thermosyphon

A thermosyphon is a device that uses natural convection to circulate a fluid. It typically consists of a closed loop with two vertical legs, one heated and one cooled. When the fluid in the heated leg becomes less dense, it rises, while the cooler, denser fluid in the cooled leg sinks. This continuous cycle of rising and sinking fluid creates a flow without the need for a mechanical pump.

Thermosyphons are used in a variety of applications. One common use is in solar water heating systems, where the sun heats the fluid in a collector, and the natural circulation then moves the hot fluid to a storage tank. They are also employed in passive cooling systems for buildings and electronics, and in some industrial processes where a simple and reliable fluid circulation method is desired.

The effectiveness of a thermosyphon depends on factors such as the temperature difference between the heated and cooled sections, the geometry of the loop, and the properties of the fluid being circulated. The fluid's thermal expansion coefficient is particularly important, as a larger expansion leads to a greater density difference and thus a stronger flow. The design must ensure that the heated section is positioned below the cooled section for gravity to assist the natural convection process.