In order to research the effect of the gravity on the critical heat flux of flow boiling

a two-phase boiling heat transfer test system was established. Using distilled water as the working fluid medium

the characteristics of fluid critical heat flux and flow resistance in narrow channel under different heating orientations were investigated through changing mass velocity

inlet subcooling and heating orientation. Their effects on the critical heat flux of flow boiling were analyzed. The results show that the maximum critical heat flux appears at the orientation angel of 0° and the minimum at 180°. The increases of mass velocity and inlet subcooling will increase the critical heat flux. The experimental data were compared with the calculated values based on the correlations of Ivey-Morris

Sudo and Wojtan

respectively

which shows that Sudo correlation was not suitable to the present experiment conditions. The predicting values with Ivey-Morris correlation and Wojtan correlation agree well with the experimental data as the orientation angel is at 0°

and the relative deviation is within 30%. However the predicting values are greater than the experimental data under other orientations.