Nucleate Boiling Heat Transfer and Bubble Dynamics of Water-in-Polyalphaolefin Nanoemulsion

In this study, an experimental study of the nucleation heat transfer and bubble dynamics inside the Water-in-PAO nanoemulsion fluid has been performed. Synchronized highspeed video and infrared thermography are used here to capture time-resolved temperature distribution data for the boiling surface and direct visualization of the bubble cycle. Data gathered included measurements of bubble growth versus time, as well as temperature history of the heater surface underneath the bubbles. Our findings demonstrate a substantial increase in nucleate heat transfer (i.e., heat transfer coefficient), and significantly different bubble dynamics of nanoemulsion fluid compared to pure water. The bubble growth rate of the nanoemulsion lies in the diffusion-controlled regime, and the growth data fit a power law at n ≈ 0.3. This is similar to the authors’ previous study of a similar fluid and is very different from conventional fluids. While the heat transfer mechanisms behind are not completely understood yet, it is hypothesized that the interfacial structures and thermal transport between surfactant molecules surrounding water nanodroplets and the base PAO fluid at elevated temperature may contribute to that.