A practical density equation for saturated vapour of helium-3 from 0.01 K to the critical point.

Based on the ideal gas state equation and the saturated vapour pressure equation of helium-3, a saturated vapour density equation is proposed, which can be applied for calculating the saturated vapour density of helium-3 from 0.01 K to the critical temperature. Above 1.4 K, the average deviation between the results by this equation and experimental data is about 0.66% and the maximum is 2%. Below 1.4 K, the results of this work show a comfortable agreement with those by virial state equation (the deviations are generally within 0.1%). Based on this new vapour density equation, the compressibility factor of saturated vapour is determined and the vaporization heat is calculated. [Reprinted with permission from Elsevier. Copyright, 2007].