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Effective cooling

  1. Jul 23, 2015 #1
    I am wondering if someone can please advice on how to improve the effectiveness of a cooling system I am using.

    I am trying to cool a substance using an 8m long conveyor belt with 3 air conditioning units with two outlets on each unit blowing down on the material. The current set up I have tried has had the a/c units equally spaced out along the belt. I am now considering either grouping all the units together at either the start or end of the belt and I am not sure what will be more effective.

    Delta T will be greatest at the beginning but the ambient air temperature may do a lot of the work for me and I should then possibly concentrate the a/c units at the end of the belt or blast it at the start?

    Material temperature = 45 degree
    Ambient temperature inside room = 20 degree
    a/c set to lowest setting = 1 degree
    material spread to a thickness around 10mm
    conveyor speed - 0.072 m/s


    Any thoughts?
     
  2. jcsd
  3. Jul 23, 2015 #2
    More detail would be helpful. What is the substance, and what do you think the dominant mechanism of heat transfer is?
     
  4. Jul 23, 2015 #3

    Nidum

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    Borrow a thermal imaging camera .
     
  5. Jul 23, 2015 #4

    The substance is meat which has been diced into small pieces. It is heated up and passed through a Tricanter to separate solids, water and oil and the substance I am left with is similar to mince meat. If left warm in a skip it turns gloopy from (I believe) the moisture content condensing and remaining in the substance. If I remove enough heat from the substance prior to the skip it will remain relatively solid. I am agitating the substance by turning it as it moves along the belt using chains to stop surface cooling only occurring. This is the experiment I am trying to prove the idea and make this crude method as effective as I can and if successful a more robust permanent system would be installed.


    Thanks

    Craig
     
  6. Jul 23, 2015 #5
    The food processing industries are usually subject to all kinds of food safety and workplace type of regulations.

    I am hesitant to give physics/engineering advice that may neglect or run afoul of those considerations, which may also depend on location.
     
  7. Jul 23, 2015 #6

    I should have been clearer this is a by-product of Leather making and going to landfill. Not actually meat but the off cuts from hides.
     
  8. Jul 23, 2015 #7
    Assuming you're talking about degrees Celsius instead of Fahrenheit, try spraying water on the meat, the evaporation should cool it down quickly, especially if you have a good blower going.
     
  9. Jul 23, 2015 #8
    A few questions.
    Have you ever checked the moisture content in the stuff?
    ie when it is hot? when it has cooled down? when it is ready for the dumpster?
    From what experience or data are you so sure that just the cooling down renders it unable to turn into gloop?
    After how much time in the dumpster has passed before it becomes gloop. Immediately, hours, days?

    Reason I ask is that if you were ambient air cooling before, it could be that it was also air drying at the same time. At a particular moisture percentage above which it will turn into gloop, and below which it will not. Bacterial action on the biological material becomes more difficult below a certain level.

    In which case, you would need to flow heated air over the "meat" to withdraw moisture to dry it out.
     
  10. Jul 24, 2015 #9
    Yes it is Celsius. Water would cool it down for sure but would be counterproductive as the outcome I am looking to achieve cooler and dry so transportation in large 20 ton skips is easier.
     
  11. Jul 24, 2015 #10

    Nidum

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    Could you contrive some rollers on your conveyor so as to mangle some of the liquid out ?
     
  12. Jul 24, 2015 #11

    No, this seems like a good idea. Information I have been provided, but never gathered myself was that below 30 degree it remains solid. Current process has been to fill up the skip half with saw dust half with waste. I am an engineering student working over the summer and thought it would be interesting to try and improve the process. My experience is limited, so bear this in mind if I have overlooked an obvious idea.


    Using no cooling and depositing straight into the skip the "meat" turns to gloop within an hour. When I ran my set up with the a/c units spaced out the "meat" stayed solid for at least 8 hours but by the time the skip was lifted, 24 hours from the filling start time, it was gloopy. It was not as bad as normal but still not great. The temperature was around 35 Degrees when it was skipped and this is why I am looking to improve cooling set up to get it nearer the 30 Degrees.
     
    Last edited: Jul 24, 2015
  13. Jul 24, 2015 #12
    It has been spun in a tricanter before the conveyor so to separate as much water and oil. Although it does have moisture content but like mince if you squeeze it very little comes out. No doubt if an industrial vacuum press or something was used it would further remove water but I don't see this as the best solution.
     
  14. Jul 24, 2015 #13

    It should also be noted that an attempt has been made previously to pass it through a steam heated dryer with a couple of intermeshed auger's pushing it through the dryer. During this process the substance again turns gloopy and as such the augers were unable to push it along. This was in the hope again to dry it out and use as Thermal plant fuel.
     
  15. Jul 25, 2015 #14
    Was worth a shot to see if you had covered all bases, hich seems to have been done.

    By gloop,
    Do you mean liquifiying?
    Or turning into a jelly ( or sticky like )?

    Just to throw another idea out there, since I wonder what the stuff make up is, if it has proteins, such as gelatin and/or collagen, those are temperature sensitive.
    You could be making Jello, or glue.
     
  16. Jul 27, 2015 #15

    By gloop I mean a watery mixture similar in appearance to vomit (sorry, just the best visual I can provide.) The substance does not feel sticky before and I have yet to stick my hand in it after but looks more soggy.
     
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