INFLUENCE OF AL2O3 NANOPARTICLE ADDITIVES ON THE THERMOPHYSICAL PROPERTIES OF AQUEOUS SOLUTION OF PROPYLENE GLYCOL AND ON THE HEAT TRANSFER COEFFICIENT IN FORCED CONVECTION FLOW IN A TUBE

For the moment, coolants that are composed of aqueous solutions of propylene glycol are widely used in chillers. Such coolants have some advantages over brines or ethylene glycol solutions: non -toxicity, low corrosivity, low crystallization temperature. However, aqueous solutions of the propylene glycol have poor heat transfer efficiency in heat exchangers at low temperatures. One of methods to improve the thermophysical properties of the propylene glycol based coolants and also increasing the heat transfer coefficient in forced convection flow in a tube is an addition of the metal or metal oxides nanoparticles. The prospects of nanoparticle additives to coolants for application in refrigeration systems have been studied. The method of preparation of the nanocoolants based on aqueous solutions of propylene glycol and Al2O3 nanoparticles has been considered. The aggregative stability of Al2O3 nanoparticles (0.53 and 1.03 % mass.) in nanocoolant has been investigated. The results of complex experimental investigation of the thermophysical properties of nanocoolant in temperature range 253-313 K are reported. The comparative analysis of thermophysical properties of nanocoolant and base fluid (aqueous solution of propylene glycol) has been carried out. The results of experimental investigation of the heat transfer coefficient in laminar flow forced convection of coolant and nanocoolant in pipe are presented. It was shown that the heat transfer coefficients for various values of the Reynolds number typical for laminar flow for the traditional coolant was generally less than for the nanocoolant.