Thermal conductivity analysis of ceramic membranes for recovering water from flue gas

Abstract

Condensation is the common mechanism of water intake from gases. Transport membrane condenser is a newly proposed technology to recover water from flue gas based on the mechanism of condensation. Most of the existing heat transfer research on transport membrane condenser focuses on water vapor phase change or fluid convection heat transfer, and there is a lack of research on the thermal conductivity of ceramic membranes. The significance of studying thermal conductivity is to optimize the overall heat transfer performance. The thermal conductivity of alumina ceramic solid materials is not good enough, which can affect the industrial application performance to a certain extent. There is currently a lack of experimental measurements or theoretical calculations to quantitatively characterize the thermal conductivity of ceramic membranes. This affects the optimization of overall heat transfer performance of transport membrane condenser. In this paper, coal fly ash is used as the raw materials to prepare macroporous ceramic membranes. Coal fly ash is a very cheap material. It can greatly reduce the manufacturing cost of transport membrane condenser using coal fly ash to prepare ceramic membranes. The classical theoretical model of thermal conductivity of porous materials is introduced, the calculation and experimental results are compared, and the validity and limitation of the classical models in analyzing the heat transfer problem of transport membrane condenser are discussed. Finally, based on the composite effective medium theory, combining with the experimental results, a modified model is proposed. The modified model reduces the average theoretical error to 7.20%, and enriches the research on the heat transfer theory of transport membrane condenser.