Thermosiphons offer a cost-efficient two phase cooling solution, but as they are wickless, they need a consistent gravitational pull to operate.

Increased Processing Power

Isothermal heat transport enables similar temperatures over large surfaces or across multiple devices, allowing processors to operate at the same high speeds.

Ideal For High Heat Loads

Power dissipation exceeds what may be moved by a reasonable number of heat pipes.

Cool Heat Loads Remotely

Transport heat to remote regions (over >200 mm) where there is cooler or more abundant airflow.

Reliable Performance

Passive two phase heat transports enables product designers to remove pumps from the system.

Tight Temperature Control

Keep multiple devices within < 2°C of each other.

Increase Usable Volume

Decrease thermal management volume for other components with effective, isothermal two-phase heat transport & cooling.

What is a Thermosiphon?

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Introduction to the Main Types of Thermosiphons

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What is a Thermosiphon?

Thermosiphons are passive, two-phase thermal management components or 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.

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How Do Thermosiphons Work?

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.

Why Use Thermosiphons?

Thermosiphons offer more cost-efficient two phase cooling than heat pipes or vapor chambers. By leveraging thermosiphons, Boyd 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.

Telecom and 5G

Cabinets and cabinet air climate units, remote radio unit (RRU),  door-type industrial climate Unit

AI & Cloud Computing

High performance semiconductors like CPUs and GPUs, cabinet cooling systems

Power Conversion

IGBTs, solar energy power conversion, door-type industrial climate unit

Why Use Boyd’s Thermosiphon Solutions?

Boyd’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, Boyd offers advanced engineering and streamlined manufacturing that enables one shot brazing.

Thermosiphon Technologies

Overcome Challenges with the Right Thermosiphon Construction

Boyd’s thermosiphon technology portfolio demonstrates our deep two-phase expertise and heritage that you can leverage to maximize reliable thermal performance in any application.

3D Direct Contact Loop Thermosiphon

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 Thermosiphon

Direct contact loop thermosiphons transport heat from 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 Thermosiphon

Air-to-Air Loop Thermosiphon 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 Thermosiphon leveraging thermosiphon technology 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.

2D Thermosiphon Fin

Heat sinks utilizing 2D thermosiphon fin 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 (>80mm) by introducing 2D thermosiphon fin that aid in fin efficiency and spreading along the airflow direction.

2D thermosiphon fin 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.

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