In the following, the specific heat average at solid and liquid states, respectively denoted Cps and Cpl and the melting enthalpies ΔHm are recorded in Table 2. The deviation given here is computed with respect to the lower heating rate of 0.5 K/min.
It can be noticed from the results of Table 2 that the specific heats before and after the phase change are very close for a given scanning rate. The phase change enthalpy was classically obtained by the computation of the Cp peak area delimited by the Cp curve and the base line defined by the sensible heat. Note that the value of 102 kJ/kg obtained with the lowest heating rate (β1⁄40.5 K/min) presents the best approximation with regards to the melting enthalpy value of 100 kJ/kg given by the manufacturer.
Fig. 6 shows the specific heat of the PCMs measured with variable sample masses (8 mg, 10 mg and 12 mg) and a constant heating rate (0.5 K/min). The similar trends are observed in the three curves. The results of specific heats at solid and liquid states as well as the phase change enthalpies are summarized in Table 3.