Isobaric heat capacity measurements of liquid HFE-7200 and HFE-7500 from 245 to 353 K at pressures up to 15 MPa

• Flow calorimeter has been designed for measuring the heat capacity of the liquid.
• The new apparatus was verified by the heat capacity of pure water.
• The measured data of HFE-7200 and HFE-7500 were reported at functions of temperature and pressure.
• A Lee–Kesler type equation was used to correlate the data.
• The applied correlation satisfactorily represented the data.

An adiabatic flow calorimeter was developed for the measurement of the isobaric heat capacity of pure liquids and their mixtures, which could be used over the temperature range of (243–393) K and at pressure up to 20 MPa. The apparatus has been validated by measuring the isobaric heat capacity of pure water at different temperatures and pressures. With the flow calorimeter, the isobaric heat capacity of HFE-7200 (1-ethoxy-1,1, 2,2,3,3,4,4,4-nonafluorobutane, CAS Registry Number: 163702-05-4) and HFE-7500 (3-ethoxyperfluoro(2-methylhexane), CAS Registry Number:297730-93-9) were measured in the termperature range from (245 to 353) K and pressure range from (0.1 to 15) MPa. The expanded uncertainty with a level of confidence of 0.95 (k = 2) of the isobaric heat capacity measurement was estimated to be within ±2%, and the repeatability of the experimental data was better than ± 1%.