涡轮增压机组与增压锅炉热力匹配计算方法研究

基于涡轮增压机组与增压锅炉匹配工作两者之间存在的热平衡关系、压力平衡关系,以及涡轮增压机组内部存在的功率平衡关系,考虑机组管路系统的阻力特性和边界条件约束等,采用集中参数法给出了增压机组与增压锅炉两者配合工作的联合工作方程组,建立了适用于研究两者工作匹配特性的热力平衡计算模型,提出了一种迭代求解计算方法。在此基础上,通过仿真试验与机组主要测试数据的对比分析,证明了计算方法的可行性,以及建立的模型的正确性和有效性。还进一步研究分析了海况环境进气温度条件变化对两者的热力配合特性的影响。本研究为建立和掌握增压锅炉装置涡轮增压机组与主锅炉的热力匹配设计方法奠定了一定的理论基础。     

二次进气超高增压系统采用MPC方式的模拟计算与研究

本文提出了一种“修正容积法”的计算模型,用于模件式脉冲转换(MPC)系统。计算与试验曲线比较,很相一致。这说明可以用于模拟计算,具有一定的精度。文中还讨论了MPC系统用于二次进气超高增压系统中的适应性。从计算结果看出,在性能上,比用定压系统时更好。     

谈脉冲增压和MPC增压

谈脉冲增压和ＭＰＣ增压南通柴油机股份有限公司钱树基为了增加单机功率，废气涡轮增压技术在柴油机上得到广泛的应用。以前用得较多的主要有两种增压系统：一种是定压系统，排气总管的容积做得较大，使排气管内的压力基本上保持恒定；另一种是变压系统，即脉冲系统见图１...     

车用柴油机涡轮增压匹配系统软件开发

根据涡轮增压柴油机的平均参数模型,建立了车用柴油机增压选型与匹配系统,可以完成对增压方案的选取、增压参数的计算以及增压器型号的选取等工作;以Visual C++为开发平台,进行了系统软件的开发;以D6114柴油机为例进行了匹配计算,并与相应的试验结果进行对比,两者吻合良好,进一步验证计算模型、程序的正确性。     

内燃机增压系统一维非定常流混合模型的研究

建立了用于内燃机增压系统流动模拟的零维与一维相结合的非定常流动混合计算模型。计算实践表明,该模型在各种计算条件下,排气压力波预测精度较高,计算流量误差一般均小于１％ ,而且计算稳定。所编制的内燃机增压系统一维非定常流混合模型计算源程序具有较强的通用性,可适用于组合式ＭＳＥＭ、ＭＰＣ、脉冲、脉冲转换器和ＭＩＸＰＣ涡轮增压系统     

某型增压柴油机排气系统的仿真研究

排气系统设计是否合理对柴油机的性能有着重要影响,为了探求某型增压柴油机采用不同排气系统的优越性,本文以内燃机性能仿真软件GT-Power为平台,建立了工作过程仿真模型,利用试验数据验证了模型的可靠性.柴油机采用脉冲增压系统,针对定压增压系统和MPC增压系统对原机的排气系统进行了重新设计,建立了定压增压系统和MPC增压系统的柴油机模型,并分别对其进行了稳态工作过程计算,着重分析研究了采用不同排气系统对该柴油机性能的影响,为该柴油机排气系统的改进提供了参考依据.     

一个车用增压柴油机的实时动态仿真模型

为进行电控增压柴油机的研究和开发,提出了一个车用增压柴油机的实时动态仿真模型。从控制的角度将系统分为压气机,发动机,废气放气装置和涡轮四个部分,将发动机每个工作循环和时间作为计算时间步长,将工作循环的平均参数作为计算目标,计算时间少,实时性好。对一台带有废气放气装置的车用增压柴油机的动态过程进行了仿真计算,计算结果与实测值进行了比较,计算精度满足实时动态仿真要求。     

用VVT法控制涡轮增压汽油机负荷和增压压力的研究

本在分析了涡轮增压汽油机负荷和增压压力的常规调节法的基础上提出了一种新的调节方法，即ＶＶＴ法，该方法是通过控制进气门的关闭定时来控制这类发动机的负荷和增压压力，从而抛弃了传统的节气门和废气放气阀等系统。研究结果表明，采用ＶＶＴ法的最大优点是能有效地降低这类发动机的爆震倾向和明显地改善其换气功，本研究采用了西柏林工业人燃机研究所开发的模拟涡轮增压汽油机工作过程的计算程序，该程序的模拟精度在中用实     

高背压环境条件下涡轮增压柴油机排气系统适应性研究

本文通过对多脉冲引射排气系统和定压增压排气系统的模拟计算,研究了高背压和高真空环境条件下废气涡轮增压柴油机的排气系统的适应性。结果表明多脉冲引射排气系统对高背压环境条件下的自由废气涡轮增压柴油机并未显示其通常的优越性,而定压增压排气系统却表明具有明显的优点。文章也拟定了4脉冲引射排气系统的模拟计算方法,讨论了多脉冲引射排气系统的排气引射系数对柴油机性能的影响。     

径流涡轮部分进气工作特性的试验和计算以及增压匹配模拟

发动机脉冲涡轮增压系统中,两支排气管共用一涡轮的情况是常有的。由于排气脉冲使涡轮两供气进口的气体状态参数不一致,产生了“部分进气”现象,使涡轮的工作特性发生变化。论文介绍了对径流涡轮工作特性进行的试验研究,分析了径流涡轮在“部分进气”工况下的工作特性,提出了数学模型与计算方法,并进行了计算。同时将此数学模型作为涡轮端的边界条件,用特性线法进行了增压匹配模拟计算。     

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.