电极组成。本研究采用溶胶一凝胶法分别制备WO3和TiO2纳米薄膜，并组装成光电致变色器件，对不同热处理和薄膜厚度下的器件的光电致变色性能进行测试分析。试验表明用提拉法制成的WO3薄膜和用旋涂法及丝网印刷制成的TiO2薄膜，都具有较好的成膜性，并且由其组装成的器件具有良好的光电致变色效果。     

五氧化二钒薄膜结构与电致变色效应

采用反应蒸发制备Ｖ２Ｏ５薄膜,用Ｘ射线衍射分析和分光光度计分别测量薄膜晶体结构和光谱特性,利用标准三电极法从锂离子电解质溶液中向Ｖ２Ｏ５薄膜注入锂离子,实验结果表明：刚制备的薄膜为非晶结构,热处理使得膜结晶：Ｖ２Ｏ５薄膜呈较强的阳极电致变色和较弱的阴极电致变色双理效应;     

NiO_xH_y 能效窗口薄膜的电致变色性

介绍了用于能效窗口的直流溅射氢氧化镍电致变色薄膜的电变色性能。讨论了不同偏置条件下的光透过谱线和循环伏安特性，薄膜厚度与光密度的变化关系，以及不同厚度的电致变色薄腊与太阳光透过率的关系。同时对电色薄膜的时间响应特性、光密度变化与注入的电荷密度的联系也进行了研究。结果表明，直接采用氢氧化镍作为制备电致变色薄膜的靶材，获得的薄膜有良好的电致变色性能，薄膜不需激活就有良好的初始电色特性。初步讨论了镍电致变色的机理，用能带理论可以定性说明镍电致变色薄膜的消着色机理。     

Cu_20/Ti0_2异质结复合薄膜的光催化性能研究

采用溶胶-凝胶法和磁控溅射技术制备Cu_2O/TiO_2半导体异质结构的光催化复合薄膜。以钛酸丁酯为原料溶胶浸渍提拉制备均匀透明的TiO_2薄膜,以金属Cu为靶源在TiO_2薄膜表面反应溅射p型Cu_2O薄膜,利用SEM、XRD、UV-Vis等分析技术对催化剂进行表征,通过染料的降解实验考查异质结复合薄膜在模拟太阳光下的光催化活性,并对其机理进行探讨。结果表明,TiO_2与Cu_2O复合后形成的异质结薄膜在模拟太阳光下具有较好的光催化活性,异质结复合扩展了催化剂的光响应范围及光响应强度,提高了量子效率,是一种充分利用太阳能的光催化复合薄膜。     

溶胶-凝胶制备工艺对TiO_2薄膜光催化性能的影响

采用溶胶-凝胶工艺制备纳米TiO_2溶胶,并通过旋涂法制备高效光催化TiO_2薄膜。研究络合剂、pH值和焙烧温度对TiO_2薄膜光催化性能的影响。络合剂能有效抑制钛酸丁酯水解速率,双络合剂制备的薄膜具有更强的光催化性。pH值能影响钛酸丁酯的水解和薄膜表面介孔结构的生长。焙烧温度决定TiO_2晶型和尺寸,同时对薄膜表面粗糙度和光学特性有重要影响。高效光催化TiO_2薄膜的最佳制备工艺为以pH值为6、双络合剂制备的溶胶为原料,旋涂后在500℃条件下焙烧3 h。     

TiO2纳米薄膜厚度对CdS纳米柱阵列 光电化学性能和稳定性的影响

利用水热合成法在导电玻璃表面上原位生长CdS纳米柱阵列（CdSNRA）,然后通过浸渍提拉法在其表面涂覆TiO₂纳米薄膜,制备CdSNRA@TiO₂异质结复合结构材料。利用扫描电镜、X射线衍射、紫外可见光吸收、拉曼光谱等手段对其形貌和结构进行表征。进一步考察了TiO₂薄膜厚度对CdSNRA@TiO₂复合结构光电极的光电化学性能的影响。结果表明,覆盖50 nm 厚TiO₂层的CdSNRA复合结构光电极在可见光下具有更好的光电性能和稳定性,这归因于CdSNRA核和TiO₂壳之间光生电子和空穴的有效分离。     

ILGAR法制备CdS薄膜新工艺的研究

采用一种薄膜制备的新方法-离子层气相反应法(ILAR)，以CdCl2为前驱体，H2S为硫源制备了CdS薄膜。利用XRD、SEM、AFM、XPS及UV—VIS透射光谱等测试分析方法对薄膜的晶型、表面化学组成、表面形貌、膜厚增长速度及光学性能进行了研究。实验结果表明：ILGAR法制备的CAS薄膜表面较致密、均匀、附着性好；在0．05MCdCl2前驱体溶液浸渍处理，薄膜以-2．8nm／cycle的恒定速率增长，且薄膜晶体沿立方(111)面具有明显的择优取向生长；400℃热处理1h，发生立方→六方晶型转变，最终为六方与立方混相结构，择优方向转为六方(002)面；薄膜经热处理后在可见光处的吸收峰发生红移，其禁带宽度降低，并且会随着膜厚的增加进一步降低。     

基于氧化钨和普鲁士蓝的可变色超级电容器

氧化钨(WO3)薄膜作为阴极电致变色材料,还原态(阳离子嵌入)时着色而氧化态(阳离子脱出)时褪色;而普鲁士蓝(Prussian blue,PB)薄膜作为阳极电致变色材料,还原态(阳离子嵌入)时褪色而氧化态(阳离子脱出)时着色.利用不同离子存储状态下WO3和PB薄膜的变色互补性,构筑了基于WO3和PB薄膜的可变色超级电容器.利用脉冲激光沉积法和电沉积法在透明导电玻璃表面制备了 WO3/PB复合薄膜,并以该复合薄膜为电极,构筑了对称型可变色超级电容器.结果表明,WO3/PB复合薄膜具有优异的循环稳定性,循环200圈后,面电容量的保持率可达83.8％;在650 nm时,由于WO3和PB薄膜在不同电压下的协同变色,超级电容器的光透过率差在完全着色与褪色时为53.2％.该超级电容器在不同充、放电状态下可清晰地显示不同的颜色组合及光对比度,从而实现利用颜色变化指示超级电容器的能量存储状态.本研究有助于推动电致变色和能量存储领域的交叉融合,为超级电容器能量存储状态的可视化提供实验依据.     

Al2O3/SiO2耐磨增透膜的制备和表征

以正硅酸乙酯(TEOS)和异丙醇铝(Al(OC3H7)3)为前驱体,采用溶胶-凝胶(sol-gel)提拉方法在玻璃基片上制得高透、耐磨的增透膜.使用XRD、UV-Vis、IR、和TEM测试和分析了溶胶和薄膜的结构及性能.研究表明:通过添加一定比例的Al2O3,使颗粒之间生成稳定致密的氧桥键Si-O-Al以及煅烧后γ-Al2O3的存在,调控了薄膜的微观结构,不仅明显提高了薄膜的力学性能,同时复合薄膜的光学透过率仍最高达99.2％.     

Ash-forming elements in four Scandinavian wood species. Part 1: Summer harvest

Woody biomass in Finland and Sweden comprises mainly four wood species: spruce, pine, birch and aspen. To study the ash, which may cause problems for the combustion device, one tree of each species were cut down and prepared for comparisons with fuel samples. Well-defined samples of wood, bark and foliage were analyzed on 11 ash-forming elements: Si, Al, Fe, Ca, Mg, Mn, Na, K, P, S and Cl. The ash content in the wood tissues (0.2–0.7%) was low compared to the ash content in the bark tissues (1.9–6.4%) and the foliage (2.4–7.7%). The woods’ content of ash-forming elements was consequently low; the highest contents were of Ca (410–1340 ppm) and K (200–1310), followed by Mg (70–290), Mn (15–240) and P (0–350). Present in the wood was also Si (50–190), S (50–200) and Cl (30–110). The bark tissues showed much higher element contents; Ca (4800–19,100 ppm) and K (1600–6400) were the dominating elements, followed by Mg (210–2400), P (210–1200), Mn (110–1100) and S (310–750), but the Cl contents (40–330) were only moderately higher in the bark than in the wood. The young foliage (shoots and deciduous leaves) had the highest K (7100–25,000 ppm), P (1600–5300) and S (1100–2600) contents of all tissues, while the shoots of spruce had the highest Cl contents (820–1360) and its needles the highest Si content (5000–11,300). This paper presented a new approach in fuel characterization: the method excludes the presence of impurities, and focus on different categories of plant tissues. This made it possible to discuss the contents of ash element in a wide spectrum of fuel-types, which are of large importance for the energy production in Finland and Sweden.     

Contents in Volume 23,2014

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Performance assessment of some ice TES systems

In this paper, a performance assessment of four main types of ice storage techniques for space cooling purposes, namely ice slurry systems, ice-on-coil systems (both internal and external melt), and encapsulated ice systems is conducted. A detailed analysis, coupled with a case study based on the literature data, follows. The ice making techniques are compared on the basis of energy and exergy performance criteria including charging, discharging and storage efficiencies, which make up the ice storage and retrieval process. Losses due to heat leakage and irreversibilities from entropy generation are included. A vapor-compression refrigeration cycle with R134a as the working fluid provides the cooling load, while the analysis is performed in both a full storage and partial storage process, with comparisons between these two. In the case of full storage, the energy efficiencies associated with the charging and discharging processes are well over 98% in all cases, while the exergy efficiencies ranged from 46% to 76% for the charging cycle and 18% to 24% for the discharging cycle. For the partial storage systems, all energy and exergy efficiencies were slightly less than that for full storage, due to the increasing effect wall heat leakage has on the decreased storage volume and load. The results show that energy analyses alone do not provide much useful insight into system behavior, since the vast majority of losses in all processes are a result of entropy generation which results from system irreversibilities.     

NEXT GENERATION ENGINEERED MATERIALS FOR ULTRA SUPERCRITICAL STEAM TURBINES

正1 ABSTRACT To reduce the effect of global warming on our climate,the levels of CO2emissions should be reduced.One way to do this is to increase the efficiency of electricity production from fossil fuels.This will in turn reduce the amount of CO2emissions for a given power output.Using US practice for efficiency calculations,then a move from a typical US plant running at 37%efficiency to a 760℃/38.5 MPa(1 400/5 580 psi)plant running at 48%efficiency would reduce CO2emissions by 170kg/MW.hr or 25%.     

Effect of co-cultivation of Chlamydomonas reinhardtii with Azotobacter chroococcum on hydrogen production

Chlamydomonas reinhardtii cc124 and Azotobacter chroococcum bacteria were co-cultured with a series of volume ratios and under a variety of light densities to determine the optimal culture conditions and to investigate the mechanism by which co-cultivation improves H₂ yield. The results demonstrated that the optimal culture conditions for the highest H₂ production of the combined system were a 1:40 vol ratio of bacterial cultures to algal cultures under 200 μE m^?2 s^?1. Under these conditions, the maximal H₂ yield was 255 μmol mg^?1 Chl, which was approximately 15.9-fold of the control. The reasons for the improvement in H₂ yield included decreased O₂ content, enhanced algal growth, and increased H₂ase activity and starch content of the combined system.     

Aerodynamic performance effects of leading-edge geometry in gas-turbine blades

The purpose of this paper is to illustrate the advantages of the direct surface-curvature distribution blade-design method, originally proposed by Korakianitis, for the leading-edge design of turbine blades, and by extension for other types of airfoil shapes. The leading edge shape is critical in the blade design process, and it is quite difficult to completely control with inverse, semi-inverse or other direct-design methods. The blade-design method is briefly reviewed, and then the effort is concentrated on smoothly blending the leading edge shape (circle or ellipse, etc.) with the main part of the blade surface, in a manner that avoids leading-edge flow-disturbance and flow-separation regions. Specifically in the leading edge region we return to the second-order (parabolic) construction line coupled with a revised smoothing equation between the leading-edge shape and the main part of the blade. The Hodson–Dominy blade has been used as an example to show the ability of this blade-design method to remove leading-edge separation bubbles in gas turbine blades and other airfoil shapes that have very sharp changes in curvature near the leading edge. An additional gas turbine blade example has been used to illustrate the ability of this method to design leading edge shapes that avoid leading-edge separation bubbles at off-design conditions. This gas turbine blade example has inlet flow angle 0°, outlet flow angle −64.3°, and tangential lift coefficient 1.045, in a region of parameters where the leading edge shape is critical for the overall blade performance. Computed results at incidences of −10°,   −5°,   +5°,   +10° are used to illustrate the complete removal of leading edge flow-disturbance regions, thus minimizing the possibility of leading-edge separation bubbles, while concurrently minimizing the stagnation pressure drop from inlet to outlet. These results using two difficult example cases of leading edge geometries illustrate the superiority and utility of this blade-design method when compared with other direct or inverse blade-design methods.     

Natural-gas fueled spark-ignition (SI) and compression-ignition (CI) engine performance and emissions

Natural gas is a fossil fuel that has been used and investigated extensively for use in spark-ignition (SI) and compression-ignition (CI) engines. Compared with conventional gasoline engines, SI engines using natural gas can run at higher compression ratios, thus producing higher thermal efficiencies but also increased nitrogen oxide (NO_x) emissions, while producing lower emissions of carbon dioxide (CO₂), unburned hydrocarbons (HC) and carbon monoxide (CO). These engines also produce relatively less power than gasoline-fueled engines because of the convergence of one or more of three factors: a reduction in volumetric efficiency due to natural-gas injection in the intake manifold; the lower stoichiometric fuel/air ratio of natural gas compared to gasoline; and the lower equivalence ratio at which these engines may be run in order to reduce NO_x emissions. High NO_x emissions, especially at high loads, reduce with exhaust gas recirculation (EGR). However, EGR rates above a maximum value result in misfire and erratic engine operation. Hydrogen gas addition increases this EGR threshold significantly. In addition, hydrogen increases the flame speed of the natural gas-hydrogen mixture. Power levels can be increased with supercharging or turbocharging and intercooling. Natural gas is used to power CI engines via the dual-fuel mode, where a high-cetane fuel is injected along with the natural gas in order to provide a source of ignition for the charge. Thermal efficiency levels compared with normal diesel-fueled CI-engine operation are generally maintained with dual-fuel operation, and smoke levels are reduced significantly. At the same time, lower NO_x and CO₂ emissions, as well as higher HC and CO emissions compared with normal CI-engine operation at low and intermediate loads are recorded. These trends are caused by the low charge temperature and increased ignition delay, resulting in low combustion temperatures. Another factor is insufficient penetration and distribution of the pilot fuel in the charge, resulting in a lack of ignition centers. EGR admission at low and intermediate loads increases combustion temperatures, lowering unburned HC and CO emissions. Larger pilot fuel quantities at these load levels and hydrogen gas addition can also help increase combustion efficiency. Power output is lower at certain conditions than diesel-fueled engines, for reasons similar to those affecting power output of SI engines. In both cases the power output can be maintained with direct injection. Overall, natural gas can be used in both engine types; however further refinement and optimization of engines and fuel-injection systems is needed.     

Exergetic evaluation of 5 biowastes-to-biofuels routes via gasification

This paper presents the exergy analysis results for the production of several biofuels, i.e., SNG (synthetic natural gas), methanol, Fischer–Tropsch fuels, hydrogen, as well as heat and electricity, from several biowastes generated in the Dutch province of Friesland, selected as one of the typical European regions. Biowastes have been classified in 5 virtual streams according to their ultimate and proximate analysis. All production chains have been modeled in Aspen Plus in order to analyze their technical performance. The common steps for all the production chains are: pre-treatment, gasification, gas cleaning, water–gas-shift reactions, catalytic reactors, final gas separation and upgrading. Optionally a gas turbine and steam turbines are used to produce heat and electricity from unconverted gas and heat removal, respectively. The results show that, in terms of mass conversion, methanol production seems to be the most efficient process for all the biowastes. SNG synthesis is preferred when exergetic efficiency is the objective parameter, but hydrogen process is more efficient when the performance is analyzed by means of the 1st Law of Thermodynamics. The main exergy losses account for the gasification section, except in the electricity and heat production chain, where the combined cycle is less efficient.     

Controls on the Karaha–Telaga Bodas geothermal reservoir,Indonesia

Karaha–Telaga Bodas is a partially vapor-dominated, fracture-controlled geothermal system located adjacent to Galunggung Volcano in western Java, Indonesia. The geothermal system consists of: (1) a caprock, ranging from several hundred to 1600 m in thickness, and characterized by a steep, conductive temperature gradient and low permeability; (2) an underlying vapor-dominated zone that extends below sea level; and (3) a deep liquid-dominated zone with measured temperatures up to 353 °C. Heat is provided by a tabular granodiorite stock encountered at about 3 km depth. A structural analysis of the geothermal system shows that the effective base of the reservoir is controlled either by the boundary between brittle and ductile deformational regimes or by the closure and collapse of fractures within volcanic rocks located above the brittle/ductile transition. The base of the caprock is determined by the distribution of initially low-permeability lithologies above the reservoir; the extent of pervasive clay alteration that has significantly reduced primary rock permeabilities; the distribution of secondary minerals deposited by descending waters; and, locally, by a downward change from a strike-slip to an extensional stress regime. Fluid-producing zones are controlled by both matrix and fracture permeabilities. High matrix permeabilities are associated with lacustrine, pyroclastic, and epiclastic deposits. Productive fractures are those showing the greatest tendency to slip and dilate under the present-day stress conditions. Although the reservoir appears to be in pressure communication across its length, fluid, and gas chemistries vary laterally, suggesting the presence of isolated convection cells.     

Hydrogen production by steam-gasification of carbonaceous materials using concentrated solar energy – V. Reactor modeling,optimization, and scale-up

A chemical reactor for the steam-gasification of carbonaceous particles (e.g. coal, coke) is considered for using concentrated solar radiation as the energy source of high-temperature process heat. A two-phase reactor model that couples radiative, convective, and conductive heat transfer to the chemical kinetics is applied to optimize the reactor geometrical configuration and operational parameters (feedstock's initial particle size, feeding rates, and solar power input) for maximum reaction extent and solar-to-chemical energy conversion efficiency of a 5 kW prototype reactor and its scale-up to 300 kW. For the 300 kW reactor, complete reaction extent is predicted for an initial feedstock particle size up to 35 μm at residence times of less than 10 s and peak temperatures of 1818 K, yielding high-quality syngas with a calorific content that has been solar-upgraded by 19% over that of the petcoke gasified.