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甲醇燃料汽车是利用发动机尾气余热提供能量催化甲醇重整制氢,将反应后的产物作为燃料通入气缸内燃烧,为发动机提供动力,可以实现汽车节能,降低排放污染。甲醇重整反应器对汽车动力性能影响至关重要,为了使反应气体达到催化反应温度,设计适当的反应器并模拟其催化换热过程尤为关键。通过热力计算设计了螺旋管式和直管式两种甲醇反应器,建立反应器模型,以化学反应宏观动力学模型为基础,基于Fluent软件对反应器的换热及化学反应过程进行数值模拟。通过对反应器的温度场、流场及各组分浓度分布等模拟结果进行分析,比较了螺旋管与直管反应器换热性能的差异。同时改变边界条件,分别探讨了水醇比、冷流流量、热流流速对反应器催化换热性能、甲醇转化率及氢气产出量的影响。 相似文献
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本文简述预反应器在生产过程中存在的各种故障和问题,通过对影响预反应器正常运行的原因分析,提出对其电加热系统技术改造的设想。经过理论分析论证和模拟试验可行后付诸实施,彻底解决了问题,从而实现了预反应器长周期稳定运行。 相似文献
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不同基板预热温度对激光金属沉积成形过程热应力影响的研究 总被引:1,自引:0,他引:1
研究不同基板预热温度对激光金属沉积成形过程热应力的影响,对于降低成形过程的热应力,抑制成形过程裂缝的产生,减小成形过程试样和基板的翘曲变形具有非常重要的意义.根据有限元分析中的"单元生死"技术,编程建立了基板预热对激光金属沉积成形过程热应力影响的三维多道多层数值模拟模型,详细分析了基板未预热和分别预热到200℃、300℃、400℃、500℃ 、600℃时对沉积成形过程Von Mise'S热应力、X方向、Y方向以及Z方向热应力的影响.在与模拟过程相同的参数下,利用镍基合金粉末分别在基板未预热和分别预热到300℃ 、400 ℃、500℃、600℃ 时进行了成形试验,试验的结果跟数值模拟结果吻合较好. 相似文献
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用CFD模拟方法对超临界水氧化反应器模型进行热工模拟计算.以甲醇溶液模拟有机废液,以空气为氧化剂,模拟计算超临界反应温度场及反应后各组分的分布,确定超临界及亚临界区域,以及反应器出口温度,确定内衬管的工况,为超临界水氧化反应器设计提供参考. 相似文献
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建立微弧沉积加工的物理模型与温度场的数学模型,利用有限元法模拟微弧沉积加工的电热过程,并对温度场模拟结果进行理论分析,揭示微弧沉积加工的放电机理,为合理选择加工参数及温度的测量提供了理论依据。 相似文献
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双螺杆反应器组合螺杆的三维流场数值模拟 总被引:1,自引:0,他引:1
利用计算流体力学法(CFD),对聚合物熔体在啮合盘和螺纹元件的组合螺杆反应器中的流动规律进行了数值模拟,并和双螺杆常规螺纹元件反应器进行了对比分析.计算结果表明,虽然组合螺杆反应器的物料输送能力小于常规螺纹元件反应器,但组合螺杆的分布性混合和分散性混合能力远好于常规螺纹元件. 相似文献
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Ik-Tae Im Nag Jung Choi Masakazu Sugiyama Yoshiyaki Nakano Yukihiro Shimogaki Byoung Ho Kim Kwang-Sun Kim 《Journal of Mechanical Science and Technology》2005,19(6):1338-1346
Effects of thermal contact resistance between heater and susceptor, susceptor and graphite board in a MOCVD reactor on temperature
distribution and film growth rate were analyzed. One-dimensional thermal resistance model considering thermal contact resistance
and heat transfer area was made up at first to find the temperature drop at the surface of graphite board. This one-dimensional
model predicted the temperature drop of 18K at the board surface. Temperature distribution of a reactor wall from the three-dimensional
computational fluid dynamics analysis including the gap at the wafer position showed the temperature drop of 20K. Film growth
rates of InP and GaAs were predicted using computational fluid dynamics technique with chemical reaction model. Temperature
distribution from the three-dimensional heat transfer calculation was used as a thermal boundary condition to the film growth
rate simulations. Temperature drop due to the thermal contact resistance affected to the GaAs film growth a little but not
to the InP film growth. 相似文献
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Bahlawane N Struckmeier U Kasper TS Osswald P 《The Review of scientific instruments》2007,78(1):013905
Chemical vapor deposition (CVD) and metal-organic chemical vapor deposition (MOCVD) have been employed to develop alumina thin films in order to protect thermocouples from catalytic overheating in flames and to minimize the intrusion presented to the combustion process. Alumina films obtained with a CVD process using AlCl(3) as the precursor are dense, not contaminated, and crystallize in the corundum structure, while MOCVD using Al(acetyl acetone)(3) allows the growth of corundum alumina with improved growth rates. These films, however, present a porous columnar structure and show some carbon contamination. Therefore, coated thermocouples using AlCl(3)-CVD were judged more suitable for flame temperature measurements and were tested in different fuels over a typical range of stoichiometries. Coated thermocouples exhibit satisfactory measurement reproducibility, no temporal drifts, and do not suffer from catalytic effects. Furthermore, their increased radiative heat loss (observed by infrared spectroscopy) allows temperature measurements over a wider range when compared to uncoated thermocouples. A flame with a well-known temperature profile established with laser-based techniques was used to determine the radiative heat loss correction to account for the difference between the apparent temperature measured by the coated thermocouple and the true flame temperature. The validity of the correction term was confirmed with temperature profile measurements for several flames previously studied in different laboratories with laser-based techniques. 相似文献
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常压下用金属有机化学气相沉积法(MOCVD),以仲丁醇铝(ATSB)为前驱体、氮气为载气在HP40钢表面制备了纳米氧化铝薄膜;用光学显微镜、扫描电子显微镜及能谱仪、X射线衍射仪、原子力显微镜等研究了沉积温度等参数对氧化铝薄膜沉积速率的影响,并对其形貌进行了观察。结果表明:随着沉积温度从503K升高到713K,薄膜沉积速率从0.1mg·cm~(-2)·h~(-1)增加到0.82mg·cm~(-2)·h~(-1);当沉积温度在593~653K范围内,可获得晶粒尺寸为10~15nm的纳米氧化铝薄膜;反应的表观活化能随氮气与ATSB蒸气混合气流速增加而降低,不同的混合气流速有不同的反应级数,ATSB的反应级为0.7±0.02。 相似文献
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建立了等离子熔积快速直接成形(Plasma Deposition Manufacturing, PDM)过程多相混态场统一模型,基于蒙特卡罗法(Monte Carlo,MC)建立热影响区(Heat Affected Zone,HAZ)晶粒长大过程的数学模型。分析了不同热源功率工艺条件下熔池温度场和流场的变化规律以及特征点的温度循环曲线,进而探究了热源功率对热影响区晶粒尺寸与分布的作用机理。对AISI316合金等离子熔积过程进行了模拟,所得的计算结果与试验结果基本一致。 相似文献
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Felipe Vásquez Jorge Andres Ramos-Grez Magdalena Walczak 《The International Journal of Advanced Manufacturing Technology》2012,59(9-12):1037-1045
This work reports a theoretical and numerical study of the parameters related to the process of laser powder deposition through a lateral nozzle. For this purpose, a 3D quasi-stationary finite element model was developed analytically and implemented numerically. The proposed model estimates the shape of the melt pool depending on the process parameters including scanning speed, powder mass flow, laser power, and physical properties. Also, phase transformations and physical properties (density, thermal conductivity, and specific heat) vary as function of temperature. In addition, thermo-capillary forces and their effect on fluid flow inside the melt pool are considered. The obtained set of equations coupled through the temperature variable was solved using COMSOL Multiphysics. The results are presented and compared with previously obtained experimental data, in which chromium powder was deposited, allowing validation of the model. Finally, variations at the melt pool geometry in terms of the operational parameters are analyzed. This model aims at estimation of melt pool geometry during laser powder deposition in time reasonably short to allow for predictable process control. 相似文献
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金属有机物化学气相淀积(MOCVD)技术是当前研制和生产先进化合物半导体材料的最主要技术。结合液态源MOCVD设备控制系统的组成与特点,给出了液态源MOCVD控制系统,该系统采用可编程逻辑控制器和触摸屏实现了整个系统的控制和管理,取得了满意的研究结果。 相似文献
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