Upward extrapolation of saturated liquid densities

The design of new energy conversion processes requires equations of state for the working fluids. For their construction saturated liquid densities are needed which are not available for some potential working fluids at higher temperatures. Hence, we investigate how Rackett-type equations behave in extrapolations from saturated liquid densities in the temperature range 0.5 ≤ T/Tc ≤ 0.75 up to the critical temperature Tc. Extrapolation methods with different inputs from the critical point are used: (a) no critical point data, (b) critical temperature, (c) critical temperature and pressure, and (d) critical temperature and compression factor. It is found that upward extrapolations of the saturated liquid densities without using critical point data can be done with some care and that the additional use of the critical temperature improves the quality of the predictions substantially.