• by: Bisola Orimalade
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Liquid Cooling and Rear Door Heat Exchangers in Modern Data Centers

What is liquid cooling?

Liquid cooling is a method that uses liquid as the primary medium to capture and remove heat generated by IT equipment. While the concept is straightforward, there are many misconceptions about the technologies available. A common belief is that only two types of liquid cooling exist.

Immersion cooling involves submerging IT equipment in a non‑conductive liquid inside a tank. The fluid absorbs heat directly from the components.

Direct chip liquid cooling (DCLC) uses small pipes to deliver cool water to heat sinks or cold plates. The warmed water is then circulated to a heat exchanger.

Both approaches have value, but they also present challenges. Immersion cooling requires significant setup costs and does not capture all of the heat produced, meaning a secondary cooling source is still needed. Direct chip liquid cooling typically captures between 60 and 80 per cent of the heat, which again leaves a portion unaddressed.

Why is liquid cooling needed in data centers?

Modern processors are smaller and more tightly packed than ever. With Moore’s Law reaching its limits, chips now generate far greater heat loads. Standard air cooling struggles to manage this demand, which has led the data centre industry to investigate liquid cooling more seriously.

Liquid cooling absorbs heat more effectively than air, making it a practical choice for facilities running high-density workloads. Without it, racks filled with advanced processors and accelerators would quickly exceed safe operating temperatures.

Rear Door Heat Exchangers, also known as Rear Door Coolers, provide a proven liquid cooling solution. Sometimes referred to as air-assisted liquid cooling, they are designed to operate as a closed-loop system.

There are two main types of rear door cooling.

Passive rear door cooling relies on IT equipment fans to draw ambient air into the rack. The hot exhaust air passes over a coil, transferring heat into the liquid inside. The cooled air is expelled back into the room.

ProActive rear door cooling works in a similar way but includes EC fans mounted within the door. These fans assist the exhaust air as it passes over the heat exchanger. The heat is transferred into the liquid inside the coil, and the resulting cooled air is expelled back into the room at or just below the ambient temperature. This design allows the ProActive Rear Door Cooler to control the room environment without supplementary cooling equipment.

Summary

All liquid cooling solutions rely on air to assist in the process. The ColdLogik Rear Door Heat Exchanger integrates this requirement as standard, removing the need for additional cooling equipment. Misleading information often circulates in the industry, but ColdLogik demonstrates that rear door cooling is a practical and proven approach for modern data centres.

Interested in working together

At QIS, we work with data centre teams to assess, plan, and implement cooling strategies that match real-world performance and budget goals. Whether you are upgrading legacy systems or planning a new facility, we can help you improve efficiency and avoid overbuilding - contact us today.