HEAT ACCUMULATION WITH MONTMORILLONITE/CARNAUBA WAX NANOMATERIALS

Abstract

A thermal energy latent accumulation using phase change materials attracts interest in energy storage under an isothermal condition. An introduction of the green chemistry principles in the creation of form-stable phase change materials occupies its justified technological niche. Information about the behavior of the molecules of materials obtained using physicochemical methods including NMR spectroscopy can be used to optimize the choice of material. The materials are required longer general thermal, chemical stability and according to the thermal cycling test for the extended performance of a system. The phase changr materials with a phase transition were obtained from melts by mixing nanosized montmorillonite with carnauba wax. As a result, a number of wax/nanomaterials solid samples were prepared by grinding with a mass ratio of 70/30, 60/40 and 50/50 %. The created composite materials had the latent heat, respectively 115.5 J g for 70/30, 107.8 J/g for 60/40 and 91.4 J/g for 50/50 samples. There is a correlation between the wax content in the PCMs 70, 60 and 50 % and the percentage of heat accumulation relative to pure wax, namely 61, 57 and 48 %. The black-grey material obtained makes it possible to reduce the time intervals of the cycle of accumulation and return of heat. The profiles of heat absorption curves for all materials break off at 100 °C and the cooling curves have two regions of heat loss. The area under the DSC curves during the first heating of the powders is more on 42 % of whole pieces of PСMs. The PCMs (50/50) 13С resonances were at around 20-40 ppm, which are the typical chemical shifts for the methylene carbons of the aliphatic region, at 62.82, 63.46 ppm for the oxygenated species, at 114.05, 116.11 ppm for the alkenes at 130.68, 133.44 ppm for the aromatic rings and at 172.92, 178.72 ppm for the carboxylic groups. 27Al spectrum has the maximum at 2.90 ppm of octahedral aluminium and at 26.53 ppm may belong to a distorted tetrahedral site. Bibl. 43, Fig. 3.