An evaluation of microencapsulated PCM for use in cold energy transportation medium

For cold energy applications, the feasibility of micro-encapsulated phase change material (PCM) and their slurry have been investigated experimentally. The thermal properties, rheological properties and the structural integrity of PCM microcapsules (MCs) have been evaluated. Two paraffin types, n-Tetradecane and n-Dodecane (melting point 5.5, -13.5°C), were microencapsulated as PCMs. MCs samples of four different size-distributions ranging from 5 μm to 1000 μm were prepared for this work. The supercooling of microencapsulated PCM induced by the smallness of MCs was detected through differential scanning calorimetry (DSC) and the heating/cooling temperature variations of slurry. Structural stability of the MCs had a dependence on their diameters. Smaller size MCs withstood the stress from the slurry flow and the volumetric expansion of phase change. Slurry which contained a high concentration of small size MCs had high apparent viscosity. Ionic surfactants were effective additives to reduce viscosity. The large reduction of slurry friction due to the turbulent drag reduction was observed during pressure drop measurements