In the case of nanofluids, the nanoparticle concentration has a significant effect on individual physical properties such as density, surface tension, and viscosity. However, there have been few studies on the comprehensive, interactive effects of nanoparticle concentration and electrification. This study demonstrates the synergetic effects of nanoparticle concentration and electrification on the breakup performance of nanofluid fuel (Al/n-decane). The secondary breakup behaviours associated with the interactive actions of gravity, surface tension, viscous forces, and electric-field force were investigated. When the Al-nanoparticle concentration of the n-decane increased, there was a linear increase in the density, and a trinomial increase in the viscosity; however, there was a piecewise influence on the surface tension. The addition of the Al nanoparticles simultaneously influenced the electrification of the nano fluid fuel, and synergistically contributed to the deformation of the Taylor cones and the secondary breakup of the jets. The effective surface tension was calculated and analysed; the results demonstrated that the Weber number decreased when the Al-nanoparticle concentration was elevated. This resulted in enlarged Taylor cone angles and minimized the average diameter of the breakup droplets. More importantly, at a critical Al-nanoparticle concentration (7.9 mg/ml), the effective surface tension was minimized; consequently, the average diameter of the breakup droplets was minimized (72 mu m). (C) 2019 Elsevier Ltd. All rights reserved.