Enhancement of heat transfer in subcooled flow boiling with microbubble emission

Subcooled flow boiling and microbubble emission boiling phenomena in a partially heated microchannel

“…The shape of the circular dots boiling curve in Fig. 18 was similar to that obtained by Suzuki [11][12][13] for MEB occurring in copper mini/ macrochannel that had many nucleation sites. It can be seen from this boiling curve that the microheater temperature was about 95°C at ONB, which is also the crossing point of the boiling curves with highly smooth surface (square dots) and with eroded surface (circular dots).…”

“…The MEB phenomena on a Pyrex glass wall of a microchannel as observed in this experiment is somewhat different from those occurring in a copper mini/macrochannel as observed by Suzuki et al [11][12][13], possibly due to different surface conditions. Also, Suzuki et al [11][12][13] found that periodic MEB is usually accompanying with large inlet pressure oscillation with loud noise, which were not observed from this experiments. Thus, MEB in microchannel was more stable than those occurred in mini/ macrochannels.…”

“…It appears that the physical mechanism for the occurrence of miniature bubbles observed by Wang et al [10] was similar to the occurrence of microbubbles in the MEB [8,9]. With the aid of a high-speed camera and a microscope, Suzuki et al [11][12][13] carried out the first series of experiments on microbubble emission boiling in subcooled flow boiling in rectangular and circular minichannels with a localized heat source at a velocity ranging from 0.25 to 2.5 m/s and inlet water subcooling from 20 to 40°C. The rectangular channels were 1-17 mm in height and 12-24 mm in width with a heat source of 10-20 mm in width and 10-50 mm in length, and the circular channels were 5, 10, and 16 mm in diameters with a heat source 10 mm in length on the wall.…”

Flow boiling of ethanol/water binary mixture in a square mini-channel

“…Mixtures of water with ethanol, propanol and butanol were examined by Suzuki et al [14] in a subcooled flow boiling system to determine the effect that the addition of an organic fluid into water would have on heat transfer. It was observed that the maximum heat flux of the system increased with the addition of the organic fluid and that no dry-out was recorded under these circumstances.…”

Heat transfer enhancement of self-rewetting aqueous n-butanol solutions boiling in microchannels

“…Similar effect on the vapor bubble was found at subcooled pool boiling. Suzuki et al [19] studied flow boiling and pool boiling of water and alcohol-water mixtures, where methanol, ethanol and especially 1-butanol and 2-propanol showed significantly increased CHF compared to pure water. The boiling experiments were carried out with highly subcooled working fluids with microbubble emission generated in the transition boiling regime.…”