Nanometer sized phase change materials for enhanced heat transfer fluid performance

A composition for enhanced heat transfer fluid performance, comprising a base heat transfer fluid and a nanometer sized phase change material. Introduction of nanometer sized phase change material into the heat transfer fluid leads to improved, high reversible thermal transport properties at elevated temperatures while ensuring low viscosity of the fluid at sub-freezing temperatures. A method for preparing of the heat transfer fluid with enhanced heat transfer performance, comprising making nanometer sized capsules having the phase change material contained therein and dispersing the capsules into the base heat transfer fluid.