Retrofit of Air-Conditioning System in Data Center Using Separate Heat Pipe System

Data center is developing quickly in China, which consumes much operating energy due to the 24 h operating annually. The energy consumption of air-conditioning (AC) system accounts for 40-50 % of the entire energy consumption in data center. There is large energy saving potential since the AC system operate annually even the outdoor environment is cold enough. The indoor thermal environment and energy utilization of a data center in Shanxi Province before and after retrofitting are tested during the July of 2012. The area of data center is 550 m(2) and there are 145 cabinets. In the original design, eight typical air-cooled CRACs (computer room air conditioner) with total cooling capacity of 600 kW provide the required indoor climate. The original AC systems cannot meet the heat dissipation demand of all the cabinets, due to the reason that 14 cabinets with rather higher heat production of 3-8 kW. The total heat production of the 14 cabinets were accounting for 1/5 total heat production of the data center. The measured outlet temperatures of the 14 cabinets were over 30 degrees C. The retrofitting is focus on the aforementioned 14 cabinets, using separate heat pipe systems in the back-plane of cabinets which are accompanied by water chiller outdoor as cold source. The on-site measurements show that the retrofit separate heat pipe air-conditioning systems can meet the temperature requirement of safety operation of the high-density cabinet. The COP of AC system can reach 2.7. The entire energy consumption of AC systems after the retrofitting can reduce 18 % energy consumption in summer.