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 250to500K at pressures up to 20MPa 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 323.15K and 0.1MPa, which confirms the reliability of the calorimeter. The uncertainty is estimated to be within 2.9% at a 95% confidence level.