Electric Grill Design

[Restrell]

Hello,

Im trying to design an electric grill to boil water in an open tank.

I need an advice on KW/ m2 to use for this purpose.

Thanks,

R

 

[IRstuff]

You can buy immersion heaters:

http://www.ebay.com/sch/i.html?_fro...on+heater.TRS0&_nkw=immersion+heater&_sacat=0

You didn't specify the time required nor the amount of water, so kW/m^2 is undefined.

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[Restrell]

Yes, i cant use immersion heaters it must be a grill underneath the tank.

Its for 16000 liters and in 8 hours period.

Thanks

 

[IRstuff]

OK, so time to dust off ye olde heat transfer equations?

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[MJCronin]

To boil water in a container, you have three, commonly used options:

1) ELECTRIC IMMERSION HEATER: Inexpensive to purchase, easy to control, Can be made permanent or "drop in"... Very common

2) INTERNAL STEAM COILS: Inexpensive to operate, must have steam available, Control is slow

3) EXTERNAL PADS (Electric or steam) A bit slower to heat liquid, somewhat more expensive than internal devices

4) CIRCULATING PUMP WITH EXTERNAL HEATER: Most expensive option, heater can be steam or electric or gas, very close temperature control

Explain more about your needs. What temperature does the liquid start out at ?

Are the sides of the tank available for heating ?

Can immersion heaters be dropped into the open top of the tank ??

Is the tank insulated ???

MJCronin
Sr. Process Engineer

 

[Restrell]

Thanks MJ,

Answering your questions:

No nothing can be inside the tank and neither in the sides of it, neglect all heat loss from the walls.

T1 = 15C T2 = 100C

I just need an idea on the KW/m2 for the grill underneath the tank.

My thought is the heat from convection plus radiation must equal the waters specific heat for that delta T and volume

 

[IRstuff]

Apparently, you are mixing metaphors, as it were.

Heating phase = deltaT*specific heat*mass/time + radiated/convected loss

Maintenance phase = radiated/convected loss

Is this for school? Student posting is not allowed.

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[Restrell]

No school, Stuff,

I need to quote this for a client, were OEMs

And Im just thinking of heat transfer principles

Thx

 

[IRstuff]

OK, so, question answered?

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[Restrell]

Do you see anywhere the suggestion of KW/m2?

No, then question not answered

 

[MintJulep]

If you neglect all heat loss from the wall then you will be wrong.

The per square meter part of the answer will depend on how many square meters you have. You either don't know, or have forgotten to tell us this part.

Other than his sloppy use of "/" to mean "and", IRStuff has explained how to approach the problem.

 

[IRstuff]

And your calculator can't divide watts by area?

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