Thread Content
The air conditioning system in the data center’s cooling room is a fundamental guarantee for the safe and stable operation of the equipment within the data center. Unlike ordinary comfort-oriented air conditioning systems, its primary purpose is to remove heat generated by the equipment, ensuring the safe and stable operation of the cooling room; it must operate continuously 24/7 to provide cooling. Data centers have high air-conditioning loads; once there is a failure in the cooling system, the heat generated by IT equipment cannot be dissipated in time. As a result, the temperature in the server room quickly exceeds the requirements set by equipment manufacturers for such environments, which may lead to system downtime or equipment damage. Therefore, it is necessary to prevent failures in the air conditioning cooling system, ensure uninterrupted cooling around the clock, and enable online maintenance. Air-conditioning cooling water systems are generally designed as open systems. Depending on the geographical environment in which data centers are located, the water quality in the circulating cooling water systems is poor. The copper tubes in condensers are usually high-efficiency threaded tubes; over time, dirt accumulation becomes inevitable in these condensers, gradually forming a scale layer that causes the temperature of the condenser to rise. When the approach temperature of the air-conditioning unit’s condenser reaches the maintenance requirements of the data center or the settings specified by the manufacturer of the unit, it is necessary to shut down the unit and clean the condenser offline. During shutdown for offline cleaning, it is necessary to isolate the main unit from the system, which inevitably has a certain impact on the entire system. Moreover, offline cleaning can affect the service life of the copper pipes as well as the main unit itself, leading to unnecessary waste of energy. Most importantly, it is not in line with the safety design and operational principles of online maintenance for data center cooling systems; therefore, it is highly significant to install online cleaning devices on the condensers of the cooling units. The \"Code for Design of Heating, Ventilation and Air Conditioning in Civil Buildings\" (GB50736-2012) stipulates that, in addition to carrying out regular water quality treatment for the circulating cooling water system in chillers, it is necessary to install automatic online cleaning devices for water-cooled shell-and-tube condensers. This approach can effectively reduce the fouling thermal resistance of the condensers and maintain a high level of cleanliness on the inner surfaces of their heat exchange tubes, thereby reducing the temperature difference at the condensation point as well as the condensation temperature. In terms of operating costs, for every 1°C increase in the condensation temperature, the power consumption per unit of cooling capacity of the compressor increases by approximately 3%-4%. Current online cleaning devices mainly fall into two categories: cleaning balls and cleaning brushes. Since the performance of cleaning balls (rubber balls) in such devices is greatly affected by water quality, and the drawback of intermittent cleaning results in poor performance when applied to data center air conditioning systems. The brush-based online cleaning device provides one-to-one cleaning, offering excellent cleaning results for the grooves in high-efficiency threaded tubes; it is currently widely used in data center facilities. Taking a Unicom data center in the Guangdong region as an example, the facility was put into use in July 2017. All 4 York centrifugal water-cooled units (with a cooling capacity of 2813 Kw) were equipped with Qinyuan WSA brush-based online cleaning systems. By May 2019, the temperature of the condensers of these units had remained stable; upon inspecting the end caps of the condensers, it was found that the inner surfaces of the copper tubes were as clean as new, which won the approval of both the owner and the maintenance team. Given the operating characteristics of data center air conditioning systems, it is highly significant to equip condensers with brushes for online cleaning, both from a safety and energy-saving perspective.