Bioagregados inteligentes: incorporação de materiais de armazenamento de energia térmica em partículas lignocelulósicas

Abstract

The use of phase change material (PCM) has been gaining prominence in research related to energy efficiency due to its ability to store energy. In recent years, there has been a great deal of research into the development and application of PCMs in various areas such as civil construction, solar systems, cold storage, among others. The aim of this work is to develop bio-aggregates with thermal energy storage capacity. To this end, the following materials were obtained: Pinus and Paineira wood particles, Crodatherm 24 commercial phase change materials and coconut oil as a natural alternative, carboxylated styrene butadiene and carboxylated acrylonitrile butadiene rubbers, and CPV ARI cement. To develop the bio-aggregate, the wood from the different species was ground in a hammer mill and classified using sieves to obtain the particles. The particles were saturated by immersion in PCM using a vacuum pump. The particles containing PCM or coconut oil were coated with rubber and sand. Wood particles without PCM or coconut oil were also coated. Finally, composites were produced, one as a reference, using only mineral aggregate, in mass proportions of 1:2.6:2.7:0.6 for cement, fine aggregate, coarse aggregate and water, respectively. To evaluate the bio-aggregates, the volume of the coarse aggregate was calculated and replaced. Ten composites were evaluated. For each species, composites with bio-aggregates were produced: wood particles only, coated particles, and particles containing PCM or coconut oil coated. The bio-aggregates were characterized by obtaining the density, mass proportion of the constituent materials, infrared (ATR-IR) and images. The composites were subjected to thermal analysis according to the DKK (dynamische kugel kalorimetrie) methodology. Mechanical analysis was also carried out in accordance with EN-196, flexural and compression tests. The bio-aggregates contained approximately 15, 30 and 55% of the mass of wood, PCM and coating, respectively. The mix used to produce the composites resulted in approximately 5 and 7% PCM mass for the Paineira and Pinus species, respectively. Thermal analysis showed that the composites were energy efficient, maintaining the temperature during the change of state for approximately 1 hour. The mechanical tests showed a reduction in flexural and compressive strength compared to the reference. However, bio-aggregates can be used in non-structural elements in civil construction, such as sealing elements and mortar coatings.