In recent years, it was found that pool boiling critical heat flux (CHF) increases in nanofluids. The CHF conditions are important for safe and economic design of many heat transfer units including nuclear reactor.
In this study, our objective is to evaluate the impact of Carbone Nano Tubes (Singlewalled CNTs and Multiwalled CNTs) and Fullerene (C-60) nanofluids at different particle concentration on pool boiling critical heat flux experimentally at saturated conditions. Multiwalled CNT and fullerene (C-60) added in the pure water at three volume concentrations (0.01%, 0.001%, and 0.0001%). Singlewalled CNT nanoparticles added in the pure water at two volume concentrations (0.0005%, and 0.0001%).
For the dispersion of nanoparticles in pure water, several treatments were performed. Multiwalled CNTs and Fullerene (C-60) prepared using acid treatment, meanwhile two treatment are using for Singlewalled CNTs: (1)Singlewalled CNTs prepared using polymer treatment, (2)Singlewalled CNTs prepared using pre polymerization of micelle treatment. The zeta potential of CNTs and Fullerene nanofluids were in the range of 13-71 mV. The zeta potential of nanofluids was constant for more than one month. It concludes that the treatment has been succeeded produces water dispersible CNTs and Fullerene nanofluids with good stability.
The critical heat flux (CHFs) of the solution is enhanced greatly for all nanofluids. Enhanced (~167.9%) CHF was observed for solutions with Multiwalled CNT nanoparticles with concentration 0.01 vol%. Enhanced (~109.4%) CHF was observed for solutions with Singlewalled CNT nanoparticles with concentration 0.0005 vol%. Enhanced (~108.9%) CHF was observed for solutions with Fullerene nanoparticles with concentration 0.01 vol%.
The pool boiling Heat Transfer Coefficient (HTCs) of the CNTs nanofluids are lower than those of pure water in the entire nucleate boiling regime. On the other hand, the pool boiling HTCs of Fullerene nanofluids are higher ...