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大功率汽轮机凝汽器汽相流动与传热特性的数值分析 总被引:15,自引:9,他引:15
介绍凝汽器汽相流场与传热特性的数值计算方法及算例分析。该计算方法采用多孔介质模型,以分布阻力和分布质量汇分别模拟冷却管束区的蒸汽流动阻力和凝结效应,利用控制容积积分法及解压力耦合方程的半隐式方法数值求解控制方程组,得出汽相速度、温度、压力、空气浓度、传热系数及热负荷等重要参数的分布。经试验研究表明,该方法能较好地预测凝汽器的工作特性以及管束布置对汽相流场和传热特性的影响。图9参8。 相似文献
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锅炉烟气走廊三维流动特性数值计算 总被引:3,自引:2,他引:1
对锅炉烟气走廊的三维流场进行了计算机模拟计算。采用k-ε模型模拟烟道内烟气走廊的气体流动;将尾部受热面处理为多孔介质;几何拓扑结构采用多块结构,以减少计算机内存的浪费;采用贴体坐标系来描述复杂的几何边界;采用基于交错网格的网格系统;对于控制方程的对流项的离散,采用混合差分(HDS)格式;求解方程使用SIMPLE算法。同时,考虑到孔隙的不连续导致速度的不连续和压力场的不连续,方程求解采用改进的Rhie-Chow法。给出了锅炉尾部烟道内流场速度、温度、湍动能及其耗散率的分布,分析了尾部烟道不均匀流场形成的原因。计算结果与实验吻合得很好。为烟气走廊影响尾部受热面寿命、减少磨损等问题而采取措施提供了理论依据。 相似文献
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余热锅炉管口区传热的数值分析 总被引:1,自引:0,他引:1
应用高温换热设备管口传热分析系统针对某天然气化工厂二次转化气余热锅炉管口区传热问题建立了物理、数学模型,进行了相应的数值分析。数值计算结果表明,新型双瓷管保护结构改善了管口区的传热性能。降低了余热锅炉管口区金属材料的温度,减缓了高温腐蚀反应速度;新型双瓷管保护结构同时改善了管口区域内保护套管的温度“畸变”,因而减轻管口区材料的热应力破坏。 相似文献
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125MW汽机凝汽器内流体流动和传热特性的数值分析 总被引:4,自引:1,他引:3
利用自行开发的凝汽器数值模拟程序PPOC3.0对125MW汽轮机凝汽器的某试验工况进行了数值计算,将得到的计算结果与试验数据进行了比较。然后,对该凝汽器在设计工况下的壳侧流场的换热情况进行了详细数值分析,并指出其中存在的问题。 相似文献
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根据能量平衡原理导出利用节点网络方程组求解一维炉衬不稳定态传热的数学模型。按照通常的间歇式工业炉的工况因素,列出3种边界条件(按预定升温制度升、降温,按固定热流升、降温,空炉随炉冷却)用FORTRAN语言编制成通用程序。为了提高计算结果的精度,程序编制时考虑了对炉衬材料的导热系数和比热的温度修正。计算结果详尽(第一计算所在时间间隔内的计算结果包括炉衬各层分界结点的温度、内表供热流量、外表散热流量、 相似文献
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Masahiro Osakabe Kazuhiko Ishida Kiyoyuki Yagi Tugue Itoh Kunimitu Ohmasa 《亚洲传热研究》2001,30(2):139-151
In order to improve boiler efficiency, latent heat recovery from flue gas is a very important concept. Condensation heat transfer on horizontal stainless‐steel tubes was investigated experimentally by using an actual flue gas from a natural gas boiler. The experiment was conducted at different air ratios of the flue gas and a wide range of tube wall temperatures. The condensation pattern was similar to a dropwise condensation near the dew point. By decreasing the wall temperature, the wall region covered with a thin liquid film increased. The heat and mass transfer behavior was well predicted with the analogy correlation at the high‐wall‐temperature region. At the low‐wall‐temperature region, the total heat transfer was higher than that predicted by the analogy correlation. © 2001 Scripta Technica, Heat Trans Asian Res, 30(2): 139–151, 2001 相似文献
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降低燃气锅炉排烟热损失方法探讨 总被引:4,自引:0,他引:4
燃用天然气的锅炉其排烟温度较高,除带走大量显热之外,烟气中还存在大量水蒸汽的潜热,若将这两部分热量充分回收,则将大幅度提高锅炉热效率。文章在对天然气的燃烧特性计算的基础上,分析燃气锅炉烟气潜热回收的效果和需要解决的问题。 相似文献
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In order to improve boiler efficiency, latent heat recovery from the flue gas is a very important concept. Condensation heat transfer on horizontal tubes was investigated experimentally by using flue gas from a natural gas boiler. The parametric studies concerning the effects of tube stages, gas velocities, SO2 in the flue gas, and Teflon‐lined tubes were conducted at a wide range of tube surface temperature. The heat transfer was enhanced at the second stage due to the wake turbulence of the first stage. No significant decrease of the condensation in the second stage due to the condensate falling from the first stage could be observed. Even at the high gas velocity condition, the condensation pattern was similar to that observed in previous low gas velocity experiments. The effect of SO2 in the flue gas on the condensation behavior could not be observed. The heat and mass transfer behaviors on stainless‐steel and Teflon‐lined surfaces were well predicted with the analogy correlation. The above results suggested that the heat and mass transfer were dominated by the convection and diffusion process on the gas side. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(2): 153–166, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10079 相似文献
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锅炉是一种特殊结构部件,既可以为热电效应为基础的温差发电器提供热源,也可以为其提供冷源,这为应用温差发电器创造了条件。应用温差发电器可以降低排烟温度,减少排烟热损失。文章对应用温差发电器的可能性以及应用后的效率进行了分析,结论是可以提高锅炉效率;提出了如何应用温差发电器件的方法.并对锅炉应用温差发电器降低排烟损失应该考虑的问题进行了分析。 相似文献
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An experimental system investigating condensation heat transfer of wet flue gas was set up, and the heat transfer performance of vapor‐gas mixture with vapor condensation was discussed. The experimental results of laminar flow in a plastic longitudinal spiral plate heat exchanger were obtained and are in good agreement with the modified classical film model. It is shown that the plastic air preheater can avoid acid corrosion in the low‐temperature field for the boiler using fuel containing sulfur and recover latent heat of the water vapor of the wet flue gas. Also some SO2 was scrubbed during the vapor condensing process in the heat exchanger. © 2001 Scripta Technica, Heat Trans Asian Res, 30(7): 571–580, 2001 相似文献
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熔融盐作为太阳能热发电中的重要的传热蓄热介质,其强制对流传热特性对如何强化对流传热和设计以熔融盐作为工质的换热器具有很重要的指导意义。建立了熔融盐-油套管式换热器内不同种类的熔融盐在不同工况下的强制对流传热模型,数值模拟并理论研究了管内熔融盐强制对流传热特性,提出数值模拟的熔融盐对流传热关联式;并将数值模拟结果与实验结果进行了对比。在此基础上分析了流速对管内熔融盐对流传热系数和热流密度的影响规律。结果表明在Re处于10000~60000的范围内数值模拟和实验结果具有较好的一致性。 相似文献