Fluidic microencapsulation of calcium chloride hexahydrate phase change material in resorcinol formaldehyde shell

Phase change material, encapsulated in micro-particles are required extensively in temperature control and heat storage applications. The encapsulation through random mixing and chemical emulsification does not allow use of inorganic salt as PCM that is otherwise known to be safe and effective. Microencapsulation of an inorganic phase change material in resorcinol resin shell is demonstrated here by co-flowing the two phases in a fluidic device, and inducing instability driven disintegration of core-sheath filament. Highly unimodal sized micro -capsules with diameter of 978 mu m +/- 75 mu m and uniform coating thickness were evident from the optical mi-croscope as well as scanning electron microscope images. The heat absorption and release characteristics of microcapsules with varied shell thickness of 1.57 mu m, 4.05 mu m and 12.8 mu m were studied by differential scanning calorimetry. The integrity of the shell was evaluated through sustained dipping of microcapsules in water, and measuring the electrical conductivity. The fractional release was restricted to about 10% of in-place PCM after 30 days. The results serve as proof of concept for the fluidic microencapsulation in general, and inorganic ma-terial in particular, which in spite of possessing many favourable aspects has not been studied till date for thermal control and energy harvesting applications.