Measurements of the Specific Heats, C(σ), and C(v) of Dense Gaseous and Liquid Ethane(*)

The specific heats of saturated liquid ethane, C(σ), have been measured at 106 temperatures in the temperature range 93 to 301 K. The specific heats at constant volume, C(v) have been measured at 19 densities ranging from 0.2 to 3.1 times the critical density, at temperatures between 91 and 330 K, with pressures to 33 MPa, at 200 PVT states in all. The uncertainty of most of the measurements is estimated to be less than 2.0 percent. As the critical point is approached the uncertainty rises to about 5.0 percent. The measurements were performed to provide input data for accurate calculations of the thermodynamic properties for ethane. They are believed to be the most comprehensive specific heat measurements available for the liquid and vapor states of ethane.