Thermosiphon cooling explained

What is thermosiphon cooling?

Thermosiphon cooling is a passive heat transfer method that uses natural convection to circulate fluid without the need for a pump or compressor. It’s widely used in outdoor telecom, energy, and industrial enclosures where efficient, low-maintenance cooling is essential.

This cooling method relies on the principle that hot fluid rises and cool fluid sinks, creating a continuous cycle that transfers heat from inside an enclosure to the outside atmosphere.

How thermosiphon cooling works

A thermosiphon system typically consists of:

• A closed loop filled with refrigerant or fluid
• An evaporator coil or surface inside the enclosure
• A condenser mounted outside the enclosure
• A sealed structure that enables natural phase change and gravity-based return flow

As heat builds up inside the cabinet, the fluid evaporates and rises to the condenser. Once cooled, it condenses back into liquid and flows back down to repeat the cycle – all without electrical input or moving parts.

Key benefits of thermosiphon cooling

• Energy-efficient (no power required for circulation)
• A closed loop filled with refrigerant or fluid
• An evaporator coil or surface inside the enclosure
• A condenser mounted outside the enclosure
• A sealed structure that enables natural phase change and gravity-based return flow

Applications of thermosiphon cooling

Thermosiphon systems are frequently used in:

• Telecom base stations
• Battery energy storage systems (BESS)
• Off-grid renewable energy installations
• Railway signaling cabinets
• Outdoor control panels for utilities and automation

Thermosiphon cooling in Vikinor products

At Vikinor, we’ve developed a compact thermosiphon heat exchanger that integrates thermosiphon cooling into a range of outdoor enclosure solutions, especially for customers operating in:

• Rural and low-infrastructure zones
• Harsh climates with high ambient temperatures
• Situations where total cost of ownership is a key decision factor

Vikinor offers models compatible with AC or DC power systems, and a range of standard and custom sizes. Like all of our cooling solutions, the thermosiphon heat exchanger is designed to reduce energy consumption while providing reliable, high performance climate control.

Thermosiphon vs. Crossflow vs. Counterflow heat exchangers

Vikinor offers three core types of passive or low-energy heat exchangers for enclosure cooling: thermosiphon, crossflow, and counterflow. Each uses a different principle to manage heat but serves similar goals – protecting sensitive equipment, reducing energy use, and maximizing uptime.

In short

• Thermosiphon is similar to crossflow but relies on gravity to circulate.
• Crossflow designs are simple and effective for moderate environments with sufficient airflow.
• Counterflow systems offer superior efficiency and are ideal for space-constrained enclosures or high ambient heat conditions.

Each has unique advantages depending on the application, location, and power availability. Vikinor can tailor a cooling solution using any of these based on your operational needs.

Limitations of thermosiphon cooling

While thermosiphon cooling is highly effective for many use cases, it’s important to understand its limits:

• It may not be suitable for very high heat loads
• Requires a vertical installation to enable gravity-fed circulation
• Performance is affected by ambient temperature and airflow around the condenser

Even so, these constraints can often be mitigated by proper system design and material selection, something Vikinor takes into account when tailoring solutions to customer needs.