Investigation of film boiling over tandem arrangement of elliptical cylinders in vertical cross-flow of saturated liquid

Abstract

The present study investigates the phenomenon of film boiling heat transfer for the tandem arrangement of elliptical heaters placed in cross-flow of saturated liquid (water) at near critical pressure conditions (P/Pc = 0.99), using the Eulerian approach-based volume of the fluid framework. The effect of vertical spacing between the heaters (pd = 7.5a to 12.5a), their aspect ratio (ψ = 0.4 to 1), degree of wall superheat (Jav/Prv = 0.6 to 1.8) and Reynolds number for liquid flow (Rel = 10 to 40) is investigated on the bubble departure dynamics and heat transfer characteristics. It is observed that the bubble departure size from the bottom heater has remained almost unchanged for all the situations whereas its departure frequency has increased upon an increase of Reynolds number and degree of superheat. The bubble size has varied significantly for the top elliptical heater and its departure frequency has increased with the decrease of aspect ratio and increase of pitch, Reynolds number and degree of superheat. The time-averaged heat transfer coefficient has increased upon an increase in pitch distance, aspect ratio, Reynolds number and degree of superheat, however, the rate of increase has diminished at a high degree of superheat.