Hello, friends. We continue to climb into the quasi-scientific jungle.
The object of today's conversation will be the fireplace. Read his definition in Wikipedia, it's something in the style of M. Zadornov (health to him). A distinctive feature of a fireplace is always that it is not designed for heating and subsequent heat transfer from the wall material. It gives the main heat due to infrared radiation from the flame, and convection (according to Wikipedia) has nothing to do with it. Those who have ever had a fireplace (I did) know that convection causes some problems here - the smoke begins to go outside, polluting the air and the fireplace itself. Moreover, this does not depend either on the quality of the engineering calculations of the fireplace master, or on the quality of the firewood. And the fireplace heats up only when the wood is burning in it, and they burn out pretty quickly. With a large room, in order to warm it up, you need to sit near the fireplace for several hours. Now imagine the 19th century somewhere in Holland,where the frosts are strong enough and the rooms are large. It is clear that in such conditions it is possible to freeze out and a fireplace is not needed here at all, but a Dutch stove is needed. Nevertheless, there are also fireplaces there. The simpler one remakes them something like this:
And why were they made at all, if they initially did not cope with their tasks? Well, obviously not for beauty. Perhaps the climate was milder in the northern latitudes, but there is still a chimney in the fireplace. Experts will confirm that in warm climates it is even more difficult to heat the fireplace due to the reverse draft. So what's the catch? Let's figure it out.
So, the fireplace. The older it is, the more it looks like a canopy over a fire, which is built right on the floor.
In addition, the height of the firebox on old fireplaces is higher than human height.
Promotional video:
Probably, the artist in childhood did not burn fires in a pioneer camp. In this case, even with good draft, half of the smoke will go out into the room. There are even prints where people sit in a luxurious palace and heat a fireplace, and clouds of smoke come from it. The feeling that these people are savages who ended up in an ownerless palace, and they did not find any worthy appointment for a fireplace, except for burning firewood in it (by the way, many historians claim that modern people came to ancient palaces as savages, at 18 century). In all old engravings, fireplaces are depicted with the largest possible size of the firebox. This is exactly what they were originally.
Naturally, in this form, they were poorly heated, and people modified them in order to somehow improve traction.
Look at the material and quality of the fireplace itself and at the white tiles that reduce the size of the firebox. The fact is obvious - the owners of the house got the fireplace ready, and it was finished. Stop. And what are the objects near the fireplace? For beauty or just accidentally caught in the frame?
As you can see, at different times and in different countries, all fireplaces have one thing in common - this is the presence of a metal sheet on the back wall of the firebox (or the design of the entire firebox in the form of a metal caisson laid on its side), and the presence of metal cups near the fireplace, which were previously considered here. Moreover, the cups can be of different sizes, the largest are placed at the corners of the fireplace. The presence of a metal sheet on the back wall is quite understandable - it serves to emit infrared rays when heated, strictly in front of you, as befits a fireplace. But the cups have nothing to do with the process of burning firewood. Here, apparently, the European mentality worked. The Europeans did not understand what these cups were for, but since they had been there since ancient times, it means that it should be so and there is no need to remove them. And these cups are nothing elseas devices for the concentration of atmospheric electricity, and their step-by-step installation increases the current in a closed conductor along which they are placed. So what happens? For a start, probably the fact that in the fireplaces of their owners in a past life no firewood was burned there. And fireplaces were not designed for this at all. Their secret is apparently in something else.
Imagine that metal ties go through the chimney pipe from the roof of the building, as in the figure, and come to a thick conductor that forms a frame at the entrance to the fireplace insert. This frame is metal-bonded to a sheet on the back wall. This connection can be single conductors, or it can be solid, as here.
When the cups are installed in close proximity to the frame, a strong eddy current begins to induce in it (probably, to understand why, it is better to read my previous articles). This current generates eddy currents in the plate on the back wall, in about the same way.
Probably, in the center of the plate, the density and current strength were such that the metal there heated up and began to radiate heat, and in such a way that, as in the proverb - no firewood or splinters are needed, live without torment. It is possible that there were also secrets inside the fireplace, and the same cups were mounted in the upper part of the firebox. In addition, there was a grate on the chimney. The chimney itself was not in vain, due to contact with a hot iron, the air deteriorated and was unhealthy, and so it was just removed due to convection.
Look at this fireplace, there is not even a place for firewood in it (unless there is a cover behind the radiator due to modern modifications).
Well, this is a real fireplace, as it should be, judging by its appearance, it is kept rather as a museum exhibit and they either did not guess with firewood, or decided to pity it. Nobody knows what the cups were for.
Until next time.
P. S. This is just a crude working version, please do not scold me for mixing physics with fantasy.