A blacksmith’s good heat and bad heat

An engineer friend visited a working blacksmith on a museum and asked him about the metallurgy and heating processes. The blacksmith pointed out that coke is the best fuel for getting a good hot furnace and that a gas-fired furnace, while able to get up to the same temperature does not produce as “good” heat as coke.

Now, this sounds almost silly…doesn’t it? Heat is heat – vibration of atoms in a substance and temperature is the measure of that rate of vibration. How can some forms of heat be better than others? Well, my friend, his curiosity piqued, wonders whether processes analogous to fluorescence might occur with infra-red. Perhaps, he suggests, as with a bright light shone on a fluorescent watch face or child’s decorative wall stars and planets, the materials store up some of the radiant energy from the burning coke and release it as fluorescent heat. The temperature would be the same, “red hot” but there would be more energy available. Is this what the blacksmith means by good and bad heat? There would be none of the potential for such a fluorescence process if the furnace is being heated directly with burning gas.

It reminds me of a concept chemical engineers use when they want to lower the temperature of a system, such as a distillation tower: they add “coolth”…the opposite of warmth, negative heat, uncoolth. It’s a concept that works for their “back-of-an-envelope”, “rule-of-thumb” calculations to set up vast quantities of refluxing liquids and reagents optimally. Is the blacksmith’s good and bad heat are nothing more than a coolth-like fudge, or is my engineer friend on to something?

3 thoughts on “A blacksmith’s good heat and bad heat”

  1. Whether it is fluorescence or not, I think one point is that the heat stays localized and concentrated because of the heat capacity of the coke. That is a lot more than the gas fired furnace. Then, when a cold object is plunged into it, like a piece of iron, with an even larger heat capacity than the coke, the heat flows into the iron more easily.

    I think this has more to do with heat capacity than fluorescence

  2. I was talking to a glass blower friend who agreed that there is good and bad heat. He suggested that coke retains the heat and also allows air to be blasted through in a way that a gas-fired furnace cannot. When I asked him specifically about an IR fluorescence effect he was dubious, but he did concede that there’s a lot of heat radiation with coke that you don’t get with gas. I suggested that that was a kind of fluorescence effect and he thought about it a bit more and said, yeah, that’s probably right…anyone got a more solid thermodynamic suggestion?

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