Spray cooling by Al2O3 and TiO2 nanoparticles in water

An experimental investigation of spray cooling performed with water based nanofluids containing Al₂O₃ or TiO₂ was conducted. The concentration of nanoparticles in the liquid was used in the experimental program was from 1 to 40 wt.%. A steel sensor with a soldered thermocouple was cooled from 200°C. The liquid was sprayed on the surface with a full cone nozzle from distances of 40, 100 and 160 mm. The heat transfer coefficient was calculated at an interval of surface temperature from 100°C to 50°C by inverse modelling, and compared with the heat transfer coefficient of water cooling. The results surprisingly show a decrease of heat transfer coefficient on the cooled surface with a concentration of the nanoparticles.