Totally Submerging a Server in Liquid Reduces Power Consumption up to 30%―Data Center Innovation by a Novel Cooling Technology

Data Centers Tackling the Heat Problem

It is said that there will be more than 50 billion devices connected to the Internet by 2020 and more than 100 trillion sensors by 2030, which will make a huge amount of data available. In such an era, the roles data centers play in collecting, managing, and analyzing data will become increasingly important.

Data centers where servers, storage, and other IT devices are operated 24/7/365 employ various technologies. In particular, technologies for cooling down the heat generated from IT devices are important to ensure data centers' stable operation.

Conventional cooling technologies require a large-scale air conditioning system, have huge power consumption, and occupy a large space. In addition, the cooling fans that generate airflow cause noise. Thus, to evolve the data center, it was necessary to resolve various issues, including those related to energy efficiency, space, and noise.

Heat Transfer Efficiency 1000x Better Than Air Cooling

Fujitsu is proposing a new form of data center, which will include cloud-based servers and center facilities, by combining the liquid immersion cooling technology for supercomputers developed by ExaScaler Inc. with Fujitsu's know-how on general-purpose computers. This new style of data center uses liquid immersion cooling technology that completely immerses IT devices such as servers, storage, and networking equipment in liquid coolant in order to cool the devices.

The liquid immersion cooling technology employs a fluorochemical inert fluid (Fluorinert) that provides high heat-transfer efficiency and insulation as a coolant. IT devices, including servers and storage, are totally submerged in a dedicated reservoir tank filled with liquid Fluorinert, and the heat generated from the devices is processed by circulating the cooled liquid through the devices. This improves the efficiency of the entire cooling system, thereby significantly reducing power consumption.

This system's primary feature is its high cooling capacity, which has a heat transfer efficiency of about 1000 times more than an air cooling system. The technology facilitates efficient cooling while conserving energy and space.

Fluorinert, which is used as the coolant, is an inert liquid that is harmless to the human body and the environment. All IT devices, including power supplies, can operate while submerged in liquid Fluorinert.

Fluorinert has high operability. It has a low viscosity, excellent draining property, and low evaporation rate. Device connectors can be inserted and extracted while submerged in liquid Fluorinert. In addition, Fluorinert does not need to be replaced as it does not deteriorate (however, it needs to be replenished as it evaporates at a rate of several percentage points per year).

Servers being exhibited (Fujitsu Forum 2016)

Resolving Energy Consumption, Space Consumption, and Noise Issues

With this excellent new immersion cooling technology that offers high cooling efficiency, servers and storage can be placed in a reservoir tank at high density. For example, 128 servers (approximately three racks of 1U, 2-CPU servers) or 32 storage units (approximately three racks of 4U storage units) can be placed in a tank. There is no need to install a large air conditioning system. As a result, the installation space needed for IT equipment can be reduced by about 70%.

This system also significantly reduces power consumption. While air cooling requires a large air conditioning system to cool the data center space and fans to locally cool parts, a liquid immersion cooling system does not need such facilities, which reduces the power consumption of the entire data center by more than 30%.

Moreover, operating devices at low temperatures reduces the failure rate. According to the Arrhenius equation, every 10-degree reduction in temperature halves the failure rate.

Although conventional cooling fans make noise, liquid immersion cooling systems make virtually no noise, which means that liquid immersion cooling systems may greatly change the installation environments in data centers.

Data Center Facilities Using Liquid Immersion Cooling Technology

Realizing a New Form of Data Centers

This liquid immersion cooling technology can contribute to cost reductions by bringing about a new form of data center, which will include cloud-based servers and center facilities.

At present, Fujitsu is evaluating this technology to apply it to data centers for the company's internal systems. In the future, Fujitsu will further advance the development of this liquid immersion cooling technology in order to innovate in data centers by making the most of the technology's excellent space-saving, energy-saving performance.