Layout scheme of hot and cold aisles in data center computer room

The most talked about hot and cold aisle system in the industry is: “Whether to arrange isolated cold aisles or to arrange isolated hot aisles?”. So in actual cases, how should we make the right choice? Now let’s not discuss how to make a choice, first let’s take a look at the differences between the two options.

1. Prerequisites for choosing a cold (hot) aisle

Not all data center computer rooms are suitable for arranging isolated cold aisles and hot aisles. It mainly depends on whether the heat generation of the data center is large. At this time, you can choose both the cold aisle and the hot aisle layout. In other cases, the author believes that it is best to choose to arrange isolated cold passages. Why do you say that?

1) After choosing to arrange the isolated hot aisle, we regard the computer room as a closed container (M1) except for the rack, and the heat generation (Q1) of a single rack remains unchanged, so it is necessary to dissipate the heat Isn’t it true that the air-conditioning air volume sent by the precision air conditioner is more? That is to say, when the calorific value is constant, the size of the container is inversely proportional to the air supply volume. From this point of view, the arrangement of isolated hot aisles will increase the power consumption of the air conditioner.

2) After choosing to arrange the isolated cold aisle, we also regard the cold aisle area as a closed container (M2), and the heat generation (Q2) of a single rack remains unchanged, so is it precise to dissipate the heat? Is the cold air volume sent by the air conditioner smaller than that of the isolated hot aisle? Because M2

2. Arrange the environment of the computer room behind the isolated cold (hot) aisle

After the isolated hot aisle is arranged, the remaining space of the computer room is in a cold air area. People who often enter and exit the computer room will feel that the computer room is very cold, but the equipment does not necessarily receive sufficient air-conditioning.

After the isolation cold aisle is arranged, the remaining space of the computer room is in a hot air area. People who often enter and exit the computer room may feel a little temperature adaptation, but the equipment has received sufficient pressure of air-conditioning.

3. Prerequisites for arranging isolated cold (hot) aisles

1) The prerequisites for arranging isolated hot aisles are: in addition to requiring the precision air conditioner to be the condition of downward air supply and upward return air, it is also particularly required that the data center computer room must have a good return air and fresh air system. Therefore, from this point of view, it is not suitable to arrange isolated hot aisles for the reconstruction of the computer room. Because the old computer room does not necessarily have a good return air system.

2) The prerequisites for arranging isolated cold aisles are: the precision air conditioner is required to be a system with downward air supply and upward return air, and at the same time, in order to ensure the air supply volume, the net space of the electrostatic floor should be at least 450mm.

4. The construction difficulty of arranging isolated cold (hot) passages

From the perspective of the prerequisites for arranging isolated cold (hot) aisles, the construction difficulty of arranging isolated hot aisles is obviously much greater than that of arranging isolated cold aisles.

1) The installation and layout of the return air duct involved in it requires a ceiling (while most large data centers currently do not need a ceiling).

2) The layout of the return air duct requires additional heat insulation materials and exhaust equipment, so that the hot air can be effectively discharged.

3) The next job is to seal the hot aisle or the cold aisle. The materials and workload of the two are similar.

5. Layout and isolation of cold (hot) aisles for post-maintenance

1) After arranging the isolated hot aisle, the hot air may not be discharged quickly, so it is necessary to increase the exhaust fan, which also brings a lot of trouble to the later maintenance. The fan is always running, and it is impossible not to fail, then It is necessary to replace the exhaust fan, and the workload will increase

2) After the isolated cold aisle is arranged, there is basically no maintenance cost in the later period. Even if the lighting in the machine room needs to be replaced, the cold aisle ceiling can be easily removed.

6. Energy-saving data after arranging and isolating cold (hot) aisles

In the case where the isolated hot aisle is allowed, is there any difference in the energy-saving efficiency data after the isolated cold (hot) aisle is arranged? The cold aisle can save energy by about 30%, and the hot aisle needs to be equipped with a return air fan, so Its energy-saving efficiency is obviously lower than 30%, and in some places it may not reach 10%. As can be seen from the figure below, a return air fan may need to be installed on the top of each (column) cabinet.

7. Layout of isolated cold (hot) passages and fire linkage

Fire protection has always been the most concerned, indispensable, but rarely used comprehensive preventive security system for data centers. Here we are not talking about fire protection, but what will happen when a single computer room encounters a fire? Because all IT equipment power supplies and cabinet power supplies are arranged at the rear of the rack, even if a part of the circuit board of the IT equipment is at the front, when the equipment catches fire, it will start to catch fire from the rear of the rack. According to the principle of extinguishing the fire first, the main fire sprinkler should be installed in the hot air area, and the auxiliary sprinkler can also be installed in the cold air area.

From this, otherwise, we can see the following conclusion: the arrangement of isolated cold aisles does not seem to have a great relationship with the fire linkage, but if the isolation of hot aisles is to be arranged, it has a great relationship with the joint defense linkage.

That is to say, it is inappropriate to use magnetic locks to close the roof when arranging cold aisles in order to be able to link with fire protection. This not only does not play a critical role in fire protection, but also increases energy consumption.