How to solve the continuous cooling of high-density computer rooms?

How to solve the continuous cooling of high-density computer rooms?

Faced with the development trend of high-density computer rooms, the configuration of continuous refrigeration facilities to maintain equipment operation during power outages and chiller restarts and protect equipment safety is an important issue that must be considered by the construction party and design unit. At present, all parties are actively exploring And implementation.

　　 When the refrigeration system is stopped, the temperature rise of the computer room varies according to the density of the data center computer room. In the traditional computer room in the past, due to the small power consumption of a single cabinet, after the cooling system is stopped, there is still a long period of time to maintain the normal operation of the equipment. For example: in a 1.2KW computer room with a single cabinet, the temperature will rise by 10.5°C after the refrigeration system stops for 10 minutes, and the computer room manager can have time to activate the backup generator or shut down the server equipment. However, as the installed density of the computer room increases, the temperature rises very rapidly. According to INTEL's experimental analysis, a data center computer room with a single cabinet power consumption of about 9KW, once the cooling system stops operating, the temperature rises from 22°C to 40°C only needs 18 It only takes 35 seconds to rise to 57°C. Once it exceeds 32°C, IT equipment will malfunction, the temperature will continue to rise, and the computer equipment will stop running or even be damaged. Therefore, for high-density computer rooms, it becomes necessary to configure an uninterrupted cooling system.

　　 1. The definition of continuous refrigeration for high-density computer rooms

In the face of the above situation, some institutions in the field of foreign data centers have conducted research. In the white paper of the UPTIME Association on continuous refrigeration systems for high-density computer rooms, the refrigeration system is divided into three levels ABC, and level A is an uninterrupted cooling system: uninterrupted The refrigeration system needs to be equipped with U for the fan and secondary pump of the precision air conditioner, and the cold storage tank level is added as a continuous refrigeration system: the continuous refrigeration system needs to be configured for the fan and secondary pump of the precision air conditioner with U, but no cold storage tank is added; the C level is Interruptible refrigeration system: the refrigeration system is not equipped with any U equipment, and the refrigeration system is stopped when the power fails. UPTIME defines the refrigeration system hierarchically and provides several solutions.

　　 2. Several solutions for continuous refrigeration of high-density computer rooms

　　For a high-density computer room, what measures should be taken to maintain the operation of the refrigeration system or part of it during the intermittent power failure? The UPTIME organization and related manufacturers have proposed several solutions.

　　 The first type is to configure the U system for the entire refrigeration system. For chilled water precision air conditioners, the chillers, cooling towers, primary and secondary pumps and precision air conditioners need to be equipped with U systems. This method can maintain the operation of the entire refrigeration system, but for high-power chillers and cooling towers, the cost of all equipped with U systems is very high, so it is rarely used at present.

　　 The second type, in a system using chilled water-type precision air conditioners, configure U for precision air conditioner fans and chilled water secondary pumps, and add a cold storage tank to the chilled water circulation system to store chilled water. When the power supply is interrupted but not restored, or the chiller cannot be started temporarily due to the power interruption, the cold storage tank and the water pump are used to provide the cold source, and the precision air-conditioning fan maintains the air circulation in the computer room to maintain the temperature or temperature of the computer room for a period of time. Prevent the computer room from heating up quickly, and wait for the power to recover or the chiller to resume normal operation.

　　The first and second methods have reached the standard of Class A uninterrupted refrigeration. In the third type, in the system using the chilled water type precision air conditioner, the fan and the chilled water secondary pump of the precision air conditioner are equipped with U, but the cold storage tank is not arranged in the chilled water circulation system. When the power supply is interrupted and is not restored, or the chiller cannot be started temporarily due to the power interruption, the fan of the precision air conditioner can still maintain the air circulation in the computer room and use the remaining chilled water in the pipeline to cool the computer room. Using this method can also slow down the rapid temperature rise of the computer room, but the effect is not as significant as the first two methods.

　　 The fourth type is that for systems using direct evaporative precision air-conditioning, neither a cold storage system can be installed, nor the residual cooling of the pipeline can be used. But it is still possible to configure U for the fan of the precision air conditioner, the purpose is only to maintain the air circulation in the data center in the event of a failure, and also to slow the temperature rise of the computer room. The third and fourth methods have reached the standard of Class B continuous refrigeration.

　　 Third, the choice of continuous refrigeration solutions for high-density computer rooms

　　 Then, for the above several continuous refrigeration solutions, how should the builder or design unit choose? In this regard, the author suggests that the construction party and design unit can choose a suitable continuous cooling solution from the above solutions according to the heat density of the data center and the importance of the data center, as well as the configuration of the backup system such as diesel engines. For example, for a computer room with a single cabinet with a power of less than 1.2KW, the estimated time for the temperature to rise to 32°C is about 10 minutes or more, and the diesel engine system can be used to provide backup power. As the power consumption of a single cabinet increases, the solution of providing U for precision air-conditioning fans can be adopted to provide air circulation, use the heat absorption capacity of the environment, and slow the rate of temperature rise. However, for a high-density computer room where the power consumption of a single cabinet reaches 6kW or more (according to ASHRAE's prediction, a single server cabinet will be more than 12kW in 2010), it is necessary to adopt a chilled water-type precision air-conditioning system, and thus choose UPTlME's Class A The intermittent refrigeration scheme provides U for the chilled water circulation system and sets a certain volume of cold storage tank to maintain the refrigeration during the power outage or during the restart of the chiller after the power outage, and wait for the complete recovery of the refrigeration system.

In short, in the face of the development trend of high-density computer rooms, configuring continuous refrigeration facilities to maintain equipment operation and protect equipment safety during power outages and chiller restarts is an important issue that must be considered by the construction party and design unit. At present, all parties are Actively explore and implement. At the same time, with the continuous planning and construction of high-density computer rooms, it is expected that more solutions will emerge to meet the continuous cooling needs of high-density computer rooms.