Minimum design temperature of loop fluid

Discussion in 'Vertical and Horizontal Loops' started by Davidren, Jun 10, 2011.

  1. Davidren

    Davidren New Member


    In closed vertical loop, how to decide the minimum design temperature of loop fluid, by coldest temperature ?

    HP only has a minimum EWT.

  2. GCI

    GCI Member

    Min EWT is a parameter which the system designer will specify after weighing costs/benefits of first cost vs. system efficiency/operating cost.

    A good starting point for minimum EWT in design is about 20-25F below the deep earth temp in your project location.

    E.G. - If the deep earth temp in your area is 50F, a good starting point for minimum EWT would be around 30F.
  3. Davidren

    Davidren New Member


    How about the minimum loop fluid temp ?
  4. GCI

    GCI Member

    If you push 3 gpm/ton through the loopfield, which is the nominal flow rate you want to shoot for in a closed-loop GHEX, the fluid will return back to the field 4-6F colder.

    If the minimum EWT coming into the unit reaches 30F, it will return to the field at 24-26F. That will be the coldest fluid temp you should see throughout the year.

Share This Page