A flow calorimeter for the measurement of the isothermal Joule-Thomson coefficient of gases at elevated temperatures and pressures. Results for nitrogen at temperatures up to 473 K and pressures up to 10 MPa and for carbon dioxide at temperatures up to 500 K and pressures up to 5 MPa

Abstract

A new isothermal flow calorimeter for gases at high temperatures and pressures is described. The calorimeter employs a throttling-capillary tube to provide both the pressure drop and the heating element. Considerable care was taken to operate the calorimeter in an isothermal environment by use of a fluidized-bed thermostat. The instrument has been used to make measurements of the molar isothermal Joule-Thomson coefficient of N 2at temperatures in the range 295 K to 473 K and at pressures in the range of 1.0 MPa to 10.0 MPa and also of CO 2at temperatures in the range 300 K to 500 K and at pressures in the range 3.0 MPa to 5.0 MPa. The molar isothermal Joule-Thomson coefficient for N 2has been measured to ± 1 J·MPa −1·mol −1and that for CO 2to ± 4 J·MPa −1·mol −1}. Agreement is found with other available experimental results and with the predictions made by the IUPAC-approved equations of state.