高原环境柴油机增压中冷一体化技术研究

针对某重型车辆柴油机高原环境(海拔高于3000m)进气密度下降显著的问题,考虑车辆动力装置结构紧凑、功率密度高等特点,提出增压中冷一体化技术:根据伯努利方程,采用计入摩擦与扩压的"等环量"设计方法对原机压气机蜗壳进行改型优化;采用对流强化传热技术与快速成型技术,设计了三种紧凑型水冷方案;从水散热器后取水,在改进后的压气机蜗壳内部冷却进气,实现增压系统上集成一体化中冷。通过数值仿真与水-汽中冷器传热台架试验,从柴油机高原进气冷却需求、中冷器传热效能、流动阻力特性等方面分析了环形中冷器的热流特性。针对改进前后的柴油机进气方案,进行增压器台架试验,将改进前后压气机特性与发动机的高原匹配进行对比分析,得出了一体化进气方案对发动机性能的影响。试验结果表明:在海拔3700m标定工况下,环形中冷器可使发动机压气机后气体温度降低30℃以上;在海拔4500m外特性工况下,采用一体化装置,取水量为10m3/h,中冷器进水温度90℃,可使柴油机功率最高提升4.5%。     

汽油机水冷中冷器进气歧管设计和性能研究

以风冷中冷器的增压汽油机为原型,设计开发与增压发动机相匹配的集成水冷中冷器的进气歧管。通过三维仿真、发动机台架试验、整车一维仿真分析,对比验证集成在进气歧管中的水冷中冷器与原风冷中冷器性能的差异。分析结果表明:发动机外特性工况下,水冷中冷器进气压力损失比风冷减少50%;水冷中冷器的增压空气管路长度缩短60%;水冷中冷器出气温度比风冷降低3℃以上。     

新型可调进气管的试验研究

本文提出一种可调进气管,即在六缸柴油机进气总管内加一可调整节气门.同时,在6102柴油机上广泛测取了不同管径和管长新进气管充气效率、压力波和整机性能参数.试验表明新进气管进气动力效应利用得到改善,充气效率、最大扭矩获得提高,燃油消耗率、排气烟度得到降低.     

进气总管长度对微型车发动机性能的影响

根据气体的波动效应分析发动机进气管长度对发动机充气效率的影响.利用GT - POWER模拟计算软件,在原发动机基础上分析计算了变进气系统的发动机在不同转速下的性能,同时研究了不同进气管长度对发动机动力性和经济性的影响.优化进气管长度使发动机在各工况都获得较高的充气效率,从而改善发动机性能并通过试验进行验证.     

卡特3306中冷器与6135增压柴油机的匹配试验与研究

通过分析617中冷器和卡特3306中冷器的结构特点,提出了用卡特3306中冷器替代原617中冷器来改善6135增压中冷柴油机的整机性能。试验结果表明,卡特3306中冷器在6135增压柴油机上配置合理,柴油机整机性能得到改善,用卡特3306中冷器匹配的6135增压中冷柴油机不仅可作为船用机型,且为其它用途的柴油机机型的发展也提供了较好前景。     

加长进气管提高R175型柴油机充气效率

本文从合理利用进气管惯性效应和波动效应可以提高发动机充气效率的原理出发，设计了一个加长进气管。通过在Ｒ１７５型柴油机上进行的对比试验表明，加长进气管可以提高发动机充气效率，降低燃油消耗率。     

铝质中冷器在大功率柴油机上的应用

本文对铝、铜质中冷器从结构性能方面进行了试验、分析和对比,认为铝质中冷器具有重量轻,传热效率高等优点。同时,介绍了16V280型柴油机铝质中冷器的试验改进情况和性能数据,经过40万公里的线路运行考核后情良好,证明机车用柴油机采用铝质中冷器是可行的。此外,还对如何提高铝中冷器的寿命用铝中冷器的清洗作了介绍。     

传统中冷器的改造与运用

分析了东风4B型机车用传统的焊接中冷器经常发生漏泄的原因,介绍了新型胀接式中冷器的结构特点,提出了采用新型胀接式中冷器芯体改造传统中冷器的技术改造方案。通过对两种中冷器所做的性能对比试验,证明了新型胀接式中冷器具有明显的降低柴油机排温和油耗的作用,推广使用将会带来显著的经济效益。     

增压中冷电控单体泵柴油机的平均值模型

在工作过程计算基础上,通过电控单体泵的电特性和供油特性分析,并利用台架试验数据建立了一台增压中冷单体泵柴油机（DDC2000）的平均值模型。在原机ECU控制下DDC2000只能按发电机特性工作在1800r／min。而根据该模型计算得到了一张不同转速和负荷下的供油MAP,采用该MAP的ECU明显增强了控制系统的稳定性。模型在稳态和瞬态工况中都能较好地仿真柴油机的响应特性,通过台架上两个点工况和一个瞬态工况的试验数据验证了该模型的正确性。     

废气涡轮增压汽油机进气系统的优化研究

对废气涡轮增压汽油机的进气管和配气相位进行优化研究.进气管优化采用模糊数学优化方法,优化后汽油机在中速区时性能参数改善较好,其中充气效率和扭矩最大增加量分别为1.4％、1.9％;配气相位优化以GT - POWER软件为研究工具,获得了不同转速工况下的最佳值,优化后汽油机的充气效率和扭矩在低、高速区域增加较大,其中充气效率和转矩的最大增加量为13.4％、19.8％.经过分析优化进气系统后,废气涡轮增压汽油机性能得到了提高.     

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%.     

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.     

Contents in Volume 23,2014

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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。     

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.     

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.