Incipience of boiling on a wire

The initial steps in the process of vaporisation of ethyl alcohol around a heated micrometric platinum wire are presented. A constant heat flux is imposed during a few milliseconds in the wire, elevating in turn the liquid temperature well above its saturation temperature until the first bubble is observed and expands before possibly collapsing. The bubble dynamics is tracked by high speed imaging as well as by acoustic emission during the bubble growth. We show that this nucleation process occurs for a fixed temperature T∗=465 K (i.e. 114 K above saturation). The maximum volume and lifetime of this primary bubble are predicted by considering the energy budget between the amount of specific energy stored in the liquid and the latent heat consumed during the vaporisation process.