Study of local boiling phenomenon on different metallic surfaces in non-circular flow passages under laminar flow conditions

Abstract

The thermal diffusivities of the metals are found to be an influencing parameter in explaining the different threshold temperatures required for the local boiling phenomenon to occur on different metallic surfaces and the Fourier number is used in the correlation to account for the thermal diffusivities. The effect of the degree of sub-cooling on local boiling is also quantified by modifying the Jakob number by replacing the term giving the difference between the temperature of the boiling liquid film and saturation temperature of the liquid, with the ratio of excess temperature to the degree of sub-cooling with an index of 0.2. The proposed final correlation comprising of local boiling coefficient, non-boiling coefficient, Fourier number and modified Jakob number is Klb = 0.11(Knb) (Fo)⁰˙²⁵(Jamod)²˙⁵.