Thermosiphons are passive, two-phase thermal management systems that have a wide variety of benefits and potential applications.
Thermosiphons are an efficient and versatile two-phase cooling solution that have grown in popularity over the last few years. In the first of our three-part blog series, we’ll be going over exactly what a Thermosiphon is and the key features that make it unique.
What makes Thermosiphons unique from other two-phase cooling systems is that they lack any kind of wicking structure. Where the wicking structure in a Heat Pipe creates a capillary pressure to return condensed fluid, Thermosiphons rely on gravity for the same process. This allows them to more efficiently carry higher heat loads across longer distances, but requires Thermosiphons to be designed and used in a specific gravity orientation. The thermosiphon evaporator must be located below the condenser so that gravity can return the working fluid.
What Are Thermosiphons?
A Thermosiphon is a passive, two-phase cooling system that relies on gravity to circulate a fluid rather than a capillary wick structure often used in heat pipes and other heat transport devices. As with all passive two-phase cooling, the liquid and vapor exist within the self-contained envelope and contain no pumps or other moving parts. While there are several different constructions for Thermosiphons, they generally all consist of three basic components: an evaporator, a fluid loop (or adiabatic section), and a condenser. The evaporator absorbs energy into the system, which causes the working fluid, usually a refrigerant or other dielectric fluid, to turn into vapor. The vapor then travels through the adiabatic section (vapor tube) due to the pressure difference between hot evaporator and cool condenser (buoyancy), where the heat is expelled from the system and the vapor condenses back into a liquid and returns to the evaporator via gravity. This process is repeated indefinitely as long as there is heat to reject from the system.
