Numerical modeling and analysis of Transport Membrane Condensers for waste heat and water recovery from flue gas

摘要

Heat exchangers based on Transport Membrane Condenser (TMC) technology use nano-scale ceramic porous membrane tubes in order to recover both latent heat of condensation and water vapor from the exhaust gases. The main objective of the current work is to propose a modeling procedure based on computational fluid dynamics for the simulation of heat and mass transfer in the TMC based heat exchangers. A new mixed condensation model based on the wall condensation and capillary condensation in the membrane has been proposed. The results obtained from the model are compared with the previous numerical and experimental data. The comparison shows that the mixed model which combines the solid wall condensation and the capillary condensation fluxes significantly improves the accuracy of the numerical results. Transport of the water vapor and other species in the flue-gas, porous media, and cooling water zones inside the TMC heat exchanger is modeled using appropriate User Defined Functions (UDFs). Using the current model the effect of inlet flue-gas and water flow rates, inlet flue-gas humidity and tube pitches of the TMC heat exchangers are studied in terms of heat transfer and recovery efficiencies.