A vapor pressure equation for n-hydrogen between the triple and critical points

Abstract

A relation between reduced vapor pressure and reduced temperature of the form ln P R = α + β/T R + γ ln T R + δT R n has been proposed to describe the vapor pressure behavior of n-hydrogen between the triple and critical points. Data obtained from fourteen sources available in the literature were used to establish the constants α, β, γ and δ and the exponent n of the proposed relationship. An error analysis indicates that n = 5.00 provides the best fit. Thus this represents a modification of the Riedel relationship which specifies that n = 6.00. Similarly, the calculation of α from the normal boiling point appears to have advantages over the use of the critical point. When applied to 281 data points this relationship produced an average deviation of 0.82%.