Acoustic and microwave method in spherical cavities for the determination of the thermophysical properties of gaseous mixtures

The experimental methods and the underlying theory for the accurate determination of the speed of sound in gases with spherical cavities have been substantially improved during the past two decades aiming at an accurate acoustic determination of the Boltzmann constant. Here, we discuss the possible use of these methods and instrumentation for the determination of the speed of sound and other thermophysical properties of binary monoatomic gas mixtures. These properties, which include the diusion and thermo-diusion coecients, are of interest for several applications, such as thermoacoustic engines and acoustic methods for the determination of the composition of ssion gases in nuclear fuel rods. Interestingly, the extremely high accuracy achievable with these experiments over a wide range of temperatures and pressures may help to discriminate among contrasting theories of acoustic propagation in gas mixtures and the competing validity of the methods commonly used to predict the transport properties of mixtures