Thermosiphon Heat
Exchange Technology

The Dantherm Thermosiphon equals energy-efficient heat exchange. It utilizes a traditional cooling system with refrigerant but without a compressor. Only moving components are the two fans and the natural convection of the refrigerant in the cooling system.

Thermosiphon technology - how it worksThermosiphon Technology

When refrigerant fluid is heated by the heat load inside a cabinet, it starts the evaporation in the internal coil. The coil absorbs the internal heat from the cabinet. Heating of the coil starts the circulation of the refrigerant.

Phase shift convective movement causes the fluid to evaporate into gas. The Dantherm Thermosiphon utilizes this phase shifting energy to generate passive heat exchange and cool down the inside of the cabinet. The only mechanically moving parts are the in- and external fans.

The Thermosiphon is driven by:

The Dantherm Thermosiphon is driven by an energy-optimizing controller and control strategy together with two energy-efficient fans with no need for a compressor.

Closed loop cooling:

The Thermosiphon generates closed loop cooling, where the internal air circuit is separated from the external, thus maintaining a clean internal environment in the enclosure. Because the tiny movements from the compressor are eliminated, a high IP Class is achieved.


When choosing a cooling technology that utilizes ambient air to cool, it is important to understand the concept of delta t (∆t):

∆t = t ambient - t internal

The capacity is stated as e.g. 288 W/K. This means that at by a difference in temperature of 1K= 1°C, the cooling capacity is 0,288kW.

Example: Average ambient temperature: 20°C, desired internal temperature: 25°C = ∆t = 5 (25-20).

Thermosiphon Technology Shelter


The entire idea of the Thermosiphon is to use as little energy as possible. When engineering the Dantherm Thermosiphon, features such as low pressure drop over the coils, fan speed regulation and energy-efficient components were of great importance. Balancing the cooling system when running passive with natural convection is quite a challenge. When done successfully, you get a cooling unit running perfectly under the stringent Telecom industry requirements, with high capacity at both high and low ambient conditions and using a minimum of energy - and this is what you get with the Dantherm Thermosiphon.

Long service life:

To obtain the best performance and desired service life, the Dantherm Thermosiphon is designed with components such as micro channel coils and industrial fans.

Control strategy:

The cooling and control strategies of the Dantherm Thermosiphon have been optimized based on Dantherm's age-long co-operation with and development for the Telecom industry's most important suppliers, vendors and operators. Specific Telecom features generate a high level of site earnings due to a focus on transmission uptime - even during installation, service, power outage or extreme ambient conditions.

Thermosiphon InstallationTechnology development:

Due to a rising demand for passive cooling, Dantherm turned their focus to the thermosiphon technology. Dantherm refined the technology to fit the modern world of heat transfer in electronics enclosures. Some of the challenges were the compact design and increased heat emissions in Telecom base stations. Using the thermosiphon technology, Dantherm was able to develop a more compact unit with higher passive cooling capacity than known air-to-air heat exchangers. Furthermore, the technology fits well as an extension of the Dantherm product line of air-to-air heat exchangers.

Thermosiphon Solutions

View our selection of energy-saving Thermosiphon passive cooling units.

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Dantherm Thermosiphon cooling a telecom site Play
DC Thermosiphon

Extremely energy-efficient
Fully industrialized
Closed loop cooling