不同纳米流体水平管内沸腾流型的模拟

Simulation of boiling flow pattern of nanofluids in horizontal tube

中文关键词: 纳米流体  两相流  沸腾传热  流型

英文关键词: nanofluid  two-phase flow  boiling heat transfer  flow pattern

中文摘要:

      对以纯水为基液的不同纳米流体管内流动沸腾进行了模拟。利用UDF编程定义流体的沸腾相变源项,将其导入FLUENT软件中分别模拟这四种流体在水平管内的流动沸腾过程。得到了四种流体流动沸腾的速度云图,以及流型分布云图。对比分析了四种流体的速度分布云图、四种流体从初始状态沸腾到1s时的流型分布云图以及四种流体层状流流型的特点。结果表明这四种流体在水平管内沸腾都会出现泡状流、弹状流、层状流以及波状流四种流型,并且沿管长方向含气量逐渐增加。在相同的时间内,纳米流体的沸腾比纯水更剧烈,而且,不同的纳米流体沸腾程度也不同。在相同的体积分数下,纳米颗粒的导热系数越大,其对应的纳米流体沸腾越剧烈。说明纳米颗粒的导热系数是影响纳米流体沸腾传热的主要因素。

英文摘要:

      Flowing and boiling process were simulated in the horizontal tube of four different nano-fluids based on pure water. The velocity contour and the flow pattern diagran of the four fluids were investigated from initial stage to 1s, using FLUENT with boiling phase change source defined by UDF program.The results demonstrate that slug flow,bubble flow,stratified flow and wave flow appeare as the four fluids boiling in the horizontal tube.The gas content is increasing along the tube length direction. In the same time scale, the boiling of the nanofluid are stronger than that of pure water but depend on the components of the nanofluid. At the same concentraction,the greater the thermal conductivity of the nanoparticles,the more intense the corresponding nano-fluid boiling.It can be concluded that the thermal conductivity of nanoparticles is the main factor affecting the boiling heat transfer of nanofluids.