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[Image] By cooling air efficiently and reducing the power consumption of air conditioners greatly, the system helps address the increasingly demanding issues of datacenters.

Along with the advances made in telecommunications society, IT equipment and systems are offering increasingly higher performance. At datacenters — the key to a telecommunications system, the major issue is to find an effective way to reduce ever-growing power consumption. The "Ref Assist" energy-saving spot cooling system not only greatly reduces the power consumption of air conditioners (occupying a high percentage in the operation of datacenters) but also works to increase space efficiency and otherwise helps address the issues of datacenters, including even larger capacities as demanded by the public.

Major issue of datacenters

At datacenters, the IT equipment and other devices must be cooled by air conditioners at all times, in order to avoid possible breakdown caused by the high-temperature heat generated from servers and other IT equipment.
With the spread of cloud computing and the use of large quantities of data in recent years, datacenters are handling increasingly larger amounts of information. And adding more servers to cope with such a situation will generate even more quantities of heat. Consequently, the power consumed by air conditioners would proportionally rise as well.

[Image] Air conditioners accounting for a large percentage of power consumed at datacenters

[Image] Breakdown of power consumption at datacenters

  • * Source: Japan Electronics and Information Technology Industries Association (JEITA), "A Survey Report on IT Trends" (June 2010)

Problems with General Air-Conditioning Systems Used at Datacenters

Commonly used floor-type air conditioners transport cooled air through underfloor space and blow it out onto the front of the server. This system cools the server efficiently, but requires high electric power for air circulation. And given the long passage for exhaust heat from the server to reach the air conditioner and the possible generation of a "mass of heat," the system tends to overcool the indoor space and consume too much power, and energy-saving measures are, therefore, urgently necessary.

[Image] A common floor-type air conditioner requires high motive power to cool the entire indoor space.

"Ref Assist" saves energy efficiently by spot cooling

Ref Assist adopts a "natural refrigerant circulation system" and "spot cooling units" to cool datacenters efficiently.
Compared to a floor-type air conditioner that circulates air through the entire indoor space, Ref Assist employs spot cooling units surrounding a server and greatly reduces the electric power needed to transport air. When Ref Assist is used together with an optional high-efficiency heat source and a free cooling system(*1), the power consumption of air conditioning can be reduced by up to 60% from that of conventional floor-type air conditioners.(*2)

[Image] Ref Assist cools datacenters efficiently, thereby cutting power consumption by up to 60%.

[Image] Energy-saving effects of Ref Assist

Heat source equipment (such as a chiller) and a free cooling system produce chilled water to cool coolant. Using either a high-efficiency heat source or a free cooling system which utilizes external air in winter or cold weather reduces power consumption more efficiently.
A value based on trial calculations performed by Hitachi, Ltd. This compares the combination of a basic system [i.e., cold water-refrigerant heat exchanger (with maximum cooling capacity of 60 kW x 1 unit), ceiling suspension-type spot cooling units (with maximum cooling capacity of 15 kW x 4 units), optional equipment (high-efficiency heat source + free cooling system)] on the one hand, with a conventional model (i.e., air conditioner for computers) on the other.

[Image] Features of the Ref Assist system

The system has been proven internationally as being optimal for enhancing energy efficiency.

[Image] The spot cooling system has been adopted as an international standard.

Growing power consumption due to the use of IT equipment is an issue not only in Japan but also in the rest of the world. Therefore, enhancing energy efficiency at datacenters is an important issue to be cooperatively addressed by all nations concerned.
Hitachi, Ltd. and formerly Hitachi Plant Technologies, Ltd. conducted demonstrative experiments for optimizing the cooling efficiency in the server rooms of datacenters, upon being commissioned by the Japanese Ministry of Internal Affairs and Communications.
These experiments clarified that the spot cooling system is suited for datacenters with high integration, and this system was approved as an international standard of the International Telecommunication Union (ITU)(*3) in November 2011. Ref Assist is expected to contribute globally as an excellent technology that helps reduce power consumption.

The International Telecommunication Union (ITU) is an ad-hoc organization of the United Nations that promotes standardization in the electrical and radio communication fields, develops telecommunication technologies, and controls communication frequencies.
  • * Hitachi Plant Technologies, Ltd. merged with Hitachi, Ltd. on April 1, 2013.

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