Experimental study on pool boiling and Critical Heat Flux enhancement of metal oxides based nanofluid

Critical Heat Flux or CHF is a phenomenon in pool boiling, which limits the thermal flux during the nucleate heating phase. Presented research paper is an investigation of the CHF of Al2O3, Fe2O3 and CuO nanoparticles in water as base fluids. Critical Heat Flux of water and nanofluids were measured at 100 °C and 0.10325 MPa using 29 × 22 W DC power supply and NiCr 32AWG wire as the primary heater. Concentration of nanoparticles in the respective base fluids was varied from 0.01 vol% to 0.1 vol% in the step of 0.1%. Nanofluids were used as the working fluid and sent to circular bath. A significant enhancement in CHF was found of nanofluid over base fluid is found in the study. As the concentration of nanoparticles in water increases, the CHF also increases up to their optimum concentration and then starts to drop and almost becomes constant at 0.1%. The enhancement is due to enhanced surface wettability, increased heat transfer coefficient and nanoparticle deposition on heating element. The decrease in CHF over higher concentration is due to probable agglomeration due to prevalent surface charges of nanoparticles.