Subcooled Water Flow Boiling CHFs for Flow Velocities at Outlet Pressures in Various Tubes
It was clearly observed that the CHF data versus outlet subcooling for each flow velocity were divided into four regions for subcoolings with pressure as a parameter: first CHF decreased down to minimum one (first region), secondly it increased up to maximum one (second region), thirdly it decreased down to minimum one (third region), and finally it again increased monotonously with an increase in outlet subcooling. The CHFs belonging to third region became significant with a decrease in diameter for the smaller tubes with diameters such as around 1 mm, and on the other hand, those almost disappeared with an increase in diameter for the larger tubes with the diameters such as around 9 mm. The CHFs belonging to second region significantly depending on pressure, and those belonging to fourth region being almost independent of pressure were well expressed by the unified flow boiling CHF correlations representing for the CHFs resulting from hydrodynamic instability, HI, including diameter effect, and those resulting from heterogeneous spontaneous nucleation, HSN, being independent of pressure, diameter and L/D ratio respectively. The correct prediction for the CHFs resulting from the HI belonging to second region with higher limit ones for a flow velocity at a pressure in the tubes with a diameter and various L/D ratios is the most important knowledge of thermal hydraulics for the design of cooling configurations for ultra-high heat fluxes required by the many future systems expected. It is attempted to confirm the CHFs for outlet subcoolings belonging to second region with a higher limit of one for a flow velocity at pressures in the tubes having various diameters and L/D ratios using existing database for flow boiling CHFs based on previously derived generalized correlation for subcooled flow boiling CHFs resulting from the HI including the effect of tube diameter and being independent of L/D ratios.
pool boiling flow boiling critical heat flux diameter length
Katsuya Fukuda Qiusheng Liu Akira Sakurai
Department of Marine Engineering, Kobe Universiy, Kobe 658-0022, Japan Kyoto University, Professor Emeritus, 605-0977,Japan
国际会议
4th International Symposium on Heat Transfer and Energy Conservation(第四届传热与节能国际研讨会 ISHTEC2012)
广州
英文
1-5
2012-01-06（万方平台首次上网日期，不代表论文的发表时间）