Particle sedimentation depression with stabilizers and surfactants on phase change materials.

The effect of the size of a combination structure of poly(ninyl alcohol) (PVA) as a stabilizer and drag-reducing surfactants in water on the sedimentation of particles of phase change materials (PCMs) in solutions was investigated. Behenyl trimethyl ammonium chloride was used as a surfactant with a 1.5 molar ratio of sodium salicylate as a counter-ion supplier at a constant surfactant concentration of 2,000 ppm in water, while the concentration of PVA was varied from 0 to 2,000 ppm. The structural size of the combined PVA and surfactant was measured with a dynamic light scattering (DLS) system. DLS analysis indicated that a large structure is formed by the interaction between PVA and surfactants. In addition, this structure becomes larger with the PVA concentration, and the occupation volume of the structure expands widely in a fluid. Thus, it was concluded that this large structure formation could cause an effective reduction of particle sedimentation in latent heat systems.