Heat pipes are fluid-filled pipes that can transport considerable amounts of heat over small areas. They are found, for example, inside computers, where they prevent the processor and other important components from overheating.
Thermal transfer in a heat pipe takes place via evaporation; latent heat is absorbed and released again when the fluid condenses. This type of thermal transfer is extremely effective and allows heat pipes to transfer 100 to 1,000 times more heat than a massive body of equal dimensions. Heat pipes therefore conduct heat better than any other known material.
The »pulsating heat pipe« (PHP) is a special type of heat pipe, which involves milling turns into flat plates made, for example, of copper or aluminum. Here, thermal transfer likewise occurs via a fluid which oscillates back and forth in pulses along the turns, driven by the heat inflow. The plates are only a few millimeters thick and can also withstand high pressure, e.g. when connected to an electronic component, or during pressing procedures in a printed circuit board stack-up.
The principle behind PHP serves as the basis for building cost-efficient »heat spreader plates«, which allow several 100 W of heat arising in certain spots to be distributed over a large area. This method can even be used to cool electronic power components with high thermal densities.
Fraunhofer IPM has air extraction, filling, assembly and packaging technologies in place to manufacture heat pipes to customer specifications. A range of different shapes, including flat heat pipes from metal and glass, can be created in this way. Various working fluids including water, ethanol and methanol are used in heat pipes. As an additional service, Fraunhofer IPM also offers heat pipe tests – e.g. using IR thermal imaging.