Research Projects

Pool boiling heat transfer is a very complex phenomenon but has many applications in thermal and energy systems such as heat exchangers, steam generators, etc. The coolant phase change is one of the most sought alternative methods to meet the increased energy demands. The nucleation of vapour bubbles on the heated surface facilitates the excess heat transfer rate in the form of latent heat. Beyond a threshold of operating conditions, due to excess vapour content, the coolant phase change hampers the heat transfer rates and damages the heated surface. Thus, it is extremely important to achieve energy extraction by controlled phase change identifying the design limits to ensure the structural integrity of the thermal and energy systems. Therefore, the proposed study aims at the development of the molecular dynamics model framework to study the bubble incipience and growth rate during the nucleate pool boiling. The conventional computational fluid dynamics (CFD) simulations are based on the continuum assumption and require initial bubble seeding which is a demerit. Hence, relying on molecular dynamics (MD) based simulations is ideal, as the bubble incipience at the nucleation site of the heated surface can be effectively probed. Therefore, the present study focuses on the implementation of the MD model framework for the simulation of bubble incipience during the nucleate pool boiling heat transfer. The developed MD model framework will be validated against the existing benchmark experimental and numerical data. The project also focuses on improving the methodology aspects of the MD simulation framework, by systematically studying the influence of different boundary conditions namely, isothermal and constant heat flux, on the bubble nucleation. Such a detailed comparison is sparse in the literature to the best of the investigators' knowledge. It is imperative that these comparisons can aid in ruling out any possible artifacts in the simulated data. Further, the proposed study will be extended for simulating the pool boiling characteristics of coolants such as liquid sodium (coolant in Fast Breeder Reactors) and R134a (refrigerant for electronic cooling applications). In addition, the pool boiling heat transfer can be enhanced by modifying the heated surface. To this end, different possible microscopic surface modifications will be analyzed to recommend suitable heated surface designs that can achieve enhanced heat transfer.

Nucleate Pool Boiling, Bubble Dynamics, Growth rate, Departure diameter, Molecular Dynamics