Experimental investigations on flow boiling performance of reentrant and rectangular microchannels – A comparative study

Laser Beam Machining, Laser Beam Hybrid Machining, and Micro-channels Applications and Fabrication Techniques

“…Jin and Kang [223] fabricated such arrays of micro-channels on both sides of bipolar plates of aluminum alloys by vacuum die-casting. Among non-traditional machining process electric discharge machining (EDM) is considered as relatively good alternative having no material hardness and channel shape restrictions [224,225]. But there are also number of problems linked with EDM and wire-EDM such as low productivity, high tool wear rate, lack of precision due to tool wear, unsuitable for batch production or multi-channels [226], thick recast layer (from 2.5 to 30 µm) [227], heat affected layer of 40-100 um [227], thick white layers (6-8 µm) with micro-cracks [228], poor surface integrity [229] and necessary post processing requirements [230].…”

“…The choice of material depends on the requirements and systems where the micro-channels have to serve for cooling applications. For example, copper micro-channels are used for heat sinks cooling [224] and silicon micro-channels for particle physics detectors [238,239]. Micro-channels in aluminum alloy can be found in [221,223,225].…”

“…In one of the study, a unique X-shaped Fig. 53 Micro-channels of different sizes fabricated by Nd:YAG pulsed laser [51] cross section was seen where the researchers study the effect of micro-channel shape on flow boiling performance of fluids passing through micro-passages of the channels [224]. They also compared the performance of X-shaped micro-channels with rectangular shaped micro-channels.…”

Flow boiling performance of Ω-shaped reentrant copper microchannels with different channel sizes

“…Besides, alteration of the cross-sectional configurations from the aforementioned open shapes to the semi-closed reentrant ones provides another promising option to promote the flow boiling performance, which has been preliminarily demonstrated in several reports [18][19][20][21]. Goyal et al [18] developed a silicon reentrant cavity heat sink by etching and bonding process for enhanced liquid cooling of silicon multichip substances.…”

“…However, all the above reentrant microchannels were fabricated by complicated and costly MEMS procedures, as the fabrication difficulties for the reentrant configurations may increase remarkably compared to those of open ones. Recently, Deng et al [21] developed a novel type of reentrant copper microchannels with unique semi-closed X-shaped configurations. Such microchannels with reentrant shape were found to play a significant role on the two-phase flow behaviors compared to conventional rectangular microchannels.…”