Abstract

This paper brings out the existence of the maximum in the curvature of the vapour pressure curve. It occurs in the reduced temperature range of 0.6-0.7 for all liquids and has a value of 3.8-4.8. A set of 17 working fluids consisting of several refrigerants, carbon dioxide, cryogenic liquids and water are taken as test fluids. There exists also a minimum close to the critical point which can be observed only when a thermodynamically consistent functional form of the vapour pressure equation is chosen. This feature, in addition to throwing some light on the behaviour of the vapour pressure curve, could provide some useful inputs to the choice of working fluids for vapour pressure thermometers and thermostatic expansion valves.

Description

ScienceDirect - Chemical Engineering Journal : Curvature of the vapour pressure curve

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