Heat pipe with 10 kW output works without electricity

Heat pipes were initially developed for manned space travel. They have long since found their way into the batteries of EVs and home electronics.

There, however, they are far, far away from the heat transfer performance now presented, or they are additionally supported by pumps and fans. The closed loop heat pipe (LHP) presented by the University of Nagoya is quite different.

According to the researchers, the size has been reduced by 18 percent compared to previous systems, heat transfer has been increased by a factor of 1.6 and heat transfer efficiency has been quadrupled. Heat transfer of between 4.5 and 10 kilowatts is thus achieved. This corresponds to the calorific value of a floor heating.

World record for performance and distance

Basically, it is a wick in which a liquid absorbs heat at one point and transfers it via capillaries to a heat exchanger, where it is released into the environment. Remarkable is the distance of 2.5 meters (8 feet) covered in the experiments, which was bridged completely without electricity and is also said to be the maximum value for a passive system ever.

This is achieved solely through the use of molecular attraction, adhesion, and gravity, which guides the liquid back to the evaporator.

In this way, for example, the batteries and other critical systems in EVs or in the associated charging infrastructure can be kept at the ideal temperature. This increases efficiency because a greater proportion of the electricity is used for propulsion instead of maintaining the optimum temperature.

Similar optimizations are expected for data centers. It could also be used to make more effective use of waste heat and solar thermal energy. Last but not least, the performance of the passive heat pipe is high enough to further increase efficiency in heat pumps or air conditioning systems by using passive heat transport for part of the heat transfer.