Subcooled flow boiling on hydrophilic and super-hydrophilic surfaces in microchannel under different orientations

Experimental Study and Mechanism Analysis of the Flow Boiling and Heat Transfer Characteristics in Microchannels with Different Surface Wettability

“…Flow visualization indicated local dryout occurring on the untreated surface at high heat flux and low mass flux, attached to deterioration in heat transfer performance. Conversely, this tendency was not observed on a super-hydrophilic surface, which was consistent with recent research conclusions [ 13 , 14 ]. However, a mechanism for alleviating the dryout phenomenon needed further study.…”

Experimental and Numerical Investigation of Micro/Mini Channel Flow-Boiling Heat Transfer with Non-Uniform Circumferential Heat Fluxes at Different Rotational Orientations

“…They found that by heating a set of square horizontal parallel microchannels (0.5 mm in size) from below, rather than from above, the heat transfer coefficient could be 14% higher at low heat fluxes and 10% higher at high heat fluxes. Similar trends were also found by Li, et al [20] for a non-uniformly heated microchannel with a width of 5 mm and depth of 0.5 mm at mass fluxes of 200 to 500 kg/m 2 s, heat fluxes between 4 to 25 kW/m 2 for deionised water. They considered vertical upward and downward flows as well as horizontal flow with heating from above and below.…”

“…However, due to thermal conduction in the microchannel substrate, this inevitably results in some degree of circumferential non-uniform heat flux on the internal wetted surface. Studies have been conducted on the influence of parameters such as the number of channels [6,7], the cross-sectional profile [8][9][10], hydraulic diameters [11][12][13][14][15], systems with uniform heating [16][17][18][19][20][21][22], the orientation of the channel [1,23,24], hydrodynamic effects like confinement [25][26][27] and the effect of varying working fluids [28,29].…”

“…Experimental studies on the effect of gravitational orientation on flow-boiling in microchannels have shown that the largest difference in local heat transfer coefficient between top-and bottom-heated channel occurs on the section of the M Vermaak, J Potgieter, J Dirker, M A Moghimi, P Valluri, K Sefiane, J P Meyer heated surface that experiences bubble nucleation and departure [20,46]. Numerical investigations into this phenomenon have shown that bubble departure during microchannel flow-boiling affects the heat transfer via the introduction of a liquid film between the vapour and the heated surface.…”

Adaptive mesh refinement method for the reduction of computational costs while simulating slug flow

“…For an inclined channel, the flow direction is rotated and the vector component of gravity parallel to the flow changes. While rotational orientation has been investigated at several different positions by researchers such as Ajith Krishnan et al [19] and Vermaak et al [20], inclined orientation is limited to flow that is either perpendicular or parallel to gravity [21,22], resulting in an area of research that needs to get more attention.…”