Tese e Dissertação

Tese: Development of microencapsulated phase change materials for energy efficiency applications

A way of reducing CO2 emissions is to decrease energy consumption in buildings. One promising approach to achieve this goal is the use of phase change materials (PCMs) as thermal energy storage systems for thermoregulation applications. However, the incorporation of PCMs in building components is challenging. Microencapsulation of PCMs has shown promising results as a passive form to improve the thermal performance of building materials, reducing the wasted energy with thermal comfort. In this context, this work is focused into two different aspects of microencapsulated phase change materials. The first is a numerical investigation of the internal temperature behavior of building walls with a thin layer of concrete with capsules. A one-dimensional transient methodology is proposed, with the presence of the microcapsules being simulated by a concentration function and the phase change process with the effective heat capacity method. The effects of the layer’s position, concentration, PCM melting temperature, and phase change enthalpy in the wall’s internal temperature profile were assessed. Moreover, we fabricated microencapsulated PCMs using poly (dimethylsiloxane) (PDMS) as a shell material and calcium chloride hexahydrate (CaCl2 · 6H2O) as PCM core. The production was performed using glass capillary microfluidic devices to ensure the production of monodisperse microcapsules with tunable geometrical properties such as size and shell thickness. The study shows a direct relationship between the position and concentration on the internal temperature as well as the reduction of internal temperature of walls. We were able to produce and stock PDMS/CaCl2 · 6H2O microcapsules with tunable properties. Finally, preliminary thermal efficiency tests were performed, demonstrating that this combination of shell/core was not ideal for these applications, however, due to the promising results presented by the numerical model, new combinations will be developed and tested in future works.

Link da defesa
https://puc-rio.zoom.us/j/91586983995?pwd=Lb21ROSVIa4yoH5cu4WtMqYi5bXK0R.1

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