ACOUSTIC DETERMINATION OF THE IDEAL-GAS HEAT-CAPACITY OF N-HEPTANE AT HIGH-TEMPERATURES

A novel high-temperature spherical acoustic resonator has been developed to obtain values of the ideal-gas heat capacity at constant volume of n-heptane, based on measurements of perturbations in the speed of sound through a reference gas (argon) caused by small successive additions of n-heptane. The resonance frequencies in (n-heptane + argon) were measured at 25 K intervals over the temperature range 298.15 to 473.15 K. Mole fractions of n-heptane were varied from 0 to 0.031. The ideal-gas vapor-phase heat capacities at constant volume were evaluated from the obtained resonance frequencies at their respective temperature. © 1990.