Analysis of Heat and Mass Transfer during Condensation over a Porous Substrate

Abstract

Condensing heat exchangers are important in many space applications for thermal and humidity control systems. The International Space Station uses a cooled fin surface to condense moisture from humid air that is blown over it. The condensate and the air are "slurped" into a system that separates air and water by centrifugal forces. The use of a cooled porous substrate is an attractive alternative to the fin where condensation and liquid/gas separation can be achieved in a single step. We analyze the heat and mass transfer during condensation of moisture from flowing air over such a cooled, flat, porous substrate. A fully developed regime is investigated for coupled mass, momentum and energy transport in the gas phase, and momentum and energy transport in the condensate layer on the porous substrate and through the porous medium.

Condensate Migration Dynamics into Porous Bed in a Nonperforated Chamber

“…Beyond the directly lateral and/or axial forced [4][5][6][7], hereafter, indirectly lateral condensate flow, i.e. using tangential or plain vapor flow, in a porous media was conducted [8]. Furthermore, also in a plain vapor, distinguishing Darcian-and non-Darcy regime for the flow in a solid matrix, was analytically carried out [9].…”

“…The above studies, a produced condensate was obtained by suction forced together with permeability [4][5][6], with surface tension [7], and with gravity [8]. It means the studies did not consider yet wetting-angle effects on the transport dynamics.…”

Conceptual Design of a Condensing Heat Exchanger for Space Systems using Porous Media

“…The heat flux, Q includes both the sensible heat and the heat of condensation. Theoretical solutions of the conjugate heat and mass transfer with condensation including porous substrate are being performed and will be reported elsewhere [5]. This analysis shows that…”