Research On Heat Transfer And Storage Properties Of Micro And Nano Carbon Material/paraffin Composites

Abstract:To a large extent, phase change heat storage technology could solve the problem of matching energy in time and space during the progress of utilization and improve energy efficiency. By contrast with other phase change storage technologies, solid liquid phase change had outstanding properties, high latent heat and small volume change during the phase change progress. However, most of the solid-liquid phase change materials had low thermal conductivity and poor heat transfer property, leading to the undue heat storage and release. As a result, the thermal conductivity improvement of the phase-change materials which have high latent heat of great significance and will have extensive application prospect.Among the most enhancement methods of thermal conductivity, materials with high thermal conductivity and low density were added in phase change materials to enhance the progress of heat transfer and the heat storage. And melting and blending is applied in this paper for the preparation of single-walled carbon nanotube(SWCNT)/paraffin composite and grapheme/paraffin composite. The apparent morphology and the key thermophysical parameters of the materials like thermal conductivity, melting point and latent heat were obtained; after that, through the establishment of a dynamic thermal response test system, the thermal respond speed of the composites is demonstrated; finally, an effective theoretical model for thermal conductivity is proposed for the improvement of the composites and it is proved that the calculation values of the model are relatively good in conformity with the experimental data. The results show that:(1) Without adding any dispersant, micro and nano carbon/paraffin composite was prepared by melt blending and ultrasonic dispersion. And the apparent morphology characterization were characterized by SEM. The experiment results showed that the composite had stable suspension and uniform distribution.(2) The main thermophysical parameters, such as thermal conductivity, melting temperature and latent heat, were tested by DSC and analysis of heat transfer theory. And the above parameters were analyzed by the influence of micro and nano carbon category and ratio(3) The experimental platform for dynamic thermal response was set up. The effect of micro-nano carbon category, ratio and heat source temperature on the above parameters was analyzed with exploring the thermal response speed of the composite.(4) The computation model of thermal conductivity effective about SWCNT/paraffin composites were obtained by proposing spatial distribution function with first-order polynomial form. The calculated value using the model is compliant with the experimental data. The effect of distribution function form and SWCNT thermal conductivity on the above computation model was studied.