Optical Measurement of Solidification Ratio in Phase Change Slurry considering Refraction in Droplets

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The objective of the present study is to develop an optical method to measure the solidification ratio of paraffin droplets suspended in phase change slurry. For the purpose, an analytical model was developed using the Monte Carlo method. The model calculates the transmittance and reflectance of the phase change slurry layer for laser beam with a wavelength of 670nm. The slurry contains paraffin particles with different diameters and different optical properties Experiments were also carried out to measure the transmittance and reflectance of the phase change slurry layer for laser beam with a wavelength of 670nm. The experiments were carried out for both solidified paraffin particles and liquid paraffin particles.From those study, following results are obtained;1. A model is developed to calculates the transmittance and reflectance of phase change slurry layer containing either solidified or liquefied paraffin droplets for laser beam with a wavelength of 670nm2. The results of the analytical model are confirmed by comparing the results with the analytical and experimental results of other researchers' studies.3. The cause of the increase in the reflectance and the decrease in the transmittance of the layer by the solidification of the paraffin particles in the layer is proved to be the formation of cavities on the droplet surfaces. And, the analytical results of the transmittance and the reflectance of the layer fit very well with the corresponding experimental results by using a solidified particle model with a dimple on the surface.By using the developed analytical model incorporating solid particle with a dimple on the surface, the estimation of solidification ratio of paraffin particles in phase change becomes possible by comparing the analytical results and the corresponding experimental ones.