Speed of SoundMeasurements in Cyclopentane at Temperaturesfrom (349 to 526) K and Pressures up to 10.0 MPa

Cyclopentane is an excellent working fluid in high-temperature organic Rankine cycle (ORC) systems. Currently, experimental measurements of the speed of sound in cyclopentane at temperatures above 353 K are not available in the literature. In this study, the speed of sound in cyclopentane is measured by the Rayleigh–Brillouin scattering method. Using the existing experimental equipment, the data are measured along six isobaric lines from 2.0 to 10.0 MPa at a temperature range of 349.40 to 525.97 K. The expanded relative uncertainty of the speed of sound measured in this experiment can be estimated to be 0.86% with the confidence level of 0.95 (coverage factor <i>k</i> = 2). The average absolute relative deviation (AARD) between our experimental data and calculated values with the equation of state (EOS) proposed as mentioned in this paper in the liquid-phase region is 0.99%, which confirms the effectiveness of the experimental results and the accuracy of the EOS. Furthermore, the data on the speed of sound from experimental results and the literature for cyclopentane are also fitted into a correlation formula related to the temperature and pressure, facilitating engineering applications.