A new shift mechanism for micro-explosion of water-diesel emulsion droplets at different ambient temperatures

•Bubble formation and micro-explosion modes of water emulsified diesel droplets were studied.•Bubble nucleation changed from single site to multiple sites as ambient temperature increased.•Bubble nucleation sites shifted from droplet center to surface as ambient temperature increased.•Expansion intensity of droplet volume could describe the bubble formation process.•Bubble formation and micro-explosion determined the evaporation behavior of fuel droplets.