Experimental Study of Bubble Dynamics During Nucleate Pool Boiling of Nanofluids
Goutham Kumar Reddy Burla and Abhijit Mukherjee
Nanofluids are stable colloidal suspensions of nanometer-sized particles suspended in traditional heat transfer fluids. During boiling of nanofluids, the dispersed nanoparticles change the surface conditions on the heated surface. A layer of nanoparticles is expected to be deposited on the surface during the boiling process which affects the boiling characteristics and the critical heat flux. The deposition of nanoparticles on the surface changes the surface contact angle as well as the bubble growth rates. In this study, nucleate pool boiling experiments have been performed using 10 nm and 30 nm-sized alumina nanoparticles dispersed in water at 10–4 vol% and 10–3 vol% concentrations. A deterioration in heat transfer was observed during boiling of nanofluids. As bubbles nucleate from the copper surface, the entire bubble growth cycle has been visualized and recorded using a high-speed camera. For each concentration of nanofluid, bubble growth period, bubble equivalent, and base diameters, and the bubble contact angle have been measured. This measured data was compared with measurements obtained during pool boiling of base fluid water. The measured bubble parameters are used to evaluate the energy transferred per bubble due to microlayer evaporation.
Keywords: Bubble dynamics, Nucleate pool boiling, Nanofluids