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.