To clarify the physical mechanism of flash evaporation, an experimental investigation was carried out with a quantity of pool water exposed to a sudden pressure drop.
The range of experimental variables include : superheats between 2.5 and 5.5°C, liquid temperature between 40 and 80°C, and liquid levels of 100 and 200 mm.
Flash evaporation is found to undergo two exponential decaying processes.
Measured values of maximum penetration depth of evaporation, non-equilibrium temperature difference, and coefficient of evaporation rate are subject significantly to the influence of liquid level, and flash evaporation is not always enhanced by the lowering of liquid level for larger values of liquid temperature.
The experimental data are also compared with data obtained in multi-stage flash evaporators.