kondensationstemperatur

Kondensationstemperatur, or condensation temperature, is the temperature at which a vapor becomes a liquid when the surrounding pressure is held constant. More precisely, it is the saturation temperature for which the vapor pressure of the substance equals the external pressure. At this temperature a gas will begin to condense upon cooling, and a liquid will boil upon heating at the same pressure.

For pure substances, Kondensationstemperatur at a given pressure is equivalent to the boiling point at that pressure. In mixtures, condensation temperature can depend on composition and can refer to dew-point conditions for air containing water vapor or to the saturation condition in vapor–liquid equilibria.

Applications include refrigeration and air conditioning, where condensation temperature is defined by the condenser pressure and is typically higher than ambient temperatures, and meteorology, where the related dew point describes when air becomes saturated with water vapor at the prevailing pressure.

Determination of Kondensationstemperatur can be done from phase diagrams or equations of state, or by empirical correlations such as the Antoine equation, which relates vapor pressure to temperature. Solving P_vap(T) = P_ext yields the condensation temperature.

Notes: The concept assumes thermodynamic equilibrium between phases and a fixed external pressure; non-ideal behavior and mixtures require more advanced models. For water at 1 atm, Kondensationstemperatur is 100°C; at lower pressures, it decreases accordingly.