"Precision" from the English word "precision" - accurate. Precision air conditioner is a stand-alone cabinet type air conditioner for accurate maintenance of air parameters in terms of temperature, relative humidity, and air mobility in a serviced room.
Temperature accuracy: ± 1 ° С
Accuracy of maintenance of humidity: + 5% rel. Ow.
Operation at ambient temperature: from + 50 ° С to -60 ° С.
Why is it necessary to use precision air conditioners?
The use of precision systems at process facilities is due to the need to compensate for large specific heat excess emitted from process equipment, which, in turn, is very sensitive to even minimal changes in temperature and relative humidity. Accordingly, the more the temperature in the room deviates from the optimum, the less is the service life of the process equipment. Precision systems provide effective compensation of significant specific heat excess and allow maintaining the required temperature and humidity parameters of the air in the room.
In case of overheating of the process equipment, for example, the PBX hall, as well as deviations from the required relative humidity, the equipment fails.
Application areas for precision air conditioners
Precision air conditioners are needed to ensure trouble-free and trouble-free operation of process equipment in the following areas:
Fixed telephony:
PBX stations;
Hardware rooms;
Mobile telephony:
Telecommunication nodes (switches, gateways);
Base and remote stations in buildings or containers;
Billing centers;
Information Technology (IT) Sector:
Server rooms;
Hardware rooms;
Computer halls, Data banks;
The medicine:
Diagnostic rooms;
Laboratories
Precision production:
Clean production in microelectronics, space industry, pharmaceuticals.
Standards and regulations
Temperature and humidity parameters of air in technological rooms
General requirements for temperature and relative humidity in process rooms
General technical requirements for buildings and premises for the installation of information technology equipment СН 512-78
Not to mention the features of the climate market. As a rule, when purchasing any technological equipment for household, and even more so industrial level, each customer thinks about the same issues.
STULZ answers all these questions positively.
Currently, there is a tendency for a large increase in heat generation in process rooms, which leads to the creation of huge air-cooling systems. Moreover, it is the density of heat generation per 1 m2 of equipment that is growing. But traditional precision air conditioning has limits to the possibilities determined by the physics of the process. Those. in the process room, it is possible to organize a cooled stream of any desired power, to build a local typhoon. It is possible, even by air flow, to raise the rack with servers in the air. But you can not cool properly. At high values of specific heat excess per m2, local overheating inside the server rack is inevitable. And in this case, no closers will help, only complicating, weighting, (and therefore reducing reliability) the architecture of the climatic equipment in the data center and, of course, dramatically increasing both capital and operating costs. The only solution to this problem is the direct supply of process chilled water in a rack or to an electronic element. Liquid elements are located at the bottom of the rack, below the installed equipment, so its contact with liquid is excluded. The controller of the cooling machine is equipped with emergency shutdown on floor leak sensors, with shut-off valves on the line with cooled liquid.
The calculated coolant temperature supplied to the heat exchanger, allows you not to fall below the dew point, which leads to a constant moisture content in the rack, and the absence of condensate on the equipment.
Positive factors of this equipment:
The system is sealed and can be used in any technological room. The most remarkable thing is that using a bundle of Cyber Chill-Datachiller solutions, or Cyber Cool, it is possible to organize guaranteed maintenance of microclimatic air parameters for a data center of any configuration. Those. using external Cyber Cool chillers and STULZ CPI intermediate pumping stations, to exit chilled water for racks of 12 degrees, or using only Datachiller, not only a direct calculator zone is organized in water cooled server racks of various capacities (up to 10. up to 15, up to 26, or 35 kW per rack), but also through the use of precision chilled water conditioners, a microclimate is maintained for the rest of the data center equipment (storage systems, routers, UPS, etc.) allocating a much smaller number in the heat and allow to apply conventional HVAC equipment.
The absence of a large recycle stream can greatly reduce the noise level in the room.
High density of the location of the heat-generating equipment in one rack. Without such racks, the Customer could install in one rack no more than one server with a heat release of 4.2 kW. The rest of the rack space was not completely filled, and additional racks had to be installed. This feature allows you to reconstruct existing data centers (data centers) by increasing their heat load by installing 2-3x racks with a water cooler of 26 kW each and placing all existing servers in them and installing additional water-cooled racks in the required amount.
When designing such water-cooling systems, it is necessary at the initial stage to design modular water-cooling units with the possibility of installing additional modules with minimal modernization of the control system. The main supply and return pipelines need to be designed with a large diameter. This will allow in the case of adding cooling modules not to change the main pipelines in the process room, but to use designed and previously mounted taps with stop valves for connecting new water-cooled racks. The commissioning works will consist only in setting up the balancing valves installed earlier on each branch of the cooled liquid.
Since its founding in 1947, Stulz has become the world leader in integrated solutions for precision air conditioning. In 2006, the turnover of this division of the company Stulz amounted to US $ 300 million (production of precision air conditioning systems and chillers; sales of air conditioning and humidification systems, including those with an RLT system, after-sales service). Today Stulz has more than 1,200 employees in 10 German branches and 9 representative offices in France, Italy, Great Britain, the Netherlands, Poland, Spain and the USA, these are partner companies in more than 100 countries of the world, an international network of specialists in air conditioning technology. Worldwide, Stulz has more than 3,700 employees.
The advantages of using precision air conditioners
Precision in English "precision" means "accurate." The accuracy of the precision air conditioner is in the output parameters of the environment: air or water, depending on the type of equipment.
The environment is determined by the Technical Conditions (TC) of the manufacturer of the equipment or the Terms of Reference (TOR) for a specific room or their group. Such systems are used in process rooms where high-tech equipment is installed with similar requirements for air temperature and humidity, as well as in operating rooms of hospitals with similar parameters and the need to precisely maintain the amount and quality of air in the work area.
All the above processes can be built with the help of industrial precision systems, whose architecture has been specially developed and annually improved to solve such problems.
The use of the word "industrial" is due to the fact that the components used in the manufacture of such systems are industrial, not domestic. Industrial components initially have a long operating life, for each component there are replaceable and maintainable parts. The manufacturer of parts and components guarantees their availability for 10 years after their removal from production.
The service life of the components, and hence the entire precision industrial system of 10 years and above. Thus, the reliability of such systems is much higher than the semi-domestic and residential systems. The use of the latter, designed for eight-hour work in the summer, modernized by electric heaters, leads to a rapid development of the resource.
To reduce the noise pressure, domestic air conditioners are initially equipped with low air flow fans. The air exchange rate of precision systems on the evaporator is three times the air exchange rate of household systems. Thus, the cooling capacity of such systems is achieved by increasing the temperature difference, namely, by lowering the outgoing air temperature from the evaporator.
The consequence of this architecture are two detrimental factors for fuel equipment:
In rooms with high-tech equipment can not install household systems.
The tasks of removing heat loads in high-tech premises can be solved only with the help of industrial equipment. Why is the precision system always used in practice? The fact is that the manufacturer of such equipment follows the requirements for compactness, noise pressure and system control.
Thinking about the security of data storage, most companies include fire alarms, anti-spam filters and backup servers. However, in recent years, the demand for air conditioning systems as a means of ensuring the safety of hardware and software has increased. Increasing the room temperature by just a few degrees can cause overheating of process equipment and, as a result, lead to data loss. Thus, in modern server rooms, a precision air conditioning system has the same meaning as a server and rack.
Neither large corporations nor medium-sized companies can afford to develop without a powerful IT infrastructure. Servers, racks and telephony systems now take up much less space than a few years ago. More and more complex data processing is performed in a small area.
However, more power in relatively small rooms also means higher heat dissipation from equipment. As soon as the temperature in electronic devices reaches a certain limit, they automatically turn off. Emergency shutdown of equipment leads to loss of processed data, and this is a disaster for any company. Even if overheating does not lead to the worst option, improper maintenance of climatic parameters in server rooms significantly reduces the life of electronic components.
Today, server rooms require a comprehensive solution for precision air conditioning, which ensures the maintenance of accurate parameters for temperature and humidity. The ideal temperature in the room should be 22 ° ± 1 ° C. Ideal relative humidity parameters: 50 ± 5%. Excessive moisture may corrode electronic components. Low humidity can destroy or damage data due to the occurrence of static electricity.
When designing server rooms, the following rule can be applied: the amount of electricity at the entrance will be converted into heat excess, which must be removed by cooling. Since the cooling in the room is required continuously, it is necessary to ensure the availability of reserve capacity. Since it may take up to 100% extra power, it is recommended to have at least one backup air conditioner or each air conditioner should have a 20% greater cooling capacity.
When developing a precision air conditioning system, it is also necessary to take into account the type, size and number of external heat excesses. Depending on the location of the conditioned room in the building, an alternative cooling system may be offered to reduce costs.
Thus, for most companies today there is a need to revise their own IT infrastructure, which is too valuable to put at risk. Security and continuous availability of critical data 24 hours a day, 365 days a year, depends on the correct air parameters in the server room. Precision air conditioning is a necessary investment that protects equipment from failures and ensures safety and continuity of operation.
The factory production technology of industrial air conditioning systems does not allow creating a vertical unit with an air cooler and a humidification chamber. The reason is the absence of a vertical drip tray and drainage and condensate drainage systems.
Vertical air flow in a precision air conditioner is due to the natural accumulation of warm air at the top of the room and very often the presence of a raised floor, used as a fresh air duct. Currently, the manufacturer of precision air conditioning declares that 1 sq. M. the occupied space of the precision equipment allows you to remove the heat load of 42kW.
The operating temperature range for precision systems is from -60 ° C to + 50 ° C. For the territory of our country is very important is the lower outside temperature barrier for the trouble-free functioning of the cooling system, which is achieved through the use of various additional components of the system. The first such component is a fan mounted on an outdoor air condenser. Lubrication of its bearing should remain viscous and not freeze over at a temperature of -60 ° C.
Constantly running refrigerant circuit: compressor + evaporator + condenser, - can work without stopping and without additional elements up to -60 ° C, but in the case of a compressor stop by a controller signal, for example, upon reaching the room temperature set in the room, the refrigerant in the above system starts to cool which is strongly favored by the cold outside air. Thus, the refrigerant, decreasing in volume, reduces the network pressure. Without exception, all compressors are equipped with a low pressure safety valve, whose function is to protect the compressor from running dry in the event of depressurization and refrigerant leakage. When the temperature is below -5 ° C, the pressure in the network reaches the low pressure setting of the valve and the compressor will not turn on, and the system will report an alarm due to the low pressure of the network.
The first way to reduce the operating range to -20 ° C is to use a smooth rotation of the outside air fan (condenser fan). Thus, with a decrease in pressure in the system, the fans will reduce air consumption, thereby increasing the condensation temperature and preventing the compressor from shutting down for a long time. This does not allow the system to cool down to the value of the low pressure alarm sensor.
The second method, most common in Kazakhstan, is to use a set of equipment to operate at temperatures from -20 ° C to -45 ° C. The kit includes a specially-sized external receiver, two bypass valves KVR and KVD, which look similar to three-way and non-return valves.
With the help of the above elements during assembly, two circuits are assembled: small and large. In normal mode, the system works along a large contour, as in the classic version. When the pressure of the network decreases, the bypass valves shunt a large circuit, forming a small one. To maintain the required network pressure, the missing refrigerant is taken by the system from the receiver, and in the event of a pressure increase, the excess refrigerant is returned to the receiver. Thus, the system with a winter kit for operation at temperatures up to -45 ° C is charged with a large amount of refrigerant during commissioning.
This system requires accurate calculation and selection of the receiver, as well as proper configuration of the bypass valves during commissioning.
The kit for operation at temperatures up to -60 ° C is distinguished by the choice of an outdoor condenser with fans operating in “at very low temperatures” and the dimensions of the receiver and bypass valves.
Pros and cons of free cooling
Back in the early 90s of the last century, a foreign manufacturer of precision air conditioning systems began to actively promote the idea of using free cooling, as an option in the winter period in standard air conditioning systems. From an economic point of view, this idea was excellent. Such a solution saves the compressor resource and, as a result, the consumed electric power. There is also no need to install a winter start kit. At first glance, the system had only one drawback: the need to install bulky air ducts to supply fresh air and the presence of large openings for the installation of external grilles. Behind all these pros and cons were two very important negative factors.
First, cold air (-26 ° C) cannot be fed to the process room, it must be heated to + 18-20 ° C. For this, a mixture of exhaust air from the heat-generating room is used. When mixing cold and warm air condensation occurs in the mixing chamber, which leads to wet air filters, and as a result, the resistance increases and air consumption decreases. To prevent this effect, the supply air is heated to + 2-3 ° С, for which it is necessary to expend electricity. At very low temperatures, more electricity is consumed than can be saved from idle compressor.
Secondly, almost all fuel-generating equipment has a TU for air humidity, usually in the range from 40 to 55% rel. vl., the range from 20 to 80% ot is allowed. Ow. In winter, the moisture content of air is close to zero. As you know, heating the air does not lead to the appearance of moisture in it, and hence the relative humidity with the free cooling described above will be below 5-10%. Thus, it becomes necessary to constantly moisten the dry outside air to a predetermined value of 40%. Humidification occurs due to the operation of an electrical electric steam generator, which requires constant electrical energy and consumable material in the form of cylinders or electrodes.
This method of free cooling can hardly be called energy saving. In this connection, it is more expedient to use free cooling systems based on the transfer of external cold through the water-glycol mixture.
Free cooling systems based on the transfer of external cold through a water-glycol mixture
In the construction of such units there are two water-to-air heat exchangers, one of which is a regular evaporator. The basis of free cooling is a plate condenser refrigerant - a water-glycol solution, installed in the case of the internal module of the air conditioner. On the street there is a dry cooler (dry cooler), connected in summer through a liquid plate condenser to a compressor. When the outside air temperature drops below + 15 ° C, the bypass valves switch the path of the cooled liquid from the plate condenser to the second air heat exchanger (air cooler). Air cooled liquid enters directly into the air conditioner cabinet and free cooling takes place, which does not change the moisture content of the air inside the room. Such free cooling is indeed cost effective.
The development of modern technologies involves the continuous improvement and introduction of new developments in existing systems. In technological rooms, a planned or sudden expansion of existing equipment takes place. All of the above requires the continuous improvement of existing precision air conditioning systems. Already today, precision industrial systems are equipped with controllers capable of expanding with no limit on the number of cooling modules. Thus, under one control system you can add and add cooling modules without changing anything for the user.
The latest trend in the development of precision air conditioning has become the remote control of the microclimate. First of all, it is connected with the development of remote points at the customer and with the tasks of minimizing the influence of the human factor on the processes and limiting the access of service personnel to the site. This allows you to remotely identify a possible failure, prepare the necessary parts and tools and in the shortest possible time to solve the emergency situation at a remote point of the customer. The controllers used in STULZ air conditioners allow you to transfer data to manage the system using any currently existing protocols (including the most common ones: SNMP and HTTP).
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