Tank hydrotest, will the water freeze? 2

[Mkotop]

Good day to all!
First time poster with a problem.

We have a 557 m3 vertical cylindrical steel tank, D=9,3m, h_fill=8,2m tank wall is cca 50 mm.
It will be filled with water from the nearby river in 3 stages. In every stage 1/3 of the volume and left to settle for 48 hours. After it's full it will be drained 1/3 of the volume every 24 hours. The filling part for each stage is roughly 4 hours, emptying rate unknown.

Temp of the river is 3°C, expected outside temperatures are -5°C at night and 4°C during the day. Wind speed not given

Question is will the water freeze at any point without the addition of antifreeze?

water 3°C c=4,21 kJ/kgK
steel c=0,49 kJ/kgK; k=25 w/m2K
Air -5°C c=0,717 kJ7kgK
Tank wall surface 237 m2

Heat loss of a full tank Q=kAdT=25*237*8=47,4 kW

If I calculated ok, the heat contained in 3°C water is (m*cp*T)

at 1/3 of Vmax: 2,344,970.00 kJ
at 2/3: 4,689,940.00
at Vmax=7,034,910.00

I know that the water will not be 3°C when the 2. and 3. stage of fill begins but don't know how to approximate.

So, this is all I got. Where do I go from here with the calculaions? I am without the clue how to add the time dimension in all of this.
Thank you!

 

[SNORGY]

Sugar will only work in a sweet service piping system.

Regards,

SNORGY.

 

[ornerynorsk]

. . . and only if designed by an MBA, eh what?!?!

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[MiketheEngineer]

Put a small pump or mixer in it and keep the water moving --- probably will solve any problems...

 

[ornerynorsk]

Although heat loss will increase by agitation in an open head design. You may see ice rimming, but it should be minimal.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[IPGBen]

Hi all,

what about the sun during daytime heating up the tank?
This might help in lowering the amount of ice formed.

BR
Ben