Milk chilling using nanoparticle enhanced phase change material capsuled inside a jacketed cylindrical module: A numerical and experimental study

In the present study, TiO2 nanoparticles at 0.20, 0.40 and 0.60% by weight fraction were used for developing nanoparticle enhanced phase change materials (NePCM) for rapid chilling of milk. NePCM capsuled inside the jackets of a cylindrical milk chilling module was taken as a test-rig for investigation. Transient energy storage and its discharge during passive milk chilling were numerically simulated using enthalpy-porosity and volume of fluid model of computational fluid dynamics (CFD) technique. The simulated results for the transient temperature fields and the solid-liquid fronts, validated with experiments, clearly visualized the rapidity of heat transfer using nanoparticles in different zones. Use of nanoparticles reduced the charging time, supercooling degree, phase-transition time and the energy discharging time during milk chilling by 25.49, 47.05, 30.18 and 42.90%, respectively. The fresh raw milk was passively chilled from 37 to below 10 °C within 1 h and the chilled milk was maintained below this safe limit using the NePCM inside the module. The test module along with charging set-up, thus studied, revealed the scope of developing a rechargeable, portable and passive chilling cum storage unit for maintaining cold-chain from the milk production points among the distantly located procurement and collection networks in the rural areas.