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以煅烧铝矾土、滑石和石英为原料,设计太阳能热发电储热用原位合成堇青石-莫来石复相陶瓷组成并制备样品,采用XRD、SEM等现代测试技术对样品的性能及微结构进行研究。探讨样品相组成及微观结构对储热陶瓷样品抗热震和储热性能的影响。结果表明,原位合成四方柱状莫来石结合原位合成条柱状堇青石可显著提高样品的抗热震性能和储热性能;经1450℃烧成的堇青石-莫来石复相储热陶瓷样品热膨胀系数为3.64×10~(-6)K~(-1)(室温~850℃);储热密度为1416 kJ/kg(0~800℃);热震30次(室温~800℃,气冷)不开裂,且热震后抗折强度增长了28.11%。满足太阳能热发电显热储热材料的要求。 相似文献
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以煅烧铝矾土、滑石及石英为原料,采用挤出成型,制备堇青石-莫来石复相蜂窝陶瓷,用这种显热储热陶瓷(简称基体)封装PCM制备潜热/显热复合储热材料。设计F系列封装剂配方组成,选择PCM为AlSi20、Na2SO4,制得PCM/蜂窝陶瓷复合储热材料,热震循环(200~900 ℃)30次,每次循环在900 ℃保温12 h。利用XRD、SEM、TG-DSC等分析相组成、微观结构、封装剂与基体结合性、基体与PCM相容性、复合储热材料的相变温度及相变焓。结果表明,经1440 ℃烧成的蜂窝陶瓷,Wa、Pa、D及a轴抗压强度分别为2.38%、6.32%、2.65 g/cm3,25.77 MPa;XRD显示相组成为堇青石、莫来石及少量镁铝尖晶石;30次热震后,Wa、Pa略有升高,D及σa略有降低。封装剂剪切强度测定结果表明,封装剂F2与基体结合强度最大,达2.53 MPa,SEM显示F2与基体结合良好。热震30次后,基体断面SEM图表明,PCM无渗漏。TG-DSC结果表明,经30次热循环后,AlSi20/蜂窝陶瓷复合储热材料的相变范围为571.7~583.5 ℃,峰值为578.3 ℃,峰值温度偏移不超过0.7%。复合储热材料具有优良的储热性能。 相似文献
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<正> 前言堇青石骨料轻质保温砖用于电热隧道窑炉烧成带,代替粘土耐火砖砌筑,具有窑体轻、保温性能好等优点。由于堇青石砖在高温下荷重软化点高,耐急冷急热,优于其它轻质耐火材料和保温材料,在1300℃以下的窑炉中使用,有着极其光明的前景。 相似文献
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柴油机排气微粒过滤器性能的研究 总被引:1,自引:0,他引:1
本文报导了在发动机台架试验中,泡沫陶瓷柴油机排气微粒过滤器的性能随柴油机工况变化的规律,为微粒过滤器的优化设计提供了一些依据。文中的数据是利用485Q 柴油机在发动机台架试验中获取的。此柴油机的排量为2.27L;压缩比为20:1;标定功率为37kW(当转速在3000r/min 时)。因柴油机排气微粒中含有部分未燃燃料的液态颗粒,这部分微粒不易被波许烟度计反映出来,所以本验试用过滤式质量浓度测量系统来测量微粒的数量。关于试验系统的设计及质量浓度测量装置,本文作者已有较详细的报导。试验时所采用的过滤材料是泡沫陶瓷。泡沫陶瓷为堇青石质(主要化学成分为SiO_2、Al_2O_3、Fe_2O_3等),平均孔径为0.3~0.5mm, 相似文献
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美国一家公司最近研制一种 D2600新型高温陶瓷纤维绝热毯,可用在2000℉以上的高温炉窑中,强度高,收缩率低,节能效益明显。这种材料的关键化学成分为高纯度铅矾土,氧化锆和二氧化硅。它的强度相当于普通绝热毯的5倍。制造工艺独特,是他们的专利。用这种专利加工,陶瓷纤维呈交叉链锁状,针形结构,具有很高的强度。不需要任何有机粘结剂。除上述特性外,这种绝热毯还具有热导性能低,热贮性低,质轻,抗热震,热反射性高和吸音性能好等特点。最适宜在陶瓷窑,钢坯与板坯加热炉,锻造炉,转炉炉门与炉罩,锅炉内衬,大包予热器上应用。 相似文献
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以红柱石为主要原料,采用原位生成堇青石技术制备高温性能优良的红柱石蜂窝陶瓷储热材料.再利用特制的封装剂将相变材料(PCM)封装在部分蜂窝陶瓷孔中,制备储热密度大的显热-潜热高温复合储热材料.采用SEM,EPMA,TG-DTA等测试方法对封装剂与陶瓷基体的结合性,PCM与陶瓷基体的适应性及复合储热材料的储热密度进行研究.结果表明红柱石蜂窝陶瓷能安全地封装PCM,封装质量分数为20%的K2SO4后的储热密度为987.70 kJ/kg(0~1080 ℃),封装质量分数为16%的NaCl复合储热密度为796.40 kJ/kg(0~810 ℃).制备的复合储热材料具有较高的储热密度,能实现高温储热. 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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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
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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