【 Weak current College 】 machine room exclusively used air conditioner and the difference between comfort air conditioning

I. current status of the refrigeration system in the engine room
Modern data centralized network era, computer miniaturization, cabinets, Server thin, blade. They are characterized by small, but increasingly, electronic power density continue to increase. In those circumstances, the engine's cooling system to withstand increasing test.
The current application in the computer room of the refrigeration system there are two main categories, one category is the machine room exclusively used precision air conditioning (the vast majority); another for comfort air conditioning, some rooms are also equipped with a humidifier, used in place of room precision air conditioning humidifier and refrigeration dual role.
However, in a real application, use the comfort of air conditioning units of the engine problems more: high-density electric equipment for heat and hot spots cause downtime, equipment failure rate and amount of comfort air conditioning maintenance.
Second, room comfortable and precision cooling system and air conditioning difference
Cause this phenomenon because of the comfort of air conditioning and room air-conditioning design standard and design capabilities.

** The sensible heat ratio (SHF: Sensibleheatfactor): heat and the ratio of total calories. In the engine room, more than 90% of the calories are dimmed, you need a high ratio of sensible heat unit.
The following briefly on these differences.
1. comfort air conditioning air volume is small, and the air temperature is too low
Comfort air conditioning design for small volume, large enthalpy difference, outlet temperature design in 6-8 ℃. Machine room exclusively used air conditioner is designed for large volume and small enthalpy difference, outlet temperature design in 13-15 ℃.
Comfort air conditioning outlet temperature is 6-8 ° c in temperature is 24 ° c, relative humidity greater than or equal to 50% of the time, 13.2 ¡æ to dew point temperature, i.e. when it is below this temperature the water vapor in the air will condense into water droplets in air conditioning is out of the doldrums droplet on near the air conditioner air force equipment extremely negative results in micro-circuit, etc. Comfort air conditioning without considering the effect of humidity on the device, the device can be effective cooling of proximal end, but due to lack of wind, causing the ACH is not enough, that is, the distance between the outlet of the device is not valid.
Machine room exclusively used air conditioner outlet temperature high (13-15 ° c). Designed to avoid the "dew point", and by large air volume high pressure (ACH minimum design is 30 times, i.e. every 2 minutes to room air effectively filter once) design solves the engine room overall cooling problems.
2. comfort air conditioning in-5 ℃ below that is not running correctly
Comfort air conditioning in the design concept is cool in summer, when to play outdoor temperature from-5 ° c and below, that is, unable to cool down, forcing it to run, the air conditioning unit of life is significantly shortened! and room is characterized by a high calorific value, the engine's air conditioning even in winter also have a cool feature! machine room exclusively used air conditioner is designed to adapt to the requirements of the outdoor temperature,-40 ° c to + 45 ℃ intervals guarantee air conditioning 24 hours to work, including the cooling and heating.
3. adjustment precision comfort air conditioning temperature too low
Comfort air conditioning temperature control accuracy of ± 3 to 5 ° c, the engine temperature guarantee only the non-uniform, the air conditioning temperature of proximal equipment Department, and the temperature fluctuation on equipment and stable operation of extremely negative. Machine room exclusively used air conditioner temperature control accuracy of temperature 1 ° c, no wave.
4. comfort air conditioning not humidity control function
Comfort air conditioning for humidity control. No humidification function, only for dehumidification. Humidity is too high and the humidity produced by the water drops too low to produce static on equipment operation is extremely negative. Machine room exclusively used air conditioner of important control parameters for humidity, can meet ± 5% of the control precision.
5. comfort air conditioning design short service life
Machine room exclusively used air conditioner in the design life of 10 years, the operational requirements for 365 days, 24 hours a day. There are already some comfort air conditioning manufacturers nominal design life of more than 5 years, but its calculated annual applying 1 ~ 3 quarters, run daily for not more than 8 hours, if you follow the machine room exclusively used air conditioner design life of its design life generally not more than 3 years.
6. comfort air conditioning only simple comfort air conditioning air filtration capacity only have simple filtering, filtering effect of the filter simply cannot meet the requirements of the engine room. Machine room exclusively used air conditioner in strict accordance with the United States ASHRAE52-76 standard design, performance are completely meet 0.5 Micron/l < 18,000 (b level), with a large amount of wind circulation, guarantee the room clean.
7. large comfort air conditioning maintenance
In terms of comfort and air conditioning, due to the failure rate is high, the customer must be the Organization of specialized personnel for maintenance, maintenance and maintenance cost is high. Machine room exclusively used air conditioner's design for the "maintenance free" and its maintenance is concentrated in the unit automatically prompted filter replacement and humidification tank cleaning, simple work, under normal circumstances, no professional maintenance team.
8. comprehensive cost high comfort air conditioning
① from one-time purchase cost, if you use the computer room air conditioning, to achieve the same refrigerating capacity prices comfort air conditioning several times, but consider using life-machine room exclusively used air conditioner service life of the air conditioning is comfort air conditioning in 2 to 4 times, that is, in 10 years time, we can only use 1 batch of machine room exclusively used air conditioner instead of application 2 batch even 3 batch comfort air conditioning.
② from running costs, in play the same cooling efficiency, comfort and air conditioning in consumption, is the power consumption of machine room exclusively used air conditioner 1.5 times. Refer to the following example, the calculation taking into account the machine room exclusively used air conditioner and comfort air conditioning sensible heat and energy efficiency ratio of the difference.
Machine room exclusively used air conditioner sensible heat ratio as high as 80% to 90%, that is, 90% efficiency for effective cooling device, only 10% of energy consumption for appropriate dehumidification. And comfort air conditioning of sensible heat ratio of 60% to 70%, 30% to 40% efficiency to excessive moisture, resulting in the engine room humidity is too low, not only threatened by electrostatic equipment, but also greatly waste of energy.
Machine room exclusively used air conditioner selection of industrial-grade compressor energy efficiency ratio up to 3.3. While the industry selected comfort air conditioningUse of high grade compressor energy efficiency ratio, i.e., 1KW power 2.9 only produces cold, below 2.9KW machine room exclusively used air conditioner
③ seen from the maintenance costs. In play the same refrigerating effect, the amount of comfort air conditioning maintenance is machine room exclusively used air conditioner maintenance of 2 times, increased maintenance cost.
So from a product's life cycle in General, from a cost perspective, select the machine room exclusively used air conditioner can save a lot of investment, operating costs, maintenance costs. The early investment comfort air conditioning is much lower than the machine room exclusively used air conditioner, but after 3-4 years, the comfort of air conditioning and machine room exclusively used air conditioner of basic fairness, since then, the cost of comfort air conditioning is getting higher than machine room exclusively used air conditioner.
Conclusion: for the engine room, to guarantee the room environment is stable and reliable, needs of machine room exclusively used air conditioner, use comfort air conditioning unit is just the beginning of the investment is reduced, but cannot guarantee that the room temperature and humidity environmental requirements, the total cost also higher than the machine room exclusively used air conditioner.