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Temperature-dependency of the heats of vaporization for water, methanol, benzene, and acetone. In thermodynamics, the enthalpy of vaporization (symbol ∆H vap), also known as the (latent) heat of vaporization or heat of evaporation, is the amount of energy that must be added to a liquid substance to transform a quantity of that substance into a gas.
Latent heat (also known as ... then the vapor's latent energy absorbed during evaporation is released as the liquid's sensible heat onto the surface. ...
L is the latent heat of vaporization at the temperature T, T C is the critical temperature, L 0 is the parameter that is equal to the heat of vaporization at zero temperature (T → 0), tanh is the hyperbolic tangent function. This equation was obtained in 1955 by Yu. I. Shimansky, at first empirically, and later derived theoretically.
J.A. Dean (ed.), Lange's Handbook of Chemistry (15th Edition), McGraw-Hill, 1999; Section 6, Thermodynamic Properties; Table 6.4, Heats of Fusion, Vaporization, and Sublimation and Specific Heat at Various Temperatures of the Elements and Inorganic Compounds
If the latent heat is known, then knowledge of one point on the coexistence curve, for instance (1 bar, 373 K) for water, determines the rest of the curve. Conversely, the relationship between ln P {\displaystyle \ln P} and 1 / T {\displaystyle 1/T} is linear, and so linear regression is used to estimate the latent heat.
λ v = latent heat of vaporization (J kg −1) γ = psychrometric constant (Pa K −1) which (if the SI units in parentheses are used) will give the evaporation E mass in units of kg/(m 2 ·s), kilograms of water evaporated every second for each square meter of area. Remove λ to obviate that this is fundamentally an energy balance.
λ v = Latent heat of vaporization. The energy required per unit mass of water vaporized. (J g −1) L v = Volumetric latent heat of vaporization. The energy required per unit volume of water vaporized. (L v = 2453 MJ m −3) E = Mass water evapotranspiration rate (g s −1 m −2) ET = Water volume evapotranspired (mm s −1)
is the heat flux from the gas to the droplet surface (J.s −1) is the latent heat of evaporation of the species considered (J.kg −1) Analytical expressions for the droplet vaporization rate, ˙, and for the heat flux are now derived. A single, pure, component droplet is considered and the gas phase is assumed to behave as an ideal gas.