Heater and Heat time Calculation

[AimHigh09]

Hello,

My First question would be Is this a feasible solution to the problem mentioned below.

Problem: To heat up an object from T25C to T63C. delT= 38C. (object is well insulated).

Specific heat capacity of the Object: 1.4 BTU/lb

Mass of the Object: 0.49KG

Change in temp delta T: 38C

Heat up time: 25 minutes.

Q = m*C*delT -> 0.49*1.44*38 = 26.8

P(Watts) = Q/t -> 26.8/0.5 = 53.4 Watts.

So is it possible to heat up the object in 25 minutes from 25C to 63C with ~54 watts power?(adding conduction losses 10% to system design)

Suppose system voltage is 12V the current would be 54/12 ~5AH.

Please guide me solving the problem, what am I missing here?

Thank you

AimHigh

 

[MintJulep]

Units.

 

[LittleInch]

Don't use BTu/lb per ?? deg F?

Use J/kg per degree C

Also time needs to be in seconds to get W.

This question is just all over the place wrt units and values.

You're mixing power and energy all over the place




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Also: If you get a response it's polite to respond to it.

 

[AimHigh09]

Firstly, thank you for your response!
My bad, thanks for pointing it out wrt Units.

I hope I made it clear now regarding the units in this reply back.

Mass of the object = 490 grams
Specific heat = 5 Joules/gram.C
Delta T = 38 C

Q = 490*5*38 = 93100 Joules or 93.1Kjoules
P(watts) = Q/t (Joules/seconds) , t = 1500 seconds.
= 93100/1500 = 62.066 Watts.

So is it possible to heat up the object in 1500 seconds from 25C to 63C with ~62 watts power? (adding conduction losses 10% to system design).
Suppose system voltage is 12V the current would be 62/12 ~5A current.

Please guide me solving the problem, what am I missing here?

Thank you
AimHigh

 

[IRstuff]

depends on the material; aluminum, maybe, alumina, maybe not
How you are heating it makes a difference

Look up Biot number in Wikipedia

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[LittleInch]

You're missing heat losses from the object as it heats up.

Also getting heat into the object can be difficult for small objects. Also depends on the material heat conduction.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[AimHigh09]

Hi,
Materials used for the Container is Al alloy 3003.
Heated using Polyimide Flexible Heaters(ohmic heaters) wrapped around the container. Finally, an insulation layer(not known what type of Insulation is required, would like to get suggestion here)is wrapped around the container.

What should be my next move? which calculation I should perform to get what I wanted?.
Please guide me so that I could save me a ton of time.

Thanks
AimHigh

 

[IRstuff]

This is the first mention of a container. Please stop dribbling information. A drawing would be extremely useful.

TTFN (ta ta for now)
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[AimHigh09]

I am sorry. I shall provide a drawing sooner. And thank you for your response.