Download document () of 20
Send email
Download
You have exceeded the download limit
Thermosiphons are passive, two-phase thermal management systems that do not require mechanical pumps or other moving parts within the fluid loop. As they rely on gravity to return condensed fluid to the evaporator, thermosiphons do not require any added electrical power to operate, making them more reliable than active cooling liquid loops in stationary applications. With the right design, thermosiphons can also help you reduce thermal management weight and volume by increasing overall system performance.
Thermosiphons operate on the same principles as heat pipes; energy is absorbed into the system where liquid is turned into vapor, vapor is transported by using the pressure difference between hot and cold regions and rejected out of the system as the vapor is condensed back into a liquid. Low overall temperature drops enable isothermal cooling over large surfaces or across multiple devices. By leveraging these temperature differentials, Thermosiphons efficiently and reliably transport heat in a wide variety of configurations throughout the thermal solution.
Thermosiphons offer more cost-efficient two-phase cooling than heat pipes or vapor chambers. By leveraging thermosiphons, Eaton enables cost and weight savings by negating the use of a wicking structure. Thermosiphons are a passive technology, so customers can achieve high heat transport without implementing costly, limited lifetime pumps. Thermosiphons also maintain low overall temperature drops which enables isothermal cooling over large surfaces or across multiple devices.
Eaton's two-phase heritage extends back decades. We’ve developed four types of thermosiphons so we can offer our customers the best-fit thermosiphon solution for your application. For additional cost savings, Eaton offers advanced engineering and streamlined manufacturing that enables one shot brazing.
Thermosiphons that dissipate heat directly from a heat source in the adjacent volume are considered 3D direct contact loop thermosiphons. Thermosiphons collect large quantities of heat at the evaporator unit and buoyancy brings heated vapor vertically up to the condenser region. The condenser region can be configured for vertical air flow (like the diagram above) or a horizontal liquid-to-air heat exchanger unit.
Direct contact loop thermosiphons transport heat from a source to air, where they’re used to transport heat away from thermal loads and into a high density fin stack to dissipate heat to ambient. Carefully angled tubes carry the thermosiphon working fluid to and from the remote condenser/liquid-to-air heat exchanger portion of the assembly. Direct contact loop thermosiphons move more heat over longer distances and with fewer tubes than a similar heat pipe assembly, reducing system complexity and costs. This thermosiphon configuration is common in enterprise applications for cooling high performance components like CPUs and GPUs to a remote area that has more volume for a cooling.
Air-to-air loop thermosiphons leverage the high capacity heat transport of two-phase systems to collect heat from a hot air flow on the evaporator coil and dissipate heat into a cooler airflow in the condenser coil. Air-to-air loop thermosiphons can remove significantly more heat in smaller volumes than conduction- or heat pipe-based heat exchangers. By using a passive two-phase cooling, air-to-air loop thermosiphons are more reliable and reduce maintenance costs that would be associated with an active liquid pumped liquid-to-air heat exchanger.
Heat sinks utilizing 2D thermosiphon fins reduce weight and improve performance over similar die cast, bonded fin and extruded heat sinks. Designers can improve fin efficiencies for heat sinks with tall fins (>80 mm) by introducing 2D thermosiphon fins that aid in fin efficiency and spreading along the airflow direction.
2D thermosiphon fins can be incorporated into a bonded heat sink or a thermally integrated enclosure. While they do not offer as much design flexibility as vapor chamber fins, 2D thermosiphon fins can offer improved performance in compact systems.
MyEatonFAQs
