Vapor–liquid equilibria and inter-diffusion coefficients for working pairs for absorption refrigeration systems composed of [HMIM][BF4] and fluorinated propanes

Abstract

Hydrofluorocarbon + Ionic liquid is a promising working pair for the absorption refrigeration system. The vapor–liquid equilibrium and inter-diffusion coefficient of hydrofluorocarbon + ionic liquid are two key parameters used to evaluate the performance of the working pair. In this work, the vapor–liquid equilibrium and inter-diffusion coefficients of 1-hexyl-3-methylimidazolium tetrafluoroborate and fluorinated propanes including R227ea, R236fa and R245fa were measured from 303 K to 343 K and up to 332 kPa. The mole fractions of the three fluorinated propanes in liquid phase at vapor–liquid equilibrium were found to increase in the order: R227ea < R236fa < R245fa; they also increased with decreasing temperature and increasing pressure, while the inter-diffusion coefficients were found to increase with increasing temperature. The non-random two-liquid (NRTL) model was used to correlate vapor–liquid equilibrium data, while the Arrhenius, Litovitz, and Vogel−Fulcher−Tammann equations were used to correlate the inter-diffusion coefficient data.