Switchpipe project

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. There are concepts for heat switches, they do have some disadvantages, however: The thermal resistance in the conductive »on« state is high, the switches are large and often complex in design, and they contain moving parts.

That is why Fraunhofer IPM is collaborating with other Fraunhofer institutes on the Switchpipe project to develop 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 the simple design, these components can be easily integrated, promise high heat transfer capabilities, and are versatile in use. For example, battery systems and other electronic systems work best at a specific »comfort temperature«. Without temperature control, capacity, performance, and service life suffer. A switchable heat pipe can significantly reduce the effort required for temperature control.

To realize switchable heat pipes, so-called programmable materials are integrated into the heat pipes as part of the project. The materials trigger the thermal switching effect through the targeted binding and release of the working medium. This in turn allows the heat conduction of the heat pipes to be regulated. Based on this concept, a demonstrator was built at Fraunhofer IPM with a switching temperature of around 60 °C and a switching factor – i.e., the ratio of thermal conductivity in the on and off states – of around 50. The dimensions, design, and switching temperature can be adapted for different applications.

Project partners

• Fraunhofer Institute for Physical Measurement Techniques IPM (coordination)
  
• Fraunhofer Institute for Chemical Technology ICT
• Fraunhofer Institute for Machine Tools and Forming Technology IWU

Project term

• 02/2019 - 12/2026

Project funding

• Fraunhofer Cluster of Excellence Programmable Materials CPM