Estimating tank's internal surface temperature based on external surface temperature
Estimating tank's internal surface temperature based on external surface temperature
(OP)
Hello,
I need help to estimate tank's internal surface temperature based on the measurements on the outside surface. The tank made of carbon steel, 1/2" thick.
What would be the algorithm for determining the temperature differential on the tank's shell? The tank is being heated internally to about 100F-200F for couple of days. Outside temperature is 70F-80F.
Thanks in advance
I need help to estimate tank's internal surface temperature based on the measurements on the outside surface. The tank made of carbon steel, 1/2" thick.
What would be the algorithm for determining the temperature differential on the tank's shell? The tank is being heated internally to about 100F-200F for couple of days. Outside temperature is 70F-80F.
Thanks in advance





RE: Estimating tank's internal surface temperature based on external surface temperature
The heat transfer will be from the fluid (at the starting time), across the fluid-to-tank-wall boundary, across the 1/2" steel wall (essentially zero! under these conditions), and then across the outside wall-to-atmosphere boundary. Since the fluid will be constantly losing heat energy to the outside, but the loss will be at a slowing decreasing rate as the tank cools down, your greatest heat loss will be at the beginning of the process. Are you worried about heat transfer rate at the start, or the end, of your "couple of days" period?
Compared to the tank-to-outside-atmosphere boundary losses, the tank wall temperature difference will be vary, very small.
(wind will affect your outside boundary heat rate significantly)
(Real world outside temperature (at night) will NOT be the 70 - 80 degrees you seem to be assuming for the daytime temperature!)
(Sun's energy could be significant as it tries to heat the south wall of the tank every day - if you are actually trying to calculate 1/2 degree increments.)
RE: Estimating tank's internal surface temperature based on external surface temperature
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RE: Estimating tank's internal surface temperature based on external surface temperature
Steel has a fairly high Thermal Conductivity(k), and thus the heat has little trouble making it through the wall of the tank.
RE: Estimating tank's internal surface temperature based on external surface temperature
RE: Estimating tank's internal surface temperature based on external surface temperature
RE: Estimating tank's internal surface temperature based on external surface temperature
RE: Estimating tank's internal surface temperature based on external surface temperature
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
RE: Estimating tank's internal surface temperature based on external surface temperature
For an indoor condition, 1/2 steel tank walls, and input water flowing into a tank, the temp difference (water-to-tank wall) with circulating or pumped (flowing) liquid will be only 2-4 degrees F. Across the (uninsultaed) tank wall, for 150 some-odd degree water and 70-80 degree, assume 1/2 difference. Your thermometer is (I think) mounted on the tank wall, so there is no tank wall-to-outside air heat loss - ===> if and only if you are measuring outside tank wall temperature.
Once the water stops flowing into the tank, the temp difference of water to tank wall through tank wall to room air quickly approaches zero, but will never actually reach zero until the room air equals the water temperature.
If you have some sort of continuous heat flow problem - like something is heating the tank internally, then you (we!) have to know how much energy that heat is, and how it decays/stays the same/increases over time.