Heat loss due to steel immersion

[ATSwork]

Hi,

I would like to ask You to help me with following problem. What will be the heat loss due to 200 kg steel immersion in a solution of water at 60C for 4 minutes.

Tom

 

[MintJulep]

200 x 60 / 4 = 3,000

 

[IRstuff]

No heat is lost, since the steel is in the water the entire time, neglecting environmental loss, natch.

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[ATSwork]

I was not too precise. I meant how much heat, the water will give the steel. I thought to use formula

Q/dt=m*c*dT

but I have 2 unknown.I understand that we are dealing with natural convection but I'm not sure which model use.

 

[EnergyMix]

.o.k so how cold is your steel when you put it in the water?

Is this a school assignment of any sort?

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[1gibson]

If steel is 60*C initially, then none.
If steel is <60*C initially, then some.
If steal is >60*C initially, then less than none.

 

[chicopee]

ASTwork, you are still not precise. You should give us the whole description such as temp of water before and after steel immersion, temp. of steel before immersion, quantity of water, quantity of steel immersed in water and out of water, water movement if not stationary. With that information the we probably can help you as long as it is work related and not a school assignment.

 

[ATSwork]

OK! I hope You will have sympathy for me. English is not my native language. Additionally I wasn't precise.

I have following problem. I have rectangular processing tank: dimensions 4x1,5x0,9 m. Volume of tank 5,4m3. Medium is water at 60C. Three times per hour I will immerse 200 kg of steel at 0C. Time of immerse is 4 minutes for each 200 kg of steel. Water is not mixed.
I have heat loss from open surface, wall and bottom. I can't determine hest loss du to steel heating.

I'm not a student but unfortunatelly I should go back to school.

I hope I was more precise.

 

[IRstuff]

Almost there. What are dimensions of the steel? Powdered steel would heat more quickly than a sphere.

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[EnergyMix]

ATSwork, if it would help there's a translation forum. You can post your question in your original language and helpful members will translate it into technical english and help suggest how to word it so you can get the best answer. You can see a link at the bottom of both my and IRStuff's posts.

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[chicopee]

The shape of the steel is very important. Is it structural steel suchas I beams, flat plates, rods, ball bearing etc...

 

[racookpe1978]

You are going to insert steel at 0 degrees Celsius (freezing !) into a small tank of water at 60 Celsius?

The (very cold!) steel will cool the water, but you have a lot of heat loss also from the water evaporating, the water losing heat into the air from above, below and the 4 sides of the tank - why is it not insulated?

So, how are you going to reheat the water back to 60 C after each immersion of the steel?

Your problem makes little physical sense.

 

[SNORGY]

It's Sunday morning and I haven't opened a textbook or started punching calculator buttons, but it sounds like a "Newton's Law Of Cooling / Heating" problem, for which I think you need the surface area of the steel immersed in addition to its mass. From there the problem ought to be straightforward.

If you navigate to the Spirax Sarco website and search for "heat loss from tanks and vats", you will find excellent treatment of the subject matter; they even have worked examples based on rectangular tanks. Add to that the heat gained by the immersed steel, and your problem will be solved.

 

[IRstuff]

It's not the tank the OP is interested in, it's what he puts in it. Not to mention that's it's a transient problem he's trying to solve.

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[SNORGY]

Refer to OP third post 17 May 16:37.

That implied to me that the tank heat loss to the environment is something that the OP is at least thinking about in addition to the head gained by the steel.

 

[IRstuff]

And, he claimed he knew what to do about the tank; I'm not saying that I necessarily agree with that assessment.

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[raghu112]

@ATSwork
You are trying solve rate of heat transfer problem, correct?
Neglect transient for a while and calculate steady state natural convection
and multiply that value with 240, you will get value of heat loss water in joules
By the way what is the shape of steel you immerse?