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Data center cooling systems come in different sizes from small server rooms to large hyper-scale facilities. The industry has grown significantly due to our increasing reliance on technology. As data centers use more resources, improving efficiency has become crucial.
Many businesses now use data centers as they move to virtual offices and cloud platforms. These facilities use a lot of energy and water thus efficiency is key to cutting costs and being environment friendly.
Cooling systems are essential in data centers. They remove heat from servers and maintain the right temperatures for IT equipment. Large data centers use specially designed cooling systems called Computer Room Air Handlers (CRAH) and Computer Room Air Conditioning (CRAC).
Air conditioning (AC) units cool electrical systems by blowing air over coils with refrigerants. Computer room air conditioning (CRAC) units work like AC units but also control temperature, humidity, and air distribution in server rooms.
The latest cooling method is the computer room air handler (CRAH) unit which uses chilled water to cool server rooms and electrical systems. This article focuses on importance of CRAC units for data center cooling because they offer energy efficiency and cost savings.
Design of Data Center Cooling Systems
Operating servers 24/7 generates a lot of heat in data centers. If servers overheat, they can shut down and have shorter lifespans which disrupt business and cause lost revenue. Thus, cooling systems are crucial to remove heat and keep data centers running efficiently. However, these data center cooling systems use a lot of energy and water.
To improve efficiency, data centers use containment strategies to prevent hot and cold air from mixing. By analyzing air movement, you can ensure that cold air reaches the IT equipment in the best way. There are two main types of air cooling designs to consider. Both use heat exchangers but have different methods for directing airflow and cooling.
Direct Aisle Cooling (DAC) System
A coil pack is placed at the top of the aisle which creates a ceiling. Heated air from the equipment goes to the heat exchangers. The exhaust air is then cooled before returning to the aisle. This system is versatile and only needs enough ceiling height. It is typically used for larger installations.
Return Aisle Cooling (RAC) System
Hot air moves through corridors or ducts to the air handling area. The hot air is cooled by heat exchangers and returned to the aisle through corridors. These corridors direct cooled air to vents which then go to raised floors and back to the aisle. Compared to the DAC system, RAC can be more optimal as it accommodates several aisles. It will allow for functional tailoring for mass cooling.
Integrate CRAC Units in Cooling Systems
Computer Room Air Conditioning (CRAC) units use chilled water instead of refrigerants for cooling. They blow air over cooling coils and reject hot air. A separate chilled water plant or chiller supplies the chilled water to the CRAC units. Hot air from the server room goes through the cooling coils where heat transfers from the air to the water which then returns to the chiller.
CRAC units will adjust fan speed to maintain the right temperature and humidity levels in the server room. These units are used in medium to hyper-scale data centers. They are more energy efficient because they use less energy and require less maintenance.
In a cold aisle system, CRAC units collect heat from the equipment. The hot air is cooled and ejected into the space under the floor, then circulated back to the server rack from below. In a hot aisle system, hot air from the floor below is cooled and then expelled above which circulate throughout the server room.
In DAC systems, CRAC units are mounted above server racks which create an enclosed aisle roof. This system does not need raised floors. CRAC units are easy to mount and can be standardized. High-performance coils and energy-efficient fans help save money for operators.
Mounting CRAC units above the server racks will also make maintenance easy. It optimizes floor space for the servers and improves hot/cold aisle containment.
Application in Data Centers
Data centers house important IT equipment like storage systems, servers, and networking gear. These setups will produce a lot of heat which can cause equipment to fail, data loss, and downtime if not controlled. CRAC units are essential for:
- Temperature Control: Keeping the temperature steady to prevent overheating and ensure electronic components work well.
- Humidity Control: Managing humidity levels to avoid static electricity, condensation, and short circuits that will harm sensitive equipment.
- Air Quality: Making sure that clean air circulates to reduce dust and particles from collecting on components.
Precise Cooling Requirements
Effective cooling in data centers means managing both wet bulb and dry bulb temperatures.
- Dry Bulb Temperature: This is the air temperature measured by a regular thermometer. Keeping the right dry bulb temperature is crucial for IT equipment performance and reliability.
- Wet Bulb Temperature: This is the lowest temperature air that can reach through evaporative cooling. It is important for managing humidity and ensuring cooling system efficiency.
Precise controlling of these temperatures help in:
- Preventing Hot Spots: Keeps temperatures even to avoid overheating in specific areas which can cause equipment to fail.
- Energy Efficiency: Proper temperature and humidity settings will make cooling systems work less which save energy.
- Preventing Dust Accumulation: Good air filtration and circulation will reduce dust buildup on electronic parts which lower the risk of overheating and electrical issues.
- Preventing Short Circuits: Maintaining the right humidity levels prevents excess moisture which can cause short circuits and electrical failures.
- Compliance with Standards: Following guidelines like AHRI 1360 ensures cooling systems meet industry performance and efficiency standards.
Conclusion
CRAC units, whether they use DX, chilled water, or in-row systems, are essential for keeping data centers running smoothly. They control temperature and humidity to protect sensitive equipment, improve performance, and save energy. Following standards like AHRI 1360 ensures these systems work efficiently and reliably which support the important work of data centers.
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