Heat pipe - Definition and Overview

A heat pipe is a heat transfer mechanism that can transport large quantities of heat with a very small difference in temperature between the hot and cold interfaces. Practical heat pipes vary from around 0.5cm diameter and 10cm long to devices 10cm or more in diameter and several metres long.

Each pipe is sized and designed to work at a particular temperature with a certain heat flow capacity. Heat pipes are sealed hollow tubes containing a fluid where the fluid and internal pressure is such that at the designed working temperature the fluid evaporates and in doing so absorbs significant latent heat from the hot end of the tube. The vapor then travels along the tube until it reaches the cold end where it loses its latent heat with the vapor returning to the liquid phase. The liquid is then transported back to the hot end by capillary action of a wick.

Not only are there no mechanical parts and no energy required to transport the heat but because of the significant amount of energy involved in latent heat, the devices are very effective at heat transfer and can carry heat quantities many times that which could be carried by an equivalent metallic conductor.

Applications of heat pipes are found in laptop computers to cool the processor and also in space technology.

See also

• CPU cooling
• Aircooling
• Watercooling
• Peltier cooling