The types of precision air conditioning in the computer room are: air-cooled, water-cooled, dual cooling source, and free cooling.
Regarding the cooling of precision air conditioning, regardless of which method is used, it absorbs heat from the outside or releases heat to the outside through the change in the state of the refrigerant inside the precision air conditioner. Unless there is a leak in the components of the precision air conditioner or in the copper pipes, the refrigerant exists in a closed environment, circulating between the compressor, condenser, expansion valve, fan, and copper pipes, while changing its own state, that is, from gas to liquid and from liquid to gas, which is referred to as internal circulation.
1. Air-cooled precision air conditioning for computer rooms
Air cooling refers to the process where the refrigerant in the air conditioning system is cooled through air. The outdoor condenser (precision air conditioning outdoor unit) dissipates heat from the refrigerant, allowing the refrigerant to release heat. Air-cooled condensers mainly consist of several groups of copper tubes and fans. Due to the poor heat transfer performance of air, it is common to add fins outside the copper tubes to increase the heat transfer area on the air side, while fans are used to accelerate air movement and enhance cooling effects. The fan speeds can be constant, adjustable, or a combination of both. Depending on the requirements of different manufacturers, there are also specifications for the distance between the indoor and outdoor units, as well as the height difference, which should be considered during selection based on actual conditions.
Air-cooled units generally use bottom air supply and upper air return. Most data centers use anti-static flooring, utilizing the space below the anti-static floor (typically 40-45 cm above the floor) as an air static pressure chamber. Air outlets are set in the direction of the intake of the equipment cabinets, where cold air passes through the cabinets and becomes warm air, which is returned through return ducts or the ceiling directly back to the precision air conditioning return (hot air is generally returned directly, so the placement of the precision air conditioning unit is very important). Therefore, the application of air-cooled precision air conditioning units is quite widespread.
The air-cooled precision air conditioning in server rooms has some disadvantages:
1. The noise and heat of the outdoor unit are significant, impacting the surrounding environment.
2. During high summer temperatures, the outdoor unit may trigger high-pressure alarms due to poor heat dissipation.
3. The fins of the outdoor unit are prone to dust accumulation; if not cleaned regularly, they will affect the cooling effectiveness of the air conditioner.
4. The cooling efficiency is relatively low, below that of water-cooled types.
5. The performance is poor in extremely cold regions.
6. Requirements for the length of copper pipes between indoor and outdoor units and the height difference between them.
2. Water-cooled precision air conditioning for computer rooms
The structure of water-cooled precision air conditioning in computer rooms is not much different from that of air-cooled types. The main difference is that in water-cooled precision air conditioning, a water-cooled plate condenser is set up in the indoor unit (compared to air-cooled precision air conditioning, the refrigerant’s internal circulation only occurs in the indoor unit, which results in a much lower working pressure for the compressor). As the refrigerant passes through the water-cooled plate condenser, it releases heat, and the cold water in the water-cooled plate condenser absorbs this heat before being pumped (usually installed outside the precision air conditioning unit) to the building’s cooling tower, where the heat is discharged into the air. Since the cooling tower is a wet heat exchange device (in which air comes into direct contact with water), it has a good cooling effect. There is also an option to use a dry-cooled outdoor condenser.
Water-cooled precision air conditioning in server rooms also has some drawbacks:
1. Electronic information equipment must be kept away from water; therefore, there are high requirements for the water pipes connected to precision air conditioning, including the quality of the pipes themselves, the routing of the pipes, and the welding techniques of the pipes. Additionally, it is essential to closely monitor for any leaks, which is a significant concern for customers.
2. Since the cooling water is circulating water, it will become very dirty after long-term contact with air, so a water filter must be installed on the water circulation pipeline.
3. Increased single point failures of cooling towers, water pumps, and water pipes require backup equipment.
4. The maintenance costs are relatively high.
5. The energy consumption ratio is not much lower than that of air cooling.
Therefore, the application of water-cooled precision air conditioning in computer rooms is relatively rare.
3. Free cooling (glycol cooling)
This type of unit is mainly used in the cold northern regions and can also be classified as a water-cooled precision air conditioning system for server rooms. Once the outdoor temperature drops below 0 degrees Celsius, a glycol solution is added to the water to ensure that the cooling water does not freeze. Unlike typical water-cooled precision air conditioning systems for server rooms, free cooling precision air conditioning systems are equipped with dry cooling towers installed outdoors, similar to the outdoor units of air-cooled precision air conditioning systems, except that the substance in the pipes is different;
4. Refrigeration with chilled water
The premise for setting up a chilled water precision air conditioning system in a machine room is the availability of chilled water, which can be sourced from central air conditioning’s chilled water or a newly established chilled water system. The precision air conditioning system for chilled water mainly consists of indoor units equipped with chilled water coils, fans, electric heaters, humidifiers, and water valves, and generally does not include a compression refrigeration system. Therefore, the initial investment for this type of unit is relatively low, but it relies on chilled water, and if chilled water is unavailable, the system will be paralyzed. Hence, there exists the following dual-cooling source system.
5, dual cold source system
The dual cooling source system is designed to ensure the reliability of cooling for precision air conditioning in the machine room, while fully utilizing the chilled water from the building’s central air conditioning. There are two combinations available:
1. Air-cooled condensation chilled water is primarily used in the chilled water system, with the air-cooled system as a backup.
2. Water-cooled condensation chilled water is primarily used in the chilled water system, with the water-cooled system as a backup.
Advantages:
Dual systems back each other up, ensuring high security and reliability.Can fully utilize the central air conditioning cooling water in the building, achieving energy-saving effects.
Disadvantages:
1. High initial investment.
2. Many pipelines take up a lot of space, causing installation difficulties.
Post time: Oct-09-2025