共查询到20条相似文献,搜索用时 93 毫秒
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唐强宋赞杨仲卿刘川川 《工程热物理学报》2014,(6):1232-1235
采用实验的方法,在鼓泡流化床燃烧装置中研究了低浓度煤层气在床内的流动和燃烧特性,考察了床层温度、气体浓度、流化风速及床料颗粒特性等操作条件变化对甲烷转化率和燃烧产物的影响。研究表明:床层温度升高,甲烷转化率显著增加;增加流化风速及进气甲烷浓度,甲烷转化率减小;颗粒粒径增加,甲烷转化率增加;CO排放浓度随床层温度的升高先增加后降低,并在床层温度约850℃时达到其最大峰值,沿流化床轴向高度CO的排放浓度先增加后降低,呈钟型分布。 相似文献
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布风板结构参数显著地影响着床层内部气固两相流流动特性,为了探究流化床干燥装置内油菜籽颗粒流化性能和空气流速脉动规律,明晰不同面板凸度、风帽开孔夹角和开口瓣数对风帽布风板布风性能的影响,提出布风板结构数的优化方案。以15.84%开孔率圆形非均匀布孔布风板为基础,根据Euler/Euler双流体模型和Standardk-ε湍流模型,采用ANSYS19.1中流体动力学分析模块Fluent软件对面板凸度(2 mm、5 mm和10 mm)、风帽开孔夹角(0°、5°和10°)和开口瓣数(四瓣、六瓣和八瓣)进行优化设计,并通过实验进行验证。结果表明:5 mm凸度球面板、四瓣风帽、5°开孔夹角布风板是油菜籽流化床干燥的最佳布风板。与平面布风板相比,凸形球面布风板的油菜籽分布均匀性好,其中凸度为5 mm球面板油菜籽平均体积分数方差(0.007 3)最小,促使其与热空气接触均匀充分。5°风帽开孔夹角有利于颗粒运动呈现脉动流动,是油菜籽干燥布风板的最佳开孔夹角。风帽开口瓣数对油菜籽流化床干燥的布风性能影响不大,相对来说四瓣风帽开口瓣数能更好地均布空气流。通过实验对模拟结果进行验证,结果发现数值模拟与实验结果... 相似文献
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流化床反应器进行药物颗粒混合、制粒和干燥工序中,颗粒含水率通常会在大范围(1%~25%)内变化。为优化生产过程,避免故障发生,需要对流化床内湿颗粒流动进行实时监测。微波层析成像(Microwave Tomography,MWT)技术具有较宽的工作频段,适用于高介电常数和高电导率介质的测量。本文利用16个天线微波层析成像传感器对顶喷流化床加湿-干燥过程进行层析成像测量,得到了不同实验条件下颗粒含水率变化曲线和截面颗粒分布图像。实验结果显示,通过对平均介电常数-颗粒含水率关系的标定,可以准确地在线测量颗粒含水率。同时,微波成像揭示了被测截面颗粒分布特征。在此基础上,结合流化床内压差数据对加湿-干燥过程中颗粒流态变化进行了深入讨论,本研究表明,微波层析成像技术应用于流化床过程监控和关键参数提取具有广泛的前景。 相似文献
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本文基于颗粒动理学理论建立了流化床中的欧拉双流体模型,采用了单气泡沿壁面运动物理模型,从颗粒分布特性、温度分布特性和瞬时传热特性三个方面对超临界水流化床和气固流化床的床层与壁面间传热特性进行了对比研究。研究表明,相同条件下,相对于气固流化床,超临界水流化床中气泡的直径和上升速度都较小;超临界水流化床中床层与壁面间的传热系数与颗粒浓度呈反相关关系,而对于气固流化床则是正相关关系;并且不同于气固流化床,超临界水流化床床层与壁面间传热系数在颗粒浓度较低处对表观速度变化比较敏感。 相似文献
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讨论了银道面内的引力场强分布和太阳在银河系中所受引力与到银心距离r的关系,指出引力场强g并不是与r的平方成反比,这是由于银河系的大小和形状不能忽略造成的.强调了万有引力定律的适用条件. 相似文献
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The investigation was made of the dependence of the intensity of Tl, Ga, Mo, Mg, Mn, Sn, Bi, Ni, Zn, Pt and Au spectral lines and the plasma parameters (temperature T, electron concentration ne, degree of 6 ionnization α) from concentration of lithium additive. 相似文献
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SJ Rose 《Contemporary Physics》2013,54(2):109-121
In this paper we describe experiments conducted with high-power lasers that are attempting to replicate, for a very short time and in miniature, conditions found in the Sun. Experiments to date have reached conditions in the outer part of the Sun. To reach the Sun's centre requires compression of material to very much greater than solid density and heating to over ten million degrees. To achieve this, a new class of experiments and a new generation of high-power lasers are required. 相似文献
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We study the Cauchy problem for the Whitham modulation equations for increasing smooth initial data. The Whitham equations are a collection of one-dimensional quasi-linear hyperbolic systems. This collection of systems is enumerated by the genus g=0,1,2, ... of the corresponding hyperelliptic Riemann surface. Each of these systems can be integrated by the so-called hodograph transformation introduced by Tsarev. A key step in the integration process is the solution of the Tsarev linear overdetermined system. For each g>0, we construct the unique solution of the Tsarev system, which matches the genus g+1 and g–1 solutions on the transition boundaries. 相似文献
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Let G be one of the local gauge groups C(X, U(n)),C
(X, U(n)), C(X, SU(n)) or C
(X, SU(n)) where X is a compact Riemannian manifold. We observe that G has a nontrivial group topology, coarser than its natural topology, w.r.t. which it is amenable, viz. the relative weak topology of C(X, M(n)). This topology seems more useful than other known amenable topologies for G. We construct a simple fermionic model containing an action of G, continuous w.r.t. this amenable topology. 相似文献
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The lightest supersymmetric particle (LSP) is a natural candidate for the cold dark matter of the universe. In this Letter we discuss how to test the mechanism responsible for the LSP stability at the LHC. We note that if R-parity is conserved dynamically one should expect a Higgs boson which decays mainly into two right-handed neutrinos (a “leptonic” Higgs) or into two sfermions. The first case could exhibit spectacular lepton number violating signals with four secondary vertices due to the long-lived nature of right-handed neutrinos. These signals, together with the standard channels for the discovery of SUSY, could help to establish the underlying theory at the TeV scale. 相似文献
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Denis de Carvalho Braga 《Physics letters. A》2010,374(42):4316-4320
In this note we present an analytical study of the stability of the equilibria of the Rikitake system. We prove that the two non-hyperbolic equilibria of the Rikitake system are unstable for all positive values of the parameters. 相似文献
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