摘要
凝汽器是发电厂的重要辅机设备,其流动与传热性能的优劣对单位发电量的能耗影响很大,为了适应我国节能减排的重大需求,优化和改进大型凝汽器的设计是十分必要的.目前凝汽器的管束布置大多基于工程经验的总结,缺乏理论分析,难以进行凝汽器管束布置的优化设计.本文介绍了动量■和质量■的概念,建立了凝汽器壳侧蒸汽流动的动量■耗散和质量■增与流动与传热分布参数之间的关系,针对4种管束布置的330 MW凝汽器,采用数值方法分析了管束布置对凝汽器壳侧压降和抽气量的影响,总结出了凝汽器管束布置的设计原则与要点.在此基础上,详细介绍了基于理论和数值分析结果所发明的仿生双连树型管束布置凝汽器的性能及其应用.
Condenser is a huge, complex shell-and-tube heat exchanger. It is the key auxiliary equipment in power plants whose designs have a very important influence on thermal efficiency of electric power generation. At present, power plant condensers are traditionally designed based on recommendations from previous designs and experimental results, often based on the standards developed by the Heat Exchange Institute. However, it does not take a number of factors into account, including the tube arrangement. Hence, to study the tube arrangement effect on condenser performance and to optimize/improve the condenser design are very important for energy saving. The condenser performances, such as the back pressure and venting rate, are strongly affected by the tube arrangement, and there are three irreversible processes for the fluid flow, heat transfer and mass diffusion in condenser. Borrowing from the entransy analysis method of heat transfer process, the momentum entransy analysis and mass entransy analysis were performed on the steam flow and air mass diffusion process in condenser. Adopting the porous media model the momentum entransy balance equation and the air mass entransy balance equation of the steam flow were deduced, then, the relation of momentum entransy loss of the steam flow and the distributed flow and heat transfer parameters in the condenser and the relation of air mass entransy increase of the steam flow and the distributed parameters of flow, heat transfer and air mass fraction were deduced. With the two relations the effects of tube arrangement on the back pressure and the venting rate are numerically investigated. The numerical analyses on four typical condensers indicate that larger momentum entransy loss relates to larger back pressure, and larger air mass entransy increase relates to less venting rate. Based on the numerical results of the four kinds of tube arrangements 330 MW condensers, the principles for tube layout in condenser are summarized. For examples, the reasonable design of the periph
出处
《科学通报》
EI
CAS
CSCD
北大核心
2016年第17期1877-1888,共12页
Chinese Science Bulletin
基金
国家重点基础研究发展计划(2013CB228301)资助
