Flashing Liquids：闪烁的液体.pptVIP

Flashing Liquids Source Models Flashing Liquids Adiabatic Flashing Adiabatic Flashing through hole Isothermal Flashing through hole Liquid pool boiling Flashing Liquids We have considered source models in terms of liquids leaking through a hole or pipe and vapors leaking through a hole or pipe. For liquids stored under pressure above their normal boiling points, we need to consider flashing. Adiabatic Flashing Liquids stored under pressure above normal boiling point. Large release of pressure (i.e. ruptured vessel). Energy to vaporize comes from liquid Adiabatic Flashing Excess energy in superheated liquid Separate variables Adiabatic Flashing Cp,l hv are functions of T. If you assume they are constant at an average value Adiabatic Flashing Determining the fraction of liquid vaporized Substitute back in average between Tb and T1 Adiabatic Flashing Design equation for fraction vaporized Flashing Liquids Adiabatic Flashing Adiabatic Flashing through hole Isothermal Flashing through hole Liquid pool boiling Adiabatic Flashing through holes Liquids stored above saturation pressure Adiabatic Flashing through holes If L 10 cm, assume incompressible liquid is flowing. If L10 cm, assume choked flow with P2=Psat. Then design equation becomes: Where Psat is at ambient conditions Flashing Liquids Adiabatic Flashing Adiabatic Flashing through hole Isothermal Flashing through hole Liquid pool boiling Isothermal Flashing through a hole For liquids stored at saturation pressure, P1=Psat. Assume choked two-phase mass flow v is specific volume (1/density) Isothermal Flashing through a hole The two-phase specific volume is vfg is difference in specific volume between liquid (fluid) and vapor (gas) vf is the liquid (fluid) specific volume fv is the mass fraction of vapor Isothermal Flashing through a hole Differentiate with respect to pressure From before we determined Isothermal Flashing through a hole All vapor formed is from liquid