Conductividades térmicas de sistemas con cambio de fasenano-fluidos y nano-compuestos

Resumo

This Ph.D. dissertation splits into two parts. In the first one we present high accuracy experimental measurements of the thermal conductivity of even and odd‐numbered n‐alkanes (npentadecane, n‐hexadecane, n‐heptadecane, n‐octadecane, n‐nonadecane and n‐eicosane) as a function of the temperature and at atmospheric pressure. In all cases, the temperature range investigated included the melting point, hence, in some of the measurements the substance was in the solid state and in some other measurements the substance was in the liquid state. To carry out the thermal conductivity measurements, the transient hot‐wire technique was employed, with an experimental setup specifically designed and built in the Applied Physics I Department (Complutense University). We include a detailed description of the experimental setup, of the analysis and data reduction method, as well as a careful estimation of reproducibility, accuracy and reliability of the experimental data obtained. In our setup, the sample crystallizes inside the measurement cell. Hence, in opposition to some previous investigation in the field, the measurements of the thermal conductivity in solid and in liquid state are performed on exactly the same sample, and using the same method and data reduction procedure. The linear alkanes investigated are the basic components of many Phase Change Materials (PCM), which nowadays are being incorporated in various technological applications in the field of renewable energies, for thermal energy storage and thermal cooling...