Encapsulation of solutions for controlling heat transfer

•Thermochromic solution was successfully encapsulated with hydrophobic silica.•Capsule size decreased with decreasing solution content in powders.•Heat transfer in powders of encapsulated solutions had a particular direction.•Speed of heat transfer increased with decreasing content of solution in powders.

Heat transfer in powders of encapsulated solutions was investigated for the content range of solutions from 90 wt.% to 98 wt.% by measuring temperature as a function of time with a visualization of temperature change under heating conditions. The encapsulation of solutions was realized by high-speed blending with hydrophobic silica nanopowders under controlling water content, blending time and speed for achieving complete encapsulation. Temperature changes in powders of encapsulated solutions demonstrated the phenomenon of controlling the direction and speed of heat transfer, differently from the liquids where convection plays the most important role in heat transfer. The speed of the temperature change was found to be dependent on solution contents, and the highest value was obtained in the case of a sample containing 90 wt.% of solution. Our results suggest that it is possible to control the propagation speed of heat by varying the content of the encapsulated solutions. Our new approach with the encapsulation technique could be applied to control a variety of reaction processes involving liquids.

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