Experimental parametric study of the pressure drop characteristic curve in a horizontal boiling channel

摘要

The main objective of this study is to provide experimental data with the aim of clarifying the behavior of the pressure drop of a boiling fluid through a horizontal heated pipe as a function of the mass flux. The steady-state pressure drop characteristic curve of a heated pipe is extremely important regarding stability issues. This characteristic curve can present a negative slope which is usually not desired. In this study, a systematic analysis on the influence of the different relevant parameters was conducted with R-134a boiling on a horizontal channel. The working pressure was found to have a determinant role on the existence of a negative slope in the two-phase flow outlet region. As the pressure is increased, this negative slope decreases. The inlet temperature has also a strong influence on the presence of the negative slope in the curve, with this slope increasing as the inlet temperature is decreased. The heating power seems to have a small influence on the negative slope, being proportional to it. Finally, the axial distribution of the heat flux has a large impact on the negative slope in the characteristic curve.