Scientists at Singapore’s Nanyang Technological University (NTU) have made a groundbreaking discovery that could revolutionize data center cooling. By spraying CPUs with a non-conductive liquid, NTU researchers have found a more sustainable and cost-effective way to cool data center servers.
Data centers in Singapore account for 7% of the country’s total electricity consumption, driven by the demand for cloud computing. The highest-temperature component in data center servers, the central processing unit (CPU), typically requires air-cooled heatsinks for cooling.
However, NTU scientists have developed a new method that uses a spray of non-conductive liquids directly on the CPU, eliminating the need for heatsinks and utilizing highly efficient heat removals mechanisms like evaporation and boiling.
The gas and excess liquid from the spray are collected in a closed system and condensed back into liquid at tropical ambient temperatures, around 30°C, for recycling back into the system. This innovative approach allows the spray-cooling system to handle much higher rack densities, up to 23kW/m3, compared to conventional air-cooled systems, estimated to handle only 7kW/m3.
Associate Professor Wong, the project leader in NTU’s School of Mechanical and Aerospace Engineering, stated that this targeted approach is particularly effective in tropical environments where high humidity and heat can overwhelm traditional air cooling systems.
Furthermore, the spray-cooled system can maintain optimal temperatures around 55°C without energy-intensive air conditioning, significantly reducing energy consumption.
The ratio of total energy consumed in the data center to the energy delivered to servers, known as Power Usage Effectiveness (PUE), can be as low as 1.08 for the new prototypes compared to the typical 1.8 PUE of traditional air-cooled data centers.
The NTU research team also found that their spray-cooled system can reduce CO2 emissions by up to 1550 tons per year at 1MW of data center IT load, compared to traditional air-cooling methods. This translates to a 26% reduction in yearly energy costs for an energy-efficient spray-cooled data center.
The prototype system consists of an enclosed spray-cooled server rack operating near atmospheric pressure, a water pump, multi-nozzle spray nozzles on each CPU, a collection system for vaporized liquid, and an air conditioning condenser for converting gas back into liquid. Unlike traditional air conditioning systems, no separate cooling system is required.
The system was designed, built, tested, and commissioned for 3 years by an interdisciplinary team including former Associate Professor Toh Kok Chuan, Associate Professor Ho Jin Yao of NTU’s Department of Mechanical and Aerospace Engineering, and research partners who are Ranjith Kandasamy and Liu Pengfei.
So far, the team of professor Wong are working with industrial partners to develop a larger pilot plant.