What is a Heat Pipe?

A heat pipe is a superconductor with extraordinary heat transfer capacity. It is composed of a vacuum-tightened vessel, wick structure and some amount of working fluid. As heat is input at the evaporator, the fluid vaporizes, creating a pressure gradient. This pressure gradient pushes the vapor to the flow along the pipe to the cooler section where it condenses giving up its latent heat of vaporization. The working fluid is then returned to the evaporator by capillary forces developed in the wick structure or by gravity. The fundamental theory is illustrated as shown:

Heat pipe’s functional cycle:

Heat is absorbed from the source through vaporization and released at a sink through condensation. The vapor travels from source to sink through the central channel, while the liquid travels from sink to source through the porous wick.

The rapid growth of the electronics and the personal computer industry has introduced challenging heat dissipation problems. Heat pipe effectively transports heat with a minimal drop in temperature.

  • Faster processor speeds
  • Higher power densities
  • Shrinking geometries

Heat pipe provides the necessary performance boost for conventional heat sinks. Cofan-USA’s extensive use of advanced heat pipe technology ensures maximum performance of our cooling solutions.

Main components:

  • Container
    > High strength, high thermal conductivity
  • Working fluid
    > High latent heat, high thermal conductivity
  • Wick/capillary structure
    > State-of-the-art copper powder sintering for maximum performance
    > Maintains effective capillary action when bent or used against gravity

Here is a comparison between wick structure of Mesh, Groove, and Powder for Dia. 6mm heat pipe, 150mm overall length.

Wick Structure
Screen Mesh Groove Sintering Powder
Ref Image
Rated Process
Easy Easy Hard
Capillary
Bad Good Better
Flat (Min.)
t = 2.0 t = 1.5 t = 2.5
Bend (Min.)
2*Heat Pipe Diameter [D]
2*D ~ 3*D 3*D
Resistance (t=3mm)
0.250~0.350 0.03~0.040 0.030~0.045
Heat Flux (t=3mm)
35 40 45
Cost
Cheap Medium Expensive