4.By forming fine openings in the surface skin and circumferential tunnels which connect them under the surface skin, bubbles are generated continuously so that an extremely high boiling heat transfer performance can be achieved.
5.To prevent the phenomenon in which sub-cooled refrigerant invades the tunnels and re-condenses the bubble inside the tunnels, fine projections are formed just beneath the openings in the surface skin to lessen the influence of the sub-cooled refrigerant. This has improved the heat transfer performance in all regions including the low heat flux region.
6.Helix slots are added inside the tube to improve the internal heat transfer coefficient so that the overall heat transfer coefficient is more improved than that of the THERMOEXCEL-E tube.