Flow Boiling Through v-Shape Microchannels

Microchannel Experimental Structure for Measuring Temperature Fields During Convective Boiling

“…Peng and Wang [2] observed an absence of partial nucleate boiling in 600 µm by 700 µm rectangular microchannels machined into a stainless steel plate with thermocouples on the backside. The same results were observed by Peng et al [3] in V-shaped microchannels with hydraulic diameters of 200 µm to 600 µm. Jiang et al [4] reported phase change in V-shaped microchannels with hydraulic diameters of 40 µm and 80 µm using a localized heating element with distributed polysilicon temperature sensors, and Lee et al [5] observed phase change in parallel rectangular channels with a 24 µm hydraulic diameter.…”

“…To understand convective boiling in microchannels, single and multiple channel structures have been developed using conventional machining [2], [3] and silicon micromachining [4] - [9]. Silicon micromachining allows integration of heaters and sensors onto the test structure.…”

Arguments on Microscale Boiling Dynamics

“…Since the vapor bubble occupies most of the cross section of the channel once nucleation happens, the bubble can only extend along two longitudinal directions. Therefore, the hydraulic diameter of a microchannel or characteristic size of a microstructure is expected to be a signi cant parameter that affects bubble generation, growth, the formed shape, the boiling regime, and the corresponding thermodynamic state and transport processes [19][20][21].…”

Boiling flow characteristics in microchannels with very hydrophobic surface to super-hydrophilic surface

“…Peng and Wang [1] carried out experiments on the flow boiling of water in a stainless steel microchannel with rectangular cross-section of 0.6 Â 0.7 mm and found fully developed nucleate boiling with no bubble growth inside the microchannels. Their findings were explained by the concept of evaporating space and fictitious boiling [2][3][4]. In a much smaller channel array with hydrodynamic diameter of 40 and 80 lm made on a silicon substrate by wet etch, three stable phase-change modes, i.e.…”