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  1. #1
    Join Date
    Dec 2007
    Location
    Hong Kong
    Posts
    2

    Confused Predictive Cooling Plant Control

    Hi, I am a new comer. Thanks for your attention to my question.

    Does anyone have an idea how the predictive cooling plant control work? What are the mathematical models to predict the cooling load of a building?
    Last edited by fatdrew14; 12-18-2007 at 04:10 AM.

  2. #2
    Join Date
    Apr 2006
    Location
    New England
    Posts
    189
    I do not have any mathematical models, but two things come to mind:

    1) Lots of variables there... fixed cooling setpoints would help. KWH - historically trended & accumulated would be necessary, and you have to factor in solar gain, oa temp, wind velocity. I imagine your best bet to predict cooling usage would be based on some non-linear graph of historical data based comprised of the aforementioned data points...

    2) Demand shaving will allow you to predict your energy usage. You can monitor your BTU usage, KWH usage, etc and plug in an electrical/energy usage setpoint. As you approach your setpoint, relax your setpoints incrementally. This is the tail wagging the dog in some sense, but will allow you to "predict" your cooling load.

  3. #3
    Join Date
    Feb 2004
    Location
    Georgia
    Posts
    354
    I don't have a mathematical explanation either, though this is exactly what a group of us do on a 24 hour basis. We take into consideration the weather, indoor and outdoor temperatures and humidities, watching peak loads, starting and stopping various equipment, adjusting setpoints, etc. Depending
    on the particular design of the system you have to manage and the potential feedback of the end result there are many factors that could influence how you manage said system and what you ultimately use to manage it.
    One major factor is what you are cooling/heating... people or machine. We have to do both, although one does ultimately take priority. Machines tend to require a fixed set of conditions and are somewhat more tolerant of variations. People require much the same but are quite less tolerant of variation. People are influenced by things like how cold or warm it is outside when they come in to a building. Just that single first impression can influence their entire day. Machines don't care whats going on outside. Get the picture here. People also tend to give more feedback... if they are hot or cold they call. Machines do the same but generally in the form of an alarm which usually means a fixed limit has been reached. A machine can tolerate a 70* temp/ 35% humidity but that might be too cool for a person or too hot for another.
    Hope thats a little help for you.
    Mike

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