Enhanced boiling with selective placement of nucleation sites
A heat transfer system includes a substrate having a heat exchange region including a surface having an enhancement region including alternating regions of selectively placed plurality of nucleation sites and regions lacking selectively placed nucleation sites, such that bubble formation and departure during boiling of a liquid in contact with the enhancement region induces liquid motion over the surface of the regions lacking selectively placed nucleation sites sufficient to enhance both critical heat flux and heat transfer coefficient at the critical heat flux in the enhancement region of the system.
1. A heat transfer system comprising:
a substrate in the system having a heat exchange region comprising a plurality of adjacent open microchannels and having an enhancement region comprising alternating regions of selectively placed plurality of nucleation sites comprising a microporous layer, laser holes, or cavities and regions lacking selectively placed nucleation sites, wherein each adjacent microchannel comprises a bottom surface, an open top and two sidewall surfaces each of which connect the bottom surface and a top surface between the adjacent open microchannels, wherein at least one of the plurality of adjacent open microchannels comprises an enhancement region comprising nucleation sites on the top surface and lacking nucleation sites on the sidewall surfaces and the bottom surface, wherein a width of the region of selectively placed nucleation sites comprises a distance of from about 100 μm to about 4 mm and a width of the region lacking selectively placed nucleation sites comprises a distance of from about 100 μm to about 4 mm, such that bubble formation and departure away from the substrate during boiling of a liquid in contact with the enhancement region induces liquid motion over the surface of the regions lacking selectively placed nucleation sites sufficient to enhance both the critical heat flux and heat transfer coefficient at the critical heat flux in the enhancement region of the system as compared to the heat exchange region surface wherein the enhancement region is replaced by a plain surface.
2. The system of claim 1 , wherein the heat exchange region surface is at least one of planar, curved, and an outside surface of a tube.
3. The system of claim 1 , wherein the critical heat flux is enhanced at least by about 50 percent and the heat transfer coefficient at critical heat flux is enhanced at least by about 50 percent.
4. The system of claim 1 , wherein the critical heat flux is enhanced at least by about 100 percent and the heat transfer coefficient at critical heat flux is enhanced at least by about 50 percent.
5. The system of claim 1 , wherein the boiling comprises pool boiling.
6. The system of claim 1 , wherein the enhancement region further comprises microstructures comprising a height of from about 0 μm to about 4 mm.
7. The system of claim 6 , wherein the microstructures comprise a width of from about 100 μm to about 4 mm.
8. The system of claim 7 , wherein a channel gap between the microstructures comprises a width of from about 100 μm to about 4 mm.