Fractal modeling of polycrystalline PCMs

We generate the grain size distribution for a material of a polycrystalline structure by a fractal modeling and use the results for theoretical predictions for peaks in the heat capacity vs. temperature plot. This is a continuation in our theoretical technique from which heat capacity peaks corresponding to first-order phase transitions can be obtained. In experiment the peaks are much broader and smaller in comparison with results of statistical mechanics for such transitions in macroscopic systems. However, we used the idea that, for a material composed of many grains, it is appropriate to apply the statistical mechanical results to the individual grains and then evaluate an average over all grains of various sizes. Then agreement between the theoretical and experimental results can be achieved. We illustrate the results of the fractal modeling for an example of pure alkane tricosane that undergoes a crystal to rotator phase transition at about 42.5 °C.