Switchable heat pipes

With the help of heat switches, heat flows can be switched on and off or regulated – very similar to what is possible with electrical switches. To be suitable for widespread use, for example for temperature control of components in electromobility, battery technology or mechanical engineering, thermal switches need to become more efficient and cost-effective. Conventional heat switch concepts have some disadvantages: The thermal resistance in the conductive »on« state is high, the switches are large and often complex in design, and they contain moving parts.

Switchable heat pipes as heat switches

Fraunhofer IPM is collaborating with other Fraunhofer institutes on a new generation of thermal switches based on switchable heat pipes. The switchable heat pipes are compact and do not require any moving parts. Due to their simple design, these components can be integrated easily and promise significantly higher heat transfer capabilities.

We are pursuing a number of concepts to realize switchable heat pipes: For example, within the »Fraunhofer Cluster of Excellence Programmable Materials CPM« framework, so-called programmable materials are integrated into the heat pipes to trigger the thermal switching effect. Alternatively, flat pulsating heat pipes (PHPs) are equipped with additional external elements to make both switchability and controllability possible.

The switching effect based on these concepts has already been demonstrated at Fraunhofer IPM and is now being implemented in application-oriented heat pipe shapes, including the familiar cylindrical tubular heat pipe or the flat pulsating heat pipe.