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  1. #1

    chiller unitl cooling load calculation for return sand coooling (foundry )

    hello guys,

    i am a newbie here and i am in nascent stage of HVAC,i am a projects engineer and recently we had project for upgrading the capacity of the sand processing plant.in this process we cool moulding sand(foundry) .

    i need to calculate the new chiller requirement for this process(how much TR chiller unit is to be procured) .
    (the existing 133tr air cooled unit is not working,present output given is 20 deg c)

    requirement :
    sand qty/hr to be cooled : 150ton
    outlet sand required : 120 deg c
    outlet sand required : 45 deg c
    blower capacity : 30000 cum/hr
    inlet air temp : Db 45 deg c @70% rh (rh is so high in rainy season ,so need to be reduced)
    outlet air temp : Db 15 deg c @50% rh
    water used : normal water

    can any body plesae help me out in calculating the new chiller requirement

    thanks in advance

  2. #2
    Join Date
    Aug 2006
    Location
    Mixing oil and fire with a big spoon.
    Posts
    4,357
    Your listed blower capacity is funny to me.

  3. #3
    X2... Haha

  4. #4
    @jayguy

    i am sorry i couldnt get you sir,is it under/over capacity.can you please be specific. we need 30,000 m3/hr air at the sand cooling unit.
    the blower is placed just before the sand cooler and the cooled air is blowed into cooling chamber.

  5. #5
    Join Date
    Aug 2000
    Location
    Austell, Ga.
    Posts
    1,294
    Sorry bharathrxz, but our North American humor is .... a little different side from the rest of the world.
    Looking at the numbers you posted and converting them to our system, I get 1751 CFM with a 86f temperature drop on one helluva' cooling coil. Of course I do not deal that much with the metric system so I could be waaaay' off. Even with the 86f drop and stated airflow it is still a far cry from existing 133 tr that you presently have. The unit that cools my house has an 1800cfm blower in it.
    Repost your numbers using our system and I assure you that you will get some much more knowledgeable answers than I can give you.
    PS Your flow rate post was funny....
    Ain't "None" of us as smart as "All" of us..

  6. #6
    @richardl
    ok sir,yes i ve understood the existing system is very low . as said by you i am changing the units

    requirement :
    sand qty/hr to be cooled : 150 tons / 330693.393 pounds
    outlet sand required : 120 deg c / 248 deg F
    outlet sand required : 45 deg c / 113 deg F
    blower capacity : 30000 cum/hr /17657 cfm
    inlet air temp : Db = 45 deg c/113 deg F @ 70% rh (rh is so high in rainy season ,so need to be reduced)
    outlet air temp : Db = 15 deg c/59 deg F @50% rh
    water used : normal water

    can any body plesae help me out in calculating the new chiller requirement

  7. #7
    Join Date
    Aug 2000
    Location
    Austell, Ga.
    Posts
    1,294
    Oooooops... I slipped a decimal point in my lil' conversion....17,657 is the corrected CFM....
    Also screwed up on the drop across the cooling coil..(Between bottles of Miller draft) 54f is the correct drop desired.
    150 tons of anything is a huge heat load dropping it by 135f.
    I can only assume that you are feeding said sand into the "Cooling Chamber" at a given rate and not trying to cool the 150 tons all at once. If so then the feed rate of the sand should(must) be controlled (metered) to obtain the desired temperature.
    Ain't "None" of us as smart as "All" of us..

  8. #8
    yes sir,the cooling chamber will have blades which mixes the sand.

    say a batch ,100 ton of sand entering the chamber @ 248 deg F and the inlet door closes .the blades arrangement mixes the sand parallely passing the cooled air from the chamber . the mixing of sand is done till 2 to 3 min or can say till the sand temperature comes down to 113 deg F.
    when the sand temperature attains the required value,the outlet gate opens and the cooled sand is sent for further storage.the hot air is sucked out through an other blower.
    and after that a new batch of sand enters the sand cooler for cooling.

  9. #9
    Join Date
    Aug 2000
    Location
    Austell, Ga.
    Posts
    1,294

    Hmm

    I worked years back at the Ford foundry in Cleveland, Ohio (Home of the famous "Cleveland" heads which would fit the 302,351 and the wimpy 400cu-in motors). I do not remember how much of the hot sand was dumped into the cooling chamber at one time but I do remember a 25,000 gallon holding tank of treated water being cooled to 35f by a pair of Tonrac model 602 centrifugal chillers each with a 250tr capacity. While I was really not interested in the actual amount of sand being cooled and how fast it was cooled, I do remember for a fact that until the large holding tank was installed that many.....many little Tonrac compressors were lost due to the severe shock loading using .just a closed chill water loop. No sand was ever cooled after the holding tank was installed until tank temperature had reached at least 40f . Either of the 250tr Tonracs would do the job. I also remember that the units were installed way up on a mezzanine where the heat from the castings always gathered around my sweating lil' body...
    Last edited by RichardL; 12-14-2013 at 09:36 AM. Reason: mispelled but
    Ain't "None" of us as smart as "All" of us..

  10. #10
    Join Date
    Jun 2009
    Location
    Ontario, Canada
    Posts
    1,029
    Isn't engineer supposed to be smarter than us and able to do all this calculation?? btu content of sand is needed to do calc
    Parts Changer Extraordinaire
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