Enhancement factor for water vapor-pressure correction in humid methane

Energy gases are mainly composed of methane, and they are dried prior to pumping to natural gas grids. To avoid condensation of water-vapor related problems, the dew-point temperature is monitored. In dew-point temperature measurements, however, the water-vapor enhancement factor is needed to correct effects caused by pressure changes and to enable unit conversions when using instruments based on indirect measurement principles. In the work reported in this paper, new experiments were carried out, and methane–water equilibrium data available in the literature were analyzed for deriving a new equation. The derived equation provides an easy calculation method for the water-vapor enhancement factor in methane as a function of pressure and dew-point temperature. An uncertainty analysis for the equation is also presented covering the whole studied pressure ranging from atmospheric pressure up to 7 MPa, and the dew-point temperature ranges from +20°C down to hydrate forming temperatures