COLD-HOT AISLE CONTAINMENT SYSTEM

What is the cold/hot aisle containment system in a computer room, and why does a computer room need cold and hot aisle isolation?
What is the cold/hot aisle containment system in a computer room, and why does a computer room need cold and hot aisle isolation?
What is the cold/hot aisle containment system in a computer room?
The cold/hot aisle containment system is a technology applied to reduce the temperature of equipment that generates heat during operation. It is mainly applied to data center computer rooms. Enterprise data center computer rooms generally face issues such as high equipment heat generation density, large power consumption, insufficient space in the computer room and cabinets, and the computer room planning failing to keep up with the growth of business demands. All along, in order to meet the continuously rising heat dissipation requirements of data center computer rooms, the number of computer room air conditioners has been continuously increased and replaced. However, there are still local heat island problems inside the computer room. The cold air and hot air mix directly, resulting in a large waste of cooling capacity.
The equipment at the upper part of the cabinet cannot obtain the required cooling capacity for equipment cooling, and the overall Power Usage Effectiveness (PUE) value is still high.

What is the working principle of the cold/hot aisle in a computer room?
With the continuous increase in the power consumption of server equipment, the heat dissipation capacity required for the cabinets needs to be greatly enhanced. Reasonable use of the cold aisle solution can greatly improve the heat dissipation capacity of the data center and make full and effective use of the cabinet and computer room space. The cold/hot aisle containment system is based on the principle of the separated and orderly flow of cold and hot air. The cold air is blown out from under the raised floor and enters the enclosed cold aisle. The equipment at the front of the cabinet inhales the cold air. After cooling the equipment, hot air is formed and discharged from the back of the cabinet to the hot aisle.
The gas in the hot aisle quickly returns to the air conditioner's return air inlet. The closed turbine rear door of the cabinet collects the hot air and is seamlessly connected to the ceiling through a vertical air duct. The hot return air is completely isolated from the cooling capacity. Therefore, the utilization rate of the internal cold air is increased, more heat generated by the equipment is carried away, and the equipment temperature is reduced.

Problems Existing in the Cold and Hot Aisles

(1) Drawbacks in Its Own Principle
Due to the principle of the cold and hot aisles, the entire air supply area needs to be enclosed (cold aisle containment). Although this can significantly reduce or avoid the loss of air volume and cooling capacity, and ultimately greatly improve the refrigeration efficiency, for this cold and hot aisle containment solution, the primary issue that has always hindered its large-scale promotion is the fire protection problem. Since all the equipment operating in the data center is IT equipment, gas fire extinguishing is usually adopted for fire protection. As the cold aisle is enclosed, once the equipment in the cold aisle catches fire, the fire protection gas cannot reach the enclosed area within the specified time, which is bound to cause greater losses.

(2) Excessive Dependence on Precision Air Conditioners
Since the temperature in the cold and hot aisles is mainly regulated by relying on precision air conditioners, the air circulation in the cold and hot aisles all needs to be adjusted by precision air conditioners. Moreover, when constructing the cold and hot aisles, the air supply area is required to be enclosed. As a result, it is very difficult for the management personnel to detect the faults of the precision air conditioners, which leads to the emergence of many problems.

Why does a computer room need cold and hot aisle isolation?
In traditional data centers, the air flow organization is disordered, with cold and hot air flowing randomly. The cold air from precision air conditioners cannot be effectively utilized, resulting in high energy consumption in the data center. Cold and hot aisle isolation can save space in the data center and improve the space utilization rate of the data center. By comparing the space of a traditional data center with that of a data center equipped with a cold aisle, the cabinet layout of the "cold aisle" solution saves 14.8% of the computer room space and increases the space utilization rate of the cabinets.

Characteristics of cold and hot aisle isolation:

(1) Modularity
The cold aisle enclosure adopts a modular design. Two corresponding cabinets on both sides of the cold aisle form a module. Each module can be installed and disassembled independently, making it convenient for users to add, reduce, or move some of the cabinets within the aisle.
(2) Safety
Each top panel can be linked with the fire protection system. Once the fire signal in the computer room is confirmed, the top panel will open automatically, allowing the fire extinguishing gas to enter the aisle for fire suppression.
(3) Convenience
It has a threshold-free design, which facilitates the unobstructed entry and exit of transportation tools such as small trolleys.
(4) Aesthetics
The material of the enclosed window of the aisle is transparent glass, and the exterior is made of cold-rolled steel plate with the same material as the cabinet. It has high mechanical strength, good transparency, a beautiful overall appearance, is consistent with the style of the cabinet, and is relatively harmonious with the computer room environment.
(5) Customization on demand
The enclosure solution can be flexibly adjusted according to the height of the on-site cabinets and the height of the space at the top of the computer room. There are full-turnover/half-turnover solutions for the top panels.
According to the width of the corridor outside the on-site enclosed aisle, the enclosed aisle can choose the push-pull door opening method or the left-right translation door opening method, and the enclosure solution can be flexibly adjusted.
(6) Installation reliability



1. All components of the aisle enclosure are installed and fixed on the load-bearing frame of the cabinet.

2. The fixing points are mainly distributed on the top surface, front surface, and side surface of the load-bearing frame of the cabinet.

3. The installation is simple, the overall coordination is beautiful, it will not damage the existing decoration of the computer room, and there is no need for open fire or welding at the installation site.



Since we are going to carry out the enclosure, we should try our best to avoid cold air leakage. What are the boundary factors?



(1) Cable perforations under the cabinets. In many current cases, the under-floor air supply cold aisle enclosure is adopted. However, in non-rigorous engineering construction, the details of the cabinets are often not noticed. The cables at the bottom of the cabinet are directly perforated at the opening of the cabinet, and no measures are taken to seal the redundant gaps. This causes cold air to enter the cabinet and reduces the temperature at the air outlet. As a user or an engineering contractor, you need to consider this point. I have always despised the practice of only promoting concepts without paying attention to the matching of details.



(2) Blind panels on the front of the enclosed aisle. Many users can see on-site that the cabinet enclosed aisle is adopted to improve the refrigeration efficiency, but from the enclosed side, many gaps can be seen, causing the mixing of cold and hot air and losing the energy-saving effect. A friendly reminder: if you adopt such a solution, please don't be stingy with a little money for sheet metal parts. Buy as many blind panels as are missing.
(3) The distance between the indoor air supply main unit and the air outlet
Many people deploy the aisle enclosure system in some very small computer rooms. They do not accept in-row cooling air conditioners and insist on the under-floor air supply method. As a result, the air outlet of the cold aisle is less than three meters away from the indoor main unit of the under-floor air supply, and the clear height under the floor is less than 400mm. The direct effect of this is that the effect is greatly reduced. There are two reasons for this:
If the air outlet of the under-floor air supply main unit is too close to the air outlet, due to the air pressure at the air outlet, the wind speed of the cold air at the bottom is too high, and the cooling fan of the equipment cannot fully absorb the cold air for cooling.
Moreover, if the clear space under the floor is insufficient in this case, the poor static pressure effect will also lead to the wind speed at the air outlet being too fast or too slow.
Therefore, as project designers, you must consider carefully how to guide customers.