The authors have been working on the development of constituent technologies that will contribute to saving energy in air cooled packaged air-conditioners, in order to reduce energy consumption in A/C facilities used in data centers, and have developed an A/C for data centers that incorporates these technologies. In the development of constituent technologies, based on the unique characteristics of year-round cooling operations in data centers, the authors endeavored to increase the efficiency of compressors in outdoor conditions at medium and low temperatures, and to expand the scope of low pressure ratio operations. The authors have also developed saving energy technologies that take into account A/C operating conditions and installation conditions; for example, preventing reduced operating efficiency resulting from long refrigerant pipes by installing the compressor in indoor units; preventing excessive cooling with A/C control using multiple temperature sensors placed in the vicinity of IT equipment; and avoiding unnecessary humidification through high sensible heat design that takes into account the heat load characteristics of data centers. Air conditioners that incorporate these saving energy technologies reduce annual power consumption by about 40% under Tokyo meteorological conditions compared to conventional computer room A/Cs.

Units: Dual