Michael R. Moldover
Thermophys. Div., Natl. Inst. of Standards and Technol., Gaithersburg, MD 20899
Acoustic resonance techniques have been developed at NIST to make accurate ((plus or minus)0.01%) speed-of-sound measurements in gases a routine matter. These techniques have been applied to many environmentally acceptable candidate replacement refrigerants. The data were used to deduce ideal-gas heat capacities and virial coefficients. These results are an important component of the computer package REFPROP that is being used by designers of refrigeration equipment. NIST is actively involved in developing acoustic methods for determining the viscosity and thermal conductivity of gases. NIST is also extending these measurement techniques to corrosive gases and to gases at high temperatures.