Abstract
This paper is dedicated to study of self-sustained evaporation front in subcooled ethanol at stepwise heat generation. The data on evaporation front velocity and microstructure at different subcoolings and pressure are presented. Experiments show that development of the evaporation front drastically depends on studied parameters. At low pressures initial vapour bubbles grow without losing interface stability and initiation of evaporation fronts doesn’t occur. At higher pressures the fronts propagate along the heater, and its structure depends on temperature.
Highlights
Under some conditions onset of boiling crisis occurs via self-sustaining evaporation fronts, bypassing nucleate boiling stage
This paper describes results of experimental study on evaporation front in subcooled ethanol at stepwise heat generation and presents data on front velocity and microstructure at different subcooling and pressure
After that evaporation front starts to propagate with its headmost point within the thermal layer (Fig. 3c)
Summary
Under some conditions (nonstationary heating, low reduced pressure, etc.) onset of boiling crisis occurs via self-sustaining evaporation fronts, bypassing nucleate boiling stage. There are a few papers dedicated to model description of a self-sustained evaporation front [1,2,3]. None of these models can describe front behaviour within a wide range of experimental parameters. Main flaw of most of the models is that they don’t take into account the microstructure of the front, namely small-scaled hydrodynamic instability, which greatly influences heat transfer through the interface [3,4,5]. The lack of experimental data on evaporation front structure at various conditions hinders its strict and complete mathematical description
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