1 Reply Latest reply on Oct 6, 2009 8:43 AM by Dan_O

    big delta-t OR it-equipment mystery


      A few days ago, I read a Nov 2006 White Paper (Doug Garday / Daniel

      Costello) on air-cooled high performance data centers. Especially case

      study 4 shows some numbers that seem to be unbelievable to me. As our

      company is planning data centers in germany since many years and we are

      always in search of contemporary knowledge, I would be glad if could

      give some comments to your floowing statement:


      "We plan to use passive chimney cabinets, which work well with warmer

      supply air temperatures. Warming the 65º F supply air by 50º F as it

      passes through the cabinets will result in return air at 115º F. We may

      decide to mix this with an additional 19 percent bypass air (66,065

      SCFM), tempering the return air to 108º F to match the capabilities of

      the RAH coils. "


      WOW! This tells me you are operating with a delta-t of 27C (50F) at the

      IT devices! Relatively warm supply air (18,3C) will be heated to 46C in

      the cabinets. What kind of IT-equipment do you use? If I look at data

      sheets most servers have an operating temp range between 5C and 35/40C.

      So we try to operate with a 16C supply air and 26/28C return air.


      So - wheres the trick that we don't know of?



      Best regards - Werner