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  1. #1
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    Cooling water in a tank....



    OK sorry for the very newbie and perhaps rediculous suggestion of wanting to use a regeration system to cool water in a tank.

    The tank holds approx 20 litres of water ...

    The problem comes from the fact that the water can reach tempratures of I would guess 40-50deg C.... from time to time.

    The idea I had is getting a Danfoss DB35 compressor unit and fit a fin evaporator submerged in the fluid (the tank will have a internal pump to stir the fluid)....

    The system has the following spec

    Cooling capacity (max w/ normal refrig. w/ direct evaporator) (l) 250
    Cooling capacity (max. deep-freezing) (l) 70

    Question is will this work given the potentially high temp the fluid can reach?

    Can I imerse the evaporator?

    Does this compromise the efficiency?

    How long would the system take to get the fluid to sat 10degc from 50degc?

    Any other suggestions?

    Thanks in advance and please indulge my ignorance here!



  2. #2
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    Re: Cooling water in a tank....

    a fridge compressor working at 50+ C is going to struggle somewhat

    . You need a high back pressure unit and keep the water below 30 at all times.

  3. #3
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    Re: Cooling water in a tank....

    Quote Originally Posted by stevebez View Post
    Question is will this work given the potentially high temp the fluid can reach?
    Yes if it is designed correctly.

    You either need low heat transfer surface in the evaporator to work with a high differential or much better use a KVL crankcase pressure regulator.

    Can I imerse the evaporator?
    If it is made of the correct materials, and it won’t freeze in any condition, then yes.

    Does this compromise the efficiency?
    Depends on how you define efficiency. Example using a pump to stir is not very efficient, the heat exchange will depend on the water velocity you get in the evaporator. Moreover the differentials will be with average water temperatures instead of using the maximum differential you get from splitting your tank into hot and cold areas and using a pump and a heat exchanger.

    How long would the system take to get the fluid to sat 10degc from 50degc?
    You must estimate your losses, subtract them from the performance of the compressor at desired conditions and you have the energy you can remove from the water per unit time. Then calculate the same on the water side adding the heat and shaft work the pump adds in your system and you can estimate the time.

    Any other suggestions?
    Have fun!
    Last edited by aramis; 03-04-2012 at 10:28 PM.

  4. #4
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    Re: Cooling water in a tank....

    Any reason why you are thinking of using a 12/24v compressor?
    Mostly found in Oxfordshire, UK :)

  5. #5
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    Re: Cooling water in a tank....

    What is the water used for?
    What is heating it up?


    .

  6. #6
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    Re: Cooling water in a tank....

    it's a trunk mounted intercooler tank reservoir... In between high speed runs I want a system to cool down the fluid reasonably quickly but , 20 mins or so is acceptable .... But not too much more... It's quite an expense to build the system but just not sure if purging the hot water and putting in ice would not be better ? But the thought of actively cooling the fluid is appealing...

    Thanks for the advice!

  7. #7
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    Re: Cooling water in a tank....

    Quote Originally Posted by stevebez View Post
    it's a trunk mounted intercooler tank reservoir... In between high speed runs I want a system to cool down the fluid reasonably quickly but , 20 mins or so is acceptable .... But not too much more... It's quite an expense to build the system but just not sure if purging the hot water and putting in ice would not be better ? But the thought of actively cooling the fluid is appealing...

    Thanks for the advice!
    I don't think you can use this compressor while moving, it is a household compressor. It should be stationary while cooling.

    It would be better to attach a heat exchanger to the air conditioning. If not possible then use an air-water heat exchanger.

    Otherwise look for a solution in ThermoKing´s scrap yard.

  8. #8
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    Re: Cooling water in a tank....

    dry ice....

  9. #9
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    Re: Cooling water in a tank....

    Quote Originally Posted by r.bartlett View Post
    dry ice....
    No, it would boil when you add it into water and you would need ventilation. Read on the security issues involved.

    I’d use common ice or brine, if you were going to use a household compressor then the energy involved must not be too high.

  10. #10
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    Re: Cooling water in a tank....

    Quote Originally Posted by r.bartlett View Post
    dry ice....
    ... ok, sorry! But you should have posted a sarcastic emoticon!

  11. #11
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    Re: Cooling water in a tank....

    Quote Originally Posted by stevebez View Post
    it's a trunk mounted intercooler tank reservoir... In between high speed runs I want a system to cool down the fluid reasonably quickly but , 20 mins or so is acceptable .... But not too much more... It's quite an expense to build the system but just not sure if purging the hot water and putting in ice would not be better ? But the thought of actively cooling the fluid is appealing.
    Thanks for the advice!
    Unfortunately a Danfoss BD35F compressor would take all night to cool the water. Even then, i doubt it would be able to handle the high water temperature for any length of time before cutting out on overload.
    The 35, 50 and 80 series compressors are variable speed, but are not designed for "quick pull-down" of the specifications you require..20 minutes.
    To the optimist, the glass is half full. To the pessimist, the glass is half empty.

  12. #12
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    Re: Cooling water in a tank....

    Does your truck have AC, if so just tie into this cooling circuit. Simple, lots of capacity, temps are not problem.

  13. #13
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    Re: Cooling water in a tank....

    A 20 litre container of water, tap water flushing and add ice will do the trick, to keep things simple.

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