Heat exchange under the longitudinal movement of wet steam in finning heat exchangers

Abstract

The paper is devoted to the study on hydrodynamics and heat exchange of two-phase medium. While designing technological equipment, when the wet steam is used as the operating medium, the features of the interaction between liquid drops and the heat exchange surface are not considered in most cases. In full, this applies to steam turbines operating on the wet steam whose moisture content depends on the primary and secondary removal of liquid drops from the separation blocks. Purpose. Improving the method of calculation of recuperative heat exchangers, if wet steam is used as the operating medium. Methodology. It is based on the analysis of the physical model of moving the two-phase medium in the heat and mass exchange conditions, considering the design characteristics of the heat transfer surface. Findings. The correlation of critical values of two-phase flow parameters was obtained to determine the lower boundary of the process of plucking the drops from the liquid film depending on the irrigation density, geometric characteristics of the channel and physical properties of the liquid and gas. Correlations were obtained for pipes with longitudinal finning as the Π-shaped profile, based on which we recommend optimizing the geometric characteristics of longitudinal finning. Originality. Determining the limit modes of secondary removal formation during the movement of a two-phase medium in separation devices and the features of heat and mass transfer of wet steam in finning recuperative heat exchangers. Practical value. The presented results make it possible to optimize the design of recuperative heat exchangers with longitudinal Π-shaped finning.