Speeds of Sound in Dense Liquid and Vapor Pressures for 1,1-Difluoroethane

Abstract

Speeds of sound in the liquid phase of 1,1-difluoroethane, CHF2CH3, were measured by a sing-around technique operated at a frequency of 2 MHz. The results cover the temperature range along six isotherms from (243 to 333) K and pressures from near the saturation line to about 30 MPa. The combined uncertainty is estimated to be within ±0.2% except for the region near the coexistence line in the upper temperature range. The vapor pressure was also measured with an uncertainty lower than ±20 kPa by detecting the phase change using an acoustic absorption technique. The speeds of sound in the saturated liquid were estimated by the extrapolation to the vapor pressure from those in the compressed liquid. The temperature and/or pressure effects on the speed of sound are discussed and compared with data for some other hydrofluorocarbons reported elsewhere.

Speed of Sound in Binary Mixtures of Pentafluoroethane and 1,1-Difluoroethane from 243.15 K to 333.15 K and Pressures up to 30 MPa

“…In our previous papers, we have reported the speed of sound in dense liquids and the vapor pressure and/or bubble-point pressure for several pure hydrofluorocarbons (CHF 2 CF 3 , 1 CF 3 CH 2 F, 2 CF 3 CH 3 , 3 and CH 3 CHF 2 4 ) and their mixtures (CHF 2 CF 3 + CF 3 CH 2 F 5 and CHF 2 CF 3 + CF 3 -CH 3 6 ) measured over wide temperature and pressure ranges. These results give valuable information that can be used to investigate the thermophysical characterization of each pure substance and the resulting mixtures.…”