Thermal Behavior Mapping of a Phase Change Material Between the Heating and Cooling Enthalpy-temperature Curves

This paper presents the results of experimental tests performed on a wall section equipped with phase change materials (PCM). The wall is quickly transferred between cold and warm enclosures to observe the PCM behavior when melting or solidification is interrupted. A 1-D model of the wall based on the enthalpy method is used to identify the enthalpy curves that provide the best fit to experimental data. Results show that the PCM experiences a quick transition between different enthalpy curves when the heat flow direction (heating or cooling) is reversed during phase-change. According to our experiments and to the comparison with the 1-D model, the PCM investigated here follows an enthalpy curve that is very close to the heating curve when a cooling process is interrupted during solidification. If a heating process is interrupted during melting, the PCM follows an enthalpy curve that is located between the heating and cooling curves. This information is important to develop models for PCM used in buildings and further work is required to assess the impact of different factors on the transitional behavior.