共查询到20条相似文献,搜索用时 78 毫秒
1.
2.
基于内部EGR率控制的柴油机排气凸轮型线仿真设计研究 总被引:1,自引:0,他引:1
以某6缸增压柴油机为研究对象,运用GT-Power仿真分析软件,在目标发动机2 200r/min和1 800r/min常用工况转速下,分析了内部热EGR率对NOx、PM、CO排放量的影响,研究得出了重型车用柴油机内部EGR率的最佳控制范围在10%左右。在此基础上,进行了二次排气凸轮开启相位对内部EGR率控制效果的仿真分析,总结出了二次开启排气凸轮的相位、升程、包角等特性参数对柴油机功率、燃油消耗率及EGR率的影响规律。最终确立了能够进行二次开启的、具有内部EGR功能的排气门凸轮设计方案,建立了排气凸轮基本型线的数学模型。针对目标样机开展了型线特性参数对燃油消耗率、功率及EGR率的影响分析。 相似文献
3.
通过双峰进气凸轮实现内部废气再循环,提出一种利用增压器匹配优化缓解因IEGR引起的进气充量降低的方法.对某非道路柴油机,采用数值模拟与试验验证的方法,研究探索了 IEGR技术方案中进气侧凸轮轴第一次开启包角及凸轮最大预升程相互关系对油耗及EGR率的贡献影响程度,以及排气开启角位置和最大预升程角位置对油耗及EGR率的影响... 相似文献
4.
5.
采用一维发动机工作过程计算软件GT-Power,建立了2种不同管路布置的高压EGR系统仿真模型,模拟研究了其对柴油机性能和排放的影响。研究结果表明:隔开取气的高压EGR系统对排气脉冲能量利用较好,可以提高废气再循环的引入能力(特别是在实现EGR比较困难的低转速大负荷工况),并改善NOx排放和燃油消耗率之间的折中关系;相对单级增压,二级增压采用隔开取气布置的高压EGR系统对性能和排放的改善效果减弱;通过优化二级增压隔开取气方式的EGR管路结构尺寸后,能够进一步改善柴油机的性能和排放。 相似文献
6.
7.
针对一台由国五升级到国六的重型柴油机原始排放(无后处理系统)超过目标设定值的问题进行研究,提出了一种通过控制各缸废气再循环(exhaust gas recirculation,EGR)率不均匀性来降低柴油机原始排放的方法。建立了柴油机各缸EGR率不均匀性的排放测试试验台架和测试方法,通过分析排放万有特性曲线图确定所研究的进气总管EGR率和柴油机运行工况点,用CO2法在稳态工况下测量各缸EGR率,分析各缸EGR率不均匀对排放性能的影响,确定了达到企业原始排放目标设定值的各缸EGR率不均匀性范围,实现了通过控制各缸EGR率不均匀性来降低柴油机原始排放及降低满足国六排放法规后处理系统匹配难度和成本的目的。 相似文献
8.
以SC11CK柴油机为研究对象,实现国Ⅲ排放标准为研究目标,提出了将推迟喷油时间、燃烧室优化、改变凸轮轴配气相位来进行柴油机内部EGR三项技术相结合,利用三项技术的共同作用来改善重型柴油机综合排放性能的技术方案.经试验验证,三项技术协同控制NO<,x>和微粒的排放量效果明显,并在保证原机性能的同时,改善了排放性能,达到... 相似文献
9.
本文介绍作者应用双峰排气凸轮在四冲程脉冲涡轮增压柴油机上实现扫气而不加深活塞顶部让阀坑的新方法.此法已在495Z及6135Z两种涡轮增压柴油机上进行了试验,并取得了有益的效果. 相似文献
10.
增压柴油机采用废气再循环的燃烧过程和排放特性研究 总被引:3,自引:0,他引:3
对于轻型车用增压中冷柴油机,采用从涡轮前取气回流到压气机后的高压EGR系统.应用真空驱动的弹簧膜片式EGR阀,在不同工况下,研究了EGR阀的流通特性,分析了柴油机的HC、CO、NOx排放、烟度和比油耗随EGR率的变化规律.研究了EGR对柴油机燃烧过程的影响,并对排放变化规律作出解释. 相似文献
11.
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. 相似文献
12.
《热能动力工程》2014,(5)
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%. 相似文献
13.
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. 相似文献
14.
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. 相似文献
15.
16.
17.
18.
As part of a pilot study investigating the role of microorganisms in the immobilisation of As, Sb, B, Tl and Hg, the inorganic geochemistry of seven different active sinter deposits and their contact fluids were characterised. A comprehensive series of sequential extractions for a suite of trace elements was carried out on siliceous sinter and a mixed silica-carbonate sinter. The extractions showed whether metals were loosely exchangeable or bound to carbonate, oxide, organic or crystalline fractions. Hyperthermophilic microbial communities associated with sinters deposited from high temperature (92–94°C) fluids at a variety of geothermal sources were investigated using SEM. The rapidity and style of silicification of the hyperthermophiles can be correlated with the dissolved silica content of the fluid. Although high concentrations of Hg and Tl were found associated with the organic fraction of the sinters, there was no evidence to suggest that any of the heavy metals were associated preferentially with the hyperthermophiles at the high temperature (92–94°C) ends of the terrestrial thermal spring ecosystems studied. 相似文献
19.
The physical aspects of the activation energy, in higher and high temperatures, of the metal creep process were examined. The research results of creep-rupture in a uniaxial stress state and the criterion of creep-rupture in biaxial stress states, at two temperatures, are then presented. For these studies creep-rupture, taking case iron as an example the energy and pseudoenergy activation was determined. For complex stress states the criterion of creep-rupture was taken to be Sdobyrev's, i.e. σred = σ1 β + (1 − β)σi, where: σ1-maximal principal stress, σi-stress intensity, β-material constant (at variable temperature β = β(T)). The methods of assessment of the material ageing grade are given in percentages of ageing of new material in the following mechanical properties: 1) creep strength in uniaxial stress state, 2) activation energy in uniaxial stress state, 3) criterion creep strength in complex stress states, 4) activation pseudoenergy in complex stress states. The methods 1) and 3) are the relatively simplest because they result from experimental investigations only at nominal temperature of the structure work, however, for methods 2) and 4) it is necessary to perform the experimental investigations at least at two temperatures. 相似文献
20.
Jaime Massanet-Nicolau Alan Guwy Richard Dinsdale Giuliano Premier Sandra Esteves 《International Journal of Hydrogen Energy》2010
Hydrogen was produced from primary sewage biosolids via mesophilic anaerobic fermentation in a continuously fed bioreactor. Prior to fermentation the sewage biosolids were heated to 70 °C for 1 h to inactivate methanogens and during fermentation a cellulose degrading enzyme was added to improve substrate availability. Hydraulic retention times (HRT) of 18, 24, 36 and 48 h were evaluated for the duration of hydrogen production. Without sparging a hydraulic retention time of 24 h resulted in the longest period of hydrogen production (3 days), during which a hydrogen yield of 21.9 L H2 kg−1 VS added to the bioreactor was achieved. Methods of preventing the decline of hydrogen production during continuous fermentation were evaluated. Of the techniques evaluated using nitrogen gas to sparge the bioreactor contents proved to be more effective than flushing just the headspace of the bioreactor. Sparging at 0.06 L L min−1 successfully prevented a decline in hydrogen production and resulted in a yield of 27.0 L H2 kg−1 VS added, over a period of greater than 12 days or 12 HRT. The use of sparging also delayed the build up of acetic acid in the bioreactor, suggesting that it serves to inhibit homoacetogenesis and thus maintain hydrogen production. 相似文献