废弃物衍生燃料(RDF-5)技术发展概述

介绍了城市生活垃圾处理RMJ型垃圾衍生燃料(RDF-5)技术工艺,分析了RDF-5燃料的特性。并从能源利用,环境污染等角度,将RDF-5燃料发电与生活垃圾焚烧发电对比,简述了RDF-5技术在各国研究及应用现状。基于对北京市生活垃圾组分、热值的分析,探讨了垃圾衍生燃料(RDF-5)技术在我国城市生活垃圾处理领域的发展前景。     

燃煤工业锅炉节能讲座——第六讲 锅炉的燃烧

锅炉是转换能量形式产生热能的设备，燃料是锅炉生产热水或蒸汽的热能的能量来源。工业锅炉使用的是化石燃料(煤、石油及其制品、天然气等)和生物质燃料(薪材、稻糠、蔗渣、沼气等)，它们都是有机燃料。有机燃料是能与空气中的氧发生剧烈化学反应(燃烧)而放出大量热量的物质。     

燃料设计改善发动机燃烧和排放的研究(1)--燃料参数设计与喷雾特性研究

研究了通过含氧燃料与柴油相互掺混来改变燃料的成分与输运参数、改善燃料的喷雾特性，从而降低了柴油机的排放。选择了几种典型的含氧燃料一乙醇、碳酸二甲脂(DMC)、甲缩醛(DMM)，测量和分析了它们以不同比例与柴油互溶后燃料的输运参数变化。为了考察混合燃料的喷雾特性，以不同比例的DMM柴油混合燃料为例，运用激光相位多谱勒(PDA)技术测量它们的索特平均直径(SMD)，并与柴油进行了比较。研究结果表明：通过含氧燃料与柴油的互溶互混，重新设计了燃料的输运参数和成分后，显著改善了燃料的喷射雾化特性。     

煤的燃料(火用)分析

作为重要的一次能源,对煤的燃料(火用)进行分析以确定其最大做功能力,具有重要的理论和现实意义.通过对有关专家研究的总结和分析,认为Rant对燃料(火用)的估算方法既具有科学性,又与实际情况相符.根据电与(火用)的等效性,用发电能力来反映燃料的做功能力,使得基于第二定律的统计更加有效,并能准确揭示其潜力的大小.     

国外新型汽车代用燃料的开发和应用前景

进入新世纪，研发和应用新型汽车代用燃料已成为发展新世纪清洁汽车燃料的一大热点。业已面世或开拓中的新型汽车代用燃料主要有：醇类(甲醇和乙醇)、生物柴油、二甲醚、天然气合成油(FT柴油)以及燃料电池用氢气、甲醇和清洁汽油。压缩天然气、LPG业已在汽车燃料中较多应用，以上各种代用燃料均处于不同的应用和发展阶段。     

煤的燃料(火用)分析

作为重要的一次能源,对煤的燃料(火用)进行分析以确定其最大做功能力,具有重要的理论和现实意义.通过对有关专家研究的总结和分析,认为Rant对燃料(火用)的估算方法既具有科学性,又与实际情况相符.根据电与(火用)的等效性,用发电能力来反映燃料的做功能力,使得基于第二定律的统计更加有效,并能准确揭示其潜力的大小.     

CG125发动机燃用生物燃料(醇燃料)初探

生物燃料是清洁能源,目前,生物燃料主要指醇类燃料。首先简要介绍了醇类燃料的性质、国内外研究以及使用醇类燃料的现状;然后,选择目前国内生产量和保有量最大的小型发动机(排量125 mL)——CG125发动机为研究对象,探讨醇类燃料在该机中应用的技术方案,以及推广应用的途径。     

车用发动机代用燃料的研究现状及发展趋势

详细介绍了车用发动机的几种代用燃料——压缩天然气(CNG)、液化天然气(LNG)、天然气合成油 (GTL)、液化石油气(LPG)、氢气、乳化燃油、醇类燃料、水煤浆、二甲醚(DME)、生物燃料、碳酸二甲酯(DMC)的研究现状。并简单阐述了代用燃料的发展趋势。     

CO_2转化燃料技术

碳科学公司(Carbon Sciences)9月底宣布,正在开发将CO2转化为低碳烃类(C1～C3)的工艺,以便进一步制成高碳烃类燃料,如汽油和喷气燃料.     

柴油机燃用二甲醚排放特性的研究

利用定容燃烧室和共轨式燃料喷射系统，对二甲醚(DME)燃料喷雾特性进行了试验研究．在单缸柴油机上，采用不同的喷孔直径、孔数、喷射率及涡流比时，对DME发动机排放性能进行了对比试验．结果表明，较少的喷孔数和较大的喷孔直径可以提高燃料喷雾的贯穿距离，抑制燃料的早期蒸发，有利于减少大负荷工况下CO、THC和NOx排放。     

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.     

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.     

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.     

Decomposition of limestone in a solar reactor

The thermal decomposition of limestone has been selected as a model reaction for developing and testing an atmospheric open solar reactor. The reactor consists of a cyclone gas/particle separator which has been modified to let the concentrated solar energy enter through a windowless aperture. The reacting particles are directly exposed to the solar irradiation. Experimentation with a 60 kW reactor prototype was conducted at PSI's 90m² parabolic solar concentrator, in a continuous mode of operation. A counter-current flow heat exchanger was employed to preheat the reactants. Eighty five percent degree of calcination was obtained for cement raw material and 15% of the solar input was converted into chemical energy (enthalpy).The technical feasibility of the solar thermal decomposition of limestone was experimentally demonstrated. The use of solar energy as a source for high-temperature process heat offers the potential of reducing significantly the CO₂ emissions from lime producing plants. Such a solar thermochemical process can find application in sunny rural areas for avoiding deforestation.     

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.     

液压系统常见的故障诊断及处理

任何工程机械式液压设备使用时出现故障是不可避免的。但是怎样确定故障的原因及找到好的解决方法，这是使用者最关心的问题。讲述了液压系统常见的故障及其排除方法。     

Biohydrogen production by Anabaena sp. PCC 7120 wild-type and mutants under different conditions: Light, nickel, propane, carbon dioxide and nitrogen

Increasing awareness of environmental problems caused by the current use of fossil fuel-based energy, has led to the search for alternatives. Hydrogen is a good alternative and the cyanobacterium Anabaena sp. PCC 7120 is naturally able to produce molecular hydrogen, photosynthetically from water and light. However, this H₂ is rapidly consumed by the uptake hydrogenase.This study evaluated the hydrogen production of Anabaena sp. PCC 7120 wild-type and mutants: hupL⁻ (deficient in the uptake hydrogenase), hoxH⁻ (deficient in the bidirectional hydrogenase) and hupL⁻/hoxH⁻ (deficient in both hydrogenases) on several experimental conditions, such as gas atmosphere (argon and propane with or without N₂ and/or CO₂ addition), light intensity (54 and 152 ??Em⁻²s⁻¹), light regime (continuous and light/dark cycles 16 h/8 h) and nickel concentrations in the culture medium.In every assay, the hupL⁻ and hupL⁻/hoxH⁻ mutants stood out over wild-type cells and the hoxH⁻ mutant. Nevertheless, the hupL⁻ mutant showed the best hydrogen production except in an argon atmosphere under 16 h light/8 h dark cycles at 54 ??Em⁻²s⁻¹ in the light period, with 1 ??M of NiCl₂ supplementation in the culture medium, and under a propane atmosphere.In all strains, higher light intensity leads to higher hydrogen production and if there is a daily 1% of CO₂ addition in the gas atmosphere, hydrogen production could increase 5.8 times, related to the great increase in heterocysts differentiation (5 times more, approximately), whereas nickel supplementation in the culture medium was not shown to increase hydrogen production. The daily incorporation of 1% of CO₂ plus 1% of N₂ did not affect positively hydrogen production rate.     

Economie d'énergie en trigénération

Trigeneration is defined as the production of three useful forms of energy—heat, cold and power—from a primary source of energy such as natural gas or oil. For instance, trigeneration systems typically produce electrical power via a reciprocating engine or gas turbine and recover a large percentage of the heat energy retained in the lubricating oil, exhaust gas and coolant water systems to maximize the utilization of the primary fuel. The heat produced can be totally or partially used to fuel absorption refrigerators. Therefore, trigeneration systems enjoy an inherently high efficiency and have the potential to significantly reduce the energy-related operation costs of facilities. In this paper, we describe a model of characterization of trigeneration systems trough the condition of primary energy saving and the quality index, compared to the separate production of heat, cold and power. The study highlights the importance of the choice of the separate production reference system on the level of primary energy saving and emissions reduction.     

Investigation of the thermodynamic and kinetic properties of La–Fe–B system hydrogen-storage alloys

La–Fe–B hydrogen-storage alloys were prepared using a vacuum induction-quenching furnace with a rotating copper wheel. The thermodynamic and kinetic properties of the La–Fe–B hydrogen-storage alloys were investigated in this work. The P–C–I curves of the La–Fe–B alloys were measured over a H₂ pressure range of 10⁻³ MPa to 2.0 MPa at temperatures of 313, 328, 343 and 353 K. The P–C–I curves revealed that the maximum hydrogen-storage capacity of the alloys exceeded 1.23 wt% at a pressure of approximately 1.0 MPa and temperature of 313 K. The standard enthalpy of formation ΔH and standard entropy of formation ΔS for the alloys' hydrides, obtained according to the van't Hoff equation, were consistent with their application as anode materials in alkaline media. The alloys also exhibited good absorption/desorption kinetics at room temperature.     

Mineralogical characterization of the intraseam layers of Lofoi lignite deposits in Florina basin (western Makedonia,northwest Greece)

The mineralogical composition of intraseam layers from Lofoi lignite deposits (northwest Greece) is the subject of the present study. The samples were examined by means of X-ray diffraction (XRD), thermo-gravimetric (TG/DTG) and differential thermal analysis (DTA), and Fourier transform infrared (FT-IR) spectrometry. The clay minerals prevail in most samples, with illite-muscovite being the dominant phase, and kaolinite and chlorite being the other major clay components. No smectite was found. Quartz and feldspars, dominate in two cases. The studied materials are characterized as clays to clayey sands, showing significant similarities with the intraseam layers of the adjacent Achlada lignite deposits.