G. Giuliani et al., A CONSTANT VOLUME APPARATUS FOR VAPOR-PRESSURE AND GAS-PHASE P-V-T MEASUREMENTS - VALIDATION WITH DATA FOR R22 AND R134A, Fluid phase equilibria, 109(2), 1995, pp. 265-279
We describe a constant volume apparatus using a spherical cell for the
experimental determination of vapour pressure and gas phase pressure-
volume-temperature (P-v-T) data for alternative refrigerants. This app
aratus has been designed for measurements in the temperature range fro
m 245 K to 365 K and for pressures up to 5 MPa. The modifications done
to the existing apparatus and the experimental procedure employed to
improve the quality of data are explained in detail. The uncertainties
involved in the measurement of temperature, pressure, mass and volume
are also discussed. New measured data for vapour pressure and P-v-T b
ehaviour in gaseous state for high purity samples of chlorodifluoromet
hane (R22) and 1,1,1,2-tetrafluoroethane (R134a) and the validation of
the experimental procedure are presented. The validation has been per
formed by comparing the measured data with correlations and data avail
able in recent literature in terms of the following statistical parame
ters: percentage deviation, absolute average deviation, bias, standard
deviation, root mean square deviation and the difference in pressure.
The results indicate that the constant volume cell with measuring ins
truments and the procedure employed gives reliable and accurate data.