Effects of condensation in microchannels with a porous boundary: analytical investigation on heat transfer and meniscus shape

Abstract

In two-phase miniature and microchannel flows, the meniscus shape must be considered due to effects that are affected by condensation and/or evaporation and coupled with the transport phenomena in the thin film on the microchannel wall, when capillary forces drive the working fluid. This investigation presents an analytical model for microchannel condensers with a porous boundary, where capillary forces pump the fluid. Methanol was selected as the working fluid. Very low liquid Reynolds numbers were obtained (Re~6), but very high Nusselt numbers (Nu~150) could be found due to the channel size (1.5 mm) and the presence of the porous boundary. The meniscus calculation provided consistent results for the vapor interface temperature and pressure, as well as the meniscus curvature. The obtained results show that microchannel condensers with a porous boundary can be used for heat dissipation with reduced heat transfer area and very high heat dissipation capabilities

Transport phenomena and dimensionless numbers: towards a new methodological approach

“…In the researches of Bénard-Marangoni convection liquid layers with deformable free surfaces [111][112][113], evaporating droplets spreading over the heated substrates [114], and in some other phenomena [115][116][117][118], the Crnumber is used as follows:…”

A Critical Review on Condensation Heat Transfer in Microchannels and Minichannels

“…Riehl et al [21] presented an analytical model for microchannel condensers with a porous boundary, where capillary forces pumped the fluid. The researchers proposed their model as a tool to aid in the design of microchannel condensers with possible applications to microelectronics cooling, microheat exchangers, and condensers in capillary pumped loops and loop heat pipes with restricted heat dissipation area.…”