Desenvolvimento de um material de mudança de fase aditivado com nanopartículas a base de carbono

Abstract

Phase change materials (PCM) are latent thermal energy stores. By promoting energy use, either by reducing the consumption of existing electrical systems, or by maintaining the operation of facilities in situations of power failure, it has applicability in various sectors of the economy, including refrigeration. PCM is a technological alternative capable of attenuating temperature fluctuation, contributing to a longer shelf life of products. The objective of this investigation is the development of a NePCM additive with nanoparticles, which acts at low temperatures, 15 to -5°C, in cooling and freezing of products such as apples, grapes, peaches, plums, lettuce and beets, with values of higher thermal conductivity when compared to the base MMF. In this research, twelve phase change materials were developed, based on water and glycerol (19.71% by mass fraction) additive with two nanomaterials, the multi-walled carbon nanotube (MWCNT), high value of thermal conductivity, 4000 W/ mK, and graphene oxide nanoplatelets (GO), stabilizing function, six functionalized with chitosan and six with sulfuric and nitric acids. In each functionalization group, the nanoenhanced phase change material (NePCM-AG) presents a concentration of nanometric materials inserted in the MMF in the proportion of 0.03 g/l or 0.06 g/l, with three variations in the mass composition of the nanopowders , 100% MWCNT, 50% MWCNT and 50% GO, 75% MWCNT and 25% GO. The density, dynamic viscosity, stability, thermal conductivity and enthalpy of each NePCM-AG are measured and discussed. Among the results, NePCM-AG1 and NePCM-AG2 stand out as they indicated a global increase in the value of thermal conductivity, 1.16% and 0.47%, respectively; enthalpy decreases in NePCM -AG with the insertion of nanoparticles, the lowest measured value is recorded in NePCM-AG9, a reduction of 1.73%, in relation to the base phase change material.