Tubular Si-infiltrated SiCf/SiC composites for solar receiver application - Part 2: Thermal performance analysis and prediction

Tubular Si-infiltrated SiCf/SiC composites composed of an inner cellular ceramic and an outer dense Ceramic Matrix Composite (CMC) skin have been fabricated by the electrophoretic deposition of matrix phases followed by Si-infiltration for pre-feasibility testing in solar receiver applications. The tubes have been considered to be used as high temperature receiver components for the solar operation of a gas turbine or a combined cycle with temperatures up to 1300 °C and typical pressures of more than 6 bar. The cellular structure inside the tube has been introduced for the improvement of heat transfer from the irradiated outer surface of the tube to the working fluid inside. Heat transfer and permeability characteristics of the composite samples have been determined experimentally as effective properties. These properties have been used in numerical models to predict the performance of such kind of components in gas turbine service conditions. It could be demonstrated, that the heat transfer rate in a tube with a porous in-lay could be increased to approximately four times compared to the rate of an empty tube of the same size. The results of the study give reason for further experimental testing in service environments.