A grooved heat pipe is a copper tube with a series of shallow grooves on the inside face of the pipe. These groove structures usually consist of axial or circumferential grooves on the inner radius of the pipe. These grooves can be created by extrusion or broaching. The cross sectional shape of the grooves can be rectangular, triangular, trapezoidal, or nearly circular.
Trapezoidal grooves are currently the most common type. The size of the grooves are large relative to those of a screen mesh or sintered metal wick, therefore the capillary pumping pressure is quite small. While the water is a liquid, it travels in the grooves and while it is a vapour it travels in the open space of the pipe. Heat pipes with grooved wick structures can operate in gravity-aided and horizontal orientations, and are capable of returning the working fluid against gravity at angles up to 5? from horizontal.
The performance of heat pipes with axial groove wicks is very good, provided that the application does not call for a significant adverse elevation against gravity.
These heat pipes are typically used in applications with radial heat fluxes up to 40 W/cm2.