Refrigerants ranked by Partial Order Theory

Abstract

Forty refrigerants used in the past, used presently, and some proposed substitutes, were studied in respect to their ozone depletion potential, global warming potential, and atmospheric life times. They were ranked using the Hasse diagram technique, a mathematical method which permits to draw diagrams representing order relations among chemicals. The refrigerants were divided into 13 chemical classes (subsets) of which the most prominent ones are the chlorofluorocarbons (CFC), hydrofluorocarbons, hydrochlorofluorocarbons and hydrofluoroethers. Order relations among these subsets were calculated applying dominance and separability degrees. The dominance degree is a measure indicating the extent to which descriptors of members of one subset are higher than those of members of other subsets; the separability degree is a measure for the incomparability or lack of order relations between elements of two subsets. By application of these measures to the 13 chemical subsets it was found that more than half of the order relations among them are complete dominances; this means a high degree of comparability among subsets permitting to find the ones most problematic in environmental terms. This is the case for the CFC and for some of the hydrofluoroethers.