Efficient and economic water and heat recovery from flue gas by novel hydrophilic polymeric membrane condenser

Abstract

The membrane technology for water and heat recovery from flue gas possesses the advantages of a simple structure and high water quality. In this study, we propose a novel hydrophilic polymeric membrane condenser (HPMC) to efficiently recover water and heat from flue gas. Compared to current hydrophilic ceramic membrane condenser (HCMC), HPMC offers the benefits of cost-effectiveness and high packing density. An experimental investigation is conducted to explore the fluid flow characteristics as well as the water and heat recovery performance of HPMC. The maximum recovered water flux reaches 6.7 kg/(m2·h), while the maximum recovered heat flux amounts to 18.6 MJ/(m2·h). Enhancing gas/water flow rates or increasing heat transfer temperature difference can significantly improve both recovered water and heat fluxes. Notably, it is found that thermal resistance primarily stems from the polymeric membrane, emphasizing the importance of enhancing the membrane's thermal conductivity to improve HPMC performance. The overall heat transfer coefficient can be enhanced by increasing the gas/water flow rate, while the influence of gas/water temperature on the overall heat transfer coefficient is relatively insignificant. Furthermore, by fitting experimental data, a correlation formula for friction factor is obtained, which greatly enhances accuracy in pressure drop calculations under practical operating conditions. Based on the technical and economic analysis, the payback period for HPMC is merely 0.3 years, significantly shorter than that for HCMC, thereby indicating a substantial potential for commercial application of HPMC. This study demonstrates that the HPMC is an excellent candidate for recovering water and heat from flue gas, and the fundamental data provides valuable foundational insights for future enhancement of HPMC.