Thermophysical dispersion properties of agricultural biomass particles in ethylene glycol

•Sunflower stalks as biomass were used to produce particles by hydrothermal carbonization and treatment in the oven with inert atmosphere.•Dispersions were prepered by suspending particles in etylene glycol as base fluid by two step method.•The density, viscosity and thermal conductivity of the dispersions increase with mass concentration of particles.•The dispersions could be potentially useful for heat transfer applications.