Results 1 to 5 of 5
  1. #1
    Join Date
    Apr 2005
    Post Likes

    derating chillers

    Does anyone have any really good information on "engineering" heat transfer with glycol and derating the tonnage and/or btu's. Just looking for facts that could help every day kind of stuff. I am also looking for information that supports the percentage loss between propylene and ethylene glycols.

    Also looking for engineering studies about derating tonnage of chillers when leaving water temps setpoints drop from standard 40 F and below. I was just told by an engineer that with every degree setpoint drop in lvn water setpoint below 40 F equals around a 3% derate in tonage.

  2. #2
    Join Date
    Aug 2006
    Mixing oil and fire with a big spoon.
    Post Likes
    from a trane catalog that i occasionally use.

    i also have a great article on the whole idea but it is from ASHRAE and it states right at the top to not distribute...sorry.

    good luck.
    Don't step on my favorite part of the Constitution just to point out your favorite part.

    Political Correctness is forced on you because you have forgotten decency.

  3. #3
    Join Date
    May 2008
    Jax Fl.
    Post Likes
    Just as a reminder, Glycol of either type impacts the specific heat [capacity] and the viscosity [pump sizing].
    Make sure it is bio and corrosion inhibited or it can cause big problems.

  4. #4
    Join Date
    Jul 2008
    Washington, DC
    Post Likes
    One thing that can go overlooked if you are retrofitting a system from water to glycol is the interaction between water treatment and glycol. It can be especially nasty on condenser water systems, open loop tower converted to closed loop drycooler. I'm not sure if your doing a retrofit or not, just throwing this out there.

    Derating will depend on the percentage of glycol in the mixture, so there is no single number. On a drycooler when you need to keep freeze protection down to say 0 there is a much bigger derating factor than if you are trying to run a chiller with 28 degree chilled fluid.

  5. #5
    Join Date
    Feb 2004
    New Mexico
    Post Likes
    Looks like you got what you need.
    I can tell you that the losses can be huge. One example was a injecting moulding machine that needed 22 deg coolant. By the time the glycol mix was considered and the low temp the 17 ton chiller dropped to 5.5 tons.
    I should have played the g'tar on the MTV. MK

    You can be anything you want......As long as you don't suck at it.

    USAF 98 Bomb Wing 1960-66 SMW Lu49

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts

Related Forums

Plumbing Talks | Contractor MagazineThe place where Electrical professionals meet.