ISSN Online: 2379-1748
ISBN Flash Drive: 978-1-56700-517-2
5-6th Thermal and Fluids Engineering Conference (TFEC)
ANALYSIS OF DYNAMICS OF MICROLAYER FORMATION AND DESTRUCTION IN NUCLEATE BOILING
Formation and subsequent destruction/depletion of microlayer have a significant effect on nucleate boiling dynamics. Understanding of the driving physical phenomena is necessary for accurate description of the heat transfer characteristics as well as for clarifying the role of microlayer in the occurrence of departure from nucleate boiling. Using a validated Direct Numerical Simulation (DNS) computational code, difficulties associated with microlayer boiling experiments can be overcome. Detailed information can be extracted from DNS results and the influential variables can be modified freely, allowing to methodically sample the parameter space. In this paper, we first present the validation of our DNS code using a sharp-interface phasechange model and the volume-of-fluid (VOF) interface-tracking method against the experimental data of nucleate boiling recently measured at the Massachusetts Institute of Technology (MIT). The conjugate heat transfer between the fluid and solid phases is accounted for with subgrid accuracy of interfacial position and the microlayer is directly captured by VOF. Then, by varying the contact angle and wall superheat, we demonstrate the occurrence of qualitative changes in microlayer dynamics. Based on these results, we classify the dynamic regimes of nucleate boiling, ranging from contact-line evaporation to microlayer evaporation. Differences between the evaporative and hydrodynamic microlayer destruction are discussed.