Mankind learned to make fire many thousands of years ago. And at first they could use only firewood as fuel, thanks to which they survived on cold winter nights, cooked their own food. Today, much has changed in the world. Oil, coal, radioactive metals and many other energy carriers became available to people. However, the relevance of firewood as an energy carrier is not a thing of the past and is not going to. Still, it is precisely them that are often used in heating baths and private country houses. Of course, observant people have often noticed that when burning different firewood, it turns out to melt a room faster or slower. It depends on the burning temperature of the wood in the stove. Let's talk about it a little more.
What is burning?
But before you figure out what the burning temperature of firewood in the stove, it would be useful to study what burning is all about.
It would seem that the answer to this question is as simple as possible. Who did not see open fire? However, with a more detailed study of the issue, it becomes not so simple. But you need to know more about him, if only in order to better understand the main issue under consideration.
Combustion itself is usually divided into three stages: heating, ignition of pyrolysis gases and ignition. We will study each of them.
Warming up is called the stage when the wood heats up to 120-150 degrees, it begins to char. The coal formed in this case may self-ignite. If the tree is heated to 250-350 degrees, then pyrolysis will begin - the process of decay of wood into gaseous components. The tree begins to smolder, but the flame does not appear.
If the temperature is further increased, then the gases formed during pyrolysis will ignite. The flame will quickly cover the entire area subjected to heating. The fire here usually has a light yellow tint.
Finally, ignition - it occurs when the temperature of firewood reaches 450-620 degrees (depends on a number of factors, which we will consider a little later). At this stage, the fire becomes self-sustaining, may cover additional areas.
As you can see, everything is much more complicated than practitioners who have repeatedly fired.
Average combustion temperatures
Now we find out what is the temperature of burning wood in the stove in the bathhouse or in the house. It should be noted right away that different types of wood have different heat dissipations. Moreover, the maximum possible indicator is indicated everywhere. In practice, it is usually impossible to achieve it due to various factors. So, the approximate burning temperature of different firewood is:
- Ash - 1044 degrees Celsius.
- Hornbeam - 1020 degrees Celsius.
- Oak - 900 degrees Celsius.
- Larch - 865 degrees Celsius.
- Birch - 816 degrees Celsius.
- Fir - 756 degrees Celsius.
- Acacia - 708 degrees Celsius.
- Linden - 660 degrees Celsius.
- Pine - 624 degrees Celsius.
- Alder - 552 degrees Celsius.
- Poplar - 468 degrees Celsius.
As you can see, the scatter is quite large. For example, a cubic meter of poplar wood produces almost half as much heat as the same amount of ash. Now, as promised above, let's talk about which parameters affect the amount of heat generated during combustion.
What affects the combustion temperature?
In fact, the indicators given above are almost impossible to achieve, especially outside of laboratory, specially created, conditions.
There are three factors affecting the speed and temperature of combustion: wood moisture, area of ignition, and the amount of oxygen in the combustion chamber. Each of them is very important and has a considerable effect on the amount of heat generated during burning of firewood. Therefore, it will be useful to consider them more carefully.
A bit about humidity
The most important factor is the moisture content of the wood. Typically, freshly chopped wood has a fairly high humidity - about 55 percent. Of course, the indicator can be either large or smaller - it depends on the time of year. For example, in the middle and late spring, humidity reaches a maximum. But in winter, wood has minimal moisture, since it does not need to feed the buds and leaves. Of course, the lower the humidity, the better the wood burns, the more heat they produce.
Which is not surprising - if you burn wet firewood, then part of the heat will be spent on the evaporation of moisture. Only after that the fuel will burn normally, generating a large amount of heat.
A few words about air supply
Also, do not forget about oxygen. From the school course, every reader knows that oxygen is necessary for burning - without it, the process simply won’t start. More precisely, the process will go, but it will be the formation of coal from wood, and not combustion. In this case, we are interested in the latter.
The more oxygen in the furnace, the better the wood will burn and, therefore, release a large amount of energy. True, fuel will burn faster than with a lack of oxygen.
If necessary, the burning rate can be changed by slightly opening and closing the damper of the furnace or boiler. But it is worth considering that with a lack of oxygen, the process is delayed, but in general the amount of heat received is reduced. Therefore, artificial stretching of the burning time cannot be called rational. The only time this is justified is the bathhouse. High temperature is not very important here, but the duration of burning is a desirable factor in order to keep the heat in the room for a long time.
To get the maximum heat, you need to ensure a constant flow of oxygen - people say they provide good traction. Indeed, a cleaned chimney combined with a slightly open blower (a special door through which fresh air enters allows the fuel to be burned most rationally.
Burning area
Finally, the burning temperature of birch firewood in the stove (as well as any other) depends on the burning area. That is, if you take a huge log and put it in the stove, then it will burn for quite a while. In this case, when the internal layer begins to burn after the burning of the outer layer, the access of oxygen is significantly complicated. Because of this, heat will be significantly less.
Chips are quite another matter. If you cut the log into 6-8 parts, then the total surface area will be much larger. Accordingly, the burning time will be significantly reduced. Therefore, the heat emission will be large, although for a long time such fuel is not enough.
Cons of wet firewood
Now let’s try to figure out why wet firewood is bad.
The most important minus has already been mentioned above - they burn worse. Since part of the heat is spent on the evaporation of moisture, much less energy is released. For example, consider birch wood - one of the most popular and common types of solid fuels in private homes.
Freshly cut wood has a moisture content of 50%. When one cubic meter is burned, 2371 kW of energy is released. If the wood is slightly dried, reducing humidity to 30%, then the amount of heat generated can be significantly increased - up to 2579 kW from the same amount of firewood. Finally, fuel is considered to be well-dried, the moisture content of which does not exceed 20%. Burning a cubic meter of such birch wood, you can get 2716 kW of energy. That is, after a good drying, the amount of energy received increases by 345 kW or about 15% - a very good saving.
An additional disadvantage of wet firewood is the difficulty of ignition. Well-dried wood is very easy to set on fire - just put a piece of birch bark or paper under them and set fire to it. In a matter of seconds, the flame will scatter along the surface of the firewood, which will soon begin to crack merrily, warming the whole house or bathhouse.
Finally, high humidity leads to the formation of large quantities of soot. She clogs the chimney and gradually degrades the draft. Because of this, fuel burns worse, in addition, the risk of burning out due to the accumulation of carbon monoxide in residential buildings is increased - it has no smell, therefore it is very dangerous.
We dry firewood correctly
As already managed to find out, well-dried firewood gives about 15% more heat than freshly cut. Consequently, it is possible to burn 15% less fuel, high-quality heating of housing. Therefore, the cost of purchasing firewood is significantly reduced. How to achieve such a desired result?
Of course, first of all, it is necessary to reduce humidity and increase the burning area - within reasonable limits. So, one should act in the same way as our distant ancestors, who did not know what physics was, but at the same time were distinguished by worldly ingenuity and wisdom. In other words - you need to chop wood. The optimal width of the logs is four to six centimeters. This size is a good compromise between the burning rate and the amount of heat generated. In addition, thanks to this, they dry faster, which is also an extremely important factor.
Drying the wood also needs to be done correctly. Having chopped it, you need to put the logs in the shade - not in the sun, as some believe. In this case, they will warm up evenly, and the maximum amount of moisture will leave them. If you put the logs in a sunny place, then the top layer will heat up more quickly and dry quickly. The capillaries narrow rather quickly, trapping moisture inside. It is almost impossible to remove it from here, and the presence of moisture will affect the burning temperature of the wood in the stove.
How to determine the burning temperature of firewood?
Many people are interested in knowing what temperature the wood burns in their fireplace or stove. Unfortunately, determining this is quite difficult. After all, the burning temperature of oak wood in the stove is about 900 degrees Celsius.
To measure such a high temperature, you need to have a special device - a pyrometer. This thing is rather highly specialized, so it is hardly possible to find it in the nearest hardware store.
Conclusion
On this our article comes to an end. Now you know what is the burning temperature of firewood in the stove. And also read about the most simple and reliable ways to increase this indicator. Surely this information will bring many benefits if skillfully put it into practice.