Cooling performance and pressure loss analysis of aeroengine exhaust gas treatment through porous media

An exhaust gas treatment concept employing porous media is proposed to reduce the water content in aeroengine exhaust, thereby mitigating contrail cirrus formation and its contribution to climate radiative forcing. By extracting water vapor and its precursors from the exhaust stream, the concept may also contribute to lowering soot emissions. The treatment unit is envisioned immediately downstream of the low-pressure turbine through an enlarged exhaust nozzle and comprises three sections: cooler, condenser, and heater. These components cool the exhaust, promote water condensation and collection, and subsequently reheat the exhaust. Although such integration may introduce additional weight and reduce engine thrust, quantifying these effects requires an assessment of cooling/heating, pressure losses, and the reduction in exhaust mass due to water removal. In this regard, this study presents a numerically supported analytical investigation of the cooling performance of porous media and the associated pressure losses. A simplified two-dimensional planar channel model with compressible flow through porous media is developed to obtain preliminary design estimates. The porous medium simultaneously enhances heat transfer and provides surfaces for vapor condensation, with its effectiveness governed by thermal conductivity, porosity, and structural characteristics incorporated through appropriate dimensionless parameters. Results demonstrate that porous media can cool the exhaust to temperatures suitable for effective condensation while maintaining total pressure losses within 1%–2% under extreme cooling conditions. Furthermore, wall cooling alone is insufficient to achieve the required temperature reduction, highlighting the essential role of porous media in both sensible cooling and latent heat removal, thereby sustaining favorable conditions for continuous condensation.