【 Weak current college 】 computer room in the fresh air system

First, the specification of the computer room of the new amount of wind

1, computer room new air flow in normal view, should follow the following three pieces of maximum value calculation:

1) room total air 5%;

2) each person ≥ 40m3/h;

3) maintenance of room required under positive pressure ventilation (host room or other rooms on the corridor between the positive pressure ≥ 4.9Pa, on outdoor positive pressure ≥ 9.8Pa).

2, the first new air volume is the total air 5% is not reasonable, since the total thermal load in the engine room and the room area and not proportional. There's not much room area though, due to the high power density, room total heat load, total air conditioner, determined by the requirements of the new amount of wind often oversized, resulting in treatment of fresh air conditioning load required; for example, a computer room, total 140m2 heat loads reach 360KW, total air about 10 000 m3/h, if by 5 per cent of new air volume required 5000m3/h.

Computer room into the fresh air's purpose is to satisfy people's needs and the maintenance of room required positive pressure values; in air-conditioning Design Handbook (Institute of electronics, editor in Chief) of the first edition in turbulent air flow in clean room, think of the new shall not be less than the total air 10%; in the second edition of this provision seems insufficient grounds, the heating, ventilation and air conditioning design specifications "in this provision does not, therefore, should be 1) added indoor air and maintain indoor positive pressure values; and 2) to ensure that new indoor air per person should not be less than 40m3/h, two of the larger value determines the new amount of wind.

Computer room can be viewed on the cleanliness requirements lower (inch 50 million level) of turbulent Cleanroom, room no exhaust, to maintain the engine room the desired positive pressure value and the Interior each person not less than 40m3/h computer room is more appropriate for the new amount of wind.

Article 3, to maintain the pressure in the engine room ventilation rate is difficult to calculate. To maintain the engine room on the corridor (or other room) of positive pressure ≥ 4.9Pa, room doors and Windows, gap outlet speed ≥ 2.8m/s, the new amount of wind to the slit area and the product of the wind speed; because it is difficult to calculate the total gap, thus maintaining the room positive pressure required fresh air also cannot be calculated.

Second, the size of the computer room air purification system for air conditioning effects

1. new advantages and disadvantages of large air volume

Advantages: 1) easier to maintain the positive pressure in the engine room; 2) can supply staff more fresh air.

Disadvantages: 1) in many parts of our country, summer outdoor air heat and moisture load are large, if the new amount of wind is big, will give the air conditioning system increases larger burden; for example the summer if 5000m3/h fresh air to the engine's State (temperature 23 ° c, relative humidity of 55%), the required cooling load in Beijing, Shanghai area required 57.5kW cooling load 72kW.

2) in colder areas, if winter new amount of wind is big, the required amount of humidity and heat quantity is larger. For example winter if 5000m3/h fresh air to the engine's State (temperature 20 ° c, relative humidity of 55%), the Beijing area desired humidification capacity 43.8kg/h; large machine room exclusively used air conditioner each humidification of only 8-10kg/h, the new amount of wind is big for a large increase in air conditioning systems.

In colder areas, the winter if webpage directly without fresh air into the engine room, heated directly when the outdoor air temperature lower than the room dew point temperature is easily cause condensation phenomenon, this point shall be fed into the fresh air heating after; if the new amount of wind is big, the required heating capacity, resulting in a waste of energy.

3) new amount of wind is big, the fresh air filter number, initial investment and maintenance workload are large.

2. the pros and cons of the new wind of small

Advantages: 1) the processing of fresh air in summer air conditioning load, the wet winter and heating also small, saves energy and run at the beginning of the investment; 2) needed new air filters to the reduced initial investment and operation, and maintenance costs are relatively small.

The bad: more difficult to maintain the engine room the desired positive pressure value. If the room is pressure value is low or even negative pressure, temperature and humidity machine room and cleanliness is very difficult to maintain; outdoor untreated air gap through doors and Windows, etc. directly into the engine room, summer in a humid area room relative humidity is too high, winter in colder regions room relative humidity is too low. As outdoor air gap without filtering by entering the room cleanliness also cannot be guaranteed.

Third, the computer room of the new amount of wind

Computer room should determine a suitable new air flow, ventilation rate too small or too large to meet the room temperature, humidity and air cleanliness requirements. It is recommended that you maintain the room required positive pressure value and each ≥ 40m3/h of the larger values to calculate the new amount of wind.

Due to the maintenance room positive pressure ventilation rate required to calculate, in accordance with the experience and reference design, clean room can be 1-2 times the ventilation air/h to calculate the new. If the room around the envelope of better sealing may be ≥ 1 ventilation/h to calculate a new amount of wind;