NTU innovators invent spray cooling for data centres

By Charles Carter, 15/06/23

Protoype spray cooling on computer components. CREDIT: NTU

Innovators at Nanyang Technological University in Singapore have developed a sustainable, spray cooling technology to cool down servers in data centres, which could reduce energy costs and carbon footprint.

Currently, Singapore’s data centres account for 7% of the country’s total electricity consumption, and as the demand for cloud computing increases, there is a growing need for a sustainable solution that reduces energy consumption and carbon footprint.

Data centres have to run energy-intensive air-conditioning systems to lower air temperatures, whereas this spray cooling method uses a special spray of non-conductive fluids to cool the CPU directly without a heatsink.

(left) NTU Singapore’s new liquid spray-cooling system replaces the heatsinks and fans in a conventional server (right). CREDIT NTU Singapore

The fluids and gases are collected in an enclosed system, condensed into liquid at tropical ambient temperatures and recirculated back into the system for reuse.

The spray-cooling prototype is capable of dissipating significantly more heat than air-cooling and handling rack densities as high as 23 kW per cubic metre.

If spray cooling is industrially adopted, it could allow for higher computing power servers to be packed into a smaller space than current data centres, which could translate into a 30% space saving.

Power usage effectiveness (PUE) of the prototype can go as low as 1.08, resulting in significant savings in cooling energy.

Based on a data centre IT load of 1 MW, the spray-cooled system could save up to 1550 tons of CO2 emission annually compared to traditional air-cooling systems.

According to Assoc Prof Wong Teck Neng, the leader of the project, the targeted approach of spray cooling is a smarter approach, especially in tropical environments, where traditional air-cooling systems are less effective. He said, “why are we spending an immense amount of energy cooling down the air around the heat source when we should be cooling it directly?”

(anti-clockwise from bottom left) Leader of the project NTU Associate Professor Wong Teck Neng, former Associate Professor Toh Kok Chuan, research fellow Ranjith Kandasamy, Asst Prof Ho Jin Yao, and research fellow Liu Pengfei, who developed the spray cooling system prototype for data centres (seen on the right). CREDIT NTTU Singapore

Spray cooling technology offers superior cooling capability, and this certainly helps to unlock the full potential of computing chips and graphics card currently in the market by overclocking beyond its normal operating range, says a spokesperson from AFTERSHOCK PC, which is Singapore’s largest high-performance custom personal computer builder, and is collaborating with Assoc Prof Wong on another sustainability project.

Close-up of the spray nozzles that are used to cool down the CPUs of a server efficiently, instead of the usual heatsink and fan combination. CREDIT NTU Singapore

The prototype system consists of an enclosed spray-cooled server rack capable of operating near atmospheric pressure, a water pump, sprays with multiple nozzles over each CPU, a collection system to collect the vapourised liquid, and an energy-efficient room-temperature condenser to convert the gases back into liquid again.

Unlike conventional air-conditioning systems, no chiller system is required.