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Isochoric p-rho-T and Heat Capacity Cv Measurements for Ternary Refrigerant Mixtures Containing Difluoromethane (R32), Pentafluoroethane (R125), and 1,1,1,2-Tetrafluoroethane (R134a) From 200 to 400 at Pressures to 35 MPa

Published

Author(s)

Joe W. Magee

Abstract

The p-p-T relationships and constant volume heat capacity Cυ were measured fro ternary refrigerant mixtures by isochoric methods with gravimetric determinations of the amount of substance. Temperatures ranged from 200 to 400 K for p-p-T and from 203 to 345 K for Cυ, while for both data types pressures extended to 35 MPa. Measurements of p-p-T were carried out on compressed gas and liquid samples with the following mole fraction compositions: 0.3337R32 + 0.3333 R125 + 03330 R134a and 0.3808 R32 + 01798 R125 + 04394 R124a. Measurements of Cυ were carried out on liquid samples for the same two compositions. Published p-p-T data are in good agreement with this study. For the p-p-T apparatus, the uncertainty is 0.03 K for temperature and is 0.01% for pressure at p>3 MPa and 0.05% at p3), with a standard uncertainty of 0.003 cm3. When all components of experimental uncertainty are considered, the expanded relative uncertainty (with a coverage factor k=2 and, thus, a two-standard deviation estimate) of the density measurements is estimated to be 0.05%. For the C^dυ calorimeter, the uncertainty of the temperature rise is 0.002 K and for the change-of-volume work it is 0.2%; the latter is the principal source of uncertainty. When all components of experimental uncertainty are considered, the expanded relative uncertainty of the heat capacity measurements is estimated to be 0.7%.
Citation
International Journal of Thermophysics
Volume
1
Issue
No. 21

Keywords

density, difluoromethane, heat capacity, mixtures, p-p-T data, pentafluoroethane, R125, R134a, R32

Citation

Magee, J. (1999), Isochoric p-rho-T and Heat Capacity Cv Measurements for Ternary Refrigerant Mixtures Containing Difluoromethane (R32), Pentafluoroethane (R125), and 1,1,1,2-Tetrafluoroethane (R134a) From 200 to 400 at Pressures to 35 MPa, International Journal of Thermophysics (Accessed April 24, 2024)
Created June 1, 1999, Updated February 17, 2017