Abstract:
Wall heat flux in the case of jet boiling is greatly dependent
on bubble size under the jet. A new force balance model has
been proposed to determine bubble size addressing the dynamic
effect of the jet on a growing bubble. Jet dynamics cause extra
two force components compared to flow boiling case: asymmetric
bubble growth force for a moving fluid and pressure force
caused by jet stagnation. The model can not be completed without
studying bubble growth under the jet. Bubble growth has
been studied in the stagnation region for jet velocity of 0:65;0:8,
and 0:9 m=s and degrees of subcooling of 13; 20, and 30 C and
in the parallel flow region for jet velocity of 0.85 m/s and 7 C of
subcooling. The instantaneous diameter of the bubble has been
measured on the boiling surface by a high speed camera. As
the force balance depends on bubble growth rate, Zuber model
for non-uniform temperature field is found to best represent the
experimental data with different b values.
Description:
Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016.
