Experimental PρT-x measurements of liquid methane-ethane-nitrogen mixtures

NASA is designing an unmanned submarine to explore the hydrocarbon rich seas of Saturn's moon Titan. Titan is the only known celestial body in our solar system other than Earth with stable liquid seas on its surface. The thermodynamic properties of Titan's seas have not been well characterized. This work investigates the solubility of nitrogen in varying liquid methane-ethane compositions and the effects of dissolved nitrogen on the density of the sea. Twenty-one pressure-density-temperature-composition (PρT-x) measurements are presented from 92 K to 96 K for pressures from 1 bar to 11 bar for varying compositions of methane, ethane, and nitrogen. These measurements are being used to aid in thermodynamic modeling of the Titan seas as well as the design of the Titan Submarine.