A Look on Fang Number

In this study, a look on Fang number (Fa) is presented. The Fa was introduced recently in 2013 by Professor Xiande Fang to provide great facilitation in describing flow boiling heat transfer coefficients. It is defined as the product of two terms. The first term is the ratio of buoyancy force to gravitational force, which has effects on bubble departure. The second term is the ratio of surface tension force to inertial force, which affects bubble formation. As a result, Fa is associated with the formation and departure of bubbles. The Fa will be expressed by using a combination of the Eötvös number (Eo), Froude number (Fr), and Weber number (We). Based on this study, it is clear that existing dimensionless numbers in literature, i.e., Eötvös number, Froude number, Weber number, and their combinations can be used to describe flow boiling heat transfer coefficients. This combination of existing non-dimensional groups (Eo, Fr, and We) leads to good correlation with flow boiling data of different working fluids such as CO₂, R134a, and R22.