Experimental study of temperature distribution in vertical narrow annuli with subcooled boiling in a naturally circulating system

Subcooled boiling in vertical narrow annuli was investigated experimentally,with natural circulation,under atmospheric pressure,and using water as working medium.Attention was focused on the effect of inlet subcooling,gap width and heat flux on temperature distribution in the axial direction.Measured data showed that the cross-section fluid temperatures were hardly affected by heating power when input power value is not very high.The wall temperature distribution from inlet to exit is not monotone because of inlet subcooling.The wall temperature in the boiling region even increases with the increase of inlet subcooling when inlet subcooling is low.Reducing the gap width or increasing heating power is beneficial for decreasing the influence of inlet subcooling.Decreasing gap width also leads to lower wall temperature.