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where temperature T is in degrees Celsius (°C) and saturation vapor pressure P is in kilopascals (kPa). According to Monteith and Unsworth, "Values of saturation vapour pressure from Tetens' formula are within 1 Pa of exact values up to 35 °C." Murray (1967) provides Tetens' equation for temperatures below 0 °C: [3]
The Antoine equation is a class of semi-empirical correlations describing the relation between vapor pressure and temperature for pure substances. The Antoine equation is derived from the Clausius–Clapeyron relation. The equation was presented in 1888 by the French engineer Louis Charles Antoine (1825–1897). [1]
The boiling point of water is the temperature at which the saturated vapor pressure equals the ambient pressure. Water supercooled below its normal freezing point has a higher vapor pressure than that of ice at the same temperature and is, thus, unstable. Calculations of the (saturation) vapor pressure of water are commonly used in meteorology.
The Antoine equation has poor accuracy with any single parameter set when used from a compound's melting point to its critical temperature. Accuracy is also usually poor when vapor pressure is under 10 Torr because of the limitations of the apparatus [citation needed] used to establish the Antoine parameter values.
Values are given in terms of temperature necessary to reach the specified pressure. Valid results within the quoted ranges from most equations are included in the table for comparison. A conversion factor is included into the original first coefficients of the equations to provide the pressure in pascals (CR2: 5.006, SMI: -0.875).
The Lee–Kesler method [1] allows the estimation of the saturated vapor pressure at a given temperature for all components for which the critical pressure P c, the critical temperature T c, and the acentric factor ω are known.
The original reason for starting a vapor–liquid phase equilibria data collection was the development [2] of the group contribution method UNIFAC which allows to estimate vapor pressures of mixtures. The DDB has since been extended to many other properties and has increased dramatically in size also because of intensive (German) government aid.
Tetens equation, calculates the saturation vapor pressure of water over liquid and ice; See also. Teten This page was last edited on 26 February 2017, at 15:35 (UTC ...