Assessing the ignition and combustion of a kerosene droplet containing boron nanoparticles coated with polydopamine and polyvinylidene fluoride

Abstract

In this study, how the coating of polydopamine (PDA) and polyvinylidene fluoride (PVDF) on boron particles affects the ignition and combustion characteristics of kerosene droplets was investigated. In this work, PVDF was first coated onto boron nanoparticles using PDA as a binder to form double-coated composite particles (denoted as B@PF), and then the B@PF particles were blended into kerosene to produce nanofluidic fuels. Various characterization techniques were used to evaluate the ignition and combustion performance of the B@PF composites and the nanofuel droplets, including scanning electron microscopy (SEM), thermogravimetric-differential scanning calorimetry (TG-DSC), laser ignition testing, and single droplet combustion experiments. The results showed that the PDA coating could effectively prevent the moisture absorption of the particles in ambient air and increase the heat release by 42.97 %, while the PVDF coating would have a negative impact on the energy properties of the particles. Pure B particles have the lowest spectral intensity under laser light, which is consistent with the DSC results. The addition of pure B particles to kerosene reduced the ignition delay time by nearly 86 %, while the PVDF coating could enhance the droplet heat transfer to further reduce the ignition delay time. However, the increase in PVDF content negatively affects the combustion rate of the droplets by decreasing the energy properties of the particles. In the final residue combustion stage, the reaction between PVDF and B2O3 increases the burning intensity of the B particles and reduces the size of the combustion residue. Based on the experimental results, a comprehensive model for the ignition, combustion and residue burning of droplets coated with both PDA and PVDF is proposed.