MMPC涡轮增压系统在柴油机上的应用

主要介绍了一种新近发明的MMPC涡轮增压系统及其性能模拟计算研究,和在8L250Z柴油机上的试验结果,说明MMPC涡轮增压系统能抗扫气干扰、增大扫气系数及降低油耗率。这是一种结构最简单、高性能的涡轮增压系统。     

混合涡轮增压系统的特点及关键技术研究

废气涡轮增压技术能回收部分废气能量而广泛用于车用发动机,但是其固有弱点限制了发动机性能进一步提高。混合涡轮增压系统是在废气涡轮增压技术基础上发展起来的一种性能优异的增压技术。本文介绍了混合涡轮增压技术来源及其研究现状,分析了它的特点和研制的关键技术,定性地论述了结构设计方案,最后进行了混合涡轮增压技术展望。     

结构最简单的MIXPC增压系统

主要介绍了最新开发的1+2 MIXPC涡轮增压系统及其排气管系。已应用于X8320ZC4B及16VPA6STC 等高增压中速机上,性能模拟计算和试验结果表明是成功的。这是一种结构最简单的MIXPC涡轮增压系统。     

柴油机涡轮增压系统

柴油机涡轮增压系统Ｊｏｈａｎ，Ｓｃｈｉｅｍａｎ１涡轮增压系统ＡＢＢ涡轮增压器适用于５０ｋｗ及以上的柴油机。废气驱动增压器涡轮，从而带动与涡轮装在同一轴上的压气机，其压缩空气通过空冷器进入柴油机扫气箱。连接柴油机气缸和增压器燃气进口之间的排气管装置定义...     

两级和三级相继涡轮增压系统比较研究

首先根据内燃机进排气系统一雏非定常流动模拟计算"有限体积法-总变差减少"程序,建立柴油机两级和三级大小相继涡轮增压系统模拟计算程序.然后利用模拟计算程序对两级和三级大小相继增压系统进行研究.研究表明:采用三级大小相继涡轮增压系统优于两级相继涡轮增压系统.     

一种创新的MMPC涡轮增压系统

主要介绍了一种最新发明的MMPC涡轮增压系统及其排气管系。可应用于不同缸数的大功率四冲程柴油机上。性能模拟计算结果表明是可行的。这是一种结构最简单、高性能的涡轮增压系统。     

基于切换点的三级大小相继涡轮增压系统研究

首先根据内燃机进排气系统一维非定常流动模拟计算＂有限体积法-总变差减少＂程序,建立了三级大小相继涡轮增压系统柴油机模拟计算程序。利用该模拟计算程序,在切换点调整时,对三级大小相继增压系统进行研究。研究表明：与切换点固定的柴油机相比,选用可变切换点的三级大小相继涡轮增压系统的柴油机,更能改善各工况下发动机性能。     

柴油机混合涡轮增压系统的研制及试验研究

混合涡轮增压系统是在常规废气涡轮增压器转轴上集成一个既能电动又能发电的高速电机,介绍了研制这一新型增压系统的关键技术和样机在增压器试验台上的试验研究.等压气机流量试验结果显示:混合涡轮增压系统从功能上达到了电动/发电的设计要求,可以根据负荷调整高速电机的工作模式和功率.混合涡轮增压系统在小流量时电动的潜力大,而在大流量时发电功率大.其次,通过调整混合涡轮增压系统的高速电机功率能够拓宽涡轮膨胀比变化范围.另外,由于采用滚动轴承等措施,样机的机械效率高于常规废气涡轮增压器,试验时最高机械效率达到96%.加速特性试验结果表明:混合涡轮增压系统的加速时间比普通废气涡轮增压器缩短40%以上,并且高速电机的电动功率越大,改善涡轮滞后的效果越显著.     

MPC增压系统的研究

1前言当前，涡轮增压柴油机仍在发展，强载程度也不断提高，舰船、机车、发电用柴油机的平均有效压力P．c一般在2．1－2．4MPa，而车用柴油机的P。c亦达到1．5－1．SMPa．与此同时，对柴油机性能的要求也越来越高，不仅要求燃油耗率b低，而且对排放也有限制，尤其是对车用柴油机．由于增压程度的提高，使低工况性能的问题更加突出，即在低工况时，由于涡轮增压系统本身的固有特性，燃烧过量空气系数较低、使燃烧质量降低、b高、燃烧最高温度T。，高、NO。高等，因此，在选择涡轮增压系统时更应计及低工况性能及其有关特性．本文仅对直列…     

涡轮增压柴油机模拟计算等压法的探讨

针对有些模拟计算可以忽略排气压力波的影响，提出了等压法计算的设想，这是一种每一工作循环缸外热力过程只计算一次的简化方法。分析结果表明，这种计算可以满足零维模型必须满足的所有制约方程，能真实地模拟涡轮增压柴油机的实际工作过程，适用于各种增压系统，但仍有待于进一步的研究与改进。根据等压法，建立了一种适用于定压涡轮系统的计算模型--“定压涡轮”模型，用于MPC增压系统的计算，计算结果与试验结果基本吻合，与容积法计算结果趋于一致，从而验证了模型的正确性，同时也表明这种缸外计算法是有效的。     

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.     

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%.     

Contents in Volume 23,2014

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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.     

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.     

汽轮机数字电液调节系统挂闸异常的技术完善

分析了200MW汽轮机数字电液调节系统在运行中存在的挂闸异常问题,采取了相应的技术处理措施,且运行实践效果良好。     

新型高压共轨ECU升压模块的数字化开发与优化

为了提高喷油器电磁阀的响应速率,提出了一种基于CPLD(复杂可编程逻辑器件)应用于高压共轨ECU的数字升压模块。鉴于该升压电路结构参数多,其升压电压的恢复响应要求高等特征,基于Pspice建立了升压电路的仿真模型,研究了不同电路参数下升压模块的输出特性,全面优化了该升压模块的性能。结果显示,该升压模块的最大转换效率可以达90%以上。在柴油发动机上对ECU的试验表明,升压电压最大波动不超过10%,其恢复时间仅为1.3ms,功率管最大温升仅为41℃,满足整机运行范围内ECU的需求。     

Trace metal chemistry and silicification of microorganisms in geothermal sinter, Taupo Volcanic Zone, New Zealand

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.     

Assessment methods of material ageing using Sdobyrev''s creep rupture model

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. σ_red = σ₁ β + (1 − β)σ_i, where: σ₁-maximal principal stress, σ_i-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.     

Production of hydrogen from sewage biosolids in a continuously fed bioreactor: Effect of hydraulic retention time and sparging

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.