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以小桐子油、小桐子生物柴油、地沟油、地沟油生物柴油、0#柴油作为研究对象,对这5种燃油的黏温特性进行了探究分析,同时在自行搭建的雾化燃烧试验平台研究燃油在炉内燃烧火焰体积、长度及火焰温度变化规律,试验结果表明燃烧温度越高,生物质燃油和0#柴油的运动黏度均减小,地沟油减少幅度最大为81.75%;试验条件相同情况下,0#柴油的火焰长度最大为288.209 mm,地沟油火焰长度的最小为207.814 mm,5种燃油燃烧温度在轴线方向先上升后下降,在径向方向波动较大;在不同工况下,随过量空气系数α或雾化压力p的增大,生物质燃油和0#柴油燃烧火焰体积及火焰长度均呈下降趋势;燃油火焰平均温度的变化趋势随过量空气系数α增大先增大后减小,随氧体积分数的增大一直上升,小桐子油增幅最大为25.90%. 相似文献
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《内燃机学报》2016,(3)
利用高速摄影和粒子图像分析技术(PDIA)研究了生物柴油、B 20(80%,生物柴油和20%,正丁醇)、P 20(80%,生物柴油和20%,正丙醇)和E 20(80%,生物柴油和20%,乙醇)的喷雾宏观和微观特性,主要对喷雾贯穿距离、喷雾锥角、索特平均直径(SMD)和液滴尺寸分布等喷雾特性参数进行了分析.结果表明:生物柴油、B 20、P 20和E 20的喷雾贯穿距离依次减小,平均锥角依次增大.随喷射压力和环境压力的增加,燃料的影响逐渐削弱,喷雾贯穿距离和锥角主要受喷射压力和环境压力的影响.喷射压力的升高使生物柴油和醇类-生物柴油混合燃料的SMD减小,小粒径液滴所占的比例有所上升.喷射压力为80,MPa、环境压力为1,MPa时,轴向距离为50,mm处,醇类-生物柴油混合燃料相对生物柴油SMD平均减小1.6,μm(5.7%,),不同醇类-生物柴油混合燃料间SMD也依次减小,但幅度略小.醇类与生物柴油掺混可以提高喷雾质量. 相似文献
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为了研究生物柴油与柴油在雾化质量方面的差异,在燃油雾化质量评价理论的基础上,采用高速摄像机和马尔文激光粒度分析仪对柴油、生物柴油的喷雾特性进行了对比研究;计算分析了喷雾发展的不同时刻的喷雾锥角、贯穿距离,以及喷雾液滴的尺寸体积分布、累计体积分布、特征直径、平均直径和发散边界。结果表明:由于生物柴油的运动粘度、密度和表面张力都大于柴油,所以生物柴油的贯穿距、平均直径、特征直径、发散边界都比柴油的大,喷雾液滴的尺寸体积分布曲线和累计体积分布曲线都偏向大颗粒方向,喷雾锥角和相对尺寸范围比柴油的小,这说明生物柴油的雾化质量差。 相似文献
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基于高压可视化定容燃烧弹试验台,利用高速摄影技术和激光粒度仪对柴油/PODE_(3-4)混合燃料喷雾特性进行研究,分析了燃料物性、喷射压力和喷孔直径对混合燃料宏观与微观特性的影响.结果表明:混合燃料的喷雾贯穿距离大于纯柴油,并呈现先增大后趋于稳定的趋势;在高喷射压力下,相比纯柴油,混合燃料的喷雾贯穿距离增幅较为明显,但平均喷雾锥角增长幅度较小;增大喷孔直径,混合燃料与纯柴油的喷雾锥角和喷雾贯穿距离都增大;喷射压力升高,混合燃料的索特平均直径(SMD)都下降,柴油下降幅度最小,D_v90降幅较为明显,说明在喷射压力影响下,大液滴更容易破碎成小液滴;随着喷孔直径增大,混合燃料的SMD、D_v10、D_v50和D_v90都呈上升趋势,说明较大的喷孔直径不利于混合燃料喷雾特性的改善. 相似文献
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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
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《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
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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
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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
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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
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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
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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