Calorimeter for measuring the isobaric specific heat capacity of fluids and fluid mixtures by the thermal relaxation method

We present a new calorimeter for measuring the isobaric specific heat capacity for fluids and fluid mixtures based on the thermal relaxation method. The calorimeter, which is equipped with a metal bellows, works in the temperature range from 250 to 500 K at pressures up to 20 MPa and is designed to satisfy the conditions of a lumped system. The calorimeter was calibrated using water and toluene. The isobaric specific heat capacity of methanol was measured at 323.15 K and 0.1 MPa, which confirms the reliability of the calorimeter. The uncertainty is estimated to be within 2.9% at a 95% confidence level