Hydraulic and thermal characteristics of a vapor venting two-phase microchannel heat exchanger

Hierarchical biphilic micro/nanostructures for a new generation phase-change heat sink

“…7b) show that the performance of the new device is achieved at 1e2 orders of magnitude lower mass flux as compared to that of prior studies. In particular, an order of magnitude difference between the results of this study and those of David et al [34] (large highlighted red stars) that implemented a vapor venting membrane is noteworthy. The arrangement utilized by David et al [34] (cf.…”

“…This requires, unlike any other two-phase heat sink discussed in literature, the heat sink to have no liquid exit. A prior effort on utilizing venting membranes in two-phase heat sinks by David et al [34] could not improve the CHF because no mechanism was implemented to constrain the bubbles and their coverage of the heat transfer surface. In essence, bubbles could freely expand and cover the heat transfer surface (cf.…”

“…While these strategies have resulted in some improvements in pool boiling heat transfer [25,26,30,33], a similar benefit has not been realized in microchannels boiling due to limitations in the permeability of micro-and nanostructures [29,31] and surface tension forces to maintain the heated surface wet. In addition, attempts have been made to displace the vapor from the vicinity of the heat transfer surface either through a vapor venting cap [34] or forming a divergent open space over the flow channel [35]. The later approach has shown a promising performance of 281 W/cm 2 at a low flow pressure drop.…”

Electronics Thermal Management in Information and Communications Technologies: Challenges and Future Directions

“…Several geometric enhancements have been proposed to suppress instabilities, such as inlet restrictions [101], channel tapering [102] and the use of surface roughness [103]. Recent work at Stanford has focused on vapor/liquid phase separation, i.e., vapor extraction from a microchannel flow using permeable membrane surfaces [104] or heat pipeinspired separation using phase-separator coatings on a porous medium which keeps liquid contained within structure by surface forces, yet allows evaporation at the boundaries. One remaining challenge with membrane vapor separation is membrane clogging.…”

Temperature Transients for Detection of Flow-regimes in a Mini/Microchannel

“…Especially for such applications, flow boiling in micro-channels has been identified to be very promising as the phase change process facilitates smaller thermal resistances [2] and the pumping power requirement too is quite small [3].…”