Heat storage materials based on nanomodified paraffin, controlled by a magnetic field

Abstract

The article presents studies of nano-modified heat-accumulating materials controlled by a magnetic field. Paraffin is used as a material with the effect of energy accumulation in the phase transition. Carbon nanotubes are used to modify paraffin. For the synthesis of carbon nanotubes used catalyst Co-Mo/Al2O3-MgO. The synthesis process is based on the CVD method. The method of obtaining nanomodified paraffin with ferromagnetic properties is described. To impart paraffin ferromagnetic properties, a ferromagnetic powder previously ground with carbon nanotubes was introduced into it. Mechanical activation was used for the ferromagnetic powder, which provided particles with an average size of 5 ?m. The analysis of charge control regimes of a paraffin-based heat-accumulating material was carried out using a non-contact method for measuring the temperature field. For this purpose, the FLUKE Ti9 thermal imager with a 160 x 120 radiation detector and a matrix in the focal plane and a measurement range from -20 to +250? was used. The morphology and structure of the synthesized carbon nanotubes were studied by scanning electron microscopy (a Hitachi H-800 transmission electron microscope). The behavior of the modified paraffin in the conditions of mineral motor oil under the influence of electromagnetic fields was studied. The design of a heat accumulator for working with a magnetically controlled heat-accumulating material is proposed. It is established that the heat transfer in the system is provided by two simultaneously occurring processes of natural and thermomagnetic convection. In turn, convection can be realized by changing the magnetic susceptibility with a change in temperature and with a geometric change in the position of a magnet or a group of magnets.