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 applications.

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

How cooling works in general (Simple analogy)

Imagine that a data center is like a room full of lamps that are turned on all the time, generating a lot of heat.

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 it 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 removed from the room and released outside, leaving the interior cool.

This process is repeated constantly so that the servers do not overheat and keep functioning.

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

In addition, power supplies, hard drives, memory, and everything that uses electricity also heat up. That electrical flow causes the materials to heat up non-stop, 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 pieces of equipment 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. Inside the evaporator, a cold liquid (called refrigerant) absorbs the heat from the air, like a sponge soaking up water. The cold air comes out and circulates through the data center to keep the servers cool. Sometimes it is called an indoor unit or CRAC (Computer Room Air Conditioner).
• Condenser (Outdoor Unit): It is outside the building. Its mission is to release the heat that the evaporator absorbed. The refrigerant, now hot, reaches the condenser, where the heat is expelled to 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 an 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 motor that makes everything work. It is inside the system (sometimes in the condenser or in the indoor unit) and its job is to move the refrigerant throughout the system.

• What it does: The compressor takes the refrigerant (a cold gas) and compresses it, increasing its pressure and temperature. This makes the refrigerant ready to release the heat in the condenser. Then, the refrigerant cools down and returns to the evaporator to absorb more heat.
• Example with DX System Gas: In a DX (direct expansion) system, the refrigerant (such as R410A) circulates between the evaporator and the condenser. In the evaporator, the gas absorbs heat from the hot air of the data center and turns into vapor. The compressor compresses it, sends it to the condenser, where it cools down and becomes liquid again. This cycle is repeated non-stop.

Think of it as a water pump that moves the refrigerant through pipes, making sure that 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 the cold air. Here are the main types:

• Perimeter: They are placed at the edges of the data center, like large standing air conditioners. They draw in hot air and blow cold air toward the servers.
• Wall or Ceiling Mounted: They are fixed to the walls. They are compact and useful in small spaces.
• Packaged: They are all-in-one units that combine evaporator and condenser in a single piece of equipment, often installed outside or on the roof.
• Backpack: Small units that are 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 directly cool nearby equipment.
• Air distribution methods:
  • Plenum injection: The cold air is blown directly into the open space of the data center.
  • Underfloor: The cold air is distributed through a raised floor with grilles, rising toward 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 organized.

Types of Condensers

Condensers also vary based on how they release heat:

• Air-Cooled: They use fans to blow air over the hot refrigerant and release the heat to the environment. They are the most common.
• 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 warm climates.
• Hybrids: They combine air and water for greater flexibility and efficiency.

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

Differences between Precision and Comfort Air Conditioning

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

• Operating Time:
  • Precision: Works 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:
  • Precision: Controls humidity with great accuracy to prevent servers from being damaged by high humidity (corrosion) or low humidity (static electricity).
  • Comfort: It does not care as much about humidity, only temperature so that people are comfortable.
• Remote Monitoring:
  • Precision: It has sensors and systems that allow monitoring temperature, humidity, and faults from anywhere, to react quickly if something goes wrong.
  • Comfort: Normally it does not have advanced monitoring; you just adjust the thermostat.
• Capacity and Precision:
  • Precision: It 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 (such as 20-25°C) for people to feel comfortable.

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

Conclusions

Precision cooling systems are essential for data centers to run smoothly. They keep servers cool and protected, working non-stop with great accuracy. The evaporator and the condenser, along with the compressor, form a team that moves heat from the inside out. There are different types of evaporators and condensers to adapt to 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 publications related to this topic. We will talk in particular about equipment from Vertiv, APC Schneider, Stulz, and many others.