Thermo-reversible kerosene gel fuels: gelation, rheology and droplet combustion

Thermo-reversible kerosene gel fuels are formulated using 1,3:2,4-di-O-benzylidene sorbitol (DBS) as a low-molecular-weight organogellant, dimethyl sulfoxide (DMSO) as a stock-solution solvent, and 1-hexanol as a co-solvent. Gelation behavior is interpreted using a Hansen solubility parameter framework, where stable gelation occurs when 𝑅 < 1 3 , while mixtures with 𝑅 ≥ 1 3 remain as suspensions. The results show that gel formation and gelation kinetics are strongly governed by formulation composition. Increasing gellant concentration enhances network formation, resulting in significantly faster gelation. Rheological measurements confirm a transition from a weaker, more deformable network at lower gellant concentrations to a stiffer and more brittle network at higher concentrations. In contrast, increasing hexanol concentration enhances network flexibility. Thermal analysis reveals that increasing hexanol concentration lowers the glass transition temperature, indicating increased molecular mobility within the gel network. Single-droplet combustion experiments demonstrate that formulation composition also influences combustion behavior. At a gellant concentration of 12 wt%, the droplet undergoes complete thermo-reversible melting and burns like liquid fuel. In contrast, at a gellant concentration of 10 wt%, combustion occurs with an outer DBS-rich shell surrounding the droplet, restricting the evaporation of unreacted fuel vapor. All tested gel fuels burn without leaving solid residue. These results establish direct links between solvent compatibility, supramolecular network strength, and droplet combustion behavior in kerosene-rich thermo-reversible gel fuels.