Heating solid to high temperature

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Discussion Overview

The discussion centers around the electrical heating of a solid block of material to a high temperature of approximately 2000 K. Participants explore methods to estimate the electrical energy required for this heating process, considering various factors such as power input, heat capacity, and potential heat loss mechanisms.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant suggests using the Stefan-Boltzmann law to estimate the power radiated by the block, noting that this power should equal the electrical power input at equilibrium.
  • Another participant emphasizes the need to account for the object's heat capacity and the temperature increase to estimate the total energy required, while also considering potential heat losses through convection and conduction.
  • A different viewpoint proposes the use of a furnace or an ordinary filament light bulb as practical heating solutions, questioning the relevance of the block's shape, size, and material properties.
  • Participants express varying degrees of confidence in their estimates, with some indicating that more precise calculations could be made but that the provided methods offer a good starting point.

Areas of Agreement / Disagreement

There is no consensus on a single method or solution for estimating the energy required to heat the block. Multiple approaches and considerations are presented, reflecting differing opinions on the best way to tackle the problem.

Contextual Notes

Limitations include assumptions about the object's properties, the neglect of phase changes, and the potential inaccuracies in estimating heat losses. The discussion does not resolve these uncertainties.

Who May Find This Useful

Individuals interested in thermal physics, electrical engineering, or practical applications of heating materials may find this discussion relevant.

phyzzy_physh
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Hi,

I want to electrically heat a uniform block of a known material to a high temperature (about 2000 K). I want to get a rough idea of how much electrical energy I need to supply to raise the material to this temperature so as to gauge what apparatus I will need. How would I go about this?

Any help would be much appreciated :)

Thanks

Fish
 
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At equilibrium the power radiated should be equal to the electrical power input.
The power radiated is given by Stefan-Boltzmann law.
P_rad=Sigma*T^4*Area
Where Sigma is the S-B constant and "Area" is the surface area of the object.
If the object is not a black body you need to multiply by a correction factor.
It will give you a minimum estimate because heat will be also lost by convection and air conduction but I suppose that at 2000 degrees the radiation will be the main factor (if the object is in air and not in some liquid).
 
nasu said:
At equilibrium the power radiated should be equal to the electrical power input.

This will give an estimate of the steady state power P required once the object is heated. To estimate the total energy needed, multiply the object's heat capacity C by the temperature increase \Delta T (assuming no phase change occurs). The energy required for heating the object in time t will be between C\Delta T and C\Delta T+Pt. More exact estimates are possible, but this gives a good first approximation.
 
Hello fish, from your post I am imagining a largish metal block and difficulties in heating this electrically .Could you not use something like a furnace?If the shape,size and nature of the metal are irrelevant you could use an ordinary filament light bulb.In normal use the filament can reach temperatures in excess of 2000 degrees.
 
Hi guys,

Thanks for your replies; I only wanted a quick rough idea of how to work this out so they were really helpful.

Dadface, the furnace is an option but I wanted to work this out before commiting to anything. :)

Thanks again guys.

Fish
 

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