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  1. #1

    Exclamation How to achieve 18deg C temperature?

    Hi all,

    I came up with a project in which there are certain areas in which the temperature requirement is 18deg C.
    District cooling system is used for the project. Rest of the areas shall have normal temperature (21deg C).

    How can I achieve 18deg C in such areas?
    Will the selection of different FCUs only in those areas enough for it?
    And what shall be the on coil & off coil temperature for the units so as to achieve 18deg C.

    District cooling system is selected at 42deg / 58deg F, with a delta T of 16.

    Please help ASAP. I am stuck with this for a project.

    Thanks & Regards.

  2. #2
    Join Date
    Jul 2012
    Location
    Western KY
    Posts
    1,221
    A lot more info needed for specifics. Don't what you got or the set up. Not sure what you mean by district. Are you talking zones with one RTU supplying VAVs or fan coils? Help us help you.

  3. #3
    Quote Originally Posted by Tommy knocker View Post
    A lot more info needed for specifics. Don't what you got or the set up. Not sure what you mean by district. Are you talking zones with one RTU supplying VAVs or fan coils? Help us help you.
    Its a district cooling system in which the chilled water is supplied by the authority until the heat exchanger, from where the heat transfer of building water takes place.
    Chilled water entering and leaving temperature i have mentioned above.

    And if information is not meeting still, can you please tell me in general how we achieve 18degC and what shall be off coil temp.? (irrespective of this project)

  4. #4
    Join Date
    Jul 2012
    Location
    Western KY
    Posts
    1,221
    Quote Originally Posted by mohsinrkhan86 View Post
    Its a district cooling system in which the chilled water is supplied by the authority until the heat exchanger, from where the heat transfer of building water takes place.
    Chilled water entering and leaving temperature i have mentioned above.

    And if information is not meeting still, can you please tell me in general how we achieve 18degC and what shall be off coil temp.? (irrespective of this project)
    OK. With what I got I'd say around 10*C water or colder.

  5. #5
    How you got.. Can u plz lemme know the procedure pf considerations?

  6. #6
    *of

  7. #7
    Join Date
    Aug 2009
    Location
    Jurupa Valley, CA
    Posts
    1,654
    To get your supply air colder with the same temp chilled water, all you can do is go with a larger coil (per unit volume of air). You can, with a cross-flow design, get nearly 0 approach, if the coil is large enough. That chilled water is supplied at 5.5C, so you should have no problem getting the supply air cold enough to keep a room at 12C - but it will probably take a large enough coil. If you really need the proper sizing and numbers, you have to know heat load, room size, air change requirements, etc. THEN you just have to to the thermodynamic calculations to figure out how many BTU's you need to remove, and what size fan coil is going to be required to do that.

  8. #8
    Thanx a ton for the useful information and help. That was really informative.
    Can you also lemme know how the coil sizing be done? Is it complicated or any thumb rule for that? To know the no. Of rows of coil?

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