Numerical study of boiling around wires and influence of active or passive neighbours on vapour film dynamics

Abstract

In the present study pool boiling around a heated wire has been simulated at atmospheric pressure, considering the wire to be at the constant temperature heat source. Film dynamics, bubble nucleation, growth, merging and pinch off has been observed in with perfectly smooth and uniform horizontal wire without any nucleation site. Effect of increase of the degree of superheat on boiling rate, measured in terms of vapour generation and bubble population has been studied next. Similar studies have been done by inclining the wire at different angles (10°, 45°, 60° and vertical), where axial and azimuthal bubble sliding and more efficient bubble merging have been observed. Bubble size and population distribution have been investigated along the length of the inclined wire to link up with corresponding enhancement in boiling rate. For understanding the effect of active and passive neighbour, horizontal boiling around two-wire system has been studied. First horizontal wires have been stacked at the same vertical plane and different active and passive combination have been simulated. Also boiling from two active wires placed at same horizontal plane has been studied for different wire spacings. For all these cases bubble life cycle has been investigated to understand the role of neighbouring wire. Effect of these neighbouring wires on boiling heat transfer and vapour generation rate has been reported.