Characteristics analysis of heat and mass transport in catalytic
reaction layers of thermally integrated reformers
In conventional fuel cells, a predominantly diffusive heat and mass transport is established in the diffusion layer. However, conventional fuel cells cannot ensure a heat and mass transport from the porous diffusion layer to the catalytic reaction layer that is sufficiently uniform for this purpose. The present study aims to provide a methodology for determining the characteristics of heat and mass transport in catalytic reaction layers. Numerical simulations are performed using computational fluid dynamics to better understand the characteristics of heat and mass transport in catalytic reaction layers of thermally integrated reformers. The present study aims to provide a fundamental understanding of the heat and mass transport in catalytic reaction layers of thermally integrated reformers. Particular emphasis is placed upon the dimensionless quantities involved in thermally integrated reformer with different catalytic reaction layer structures. The results indicate that a vapor-liquid equilibrium exists when the escape tendency of the specie from liquid to a vapor phase is exactly balanced with the escape phase at the same temperature and pressure. It may be beneficial to utilize the thermodynamic work potential provided by the transfer of heat to drive the separation process in the desired direction. If a chamber partition operates below its maximum heat transfer flux capability, this flux often can be increased by augmenting adjacent latent energy transfer which transfers through the partition as sensible energy. The external balance establishes the net enthalpy offset and therefore the temperature difference and the net amount of liquid that may be evaporated or condensed. A pure diffusive heat and mass transport would lead to an uneven reaction density or current density in the catalytic reaction layer, on account of a corresponding lack of uniformity in the heat and mass transport in the same catalytic reaction layer. A high pressure-drop in the thermally integrated reformer is to be avoided, since a high-pressure drop is associated with correspondingly high-power losses, which in turn results in a low overall efficiency. The conduit surface may vary along the general direction of flow to provide the zones either intermittently or preferably continuously as with an undulating membrane surface. When tubular membranes are employed, which membranes are preferably circular in cross section, the zones are preferably provided by circumferential furrowing.
Keywords: Integrated reformers; Temperature differences; Membrane surfaces; Dimensionless quantities; Heat transport; Mass transport