Membrane heat exchanger for novel heat recovery in carbon capture

In this work, we experimentally demonstrate a commercial ceramic membrane heat exchanger (CMHE) with an average pore size of 4 nm for novel heat recovery in post-combustion carbon capture. The CMHE shows superior performance over a conventional stainless steel heat exchanger (SSHE) with the same dimensions in recovering heat from the stripped gas mixture (H₂O(g)/CO₂) on top of the stripper in a monoethanolamine-based rich-split carbon capture process. Due to the coupled mass and heat transfers of water vapor through the membrane, the CMHE has higher heat flux, heat recovery and overall heat transfer coefficient than the SSHE. Liquid water transfer dominates the mass transfer mechanism in the CMHE. Thermal conduction contributes to more than 80% of the total heat transfer, dominating the heat transfer through the membrane heat exchanger. Our study demonstrates that membrane heat exchangers can be excellent candidates for heat recovery in post-combustion carbon capture. In further research, more types of membranes with higher thermal conductivities (e.g., porous metal membranes with lower porosity and smaller thickness) should be fabricated and tested for further performance enhancement.