Temperature and Pressure Dependences of Thermophysical Properties of Some Ethylene Glycol Dimethyl Ethers from Ultrasonic Measurements
Résumé
In this work, the speed of sound was measured in monoglyme (monoethylene glycol dimethyl ether or MEGDME) and diglyme (diethylene glycol dimethyl ether or DEGDME) in the temperature range at pressures up to 100 MPa using a pulse echo technique operating at 3 MHz; several thermophysical properties were determined in the same P-T range from these measurements. Furthermore, the density, isothermal compressibility, and isobaric thermal expansion coefficient, determined from volumetric data (direct method) and from acoustic measurements (indirect method) for four glymes have been compared. The comparison was extended to a second-order derivative of density with pressure, namely, the nonlinear acoustic parameter B/A.