23 September 2011
Recently, hydrofluoroolefins (HFOs) are considered as candidate groups of new
refrigerants due to their mild impact on the environment. However, the accumulation of
experimental measurements information about their thermodynamic properties is insufficient.
Reliable equations of state for these working fluids are necessary to evaluate the cycle
performance of refrigeration systems. In order to develop a reliable equation of state for a
fluid, various thermodynamic property measurements of the fluid are required. Among them,
isochoric specific heat capacity (cv) measurements in the liquid phase provide a very useful
check for calculations of the second derivative of the pressure with respect to temperature,
which is essential information to develop a equation of state but is challenging to measure
accurately. For liquid refrigerants, we have been reported several measurements with a twincell type adiabatic calorimeter. The adiabatic method is generally accepted in lots of
techniques to give the most accurate results. In this work, isochoric specific heat capacity (cv)
measurements for a new refrigerant mixture of HFC-32 + HFO-1234ze(E) are measured at
temperatures from 268 K to 457 K and at pressures up to 30 MPa. Behavior of the measured
cv data are compared with that of the component substances.