Flow boiling heat transfer and visualization in narrow channels

摘要

The present study focuses on the experimental investigation of boiling heat transfer in single narrow channels. Three different test sections are em ployed. Water, ethanol, n-hexane, n-octane, and a mixture of n-hexane and n-octane are the working fluids In contrast to many of the available experimental studies, infrared thermography is employed here to register the outer wall temperatures. Hence, the identification and characterization of different boiling regions and boiling mechanisms as well as the analysis of the temporal behavior of the wall temperature is possible. Flow boiling visualization is also undertaken using a high speed camera. An extensive test of the available correlations for predicting heat transfer and pressure drop is also presented. The main aim of this work is to combine two measurement techniques in order to correlate quantitative and qualitative values of the heat transfer coefficients with the observed boiling regimes. Thanks to the assembly of a large database, an exhaustive data analysis, partially supported by numerical simulations, could be achieved.