BUBBLE DYNAMICS AND POOL BOILING HEAT TRANSFER FROM TRIANGULAR AND RECTANGULAR GROOVED SURFACES
This paper presents experimental studies of pool boiling heat transfer from plain and grooved surfaces to water at atmospheric pressure. Visualisation technique was used to investigate boiling phenomenon with high speed digital camera with image acquisition speed of 1000 fps with resolution of 320 × 240 pixels. It is observed that surface modification with grooves improves the boiling heat transfer and that rectangular grooves resulted in 20% increase in heat transfer coefficient compared to triangular grooves. Various aspects of bubble behaviour on plain and grooved surfaces were investigated. The overall growth rate was faster and bubble departed earlier for the plain surface. The buoyancy and surface tension forces dominated the force balance on the plain surface. Increase in microlayer evaporation and liquid-vapour exchange due to large size bubbles is assumed to be the reason for increased heat dissipation due to grooves.