Convective heat and mass transfer. Single phase flow

Abstract

This mass transfer coefficient was valid for vanishing convective flows and had to be corrected for finite convective flows. These equations describe convective heat and mass transfer, but they are nothing more than definition equations for the heat transfer coefficient α and the mass transfer coefficient β, and should in no way be seen as laws for heat and mass transfer. Rather the laws of nature for the course of processes of heat and mass transfer are hidden in the heat and mass transfer coefficients. Generally both are not constant, but locally variable and in transient processes they also change with time. In addition they depend on the flow, the properties of the fluid and the geometry of the heat or mass transfer surfaces. Therefore, the definition equations for heat and mass transfer coefficients given above are not suitable for describing the mechanisms of heat and mass transfer. This is only possible with an in depth study of flow and will be the subject of the following exposition.