Technical cooling supply

Systems for heat transfer, refrigeration, and heat dissipation

An efficient technical cooling system provides the foundation for safely, efficiently, and continuously removing the heat generated by IT equipment from the data center. Depending on the location, power density, and system design, different systems and temperature levels are used for this purpose. The key factor is the interplay of heat transfer, cooling, recooling, and control—all customized to ensure availability, energy efficiency, and future requirements.

In direct evaporation (DX), a refrigerant circulates between the evaporator and the condenser. It absorbs heat from the data center and releases it outside the IT area.

DX systems can, for example, supply room air conditioners or row cooling units. They enable compact and decentralized system configurations. During planning, factors such as pipe lengths, refrigerant quantities, redundancy, and maintenance must be taken into account.

In water-based systems, heat is transported via a central water loop to which various loads can be connected. These include room climate control and CRAH systems, in-row coolers, rear-door heat exchangers, closed-loop rack cooling systems, and CDUs for direct liquid cooling.

Chilled water and liquid cooling are therefore not competing cooling methods. Rather, the building’s water circuit can serve as the infrastructure to which a liquid cooling system is connected via a CDU or a heat exchanger.

The terms “cold water,” “warm water,” and “hot water” primarily describe the temperature level of the cooling circuit. Higher supply and return temperatures can increase the proportion of free cooling and improve the conditions for utilizing the generated heat.

Free cooling utilizes suitable outdoor conditions to dissipate heat with reduced or no active compressor operation.

In direct free cooling, treated outdoor air is directly incorporated into the cooling process. In indirect free cooling, outdoor air remains separate from the air or liquid inside the data center. Heat is transferred to the environment via a heat exchanger.

How long free cooling can be used depends not only on the outdoor temperature but also on the temperature level of the cooling circuit, humidity, recooling technology, and the location.

If the outdoor conditions are not sufficient for free cooling, chillers provide the necessary cooling capacity. Free cooling and mechanical refrigeration can complement each other.

The selection of the refrigerant depends on the system design, energy efficiency, safety, environmental impact, and regulatory requirements. Refrigerants are the working fluids of the refrigeration system—not a form of cooling in and of themselves.

Cooling as a comprehensive, integrated system

In practice, multiple approaches are often combined. For example, a high-density area can cool processors and GPUs using direct liquid cooling, while the remaining server heat is dissipated via air. A CDU transfers the heat to a building-side water loop, which dissipates it via free cooling, a chiller, or a combination of both.

This creates a continuous thermal chain

iot--connect
IT component

Heat flow

Server or rack

Heat flow

Cooling circuit

Cooling

Recooling

Cooling

hospital
Environment or waste heat recovery

Cooling

All the information about your cooling solution

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