新型空冷凝汽器单元及其传热特性研究

发布时间：2018-05-12 00:14

本文选题：双曲型空冷单元 + 圆台型空冷单元　；参考：《华北电力大学》2016年硕士论文

【摘要】：直接空冷技术在如今富煤贫水的内陆广大地区已应用越来越多,空冷带给人们的好处是巨大的,但是空冷凝汽器换热的缺陷也随之越来越明显。直接空冷单元的“Λ”形结构是广泛被人们赞同的,同时也是空冷单元内部流场温度场分布不均的主要原因。为了解决这些问题,使其更经济安全,前人做了许多努力。本课题致力于推陈出新,突破局限,提出新的空冷凝汽器单元结构,并对其传热特性进行研究,这对改进传统直接空冷技术具有重要的现实意义。本文以改进现有直接空冷凝汽器单元典型结构中所存在的问题为目的,首先,以龙山电厂600MW机组的模型为比较对象,模拟了两种我们自己提出的新型空冷单元的流动和传热情况,又在双曲型空冷单元顶部加装挡板和半翅片挡板,并对挡板孔隙率对双曲型空冷单元换热的影响进行了模拟分析,得到最佳双曲型空冷单元的形式;其次,在考虑双曲型空冷单元制作安装和换热面积的基础上对其进行改进,将双曲换热面改成圆台面的形式,对圆台型空冷单元的流动传热特性与顶部孔隙率的关系进行了探讨,得出有利换热和安全使用的最佳孔隙率;再次,又讨论了遮风板对圆台型空冷单元的换热的影响,对遮风板的形式进行了优化;最后,将以上各种形式的空冷单元在不同的入口风速和环境温度下进行比较,得到最有利于换热、并且适宜长久安全使用的新型直接空冷单元形式;这些都为传统直接空冷技术的改进提供了重要的理论依据。
[Abstract]:Direct air cooling technology has been used more and more in the inland areas with rich coal and poor water. The benefits of air cooling are great, but the defects of air cooling condenser heat transfer are becoming more and more obvious. The "A" shape structure of the direct air-cooled element is widely accepted by people, and it is also the main reason for the uneven distribution of the flow field temperature field in the air-cooled unit. In order to solve these problems and make them more economical and safe, the predecessors have made a lot of efforts. This paper is devoted to bring forth new ideas and break through the limitation, and put forward a new unit structure of air-cooled condenser and study its heat transfer characteristics, which is of great practical significance to improve the traditional direct air-cooling technology. This paper aims at improving the existing problems in the typical structure of direct air-cooled condenser units. Firstly, the model of 600MW units in Longshan Power Plant is taken as a comparison object. The flow and heat transfer of two new air cooling units proposed by us are simulated, and the baffles and half fin baffles are added to the top of the hyperbolic air cooling units. The effect of the porosity of the baffles on the heat transfer of the hyperbolic air cooling units is simulated and analyzed. The optimal form of hyperbolic air cooling unit is obtained. Secondly, the hyperbolic heat transfer surface is changed into a round table surface based on the consideration of the fabrication, installation and heat transfer area of the hyperbolic air cooling unit. The relationship between the flow heat transfer characteristics and the top porosity of the round type air cooling unit is discussed, and the optimum porosity favorable for heat transfer and safe use is obtained. Thirdly, the effect of the shielding plate on the heat transfer of the round platform type air cooling unit is also discussed. The form of the baffle is optimized. Finally, the air cooling units mentioned above are compared at different inlet wind speeds and ambient temperatures, and the results show that the air cooling units are most favorable for heat transfer. And a new type of direct air cooling unit is suitable for long-term safe use, which provides an important theoretical basis for the improvement of traditional direct air cooling technology.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TM621;TK124

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