evelopment of data center air conditioning system
CRAC
With the development of the data center industry, the data center air conditioning technology is developing rapidly, which can be divided into three periods:
Early data center air conditioning system (1950-1970)
In the early stage, the machine room was built for a computer (large, medium and small), and there was no uniform standard, which was completely groping for construction.
Because there is no special rooms dedicated air-conditioning equipment, this is the room of air conditioning in the common civil air conditioning or use of the building air conditioning system cooling comfort air-conditioning equipment, however, the comfort air conditioning is designed according to the environmental conditions of people demand, not in order to process the data of heat load and heat load of cooling function only, no temperature control precision, no humidity control function, no strict dust control measures, no test indicators.
The following problems are encountered in the use of comfortable air conditioning in the machine room:
The comfort air conditioner can not keep the temperature of the machine room constant, which may lead to a greatly reduced life span of electronic components.
Unable to maintain the temperature uniformity of the machine room, the local environment can easily overheat, resulting in the sudden shutdown of the machine room electronic equipment.
Unable to control the humidity of the machine room, the humidity of the machine room is too high, which can lead to condensate water, which may cause a local short circuit of the microcircuit.
Low humidity in the machine room can produce damaging static electricity, resulting in abnormal operation of the equipment.
The lack of wind and filter effect, the cleanliness of the machine room is not enough, the accumulation of the dust will result in the difficulties in the heat dissipation of the electronic equipment, easy to overheat and corrosion.
The design selection of comfortable air conditioning is poor, which results in a large amount of air conditioning maintenance and short life span.
Development data center air conditioning system (1970-2000)
There is a machine room specially designed for computer system, with special cabinet (big, medium and small cabinet), and start to develop the standard, including the site selection, area, etc.
Rooms also from the common civil comfort air conditioning refrigeration and cooling, turning to adopt constant temperature and humidity room dedicated precision air conditioning, room dust removal using fresh air system and equipment room of positive pressure dust removal, so as to realize the data center are kept moderate constant, good clean air, a remote monitoring requirements, etc.
The special precision air conditioning of the machine room is very different from the traditional comfort air conditioning in the design, which is shown in the following aspects:
Large air volume, small enthalpy difference
Year-round refrigeration operation
Constant temperature and humidity control
There are various ways to send wind
High reliability
Innovation phase data center air conditioning system (2000 - present)
With the development of the Internet, the advent of informatization has gradually increased the demand for data centers.
Data centers are also gradually moving into various industries, and there are differences in understanding and requirements of data centers.
Generally think that enterprise data center is a cost center, data center leasing firms think data center is a profit center, the financial sector to the data center strict reliability, manufacturing data center for ease of use and the cost is very high.
A variety of different requirements promote the rapid development of data center industry and the generation of innovative solutions.
In the case of air supply innovation, from the next air supply to the air conditioning equipment near the power supply;
With the innovation of cold source, the application of natural cold source is becoming more and more popular.
Innovation of construction mode and modular scheme;
Industrial innovation, large-scale data center introduction of industrialization concept;
The innovation of all kinds of air-conditioning equipment, the energy efficiency, performance and control of the equipment are not the same as ten years ago.
The development trend of data center air conditioning system
In order to guarantee the high availability of the air conditioning system in the data center, in the design of air conditioning system, the usability, energy saving and dynamic cooling are the future development trends.
availability
Data centers require far more usability than commercial buildings, and air conditioning systems do the same.
At present, the requirements for usability are generally divided into grade A and B, which require redundant design of air conditioning system and emergency plan for failure.
The traditional distributed air-conditioning system is highly available, and the single unit will not affect the normal operation of the data center.
The centralized cold source system in large data center application brings more challenges to usability, and multiple nodes need to design redundant schemes that can be backed up.
Green energy saving
Along with the concept of green data center, the green data center with energy saving and environmental protection has become the construction and use of data center and the consensus of equipment suppliers.
In the low carbonization trend, the data center needs to do something;
The refrigeration system is a major power hog in the data center, accounting for 30% to 45% of the total energy consumption of the whole system, and the energy saving of the refrigeration system has received unprecedented attention.
Optimization of air supply, cold and heat channel layout, isolation of cold and hot channels, intelligent group control and utilization of outdoor natural cold source have shown a phenomenon of blooming flowers and flowers.
There are also data centers that use heat recovery devices to generate hot water for use as a life, bath, swimming pool and other USES to reduce the carbon consumption of the entire system.
In terms of temperature and humidity setting, ASHRAE recommended temperature range in the 2011 version of 18 ℃ to 27 ℃, humidity range is recommended by more than 5.5 ℃ the dew point temperature, relative humidity is less than 60% relative humidity and dew point temperature of 15 ℃;
The relaxation requirement can reduce the energy consumption of the cooling, heating, humidification and dehumidification of the machine room while ensuring the normal operation of the machine room equipment, and reduce the energy consumption of the air conditioning system and the high energy consumption.
In terms of energy saving room air conditioning equipment, variable volume compressor, EC fan with high efficiency, energy-saving intelligent control, the application of the technology such as using natural cold source make the efficiency of computer room air conditioning unit and more flexible.
The attention to water has also gradually entered the field of vision, WUE, water consumption and circulating water application, and the application of rainwater is also valued in the design of data center.
dynamic
In the construction and application center of new data center, "on-demand refrigeration" or "dynamic refrigeration" also become an important evaluation criterion in data center cooling scheme.
The so-called "on-demand refrigeration" refers to the cooling output of air conditioning in the data center with the change of IT heat load, which is a dynamic and adjustable output.
As data center fever density increasing, data center air conditioning out to provide a stable, reliable, and green cooling at the same time, how to prevent the local hot spots have also become one of the need to consider the demand of cooling scheme.
The development of virtualization in data makes the heat of the server and other devices more volatile, including different time and different space changes.
The cooling temperature required for different IT equipment in the machine room is different, and even the cooling temperature of the same type equipment is different in different ages.
This correspondingly requires the refrigeration system to adapt to this trend, and can provide dynamic refrigeration schemes to meet the needs of different Spaces at different times.
Therefore, dynamic refrigeration is more suitable for virtualization requirements.
At present, the main applications of dynamic refrigeration are air volume intelligent adjustment (temperature control or static pressure control), variable capacity compressor technology, intelligent control system, etc.
The dynamic intelligent refrigeration technology is used to distinguish the cooling needs of different equipment in the data center.
Dynamic intelligent cooling technology by establishing multiple sensor group of sensors to monitor the temperature according to the heat dissipation demand in dynamic supply airflow, the air volume size can adjust at any time according to need, so as to achieve energy saving purpose.
The utilization rate of cold source is another important way to improve the cooling efficiency of data center.
In terms of air distribution optimization, from the initial large space natural air supply way, gradually upgrade to such as floor air supply, air duct air supply and some extensive way of organized supply air, and then to the current cabinet air supply or the operation of the closed channel cooling way, even more frontier for cabinets, chip, heat dissipation component cooling way of application.
High density
Unit power consumption increased as the data center, computer room calorific value more and more high, and high power density rack server, the application of the high-density devices such as blade servers, the cause of a single cabinet power continuously improve, a sharp rise in the heat of unit area, so the high density of room some problems emerged gradually.
After a lot of experimental verification, when the heat load of a single cabinet (server) is too high, the following problems can be solved by adopting the traditional air conditioning of the machine room.
The temperature control of the machine room is not ideal, there will be local "hot spot";
Because the equipment needs to take away so much heat through a large amount of circulating wind, the traditional air conditioning system will take up a lot of room space.
On the supply air duct units need to adopt the sectional area of size is very huge, overhead floor air supply unit under the height of the need to improve is to, cause is already running in the computer room will not be able to continue to use.
Therefore, the air-conditioning refrigeration system must be improved accordingly.
The high thermal density refrigeration system is an important part of the refrigeration system of the machine room.
At present, high density refrigeration, the application of more mature technology mainly has closed and cold hot channels, and the new technologies such as backplate cooling and chip cooling are the future development direction.
What's more, in the application of high heat flux, abandon the traditional way of convection and adopts thermal cooling method, such as the microchannel cooling technology, cold Plate (Clod Plate), the application of the cooling technology and so on.
In combination, the application of the elements related to free-cooling application, accurate delivery and fixed-point Cooling has become the hot spot and development direction of the current data center Cooling technology.
