引入惰气强化对流传热过程研究

引入惰气增强传热具有清洁、增加的压力降小和不干扰流体流动等优点．在传热实验装置的竖直向上矩形管道入口处引入氮气，通过对一般对流传热与引入氮气情况下的传热实验进行对比，考察了引入氮气对传热的增强作用。结果表明：混合对流传热时。传热的增强更加显著，引入惰气对对流传热的增强程度要明显好于对过冷沸腾传热的增强．通过对惰气增强传热的机理进行分析，提出惰气对传热的增强作用，是气泡引起液速增加而产生的湍动增强和气泡滑移而产生的边界层湍动增强这两种机理叠加作用的结果。

Convective heat transfer enhancement by inert gas injection

Heat transfer enhancement by inert gas injection has some characteristics: cleanness, low-pressure drop increase and light obstacles to flow liquid, etc.. Convective heat transfer enhancement in water upflow is investigated by N_2 injection at the inlet of a channel of rectangular cross-section. The heat transfer coefficient by inert gas injection is remarkably increased as compared to that of single phase flow. The increase is greatly notable during the mixed-convection flow. The enhancement of convective heat transfer is more obvious than that of subcooled flow boiling by inert gas injection. Moreover, a possible mechanism of heat transfer enhancement by inert gas injection is proposed, which consists of the increased turbulence resulting from increasing liquid velocity and heat transfer boundary disturbance due to sliding bubbles.