基于金属片积碳试验的汽油清洁剂性能测试

为研究汽油清洁剂对发动机喷油器头部积碳的影响规律,以聚醚胺、聚异丁烯胺和曼尼希碱3种汽油清洁剂为研究对象,在金属片积碳试验台架上试验研究其对汽油积碳的影响。对3种汽油清洁剂进行热重测试,在试验台架上对无清洁剂汽油和聚醚胺、聚异丁烯胺、曼尼希碱的质量分数分别为0.5‰和1.0‰的清洁剂汽油进行9个温度条件下的积碳试验,并对生成的积碳进行显微红外光谱测试。结果表明:热稳定性对汽油清洁剂的清洁效果存在重要影响;聚醚胺、聚异丁烯胺和曼尼希碱对汽油积碳的抑制作用与温度密切相关;温度高于180℃时,聚醚胺或聚异丁烯胺质量分数高的清洁剂汽油,金属片积碳反而增加,清洁剂的质量分数对汽油清洁剂的清洁性能存在较大影响。     

柴油发动机预混汽油对排放物的影响研究

利用一台单缸柴油发动机进行了进气道预混合汽油压燃的试验研究。通过安装在进气道的电控喷油器喷射汽油,实现汽油和空气的预混合。汽油和空气的混合气在缸内经过压缩之后,由少量的直喷柴油引燃。研究不同的汽油比例对燃烧参数和排放特性的影响。研究结果表明,随着汽油比例的提高,指示热效率降低,HC,CO增加,NOx与SOOT降低;在小负荷下,随着汽油比例的增加,缸内最大爆压降低;而在大负荷下,随着汽油比例的增加,缸内最高压力增加。     

不同燃料对GDI喷油器积碳的影响

针对缸内直喷汽油机喷油器积碳问题,借助光学显微扫描镜和傅里叶转换红外光谱分析仪等光学检测仪器,结合道路耐久性和喷油器流量损失试验,研究了93#汽油和E10乙醇汽油对缸内直喷汽油机喷油器积碳的影响.结果表明:燃用E10乙醇汽油的喷油器比燃用93#汽油的喷油器积碳严重;两种燃料下积碳沉积物中主要含有甲基、亚甲基、羟基、胺基、烯烃和硫化合物等官能团;燃用E10乙醇汽油的喷油器积碳中所含羟基和硫化物官能团明显.     

延迟焦化汽油回炼至催化裂化提升管探讨

将延迟焦化汽油后续加工流程由柴油加氢精制改至催化裂化装置提升管进行加工,一方面可提高汽油池辛烷值和催化裂化装置轻液收,另一方面可降低全厂氢气消耗。但在生产流程改造后加工存在一些问题,因为操作原因,会导致气压机发生喘振故障,影响催化剂流化,造成反应温度以116.25℃/h的速率降低到460℃,发生装置联锁停止进料异常事故;延迟焦化汽油回炼比例提高1个百分点,催化裂化稳定汽油辛烷值下降0.26个单位、催化裂化稳定汽油硫含量增加30.5mg/kg。解决方案如下:针对性研究压机操作,并组织培训事故预案;调和汽油时,提前考虑到对汽油池影响,避免出现产品不合格情况;S Zorb装置提高反应温度和吸附剂加入量。经过上述措施,解决了生产中出现的问题。对改造后的装置物料平衡进行了核算,汽油收率为57.38%,液化气收率为26.67%;焦化汽油经过提升管裂解后,原油每吨利润增加303.62元。     

压电陶瓷温度效应对燃油喷射特性的影响仿真

基于Matlab/Simulink建立了压电执行器非线性数学模型来描述执行器的电-机转换过程,在试验的基础上对压电材料的压电常数和电容进行了温度修正,并耦合喷油器其他机-液部分,建立了完整的压电喷油器电-机-液模型,经试验验证,执行器数学模型误差为4.6%,喷油器模型误差为7.8%.分析了不同工作温度下压电喷油器喷射特性和各腔室压力波动特性,结果表明:工作温度的升高使得执行器输出位移增加了24.6%,球阀腔泄油后最低压力降低,各腔室压力建立过程后移,针阀升程增加,关闭时刻推迟;在喷油脉宽为0.1 ms时温度的影响更加明显,温度升高至150℃时,相比于30℃,油量偏差率最高至70%,喷油速率峰值增加了约24%,最高喷射压力提高了9 MPa,喷油持续期增加了0.06 ms;脉宽较大(ET=1.0 ms)时,开启阶段喷油速率、最高喷射压力和喷油速率峰值影响不大,但喷油关闭时刻推迟了0.11 ms左右.     

温度对高压共轨喷油器喷射性能的影响

温度对柴油的物性参数影响很大,为了研究温度对高压共轨喷油器喷射性能的影响,建立了柴油物性参数随温度和压力的变化公式,并构建和简化了喷油器的数学模型。利用软件AMESim建立了喷油器模型,根据试验数据验证了模型的正确性。在不同温度下仿真计算了喷油特性,得到了不同温度下喷油器的喷油速率曲线和一次喷油量曲线。结果表明,温度对喷油器的喷油速率有一定的影响。对喷油器的设计改进提供了理论指导。     

汽油直喷喷油器响应特性仿真分析及优化

以汽油缸内直喷(GDI)喷油器为研究对象,以JMAG电磁仿真软件为计算平台,建立喷油器电磁阀三维电磁场有限元模型,通过试验,验证了计算模型,运用模型研究了对喷油器响应特性的影响因素,并以提高喷油器响应特性为出发点,对喷油器电磁阀的驱动电流和关键结构参数进行了设计优化,通过分析计算,为喷油器驱动控制以及结构参数的合理设计提供了理论依据。     

高背压下GDI油束喷雾特性的试验

在定容弹中,利用高速摄影和相位多普勒粒子测试技术(PDPA)研究了喷射压力、背压和喷射脉宽对汽油直喷(GDI)发动机多孔喷油器喷雾特性的影响,包括喷雾贯穿距、粒度和速度特性.结果表明:随着喷雾的发展,油束有往喷油器中心方向运动的趋势;在不同喷射压力和背压下,喷雾贯穿距均出现两阶段发展趋势;喷射压力和背压对喷雾的粒度和速度特性有着明显影响.提高喷射压力会明显降低索特平均直径(SMD),并会增加油滴速度.增加背压会导致SMD变大,并使油滴速度降低.SMD会随PDPA测量体位置远离喷油器而增大,这是由于在远离喷油器位置处,油滴间聚合作用占主导因素.在喷射脉宽大于0.8,ms时,喷射脉宽的变化对喷雾头部的速度影响不大,但是喷油脉宽的增加会导致SMD变大.     

ZH1105W型柴油机喷油器孔组件的结构工艺性

1 原喷油器孔组件的结构及其工艺性第一代ZH1105W型柴油机,喷油器孔组件如图1所示,由气缸盖1上喷油器孔如图2所示,喷油器铜套2和密封环3组成,我们称其为喷油器孔组件。其最终功能是容纳喷油器并将喷油器与冷却水隔离。喷油器孔其主要功能是: a.形成容纳喷油器铜套空间; b.可固定喷油器铜套; c.容纳密封原件。喷油器铜套2的主要功能是: a.隔离冷却水; b.容纳喷油器; c.散发热量,与喷油器孔和密封原件形成安装喷油器的无冷却水空间A和隔离冷     

ZH1105W型柴油机喷油器孔组件的结构工艺性

1原喷油器孔组件的结构及其工艺性第一代ZH1105W型柴油机,喷油器孔组件如图1所示,由气缸盖1上喷油器孔如图2所示,喷油器铜套2和密封环3组成,我们称其为喷油器孔组件。其最终功能是容纳喷油器并将喷油器与冷却水隔离。喷油器孔其主要功能是: a.形成容纳喷油器铜套空间; b.可固定喷油器铜套; c.容纳密封原件。喷油器铜套2的主要功能是: a.隔离冷却水; b.容纳喷油器; c.散发热量,与喷油器孔和密封原件形成安装喷油器的无冷却水空间A和隔离冷     

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.