“The only company demonstrating liquid cooling technology in Korea is LG Uplus. While we are still a latecomer in the global market, we plan to accelerate commercialization while operating a demo room.”
On the 12th, Baek Seong-jun, the head of the AIDC (AI Specialized Data Center) project, said during a meeting at the LG Uplus Pyeongchon 2 Center in Anyang, Gyeonggi Province. In May, LG Uplus established the 'liquid cooling demo room (laboratory)' at the Pyeongchon 2 Center, making it the first data center in Korea to do so. The company expects that once liquid cooling technology is commercialized, it could reduce power consumption by 7 to 8 times compared to existing air cooling methods while maximizing GPU (graphics processing unit) performance.
Upon entering the demo room, two server racks equipped with Direct to Chip technology were located on one side, while a tank for immersion cooling equipment was on the other. The test equipment was prepared by LG Uplus to demonstrate liquid cooling technology. Baek noted, “It took about six months to install the demo room, from design to equipment receipt. Through the demonstration process, the company is gaining operational know-how while experiencing trial and error.”
◇ There are limitations with air cooling... liquid cooling improves power efficiency by 7 to 8 times
The liquid cooling method offers higher power efficiency compared to air cooling. Simply put, the air cooling method blows cold air onto the servers to cool them down. However, since air has a lower specific heat (the amount of heat required to raise the temperature of a substance) than water, it has limitations in handling the heat from hot servers. Each server costs about 300 million won based on the NVIDIA H100. If the server temperature is too high, performance may decrease, and hardware could be damaged, making cooling technology essential for AIDC competitiveness.
In response, LG Uplus focused on cooling methods using liquids. There are two approaches to liquid cooling: direct chip cooling and immersion cooling. Direct chip cooling involves sending coolant from a coolant distribution unit (CDU) to cold plates attached to the CPU and GPU to absorb heat. Immersion cooling involves placing servers in an immersion tank filled with specially treated oil that does not conduct electricity to reduce heat. The key component, the CDU, manages the uniform distribution of coolant and insulating oil throughout the server.
While the liquid cooling method has already been commercialized abroad in AIDC, it has not been adopted domestically due to costs and technical issues. When liquid cooling technology was first commercialized, immersion cooling caught attention first; however, it requires the installation of a new tank filled with insulating oil instead of the server racks typically used in AIDC. Since it requires about 700 liters of insulating oil, it is heavy and less efficient in space utilization compared to the direct chip cooling method that uses server racks.
A representative from LG Uplus stated, “We are focusing on demonstrating direct chip cooling technology considering space efficiency and the potential for utilizing server racks.”
◇ “Leading the domestic AICD market with liquid cooling technology”... aiming for commercialization by next year
In the demo room, two test server racks for direct chip cooling each had two servers installed. One side of the rack had pipes slightly thicker than a 500 won coin. The pipes carried green coolant mixed with a chemical called glycol to prevent decay. This coolant flows through the pipes, directly absorbing heat from the metal plate right above the chip. While pipes are usually made from stainless steel, LG Uplus is experimenting with transparent and lightweight plastic.
Baek explained, “When we applied air cooling methods, we could only handle up to 13 kW per rack. However, using direct chip cooling technology, we can test up to 100 kW per rack. The space and power efficiency is about 7 to 8 times better.”
Inside the demo room, there was a 50 kW immersion cooling tank. Within the tank filled with insulating oil, the servers were positioned. While it looked like they could catch fire at any moment, insulating oil does not ignite because it is a highly flammable substance with an ignition point around 200 degrees Celsius.
However, since Korea is a latecomer in global liquid cooling technology, it remains to be seen whether LG Uplus can accelerate commercialization. Currently, LG Electronics has begun producing CDUs within the LG Group. LG Uplus plans to actively apply liquid cooling technology at the Pyeongchon 2 Center, the largest data center in the metropolitan area, and at the upcoming Paju AIDC by next year.
A representative from LG Uplus noted, “We have been receiving continuous inquiries from client companies,” and added, “With construction companies and private equity funds entering the IDC market, we will lead the market by introducing liquid cooling technology.”