Introduction of three air supply methods in data center
The equipment in the data center is densely arranged, the heat is concentrated, and the sensible heat is large. Therefore, it is necessary to have reasonable distribution and distribution of airflow organization to effectively remove heat in the equipment room, so it is necessary to have reasonable distribution and distribution of airflow organization to effectively Remove the heat in the equipment room to ensure that the equipment in the equipment room meets the requirements of the air environment such as temperature and humidity, cleanliness and air supply speed.
The air supply system of the data center air conditioning system is divided into the air supply mode of the machine room and the air supply mode of the cabinet.
Air supply in the engine room includes air supply on the hood, air supply from the air duct, and air supply under the floor. The most common method is the air supply under the floor.
The close air supply of the cabinet is also called close-range cooling and precise cooling, including inter-row cooling (side front air supply, side rear return air), and closed cabinet internal refrigeration.
At present, the airflow organization of the computer room air conditioning system commonly used in the data center has the following methods: return air return air, return air before return air (or side return air). Regardless of the type of airflow organization, the requirements of data center equipment and related specifications should be met.
The national standard "General Specification for Electronic Computer Sites" (GB2887-2000) and the National Standard "Design Specification for Electronic Information System Computer Rooms" (GB50174-2008) are as follows:
The main room maintains a positive pressure inside (such as the pressure difference between the machine room and other rooms and corridors should not be less than 5Pa, and the static pressure difference between the room and the room is not less than 10Pa), preventing outdoor air from penetrating and destroying the air parameters in the equipment room.
Ensure the number of air changes in the equipment room to ensure accurate adjustment of air parameters in the equipment room.
The noise limit of the host room (such as the sound pressure level is less than 68dB), should use high-efficiency, low-vibration, low-noise air conditioning, air supply equipment.
1, the wind on the hood
The installation of the air supply method on the hood is relatively simple, the overall early education is lower, and the requirements for the machine room are also lower, so it is used more in the small and medium-sized machine room.
The effective air supply distance of the blower unit on the hood is relatively close, the effective distance is about 15m, and the two pairs of blows only reach about 30m, and the return air is easy to receive the influence of various conditions of the machine room (such as the cable rack and cabinet placement). , air conditioning, the shape of the machine room, etc., so the temperature field in the machine room is relatively not uniform. This type of air supply also requires the design to consider the smooth return air of the unit, and there is no obstruction within 1.5m from the front of the return air outlet.
There is obvious short-circuit between hot and cold air in the air supply on the hood, and the cooling efficiency is low. It is only applied to small data center equipment rooms and low heat density.
Air supply on hood: GD-A2 series square diffuser, GD-A2 series double louver air outlet, GD-A7 series line grooved air outlet, GD-A6 series fixed 0 degree line nozzle, GD-A4 series egg grid outlet
2, air supply on the duct
The air supply method on the air duct is similar to the air conditioning air supply method. The air conditioning duct design must be carried out in accordance with the national standard "Code for Design of Heating Ventilation and Air Conditioning Engineering" (GB50019-2003). The air duct must also be installed in accordance with the national standard. Installation and acceptance of the Code for Construction and Acceptance of Heating Ventilation and Air Conditioning Engineering (GB50243-2002). The air supply vents can be opened at suitable locations according to the requirements of the process, so that the overall air conditioning effect is good.
The cost of air supply on the air duct is higher than that of the hood. The installation and maintenance are also complicated, and the height of the machine room is also high. In the hood, the air supply cannot meet the air supply distance, and the air-conditioned room requires a place with uniform air-conditioning effect. It is generally recommended to use this type of air supply mode. When the design of the air duct and the fan is reasonable, the air supply distance can reach nearly 100. Meter. In order to make the room still have a suitable height after the installation of the duct, the net height of the room floor is generally required to be ≥ 4m.
The air supply on the air duct needs to be specifically designed for the air duct system combined with the equipment room. The air duct of the air supply can be divided into a main air duct and a branch air duct, and the main air duct is generally directly taken out from the air conditioning unit or the static pressure tank, and the air duct is led to the independent air duct. The air duct system in the equipment room should adopt a low-speed air supply system. The wind speed of the main air duct can be about 8m/s, and the wind speed of the air duct can be about 6.5m/s. The ratio of the width of the air duct should not be greater than 4 The static pressure box in the equipment room is generally installed in the upper part of the air conditioner, and is sent to the static pressure box from below by the air outlet of the air conditioner. The width of the static pressure box is more than 2-3 times the size of the air outlet. The height of the static pressure box is generally about 1m. The wind speed of the air duct air outlet is generally about 5m/s. The above data is commonly used data selected according to the specifications, and it is possible that the design of the duct system is different.
There are two common ways of air supply on the air duct: one for each air conditioning unit to connect the air duct to the outside, and the other for the multi-unit air conditioning unit to supply air to the static pressure box, which is led by the static pressure box. The air duct supplies air. The advantage of the second air supply mode is that it is easy to implement backup redundancy. After there is a shutdown in the air conditioner, the cooling capacity of the remaining air conditioning units can still be sent to each area of the equipment room via the static pressure box; the disadvantage is that it requires a larger static The pressure box requires a large space and costs are high.
Air duct damper: GD-C301 manual air volume control valve, GD-C304 round control valve
Some of the operator's computer rooms built earlier have used air supply on the air duct to supply air. With the increase in the number and density of servers, the air supply method on the air duct has low cooling efficiency and is built. Defects such as difficulty in adjustment and high noise.
3, under the floor air supply
The air supply under the floor is the main form of air conditioning and air supply in the data center. It is widely used in data centers such as financial information centers, enterprise data centers, and operators IDC.
The electrostatic floor is laid in the data center computer room. The height of the electrostatic floor is 20-100cm, even up to 2m. The cold air of the air conditioner of the computer room is sent to the bottom of the static floor to form a large static pressure box. The static pressure box can reduce the air supply. System dynamic pressure, increase static pressure, stabilize airflow, reduce airflow vibration, etc., making the air supply effect more ideal. The cold air is then sent to the server rack through the perforated floor. The return air can return to the wind through the floor space in the machine room or the dedicated return air duct (the space above the ceiling).
There are many advantages to the air supply under the floor, including high cooling efficiency, simple installation, and clean installation.
It should be noted that if the floor below is used as the cable routing space, the problem that is easy to occur in use is that the underfloor wiring is congested, and the air supply is not smooth, resulting in an increase in air conditioning energy consumption.
Under the floor air supply: GD-A904 seat air outlet, GD-A5 floor air outlet
Practice has proved that many computer rooms use under-floor air supply and under-floor wiring. Due to the increasing number of cables under the floor during application, the air supply under the floor is not smooth, the airflow is unreasonable, and even wind shorts are serious. Problems such as the temperature/humidity control in the area where the air conditioner is relatively strong, and the temperature in the area far from the air conditioner is too high to be effectively controlled. In this case, in order to ensure proper temperature control of the remote device, the temperature set point has to be lowered. For example, if the temperature set point is lowered to 18 °C, the temperature around the device at the far end of the air conditioner can be guaranteed to reach 24 °C. Obviously this will increase a lot of energy consumption. In addition, many computer rooms cannot change the wiring due to business characteristics (such as the inability to suspend the operation of the equipment). Only air-conditioning equipment can be added. The air temperature and humidity of the equipment room can be ensured by increasing the air volume. The cooling capacity of the original air-conditioning equipment is sufficient. This has greatly increased the energy consumption of the computer room.
To avoid the problem of airflow obstruction under the floor, there are two ways: First, to ensure a reasonable floor height. At present, many new machine rooms have adjusted the floor height from 300mm to 400mm or even 600-1000mm, with reasonable air volume. Wind pressure configuration, and reasonable under-floor routing, can ensure good air conditioning system efficiency; instead, it uses the underfloor air supply and cable routing.
The air supply under the floor and the cable routing on the cable rack take into account the advantages of efficient cooling and air supply on the floor, quiet and tidy, easy cable expansion and maintenance of the cable rack, and the best way to supply air in the data center cooling room. One way.