Liquid vapor mixture, also called two-phase mixture or two-component mixture, refers to a system consisting of both liquid and vapor phases of a substance coexisting together. In a liquid vapor mixture, the liquid phase and the vapor phase are in thermal and mechanical equilibrium with each other. The relative proportions of the liquid and vapor phases depend on the temperature, pressure, and the properties of the substance.
At a given temperature and pressure, there is a unique point called the saturation point or saturation condition where the liquid and vapor phases can coexist. The saturation temperature corresponds to the boiling point of the substance at a specific pressure. During evaporation or boiling, heat is supplied to the liquid vapor mixture, causing the liquid phase to vaporize and form vapor bubbles within the liquid. These vapor bubbles then rise to the surface, resulting in the release of vapor from the liquid phase.
Conversely, during condensation, heat is removed from the vapor phase, causing it to condense and form liquid droplets. This condensation typically occurs at the surface or interface of the liquid vapor mixture. The behavior of a liquid vapor mixture is described by various thermodynamic properties, such as saturation pressure, saturation temperature, vapor quality, and specific enthalpy. These properties help characterize the state and composition of the mixture.
Liquid vapor mixtures are encountered in various practical applications, including steam power plants, refrigeration systems, distillation processes, and phase change heat transfer devices. Understanding the behavior and properties of these mixtures is essential for designing and analyzing such systems.