A constant heat transfer tube (CCHP or simply "Standard heat pipe") has a fixed thermal conductivity between the evaporator and the condenser and is the most popular type of two-phase device used to cool electronic devices. Other types of heat pipes include:
When spreading heat over a large surface area, soaking plates are much better than heating because they have a large, continuous vapor space. Physically, they require the addition of internal columns or shims that provide structural support for the device while allowing steam to move freely. Options for freestanding plates include a traditional two-piece design (using two stamping plates glued together) or a less costly one-piece design (starting the manufacturing process with very large flat tubes).
The Variable Heat transfer tube (VCHP) is used to minimize temperature fluctuations in the evaporator and contains non-condensable gases, such as nitrogen or argon, to effectively increase or decrease the available steam space depending on changes in ambient temperature.
A thermosiphon has a higher power handling capacity (Qmax) than a standard heat pipe of the same diameter, but gravity must be used to return the liquid to the heat source. In their simplest form, they have no core structure along a smooth inner wall, but can also contain a core structure near the evaporator (heat source).
Loop heat pipes are designed to transmit heat over longer distances (up to several meters) than conventional heat pipes and work well in any direction, but are quite expensive due to their complexity.
Rotary heat pipes are used to eliminate heat generated by motors and other rotating machinery, such as RF rotary joints used in telecommunications. Their most common designs use a spiral groove wick similar to a rifle barrel, which forces the condensed liquid back to the heat source as it spins.
The advantage of oscillating heat pipes over standard heat pipes is that they resist gravity well. They are also capable of running longer distances than standard heat pipes, which makes them suitable for applications that need to transfer heat over a larger area.
