Heat transfer
Heat transfer
(OP)
Looking for a formula to calculate heat transfer to water.
Specifically: water temperature 45 degrees F, plastic tank with 600 gallons of water, constant room temperature.
Would like to adjust the variables to determine time and temperature of the water.
Considering pretreating the water prior to heating; temperature change a factor.
Thanks in advance,
Specifically: water temperature 45 degrees F, plastic tank with 600 gallons of water, constant room temperature.
Would like to adjust the variables to determine time and temperature of the water.
Considering pretreating the water prior to heating; temperature change a factor.
Thanks in advance,





RE: Heat transfer
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RE: Heat transfer
I would assume a constant room temperature and would want to determine how long it would take the water to increase x degrees.
The tank would be an 850 gallon plastic (polyethylene resin, 48" diameter); the surface area could also be a variable, as this specific tank would not be filled all the way.
RE: Heat transfer
RE: Heat transfer
RE: Heat transfer
Q = htc * area * delta_temperature as a starting point.
However, transient analysis is substantially more complicated. Nevertheless, the problem as described yields a lower bound of 76 hrs to reach 65F in 70F ambient, but this is the ABSOLUTE best case, which is impossible to achieve, and assumes infinite thermal conductivity, fixed deltaT, and infinite mixing in the water, etc.
Suggest you start with:
https://en.wikipedia.org/wiki/Convective_heat_tran...
https://en.wikipedia.org/wiki/Biot_number
https://en.wikipedia.org/wiki/Fourier_number
https://en.wikipedia.org/wiki/Thermal_diffusivity
https://www.google.com/url?sa=t&rct=j&q=&a...
https://hal.archives-ouvertes.fr/hal-00743917/docu...
http://s3.amazonaws.com/academia.edu.documents/391...
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RE: Heat transfer
Thank you for the help.
RE: Heat transfer
Initial temperature is 45 deg F. What is your critical final water temperature - sounds like you are worried about the room heating up 600 gallons of chilled water, assuming the room is hotter than 45 degrees on most days In which case condensation of the room humidity will be a problem too - for draining off that condensed water on the plastic.
What is your proposed insulation thickness and plastic wall thickness of the 600 gallon container?
Is the water stagnant or moving? (Probably stagnant.)
Is the room air stagnant or fan-driven?
RE: Heat transfer
Initial temperature may vary 40-50 F
Tank is uninsulated
We anticipate that the water temperature will increase.
The question is how long would it take.
Eventually the water will be heated to 180 degrees for brewing beer.
The change in temperature would reduce the required BTUs.
RE: Heat transfer
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RE: Heat transfer
RE: Heat transfer
That is true (BTU consumption); this will happen anyway when the water is processed/stored. It would reduce the number of tankless water heaters required.
racookpe1978,
The temperature of the slab would also be a factor; slab on grade, uninsulated.
Thank you both for the feedback.
RE: Heat transfer
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