A compound thermodynamic model for transient bubble growth in microscale

Based upon the classical bubble dynamics, a new compound thermodynamics model coupling with heat transfer mechanism for the bubble growth and collapse during explosive boiling under pulsed heating is presented from a hydrodynamic and thermodynamic perspective. The highlight in this analysis is that the relationship between the variation of the vapor temperature and the vapor pressure inside of a bubble satisfies the conditions of a polytropic process. With a selected compound polytropic index (CPI) and a determined vapor temperature variation for each different stage during the entire bubble evolution under pulsed heating, the bubble behavior can be described and predicted quite well when compared to the experimental observations for pulse ranges. For the first time, this model reveals the vapor pressure and temperature variation occurring during the bubble evolution and provides an in-depth understanding and insight into the bubble dynamics under pulsed heating. The thermodynamics analysis provides a first order solution to guide future thermal bubble MEMS design.