Definition of Thermal Energy and the BTU

[sm0ky2]

Hi guys. I'm putting this in the do-it-yourself category,
Because we don't really have a category for this.
Attached to this is I guess you would call the oldest
Do-it-yourself project in human history.


I'm talking about the camp fire, and from a time when fire
Could have very well meant life or death.


And Ancient Metal Smelting
(And yes I will give you the device)


From a time, the historians tell us, was 230-250 thousand
Years ago...


This came to me from a friend, who had a stack of old photos
1970's sometime, and research papers done from his dads
tour of museums at that time. The subject of interest was in these
particular fire pits that, according to the exhibits, would stay lit
for a week, sometimes more. And my friend wanted me to explain
to him how it worked.


Well, I was an Eagle Scout, so I knew a thing or two about campfires,
(or so I thought), and the best of mine, I could go out two or three days
later and stir the coals and find something lit, but a week sounded ridiculous.


So I told him I would read through what he had and see if I could dig up any other
stuff on these.


Well, what I found, places Heat Energy into a category that more closely resembles
light and sound, and electromagnetism.


I'll do my best to explain:  we can define heat in terms of a group of thermal energy,
and by doing so, we give this volume of energy a sort of linear definition in terms of
transfer of energy, through solids and through gas.


But less talked about, is that we can also define heat energy in terms of a wave.
We can see heat waves when light hits them and reflects to our eyes.
On a hot road, or coming out of our ovens.


We can measure them, and catalog the data of waves of packets of heat.
But nowhere do I see anyone talking about the frequency of these waves.
At least not in any definitive manner applicable to the quantity of heat energy.


I did find studies done on the interference patterns of heat waves, but
nothing that applied to this guys question.


The reason I'm mentioning heat waves and ancient caveman technology,
Is because that is where the research led me. As it turns out, frequency and
Heat waves had nothing to do with the fire staying hot, as that technology had developed
much earlier than the furnaces he gave me.


What THESE people were doing, clearly had nothing to do with cooking food.
There is only two things a person would conceivably do with these temperatures
And those are to smelt metals, or make your own sort of personal lava / obsidian.


We'll get to that, but first I will walk you through the origins of this stuff.
These fire pits were found in Cave Man exhibits in museums across the US and Europe
In the 1970's.
I don't remember paying much attention in the 80's so I don't know if they were still there
when I was a kid, but they are nowhere to be found now, and no one in the museums will
give me any info. I am told only that I can bring them cataloge numbers or something and fill
out a request to view a catalogued artifact.
The problem is, we don't have lists of all of the stuff they keep in their basements.


So, this technology is known as ashenware, which later developed into ashenclay, or clay ash.
The modern official description states that the cavemen mixed ashes with clay and made these mounds
To cook their food.


Well, that's not what the historians said in the 70's.


First: the ashenware was always placed first. As if the base structure was created first,
From rocks and ashes mixed with water to form a brittle clay.
The Actual clay was placed on top of these structures, and in the layer where they touched
Yes, there was some "mixing". Then was just clay.


And not just clay, but specifically measured, flat interiors of the furnace.
With strange notches, which made these particular furnaces a unique type.

[sm0ky2]

They were built different sizes and I did not see the correlations
until I started reading the technical descriptions made by this guys dad.


These furnaces, no matter their size, were build with explicit proportions,
and always this shape in the bottom.


I also noticed that there was nowhere
To cook food


You had a place to put coals or wood into, but the top was, what the historians
refered to as an exhaust vent that produced temperatures over 2000 degrees.
(1093c)


Which, as a chef, I assume would destroy your food.


And there was always these 3 proportions, and a 4th which
was mostly proportional but varied slightly.


Why did they need such heat?
Well 1200 years later in time, the same furnaces were found
With additional mounding on top of the original style furnaces,
and a large square oven on top, whose dimensions were perfectly
divisible by the previous dimensions.


Anyways, the ashenware technology that predates these by a few
tens of thousands of years, does stay hot for a week. You go to it
7-9 days later, stir the ashes and the whole pit lights back up.
How do I know? Because I built one.


Next, I added a layer of clay. And made the witch-furnace.
I call it a witch furnace because it reminds me of an old timey
American fire pit with a open face chimney, often found in places
where witches were rumored to live. In actuality was probably old
loners who lived in the woods..... anyways they look like that.
Except they don't have an open face. They are just an ugly mound, or
square or conical chimney, at the edge of a large fire pit.


But inside is a chamber, the height varied but was the bottom section
of these devices. And inside was a square design that was two over-layer squares.
Or a square with cut-outs on 3 walls of specific length and depth, and both of those
Dimensions were proportional to the height of the base+chimney to a narrow opening
on the top.


Now - the dimension of the (later) cube on top was always divisible by a common factor.


Why?


Well, as it turns out, there is a frequency effect inside this thing.
And even without heat (and I waited two weeks to be sure)
A vortex of air forms inside with even the slightest movement of air outside.
It does it when I cannot even detect wind, but I assume there must be "some wind".
You can see ashes or cig smoke just tornadoe up the chimney.
But when there IS heat, just a small handful of twigs or grass can send fire 4 ft out the top
And heat steel to a glowing red. I've melted alumin and glass. And as I perfect my construction
I will update you guys on this.


There are no bellows
No hair dryer
And I haven't even build a lid.


The thing sounds like a rocket engine


I'm trying to get a video onto my YouTube but google is being a $&@!!


Worse case I will upload a schematic to show the dimensions.


The real topic that is risen here is not that we can make our own forge,
Or even wether or not that is what the cavemen were doing with this.


But it is concerning this frequency effect of convection and heat generation.
And how this applies to our definition of a quantity
Of heat energy.


If you have access to a convection oven, place the blower fan on a timer circuit.
And pulse it across a frequency sweep.
Find the peaks and troughs of the rate of change of the oven temp vs freq.
Now take the frequencies where rate of change peaks, and compare those wavelengths
to the internal dimensions of your convection oven.


I think you will quickly see that that situation resembles what happens in
your microwave.

[sm0ky2]

sorry about the delay, finally got access to my youtube channel.

here is a short video of my first successful melting of Aluminum.

https://youtu.be/HmzSO1UChAk

i'll upload a schematic tonight.

but I want to talk a little more about these dimensions, and why they do what they do.

the insets (square within a square), are cut back into the walls, on 3 sides. open in the front, up to the height of the chamber. The depth of the inset is 1/16 of the length of the inset.
mine are based on the earliest version I could find, which is 1/2 inch inset and 8 inches in length.
the inner square is 4 inches smaller, which leaves these square corners sticking about, which are about 2 inches, I say about, because the exact dimensions of those squares seemed less important
to the cavemen, as they varied by up to 1/4 of an inch.
that doesn't seem like much variance, but when you compare the precision of the other dimensions,
you can see that these guys didn't make a mistake by even 1/20th of an inch. they were all exact.
the historians measured with micrometers, and I don't have that sort of thing. I converted it to inches and rounded off a tiny fraction, but kept the proportions the same.

the height of the chamber had no direct correlation to anything, as it was anywhere from 8-14 inches, and was different from device to device. mine is ~10 inches tall.

chimney is smooth walled and becomes more narrow as it rises. some groups of cavemen made them round, others made them square or flat walled inside. but the total height was important.

in the example I recreated, the height is 32 inches, or 4x the 8-inch dimension.

in the later ovens, which had a square chamber on top of the chimney
it's length and width and height were 24 inches, or 3x the 8-inch dimension.
im assuming they had some kind of door, but that wasn't talked about in any of the papers I read.
otherwise, how would they make use of it?

I haven't gotten to the upper chamber yet, as I want to perfect the bottom part of this device,
before I move on to more advanced versions.

but as you can see in the video, this device is able to reach incredible temperatures with very little
fuel, and no forced air. the air-flow is completely natural, and built-in.
the hotter I get it, the stronger the air-flow of the vortex, but the frequency (the hum it makes)
is always the same tone when it gets going. sounds like a jet engine or something.
reminds me of those pulse-rockets.

[sm0ky2]

What does this have to do with the BTU?
Well, a lot actually. But before I start making outrageous claims,
which, if true, could upset the realm of physics...


Let's talk about how we USE the BTU.


When we measure the BTU (or energy of the combustible content)
Of Wood: this is traditionally done with a wood stove.
Greater accuracy is obtained by pelletizing the wood
For more consistent burning.
In almost every example, the approximate BTU for wood
Comes out to around 7000 /Lb.
In fact, most plant debris is measured close to that.


When we consider a quantity of water, heated to a boil,
By a quantity of fuel, in a traditional wood stove,
We find the estimate of the BTU of wood to be consistent
with the scientific standard values.


I've tested similar quantities of wood (small sticks/twigs)
In a variety of small fire containers and wood burning stoves.


How much heat energy are we talking about?
One gallon of water requires approx 8.34 BTU's
Per degree of temp. increase. 212-60= 152
152x8.34= 1268 BTU's to bring a gallon to boiling.
0.18 Lbs of wood, burnt at maximum efficiency.
Or ~2.88 ounces of sticks.
The cedar that grows around here, this is about 3 cups of
1-2 inch twigs. Avg 1/4 inch diameter.


In a variety of modern wood stoves,
Commercial and homemade, this amount would barely heat the water.
In fact, in most stoves the twigs burn up so fast that it is nearly
Impossible to harness 100% of the woods energy.
And in most cases, it took 3 or 4 times that BTU's worth of wood
To boil a gallon of water.
A lot of heat is lost due to inefficienties of the stoves.


With the caveman furnace I can easily boil the water in a couple of minutes.
It is in fact, faster than my gas powered store be inside by 2 mins.


Turning off my water heater, and watching the meter, I was able to get a number
for the quantity of gas used, and reverse engineering the BTU I find that
my gas stove runs at about 40% efficiency.
This is better than the 20-30% of a wood stove.


This is where the problems begin.
These "cavemen" that lived some 230-250,000 yrs ago, somehow managed to
Make a furnace that operates at ~120% efficiency.


Wtf?  Ok well, it can't be greater than 100%, at best.
So let's look for another solution.
Is our value of the BTU of wood correct?
Is the value of the BTU itself correct?


We'll deal with the second one, but first things first.


How did we come up with 7,000/lb?


It appears, upon lots of digging, that this number is inherented.
And by that I mean: passed along from source to source, making it
difficult to find the origin.


Until you get back into the 1980's and older research
There we find intense measurements done, with ranges of
5000 to 11000 BTU's per lb of wood.
And that density is only one of several factors, including oil content,
Hydration, and chemical composition of the plant.


The local firewood salesman tells me the accepted standard is 8600/lb
And he uses that fact to sell his different woods based on their density,
and various characteristics of the flames each type produces.


Wait what? Different wood produces different flames?
Why?
Well, it turns out those chemicals actually burn at different temperatures!!
The color of the flame presents itself as a scale by which we can grade our wood.


A physicist at the University of Texas tells us that the temperature the wood burns at
does not affect the actual BTU values, but that hotter flames simply burn more BTUs faster....
My barrage of questions that followed that statement went unanswered, he was unable to
explain this line of reasoning, that it was "what he was taught".


Ok, back to the caveman stove, if our value of BTU's per lb
actually has a range of several thousand BTU's, we not only don't know the true efficiency
of our wood burning devices, but we also can't compare it to a gas stove.


Let's assume that this local cedar or medium wood density, was the maximum of 11000/lb.
This means the caveman furnace is operating at ~85%.
Ok this sounds more within reason.


The problem still exists, that these "cavemen" made stoves that we're 2-3 times more efficient
than our modern stoves.


And this physicist had no comments on the vortex.
he said that rising convection currents have two main components
Thermal Displacement (the whole heat rises thing)
and air drawn upwards by the 'licking' of the flames.
And that they sometimes cause the flame to take on circulation patterns.
Also, he told me that frequency has nothing to do with convection
And that wood flames don't 'lick' at a set frequency, they are random.


Thanks Doc,


However, the caveman furnace CLEARLY makes the same tone,
regardless of what is burnt in it. Paper, wood, charcoal, cardboard, gasoline, alcohol
paint thinner...


And why would a primitive race of cavemen build meticulously intricate interiors
for a useless chimney......
And the heat!!??!! Why did cavemen need all that heat?
Then we find in a museum in Columbus, Ohio - 40,000 yr old metal arrowheads.


They were smelting 250,000 yrs ago.
(No I didn't find any metal artifacts that old)
But the fact that these furnaces existed proved they were doing a lot more than
we give them credit for.


Even my crappy replication gets plenty hot enough to melt a several different metals.


I am experimenting with this tech to see if other frequency (or spatial dimension) related effects occur.
I'll keep you guys posted with what I find.

[madddann]

Hello sm0ky2!
Could you please post a schematic with the dimensions (and ratios)? I'm interested in the workings of this caveman stove.

Thanks for sharing!