The temperature of burning wood in the oven: types of wood, comparative characteristics and the value of the thermal unit

2024 Author: Henry Conors | [email protected]. Last modified: 2024-02-12 02:40

Humanity learned to make fire many thousands of years ago. And at first they could only use firewood as fuel, thanks to which they survived on cold winter nights, cooked their own food. Much has changed in the world today. People have access to oil, coal, radioactive metals and many other energy sources. However, the relevance of firewood as an energy carrier has not become a thing of the past and is not going to. Still, they are often used for heating baths and private country houses. Of course, observant people have noticed more than once that when burning different firewood, it turns out to heat the room faster or slower. It depends on the temperature of burning wood in the stove. Let's talk about it a little more.

What is combustion?

But before you figure out what the temperature of burning wood in the stove, it would be useful to study what combustion is in general.

It would seem that the answer to this question is as simple as possible. Who hasn't seen open fire? However, on closer examination, heis no longer so simple. But you need to know more about it, at least 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. Let's study each of them.

Warming up is the stage when the wood is heated to 120-150 degrees, it begins to char. The coal formed in this case may ignite spontaneously. If you heat the tree to 250-350 degrees, then pyrolysis will begin - the process of decomposition of wood into gaseous components. The tree begins to smolder, but no flame appears.

If you further increase the temperature, the gases generated during pyrolysis will ignite. The flame will quickly cover the entire area that has undergone heating. The fire here usually has a light yellow tint.

Finally, ignition - it occurs when the temperature of the 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 lit a fire think.

Average combustion temperatures

Now let's find out what is the temperature of burning firewood in a stove in a bathhouse or in a house. It should immediately be noted that different types of wood have different heat transfer. 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 – 1044degrees 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 spread is quite large. For example, a cubic meter of poplar firewood emits almost half as much heat as the same volume of ash. Now, as promised above, let's talk about what parameters affect the amount of heat released during combustion.

What affects the combustion temperature?

In fact, the above indicators are almost impossible to achieve, especially outside of specially created laboratory conditions.

There are three factors that affect the rate and temperature of combustion: the moisture content of wood, the area of ignition and the amount of oxygen in the combustion chamber. Each of them is very important and has a significant impact on the amount of heat released during the combustion of firewood. Therefore, it will be useful to consider them more closely.

A little about moisture

The most important factor is the moisture content of the wood. Usually, freshly cut wood has a fairly high moisture content - about 55 percent. Of course, the indicator can be both large and small - it depends on the time of year. For example, in the middle and late spring, the humidity reaches its maximum. But in winterwood has minimal moisture, as it does not need to nourish the buds and leaves. Of course, the lower the humidity, the better the firewood burns, the more heat they emit.

What 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, releasing a large amount of heat.

A few words about air supply

Also, don't forget about oxygen. From the school course, every reader knows that oxygen is necessary for combustion - without it, the process simply will not start. More precisely, the process will go on, 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, the 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 heating boiler. But it should be borne in mind that with a lack of oxygen, although the process is delayed, in general, the amount of heat received is reduced. Therefore, artificial extension of the burning time cannot be called rational. The only case where this is justified is a bath. The high temperature is not too important here, but the duration of burning is a desirable factor so that the heat remains in the room for a long time.

To get maximum heat, you need to provide a constantan influx of oxygen - people say to provide good traction. Indeed, a cleaned chimney in combination with an ajar blower (a special door through which fresh air enters allows you to burn fuel most rationally.

Burning area

Finally, the combustion temperature of birch firewood in a 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 long time. At the same time, when, after the combustion of the outer layer, the inner layer begins to burn, the access of oxygen is significantly complicated. Because of this, heat will be released noticeably less.

It's a completely different matter - small chips. If you cut a log into 6-8 parts, then the total surface area will be much larger. Accordingly, the burning time will be noticeably reduced. Therefore, the release of heat will be large, although such fuel will not be enough for a long time.

Cons of wet firewood

Now let's try to figure out why wet firewood is bad.

The main disadvantage 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 fuel in private homes.

Freshly cut wood has a moisture content of 50%. The combustion of one cubic meter releases 2371 kW of energy. If you dry the wood a little, reducing the humidity to 30%, then you can significantly increase the amount of heat generated - up to 2579 kW from the samethe amount of wood. Finally, fuel is considered to be well-dried if its moisture content does not exceed 20%. By 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 savings.

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 it on fire. In a matter of seconds, the flame will scatter over the surface of the firewood, which will soon begin to crackle cheerfully, warming the whole house or bath.

Finally, high humidity leads to the formation of a large amount of soot. It clogs the chimney and gradually worsens the draft. Because of this, fuel burns worse, and there is also an increased risk of blackout due to the accumulation of carbon monoxide in living quarters - it does not smell, therefore it is very dangerous.

Properly dry firewood

As we have already found out, well-dried firewood gives about 15% more heat than freshly cut wood. Therefore, you can burn 15% less fuel, heating your home with high quality. Therefore, the cost of purchasing firewood is significantly reduced. How to achieve such a desired result?

Of course, first of all, you need 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 is, but at the same time were distinguished by worldly ingenuity and wisdom. In other words, firewood needs to be chopped. Optimal log width- four to six centimeters. This size is a good compromise between the burning rate and the amount of heat generated. It also dries them faster, which is also a very important factor.

Dry wood also needs to be done correctly. After cutting 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 and dry quickly. The capillaries shrink fairly quickly, trapping moisture inside. It is almost impossible to remove it from here, and the presence of moisture will affect the combustion temperature of firewood in the stove.

How to determine the burning temperature of firewood?

Many people are interested in knowing what temperature firewood burns in their fireplace or stove. Unfortunately, it is quite difficult to determine this. After all, the temperature of burning oak wood in the oven is about 900 degrees Celsius.

To measure such a high temperature, you need to have a special device - a pyrometer. The thing is rather highly specialized, so you can hardly find it in the nearest hardware store.

Conclusion

This concludes our article. Now you know what the temperature of burning wood in the oven is. And also read about the simplest and most reliable ways to increase this figure. Surely this information will bring a lot of benefits if it is skillfully applied in practice.