Precision Cooling for Data Centers

Data centers are like the digital hearts of the world: they store and process the information we use every day, from videos to apps.

But these hearts generate a lot of heat 🔥, and if they’re not properly cooled, they can fail. Here we’ll explain in a simple way how the systems of precision cooling work, designed specifically to keep data centers running smoothly.

How Cooling Works in General (Simple Analogy)

Imagine a data center is like a room full of lamps that are always on, generating a lot of heat. If you do nothing, the room becomes an oven.

The cooling system is like a giant fan and a bucket of cold water to keep the place cool.

In simple terms:

• The system takes the hot air generated by the servers (the lamps).
• It cools the air using a special liquid or gas that absorbs the heat, like when you put a cold drink on a hot day and feel relief.
• Then, that heat is taken out of the room and released outside, leaving the inside cool.

This process repeats constantly so that the servers don’t overheat and keep running smoothly.

👉 And why do servers generate heat? Because a processor, whether CPU or GPU, usually runs between 65 and 90 degrees Celsius. And they stay hot all the time!

Also, power supplies, hard drives, memory, and everything that uses electricity heats up too. This electrical flow causes the materials to heat up nonstop—24 hours a day, 7 days a week, 365 days a year.

Evaporator and Condenser: What Are They and What Do They Do?

In a cooling system, there are two main units that work together: the evaporator (inside) and the condenser (outside). They are like a team that moves heat from one place to another.

• Evaporator (Indoor Unit): It is inside the data center. Its job is to take the hot air from the room and cool it down. Inside the evaporator, a cold liquid (called refrigerant) absorbs the heat from the air, like a sponge soaking up water. The cold air is released and circulates through the data center to keep the servers cool. It is sometimes called the indoor unit or CRAC (Computer Room Air Conditioner).
• Condenser (Outdoor Unit): It is outside the building. Its job is to release the heat that the evaporator absorbed. The refrigerant, now hot, arrives at the condenser, where the heat is expelled into the outside air (like when you blow hot air to cool your soup). Then, the refrigerant cools down again and returns to the evaporator to repeat the cycle. It is also called outdoor unit or condenser.

In summary: the evaporator cools the data center, and the condenser takes the heat outside.

The Compressor: The heart of the system

The compressor is like the engine that makes everything work. It’s inside the system (sometimes in the condenser or the indoor unit), and its job is to move the refrigerant throughout the whole system.

• What It Does: The compressor takes the refrigerant (a cold gas) and compresses it, increasing its pressure and temperature. This prepares the refrigerant to release heat in the condenser. Then, the refrigerant cools down and goes back to the evaporator to absorb more heat.
• Example with DX Gas System: In a DX (direct expansion) system, the refrigerant (like R410A) moves between the evaporator and the condenser. In the evaporator, the gas absorbs heat from the hot air in the data center and turns into vapor. The compressor compresses it and sends it to the condenser, where it cools down and becomes liquid again. This cycle repeats constantly.

Think of it like a water pump that moves the refrigerant through pipes, making sure the heat always leaves the data center.

Types of Evaporators

Evaporators come in different shapes and sizes, depending on how they are installed and how they distribute cold air. Here are the main types:

• Perimeter: They are placed at the edges of the data center, like large standing air conditioners. They pull in hot air and blow cold air toward the servers.
• Wall-Mounted or Ceiling-Mounted: They are fixed to the walls. They are compact and useful in small spaces.
• Packaged: Units are all-in-one systems that combine the evaporator and condenser in a single unit, often installed outside or on the roof.
• Backpack: Units are small systems installed directly on racks or servers, like a backpack attached to the equipment.
• In-Row: They are placed between the server racks, in the middle of the aisle, to cool the nearby equipment directly.
• Air Distribution Methods:
  • Full Plenum Injection: Cold air is blown directly into the open space of the data center.
  • Underfloor: Cold air is distributed through a raised floor with vents, rising up to the servers.
  • Hot Air Return: The system collects hot air from the servers and cools it before returning it as cold air.

Each type is chosen based on the size of the data center and how the servers are arranged.

Types of Condensers

Condensers also vary depending on how they release heat:

• Air-Cooled: They use fans to blow air over the hot refrigerant and release heat into the environment. They are the most common type.
• Water-Cooled: They use water to absorb heat from the refrigerant. The hot water is then cooled in a cooling tower. They are more efficient in hot climates.
• Hybrid: They combine air and water for greater flexibility and efficiency.

The type of condenser depends on the climate, available space, and energy consumption.

Differences Between Precision Air and Comfort Air

Precision air (used in data centers) and comfort air (used in homes or offices) are like distant cousins: they work on the same principle but operate differently because they have different goals.

• Operating Time:
  • Precision: It runs 24/7, all year round, because data centers never shut down.
  • Comfort: It is only used when people are present, like in a 9-to-5 office.
• Humidity Control:
  • PrecisionIt controls humidity very precisely to prevent servers from being damaged by high humidity (corrosion) or low humidity (static electricity).
  • ComfortIt doesn’t focus much on humidity, only on temperature to keep people comfortable.
• Remote Monitoring:
  • Precision: It has sensors and systems that allow monitoring temperature, humidity, and failures from anywhere, so you can react quickly if something goes wrong.
  • Comfort: It usually doesn’t have advanced monitoring; you just adjust the thermostat.
• Capacity and Precision:
  • PrecisionIt can handle large amounts of heat and maintain exact temperatures (for example, 22°C ± 1°C).
  • Comfort: It only needs to maintain a wide range (like 20-25°C) to keep people comfortable.

In summary, precision air is like a doctor taking care of a very delicate patient (the servers), while comfort air is like a fan that cools you at home.

Conclusions

Precision cooling systems are essential for data centers to run smoothly. They keep servers cool and protected, working nonstop with great accuracy. The evaporator and condenser, together with the compressor, form a system that moves heat from inside to outside. There are different types of evaporators and condensers to fit each data center, and precision air is much more advanced than comfort air because servers need special care.

On our blog, you can find other posts related to this topic. We will talk specifically about equipment from Vertiv, APC Schneider, Stulz, and many others.