Stick and oscillatory behavior of bubbles due to TiO2 nanoparticle coating in subcooled pool boiling on a wire

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Official URL: http://dx.doi.org/10.1063/1.4986559

Nanoparticles are found to alter the contact angle and wettability characteristics, thereby inducing a significant effect on pool boiling. Generally, boiling of nanofluids results in deposition of nanoparticles on the heating surface. Therefore, it is difficult to distinguish whether nanoparticle coating or dispersion is dominating in boiling. The present study reports on sticking and oscillatory behavior of bubbles in pool boiling on a platinum wire to further broaden our understanding of these underlying phenomena. Four different cases, namely, pure deionized water on both pristine and TiO2 nanoparticle coated wires and TiO2 nanoparticle/water nanofluids at two mass fractions of 0.002% and 0.005% on pristine wire, were tested to unravel bubble dynamics in pool boiling in the presence of nanoparticles. Moreover, particle-particle interactions and nanoparticle coating effects on the contact angle were investigated by comparing the results and describing acting forces on bubbles. The presence of both coated surfaces and dispersed nanoparticles led to the sticking and oscillatory behavior of bubbles at a high mass fraction, which was explained by the force balance analysis.