Experimental study on static flash vaporization of aqueous NaCl solution at different flash speed: Steam-carrying effect

Flash speed was defined as mean decreasing rate of non-equilibrium fraction during fast evaporation stage. Experimental study on steam-carrying effect during static flash at different flash speed was carried out. Different flash speeds were generated by installing thin orifice plates with different diameters (5–80 mm) between flash and vacuum chamber. Steam-carrying ratio was defined as mass ratio of entrained liquid to flash steam. Results suggested that, first, accelerating flash speed could significantly increase steam-carrying ratio. Second, a peak value of steam-carrying ratio existed with increasing superheat, but the peak value quickly dropped with shrinking orifice diameters. Third, due to steam-carrying effect, increasing flash speed aggravated height drop of waterfilm during flash, but had nearly no influences on equilibrium salt concentration of waterfilm. At last, an enhanced model for steam-carrying effect during static flash at different flash speed was set up, depend on which, steam-carrying ratio, height drop of waterfilm as well as equilibrium salt concentration of waterfilm could be computed within acceptable error range.