CNs−Bi12O17Cl2复合体系制备及光催化降解性能研究

采用简易水解法制备了一系列CNs−Bi₁₂O₁₇Cl₂复合半导体材料并对其物相、光学性质和光催化降解性能进行了分析表征。X射线衍射光谱表明复合体系衍射峰与四方晶相Bi₁₂O₁₇Cl₂一致,紫外可见漫反射光谱证明复合材料在可见区域具有较强的光吸收能力,由此可提高光催化活性。在可见光照射下,复合体系相对于纯Bi₁₂O₁₇Cl₂对亚甲基蓝具有更高的降解效率,特别是具有合适组分的样品CB50可以在180 min后完全去除20 mg·L⁻¹的亚甲基蓝分子,这主要是由于CNs的引入抑制了光生载流子的复合,使复合体系表现出更高的光催化降解性能。最后,提出了可能的光催化机理。     

奥氏体钢SP2215和马氏体钢X19CrMoNbVN11−1在高温高压超临界CO2环境下的腐蚀行为研究

超临界CO₂布雷顿循环具有循环效率高、体积小等优点，实际应用中循环系统部件面临因焊接及叶片自身旋转等拉应力的存在而加重腐蚀的问题，因此探明部件材料腐蚀行为是其在工程领域中应用的前提条件之一。搭建了超临界CO₂布雷顿循环实验台，模拟实际应用工况，并添加四点应力装置为样件施加载荷。研究了奥氏体钢SP2215和马氏体钢X19CrMoNbVN11−1(简称X19)在20 MPa/550 ℃的CO₂环境中未加载和加载应力下的腐蚀行为（900 h）。利用X射线衍射、X射线光电子能谱、扫描电镜及X射线能谱对两种材料腐蚀产物的形貌和成分进行了分析，并对材料的腐蚀行为进行了对比，结果发现： SP2215样件的氧化物主要为Cr₂O₃ 和Fe₃O₄，但应力加载样件表面Fe₃O₄信号更强烈。应力加载加剧了样件的腐蚀，增加了氧化膜厚度，使样件表面发生了严重的氧化层脱落。未加载的X19 表面出现了单质碳，生成的氧化物为Fe₃O₄与FeCr₂O₄，且可能存在分层现象。SP2215抗腐蚀能力优于X19，实验中并未出现明显的渗碳腐蚀现象。研究可为超临界CO₂布雷顿循环工程应用选材提供参考。     

主动式冷梁性能对房间气流组织影响模拟研究

以某主动式冷梁送风房间为模型，利用计算流体力学（CFD）软件模拟了主动式冷梁性能对房间气流组织的影响，并将模拟值和实测值进行了对比，验证了模型的准确性。利用该模型研究了主动式冷梁出风速度、出风温度、出风角度、出风高度以及回风口位置对房间气流组织的影响。结果表明：若仅改变出风速度，当出风速度从1 m·s⁻¹增大到4 m·s⁻¹时，预期平均通感P_M下降，不适人员比例P_D先降后升，出风速度为2 m·s⁻¹时，P_D最小，为9%，此时人员对环境的满意度最高；若仅改变出风角度，当出风角度为45°时房间气流组织分布最佳；若仅改变出风高度，当出风高度为2.33 m时房间气流组织分布最佳。在出风温度为20 °C、出风速度为4 m·s⁻¹时，比较不同回风口位置（上部、中部、底部）时距离地面高度Y=1.2 m截面的气流组织变化，发现回风口位于底部时该截面温度最高，空气速度最小，空气龄最大，P_D最小，为28%，此时人体冷热感觉较舒适。     

废弃印刷线路板共热解影响因素及热解产物表征

热解是资源化利用废弃印刷线路板的重要方法之一。分别以沸石和Fe₃O₄为共热解剂，探讨了共热解剂与废弃线路板的质量比以及热解温度对液相产物产率的影响，并对热解后固、液、气三相产物进行了表征。结果表明，共热解剂的添加不会影响热解油的产率，但可有效降低液相中溴化有机物的含量。热解液相产物组分分析结果表明，直接热解废弃线路板时会有大量溴化有机物释放到液相产物中。加入共热解剂后，苯酚及其同系物成为液相产物的主要成分，溴变成主要以无机溴化物的形式存在。同时，不同共热解剂对废弃线路板的热解影响也不同。Fe₃O₄共热解时，液相产物中小分子苯类物质更多，这可能是由于铁类物质对大分子有机物的分解作用更强。共热解剂在高温下比较稳定，热解后固体主要含有共热解剂、玻璃纤维以及重金属，而热解气的主要成分则为H₂、CH₄和CO₂。     

镍基镁渣催化剂对生物质焦油模化物催化重整特性实验研究

采用湿浸渍法制备Ni/γ-Al₂O₃和Ni/MS(magnesium slag)催化剂,选择糠醛、甲苯、萘、芘作为生物质焦油的模化物,研究不同镍基催化剂对四类焦油模化物在固定床反应器内进行催化重整的重整特性。结果表明,Ni/MS催化剂在催化所有模化物的重整反应时,气相碳转化率和气体产率均明显高于Ni/γ-Al₂O₃催化剂。当水分子物质的量与碳原子物质的量之比为1.5时,糠醛的气相碳转化率达到最高值86.54%。X 射线衍射 (XRD)结果表明,Ni/MS催化剂上存在的多种固溶体（NiO-Fe₂O₃、NiO-MgO）形成了多种活性位点。     

氢发动机SCR催化器的NOx转化效率模拟

建立一维选择性催化还原（selective catalytic reduction，SCR）催化器模型，采用稳态、瞬态小样试验标定SCR化学反应动力学机理，并分析SCR催化器对氢发动机排气中NO_x的催化还原过程。结果表明：入口O₂体积分数对NO_x催化还原有抑制作用，但入口H₂O体积分数对NO_x转化效率没有明显影响；当温度为250~400 ℃时，线性温升工况NO_x转化效率高于稳态工况且超过98%；氢发动机排气温度和原排NO_x体积分数随功率增大而增大，当功率大于60 kW且氨氮比等于1时，SCR催化器转化效率小于95%；增加氨氮比对NO_x转化效率的提高作用较小，这是由于在高温条件下增加的NH₃倾向与O₂反应。     

农村生活与生产综合污水生物处理的A/O工艺启动策略与特性研究

为实现新时期各类典型性农村综合污水的治理,选择了一种农村生活与生产综合污水作为研究对象,研究了利用兼氧/好氧（A/O）工艺处理农村生活和生产综合污水的启动过程。结果表明：采用逐步递增生产废水和污泥接种培养的启动策略能够实现处理工艺的快速启动;pH、化学需氧量（COD）、氨氮（NH₄⁺−N）、总磷（TP）以及色度在启动过程中各阶段的变化情况的分析结果表明,A/O工艺能够通过兼氧池和好氧池的协同配合达到理想的污水处理效果。     

城市垃圾焚烧飞灰物理化学性质及重金属风险分析

对7种城市垃圾焚烧飞灰的物理化学性质进行了详细表征。针对飞灰中重金属成分复杂的特点对重金属含量、形态分布和浸出毒性进行了分析,并进行了风险评估指数和风险指数计算。飞灰的化学组分和晶相结构分析显示,城市垃圾焚烧飞灰中含有大量的CaO、CaSO₄、SiO₂、Al₂O₃、NaCl和KCl等化合物,具有资源化利用的潜力。但同时飞灰中含有大量的重金属,其中Pb和Cd的生态风险高,浸出毒性高于飞灰直接处理和处置要求。研究结果表明,垃圾焚烧飞灰需进行处理至达到一定要求后才能进行资源化利用。     

F-76燃料骨架机理构建方法研究

为开发出结构紧凑、高精度和包含多环芳烃（polycyclic aromatic hydrocarbons, PAHs）的高碳燃料模型燃料机理并应用于计算流体力学（computational fluid dynamics, CFD）模拟,提出了一种集成详细的C₀—C₄核心机理和骨架的C₅—C_n机理来发展高碳燃料骨架反应机理的新方法。利用该方法为基础燃料分别为正十六烷（NC₁₆H₃₄）、2,6,10-三甲基十二烷（C₁₅H₃₂-26X）和正丁基苯（C₆H₅C₄H₉）的模型燃料构建相应的骨架反应机理。然后基于机理简化手段获得了包含164个组分和654个基元反应的骨架机理。利用激波管点火延迟时间、流动反应器氧化数据、层流火焰速度和熄火极限等基础燃烧数据对构建的机理进行验证。然后,将该骨架机理耦合到三维CFD喷雾模型中,来模拟定容喷雾燃烧室（constant volume spray combustion chamber, CVSCC）中的喷雾燃烧过程。结果表明喷雾燃烧特性的模拟值能与实验值吻合良好,证明了所构建骨架机理在燃烧CFD模拟中的有效性。     

结构型载氧体固定床化学链重整制氢的实验研究

采用浸渍法制备球形与拉西环形两种不同结构型Ni基载氧体,用于甲烷化学链重整制氢反应。在固定床中考察反应温度、进气水碳物质的量的比和空速对载氧体活性及稳定性的影响,并对比研究两种不同结构型载氧体的性能。结果表明：两种载氧体均可以保持较好的活性,相对而言球形载氧体更易积碳。在800 ℃以上时两种载氧体均具有较高的甲烷转化率及产物选择性,拉西环形载氧体在高温下性能下降得较慢。过高的水碳物质的量的比会抑制重整反应的进行,但拉西环形载氧体在高水碳物质的量的比下仍能保持较高的产物选择性。随着空速的增大,拉西环形载氧体的甲烷转化率降低,而对球形载氧体来说,当空速在3 500 h^?1左右时甲烷转化率和氢气产率均最高。经过20次循环稳定性测试,两种载氧体颗粒均出现了不同程度的积碳烧结,其中拉西环形载氧体结构保持得较好,积碳在氧化阶段能被部分清除。     

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.