Data center cooling refers to the equipment, systems, methods, and techniques that regulate the temperature, humidity, and airflow within a data center facility. Thousands of servers, IT equipment and other electronic devices running around the clock in a data center generate a lot of heat, and data center cooling cools this equipment down to maintain optimal performance.
How is a Data Center Cooled?
Data center cooling systems use a range of technologies, key components, and equipment to keep data centers in top shape, with the core goal of efficiently removing and discharging waste heat generated by servers and other equipment to the outside environment. The main technology schools include:
Principle: Utilizes cool air. The computer room air conditioner (CRAC/CRAH) produces cold air and sends it through raised floors or ducts to the front of the server cabinet (cold aisle). The server fan draws in the cold air to cool the internal components, and the heated air is discharged from the rear (hot aisle), where it is drawn back, cooled, and recirculated by the air conditioning system.
Key Technology Points:
Cold/Hot aisle isolation: Physically isolates hot and cold airflow, avoiding short-circuiting of mixed air and dramatically improving efficiency (basic but extremely important!)
Raised floor air supply: Utilizing the under-floor space as a static pressure box to evenly deliver cold air.
Precise air supply: Use air ducts and blind plates to block the empty space to ensure that the cold air is accurately delivered to the air inlet of the equipment.
Advantages: Mature technology, relatively simple deployment, low initial cost, high maintenance familiarity.
Disadvantages: relatively low efficiency (especially for high-density cabinets), high noise, occupying more space (requires a large channel), attenuation of the efficiency of long-distance cold air delivery. Suitable for low and medium density scenarios.
Water cooling
Principle: The use of water (or other liquids) as a refrigerant. The specific heat capacity of water is much larger than air (heat absorption capacity is about 4 times stronger), so the efficiency is higher.
Common forms:
Chilled water system: The chiller produces chilled water (e.g. at 7°C), which is pumped through pipes to cooling coils in the server room (usually close to the heat source or integrated in the cabinet). The hot air in the server room flows through the coils to be cooled, and the chilled water absorbs heat and warms up before returning to the chiller to cool down. This is currently the mainstream high-efficiency solution for large data centers.
Water-side natural cooling: Using the external natural environment (cold air, lake/sea water) to directly or indirectly cool the chilled water circulating system, the compressor can be drastically reduced or even shut down in cold seasons/areas, which significantly saves energy (free cooling!). Common methods: cooling towers, plate heat exchangers, dry coolers.
Direct Evaporative Cooling: Direct cooling of air using the principle of heat absorption by water evaporation (e.g. large humidifiers). Excellent and energy efficient in dry areas.
Advantages: high cooling efficiency, suitable for high densities, high energy saving potential (especially in combination with natural cooling), relatively low noise.
Disadvantages: More complex systems, high initial investment, specialized water treatment (anti-scaling, corrosion, microbiology), risk of water leakage (requires sophisticated testing and protection).
Principle: Groundbreaking coolant (special non-conductive liquid or water) in direct contact with the heating element (chip) or submerging the entire server. Inefficient air heat transfer is skipped.
Main Types:
Direct Liquid Cooling (Direct to Chip Liquid Cooling)
The metal cold plate (containing micro-channels) closely fits the CPU/GPU and other major heat generating chips. The coolant flows through the inside of the cold plate, directly taking away the heat from the chip. The rest of the server is still air-cooled. The current mainstream liquid cooling form.
Single-phase immersion: The server is completely immersed in a non-conductive, non-volatile (high boiling point) coolant. The liquid is circulated internally and heat is carried out to an external heat exchanger by convection or pump drive.Phase Change Immersion: The server is immersed in a low boiling point coolant. The liquid contacts the heat chip and absorbs heat and boils (phase change), the vapor rises to the condenser and cools back to a liquid drop, and the cycle repeats. Maximum efficiency!
Core Advantage:
1.Superior Heat Dissipation Capability: Easily cope with ultra-high densities of 50kW/cabinet or even 100kW+ (a must for AI/GPU clusters!) Extreme Energy Efficiency: Dramatically reduce or even reduce the amount of energy needed to power the system.
2.Ultimate Energy Efficiency: Dramatically reduce or even completely eliminate server fan energy consumption; coolant transfer pumps consume far less energy than large fans; it is easier to utilize high-temperature return water to achieve efficient natural cooling.
3.Quiet: Fan noise virtually disappears in the server room.
4.Space Savings: Allows for more compact server room designs.
Challenges: High initial cost, high retrofit or deployment complexity, specialized IT equipment design/certification (especially immersion), coolant selection and management (cost, maintenance, environmental).
Principle: Not a stand-alone technology, but utilizes the coldness of the external natural environment (low-temperature air, bodies of water) to carry out part or all of the cooling tasks, reducing or avoiding the use of energy-intensive compressors.
Realization:
Air-side natural cooling: When the outside air is sufficiently cold and clean, the filtered fresh air is introduced directly (or the indoor air is cooled indirectly through a heat exchanger).
Water-side natural cooling: cooling tower, plate heat exchanger, dry cooler, etc., the use of low-temperature air or natural water to cool the chilled water system circulating water.
Seawater/lake water cooling: Direct extraction of deep low-temperature seawater/lake water as cooling source (requires strict corrosion prevention and water treatment).
Key point: Energy efficiency depends on local climate conditions (duration of low temperatures) and system design. It is a key factor in evaluating the PUE (energy efficiency index) of a data center.
These are the main cooling systems in a data center. With the explosive growth in demand for high-density computing such as AI and HPC, liquid cooling (especially direct liquid cooling) is moving from the “frontier” to the “mainstream”. Welcome to contact Lori consulting for relevant cooling solutions.
