Calorific value of various types of fuel. Comparative analysis
In this lesson, we will learn how to calculate the amount of heat that fuel releases during combustion. In addition, consider the characteristics of the fuel - the specific heat of combustion.
Since our whole life is based on movement, and movement is mostly based on the combustion of fuel, the study of this topic is very important for understanding the topic " thermal phenomena».
After studying issues related to the amount of heat and specific heat, let's consider the amount of heat released during the combustion of fuel.
Definition
Fuel- a substance that in some processes (combustion, nuclear reactions) releases heat. Is a source of energy.
Fuel happens solid, liquid and gaseous(Fig. 1).
Rice. 1. Types of fuel
- Solid fuels are coal and peat.
- Liquid fuels are oil, gasoline and other petroleum products.
- Gaseous fuels include natural gas.
- Separately, one can single out a very common lately nuclear fuel.
Fuel combustion is a chemical process that is oxidative. During combustion, carbon atoms combine with oxygen atoms to form molecules. As a result, energy is released, which a person uses for his own purposes (Fig. 2).
Rice. 2. Formation of carbon dioxide
To characterize the fuel, such a characteristic is used as calorific value. Calorific value shows how much heat is released during the combustion of fuel (Fig. 3). In calorific physics, the concept corresponds specific heat of combustion of a substance.
Rice. 3. Specific heat combustion
Definition
Specific heat of combustion - physical quantity, which characterizes the fuel, is numerically equal to the amount of heat that is released during the complete combustion of the fuel.
The specific heat of combustion is usually denoted by the letter . Units:
In units of measurement, there is no , since the combustion of fuel occurs at an almost constant temperature.
The specific heat of combustion is determined empirically using sophisticated instruments. However, there are special tables for solving problems. Below we give the values of the specific heat of combustion for some types of fuel.
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Substance |
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Table 4. Specific heat of combustion of some substances
From the given values it can be seen that during combustion a huge amount of heat is released, so the units of measurement (megajoules) and (gigajoules) are used.
To calculate the amount of heat that is released during the combustion of fuel, the following formula is used:
Here: - mass of fuel (kg), - specific heat of combustion of fuel ().
In conclusion, we note that most of the fuel that is used by mankind is stored with the help of solar energy. Coal, oil, gas - all this was formed on Earth due to the influence of the Sun (Fig. 4).
Rice. 4. Formation of fuel
In the next lesson, we will talk about the law of conservation and transformation of energy in mechanical and thermal processes.
Listliterature
- Gendenstein L.E., Kaidalov A.B., Kozhevnikov V.B. / Ed. Orlova V.A., Roizena I.I. Physics 8. - M.: Mnemosyne.
- Peryshkin A.V. Physics 8. - M.: Bustard, 2010.
- Fadeeva A.A., Zasov A.V., Kiselev D.F. Physics 8. - M.: Enlightenment.
- Internet portal "festival.1september.ru" ()
- Internet portal "school.xvatit.com" ()
- Internet portal "stringer46.narod.ru" ()
Homework
Lesson development (lesson notes)
Line UMK A. V. Peryshkin. Physics (7-9)
Attention! The site administration site is not responsible for the content methodological developments, as well as for compliance with the development of the Federal State Educational Standard.
"To warm others, the candle must burn out"
M. Faraday.
Target: To study the issues of using the internal energy of the fuel, the release of heat during the combustion of fuel.
Lesson objectives:
educational:
- repeat and consolidate knowledge on the material covered;
- introduce the concept of fuel energy, specific heat of combustion of fuel;
- continue developing skills in solving computational problems.
developing:
- develop analytical thinking;
- develop the ability to work with tables and draw conclusions;
- develop the ability of students to put forward hypotheses, argue them, competently express their thoughts aloud;
- develop observation and attention.
educational:
- bring up careful attitude to the use of fuel resources;
- to cultivate interest in the subject by showing the connection of the studied material with real life;
- develop communication skills.
Subject Results:
Learners should know:
- the specific heat of combustion of fuel is a physical quantity showing how much heat is released during the complete combustion of fuel weighing 1 kg;
- when fuel is burned, significant energy is released, which is used in everyday life, industry, agriculture, power plants, and road transport;
- a unit of measurement for the specific heat of combustion of fuel.
Learners should be able to:
- explain the process of energy release during the combustion of fuel;
- use the table of specific heat of combustion of fuel;
- compare the specific heat of combustion of fuel various substances and the energy released during combustion various kinds fuel.
Students must apply:
- formula for calculating the energy released during the combustion of fuel.
Lesson type: lesson learning new material.
Equipment: a candle, a plate, a glass, a leaf of a plant, dry fuel, 2 spirit lamps, gasoline, alcohol, 2 test tubes with water.
During the classes
1. Organizing moment.
Greeting students, checking readiness for the lesson.
It is known that the great scientist M. V. Lomonosov worked on the treatise “Reflections on the Cause of Heat and Cold” back in 1744. Thermal phenomena play a huge role in the world around us, in the life of man, plants, animals, as well as in technology.
Let's check how well you have mastered this knowledge.
2. Motivation for learning activities.
Do you have any questions about homework? Let's check how you handled it:
- two students present the solution of home problems on the blackboard.
1) Determine the absolute humidity of the air in a pantry with a volume of 10 m 3 if it contains water vapor weighing 0.12 kg.
2) The pressure of water vapor in the air is 0.96 kPa, the relative humidity of the air is 60%. What is the pressure of saturated water vapor at the same temperature?
- 1 student (Dima) fills in the diagram on the board;
task: sign next to each arrow the name of the processes and the formula for calculating the amount of heat in each of them
- In the meantime, the guys are working at the blackboard, we will complete another task.
Look at the text shown on the slide and find the physical errors in it that the author made (suggest the correct answer):
1) On a bright sunny day, the guys went camping. To make it not so hot, the guys dressed in dark suits. By the evening it became fresh, but after swimming it got warmer. The guys poured themselves hot tea in iron mugs and drank it with pleasure, without getting burned. It was very cool!!!
Answer: dark absorbs heat more; during evaporation, the body temperature decreases; The thermal conductivity of metals is greater, so it heats up more.
2) Waking up earlier than usual, Vasya immediately remembered that at eight in the morning he had agreed with Tolya to go to the river to watch the ice drift. Vasya ran out into the street, Tolya was already there. "Here's the weather today! - instead of a greeting, he said admiringly. “What a sun, and the temperature in the morning is -2 degrees Celsius.” "No, -4," objected Vasya. The boys argued, then realized what was the matter. “I have a thermometer in the wind, and you have it in a secluded place, so yours and shows more”, Tolya guessed. And the boys ran splashing through puddles.
Answer: in the presence of wind, evaporation occurs more intensely, so the first thermometer should show a lower temperature; At temperatures below 00C, water freezes.
Well done, all errors found correctly.
Let's check the correctness of the solution of the problems (the students who solved the problems comment on their solution).
And now let's check how Dima coped with his task.
Did Dima name all the phase transitions correctly? What happens when a wooden stick is placed in a flame? (She will burn)
You correctly noticed that the combustion process is taking place.
Probably, you have already guessed what we will talk about today (put forward hypotheses).
What questions do you think we will be able to answer at the end of the lesson?
- understand the physical meaning of the combustion process;
- find out what determines the amount of heat released during combustion;
- find out the application of this process in life, in everyday life, etc.
3. New material.
Every day we can watch how natural gas burns in a stove burner. This is the combustion process.
Experience number 1. The candle is fixed at the bottom of the plate with plasticine. Light a candle, then close it with a jar. A few moments later, the flame of the candle will go out.
A problematic situation is created, in the solution of which the students conclude: the candle burns in the presence of oxygen.
Questions for the class:
What is involved in the combustion process?
Why does the candle go out? What are the conditions under which combustion takes place?
What is energy released from?
To do this, remember the structure of matter.
What is the substance made of? (from molecules, molecules from atoms)
What types of energy does a molecule have? (kinetic and potential)
Can a molecule be divided into atoms? (Yes)
To divide molecules into atoms, it is necessary to overcome the forces of attraction of atoms, which means that work must be done, that is, energy must be expended.
When atoms combine to form a molecule, on the contrary, energy is released. Such a combination of atoms into molecules occurs during the combustion of fuel. Conventional fuel contains carbon. You correctly determined that combustion is impossible without access to air. During combustion, carbon atoms combine with oxygen atoms in the air, forming a carbon dioxide molecule and releasing energy in the form of heat.
And now let's conduct an experiment and see the simultaneous combustion of several types of fuel: gasoline, dry fuel, alcohol and paraffin (Experiment No. 2).
What is common and how is the combustion of each type of fuel different?
Yes, when any substance is burned, other combustion products are formed. For example, when wood is burned, ash remains and carbon dioxide, carbon monoxide and other gases are released. .
But, the main purpose of fuel is to give heat!
Let's look at another experience.
Experience #3:(on two identical spirit lamps: one filled with gasoline, the other with alcohol, the same amount of water is heated).
Experience questions:
What energy is used to heat water?
And how to determine the amount of heat that went into heating the water?
In which case did the water boil faster?
What conclusion can be drawn from experience?
Which fuel, alcohol or gasoline, gave off more heat during complete combustion? (gasoline is more heat than alcohol).
Teacher: A physical quantity showing how much heat is released during the complete combustion of a fuel weighing 1 kg is called the specific heat of combustion of the fuel, denoted by the letter q. Unit of measure J/kg.
The specific heat of combustion is determined experimentally with rather complex instruments.
The results of the experimental data are shown in the textbook table (p. 128).
Let's work with this table.
Table questions:
- What is the specific heat of combustion of gasoline? (44 MJ/kg)
- What does this mean? (This means that the complete combustion of gasoline weighing 1 kg releases 44 MJ of energy).
- Which substance has the lowest specific heat of combustion? (firewood).
- Which fuel produces the most heat when burned? (hydrogen, since its specific heat of combustion is greater than the others).
- How much heat is released during the combustion of 2 kg of alcohol? How did you define it?
- What do you need to know in order to calculate the amount of heat released during combustion?
They conclude that in order to find the amount of heat, it is necessary to know not only the specific heat of combustion of the fuel, but also its mass.
This means that the total amount of heat Q (J) released during the complete combustion of m (kg) fuel is calculated by the formula: Q = q · m
Let's write in a notebook.
And how to find the mass of combustible fuel from this formula?
Express the specific heat of combustion from the formula. (You can call the student to the board to write formulas)
Physical education minute
We are tired. Let's loosen up a bit. Straighten your back. Straighten your shoulders. I will name the fuel, and if you think that it is solid, lower your head down, if it is liquid, then raise your hands up, and if it is gaseous, pull your hands forward.
Coal is hard.
Natural gas is gaseous.
Oil is liquid.
Wood is solid.
Gasoline is liquid.
Peat is hard.
Anthracite is hard.
Kerosene is liquid.
Coke oven gas is gaseous.
Well done! The most attentive and athletic we have ... Sit down.
Teacher: Guys! Let's think about the question: "The process of combustion is a friend or foe to a person?"
Experience number 4. Let's repeat the experiment with a burning candle, but now we put a leaf of a plant next to the candles.
See what happened to the plant next to the candle flame?
That. when using fuel, one should not forget about the harm of combustion products to living organisms.
4. Fixing.
Guys, tell me please, what is fuel for us? Food plays the role of fuel in the human body. Different types of food, like different types of fuel, contain a different amount of energy. (Show the table on the computer "Specific calorific value of food products").
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Specific calorific value of fuel q, MJ/kg |
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wheat bread |
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Rye bread |
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Potato |
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Beef |
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Chicken's meat |
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Butter |
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Fat cottage cheese |
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Sunflower oil |
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Grape |
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Chocolate roll |
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Creamy ice cream |
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Kirieshki |
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Sweet tea |
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"Coca Cola" |
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Black currant |
I suggest that you unite in groups (1 and 2, 3 and 4 desks) and complete the following tasks (according to the handout). You have 5 minutes to complete, after which we will discuss the results.
Tasks for groups:
- Group 1: when preparing for lessons for 2 hours, you spend 800 kJ of energy. Will you restore your energy reserve if you eat a pack of 28g chips and drink a glass of Coca-Cola (200g)?
- Group 2: how high can a person weighing 70 kg rise if he eats a sandwich with butter (100g wheat bread and 50g butter).
- Group 3: is it enough for you to consume 100 g of cottage cheese, 50 g of wheat bread, 50 g of beef and 100 g of potatoes, 200 g of sweet tea (1 glass) during the day. Required amount energy for a 8th grade student is 1.2 MJ.
- Group 4: how fast should an athlete weighing 60 kg run if he eats a sandwich with butter (100 g of wheat bread and 50 g of butter).
- Group 5: how much chocolate can a teenager weighing 55 kg eat to replenish the energy he expended while reading a book while sitting? (In one hour)
Approximate energy consumption of a teenager weighing 55 kg in 1 hour for various activities
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washing dishes |
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Preparing for lessons |
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Reading to yourself |
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Sitting (at rest) |
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physical exercise |
- Group 6: Will an athlete weighing 70 kg restore energy after swimming for 20 minutes if he eats 50 g of rye bread and 100 g of beef?
Approximate energy consumption of a person in 1 hour for various types of activities (per 1 kg of mass)
The groups present the solution to the problem on a piece of paper, then go to the blackboard in turn and explain it.
5. Reflection. Summary of the lesson.
Let's remember what tasks we set ourselves at the beginning of the lesson? Have we achieved everything?
The guys in a circle speak in one sentence, choosing the beginning of the phrase from the reflective screen on the board:
- today I found out...
- it was interesting…
- it was difficult…
- I did assignments...
- I realized that...
- Now I can…
- I felt that...
- I purchased...
- I learned…
- I managed …
- I was able...
- I'll try…
- surprised me...
- gave me a lesson for life...
- I wanted…
1. What new did you learn in the lesson?
2. Will this knowledge be useful in life?
Grading the lesson for the most active students.
6. D.z
- Paragraph 10
- Task (1 to choose from):
- Level 1: How much heat does 10 kg of charcoal produce when burned?
- Level 2: Complete combustion of oil released 132 kJ of energy. What mass of oil burned?
- Level 3: how much heat is released during the complete combustion of 0.5 liters of alcohol (alcohol density 800 kg / m3)
Mankind, in the course of its evolution, has learned to receive thermal energy by burning different types fuel. The simplest example is a fire made of wood, which was kindled primitive people, and since then peat, coal, gasoline, oil, natural gas - all these are types of fuel, burning which a person receives thermal energy. So what is the specific heat of combustion?
Where does heat come from during combustion?
The process of fuel combustion itself is a chemical, oxidative reaction. Most fuels contain large amounts of carbon C, hydrogen H, sulfur S and other substances. During combustion, C, H, and S atoms combine with O 2 oxygen atoms, resulting in CO, CO 2, H 2 O, SO 2 molecules. In this case, a large amount of thermal energy is released, which people have learned to use for their own purposes.
Rice. 1. Types of fuel: coal, peat, oil, gas.
The main contribution to the heat release is made by carbon C. The second largest contribution is made by hydrogen H.
Rice. 2. Carbon atoms react with oxygen atoms.
What is the specific heat of combustion?
The specific heat of combustion q is a physical quantity equal to the amount of heat released during complete combustion of 1 kg of fuel.
The formula for specific heat of combustion looks like this:
$$q=(Q \over m)$$
Q is the amount of heat released during the combustion of the fuel, J;
m is the mass of fuel, kg.
The unit of q in the international system of units SI is J/kg.
$$[q]=(J \over kg)$$
To denote large values of q, off-system units of energy are often used: kilojoules (kJ), megajoules (MJ) and gigajoules (GJ).
The q values for different substances are determined experimentally.
Knowing q, we can calculate the amount of heat Q, which will result from the combustion of fuel of mass m:
How is the specific heat of combustion measured?
To measure q, devices called calorimeters are used (calor - heat, metreo - measure).
A container with a portion of fuel is burned inside the device. The container is placed in water with a known mass. As a result of combustion, the released heat heats the water. The value of the mass of water and the change in its temperature allow us to calculate the heat of combustion. Next, q is determined by the above formula.
Rice. 3. Measurement of specific heat of combustion.
Where to find q values
Information on the values of specific heat of combustion for specific types of fuel can be found in technical reference books or in their electronic versions on Internet resources. They are usually presented in the form of a table like this:
Specific heat of combustion, q
Resources explored, modern species fuel is limited. Therefore, in the future they will be replaced by other energy sources:
- atomic, using the energy of nuclear reactions;
- solar, converting the energy of sunlight into heat and electricity;
- wind;
- geothermal, using the heat of natural hot springs.
What have we learned?
So, we have learned why a lot of heat is released during the combustion of fuel. To calculate the amount of heat released during the combustion of a certain mass m of fuel, it is necessary to know the value q - the specific heat of combustion of this fuel. The q values were determined experimentally by calorimetry methods and are given in reference books.
Topic quiz
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When a certain amount of fuel is burned, a measurable amount of heat is released. According to the International System of Units, the value is expressed in Joules per kg or m 3. But the parameters can also be calculated in kcal or kW. If the value is related to the unit of measure for the fuel, it is called specific.
What is the calorific value of different fuels? What is the value of the indicator for liquid, solid and gaseous substances? The answers to these questions are detailed in the article. In addition, we have prepared a table showing the specific heat of combustion of materials - this information will be useful when choosing a high-energy type of fuel.
The release of energy during combustion should be characterized by two parameters: high efficiency and the absence of the production of harmful substances.
Artificial fuel is obtained in the process of processing natural -. Regardless of the state of aggregation, substances in their chemical composition have a combustible and non-combustible part. The first is carbon and hydrogen. The second consists of water, mineral salts, nitrogen, oxygen, metals.
According to the state of aggregation, fuel is divided into liquid, solid and gas. Each group further branches into a natural and artificial subgroup (+)
When burning 1 kg of such a "mixture", a different amount of energy is released. How much of this energy will be released depends on the proportions of these elements - the combustible part, humidity, ash content and other components.
The heat of combustion of fuel (HCT) is formed from two levels - higher and lower. The first indicator is obtained due to water condensation, in the second this factor is not taken into account.
The lowest TCT is needed to calculate the need for fuel and its cost, with the help of such indicators, heat balances are compiled and the efficiency of fuel-powered installations is determined.
TST can be calculated analytically or experimentally. If the chemical composition of the fuel is known, the Mendeleev formula is applied. Experimental procedures are based on the actual measurement of heat during fuel combustion.
In these cases, a special combustion bomb is used - a calorimetric bomb together with a calorimeter and a thermostat.
Features of calculations are individual for each type of fuel. Example: TCT in engines internal combustion calculated from the lowest value, because liquid does not condense in the cylinders.
Parameters of liquid substances
Liquid materials, like solid ones, are decomposed into the following components: carbon, hydrogen, sulfur, oxygen, nitrogen. The percentage is expressed by weight.
The internal organic fuel ballast is formed from oxygen and nitrogen; these components do not burn and are included in the composition conditionally. The outer ballast is formed from moisture and ash.
High specific heat of combustion is observed in gasoline. Depending on the brand, it is 43-44 MJ.
Similar indicators of the specific heat of combustion are also determined for aviation kerosene - 42.9 MJ. Diesel fuel also falls into the category of leaders in terms of calorific value - 43.4-43.6 MJ.
Relatively low TST values are characteristic of liquid rocket fuel, ethylene glycol. Alcohol and acetone differ in the minimum specific heat of combustion. Their performance is significantly lower than that of traditional motor fuel.
Properties of gaseous fuel
Gaseous fuel consists of carbon monoxide, hydrogen, methane, ethane, propane, butane, ethylene, benzene, hydrogen sulfide and other components. These figures are expressed as a percentage by volume.
Hydrogen has the highest heat of combustion. When burning, a kilogram of a substance releases 119.83 MJ of heat. But it has a high degree of explosiveness.
High calorific values are also observed in natural gas.
They are equal to 41-49 MJ per kg. But, for example, pure methane has a higher heat of combustion - 50 MJ per kg.
Comparative table of indicators
The table shows the values of the mass specific heat of combustion of liquid, solid, gaseous fuels.
| Type of fuel | Unit rev. | Specific heat of combustion | ||
| MJ | kW | kcal | ||
| Firewood: oak, birch, ash, beech, hornbeam | kg | 15 | 4,2 | 2500 |
| Firewood: larch, pine, spruce | kg | 15,5 | 4,3 | 2500 |
| Brown coal | kg | 12,98 | 3,6 | 3100 |
| Coal | kg | 27,00 | 7,5 | 6450 |
| Charcoal | kg | 27,26 | 7,5 | 6510 |
| Anthracite | kg | 28,05 | 7,8 | 6700 |
| wood pellet | kg | 17,17 | 4,7 | 4110 |
| Straw pellet | kg | 14,51 | 4,0 | 3465 |
| sunflower pellet | kg | 18,09 | 5,0 | 4320 |
| Sawdust | kg | 8,37 | 2,3 | 2000 |
| Paper | kg | 16,62 | 4,6 | 3970 |
| Vine | kg | 14,00 | 3,9 | 3345 |
| Natural gas | m 3 | 33,5 | 9,3 | 8000 |
| Liquefied gas | kg | 45,20 | 12,5 | 10800 |
| Petrol | kg | 44,00 | 12,2 | 10500 |
| Diz. fuel | kg | 43,12 | 11,9 | 10300 |
| Methane | m 3 | 50,03 | 13,8 | 11950 |
| Hydrogen | m 3 | 120 | 33,2 | 28700 |
| Kerosene | kg | 43.50 | 12 | 10400 |
| fuel oil | kg | 40,61 | 11,2 | 9700 |
| Oil | kg | 44,00 | 12,2 | 10500 |
| Propane | m 3 | 45,57 | 12,6 | 10885 |
| Ethylene | m 3 | 48,02 | 13,3 | 11470 |
The table shows that hydrogen has the highest TST of all substances, and not only of gaseous ones. It belongs to high-energy fuels.
The combustion product of hydrogen is ordinary water. The process does not emit furnace slag, ash, carbon monoxide and carbon dioxide, which makes the substance an environmentally friendly fuel. But it is explosive and has a low density, so such fuel is difficult to liquefy and transport.
Conclusions and useful video on the topic
On the calorific value of different types of wood. Comparison of indicators per m 3 and kg.
TST is the most important thermal and operational characteristic of fuel. This indicator is used in various fields of human activity: heat engines, power plants, industry, home heating and cooking.
Calorific values help to compare different types of fuel in terms of the degree of energy released, calculate the required mass of fuel, and save on costs.
Do you have something to add, or do you have questions about the calorific value of different types of fuel? You can leave comments on the publication and participate in discussions - the contact form is located in the lower block.
The tables present the mass specific heat of combustion of fuel (liquid, solid and gaseous) and some other combustible materials. Fuels such as: coal, firewood, coke, peat, kerosene, oil, alcohol, gasoline, natural gas, etc. are considered.
List of tables:
In an exothermic fuel oxidation reaction, its chemical energy is converted into thermal energy with the release of a certain amount of heat. The resulting thermal energy is called the heat of combustion of the fuel. It depends on its chemical composition, humidity and is the main one. The calorific value of fuel, referred to 1 kg of mass or 1 m 3 of volume, forms the mass or volumetric specific calorific value.
The specific heat of combustion of fuel is the amount of heat released during the complete combustion of a unit mass or volume of solid, liquid or gaseous fuel. In the International System of Units, this value is measured in J / kg or J / m 3.
The specific heat of combustion of a fuel can be determined experimentally or calculated analytically. Experimental methods for determining the calorific value are based on the practical measurement of the amount of heat released during the combustion of fuel, for example, in a calorimeter with a thermostat and a combustion bomb. For fuel with known chemical composition the specific heat of combustion can be determined from Mendeleev's formula.
There are higher and lower specific heats of combustion. The gross calorific value is equal to the maximum amount of heat released during complete combustion of the fuel, taking into account the heat spent on the evaporation of the moisture contained in the fuel. The lower calorific value is less than the higher value by the value of the heat of condensation, which is formed from the moisture of the fuel and the hydrogen of the organic mass, which turns into water during combustion.
To determine fuel quality indicators, as well as in heat engineering calculations usually use the lowest specific heat of combustion, which is the most important thermal and operational characteristic of the fuel and is given in the tables below.
Specific heat of combustion of solid fuel (coal, firewood, peat, coke)
The table shows the values of the specific heat of combustion of dry solid fuel in the unit of MJ/kg. The fuel in the table is arranged by name in alphabetical order.
Of the considered solid fuels, coking coal has the highest calorific value - its specific heat of combustion is 36.3 MJ/kg (or 36.3·10 6 J/kg in SI units). In addition, high calorific value is characteristic of coal, anthracite, charcoal and brown coal.
Fuels with low energy efficiency include wood, firewood, gunpowder, freztorf, oil shale. For example, the specific heat of combustion of firewood is 8.4 ... 12.5, and gunpowder - only 3.8 MJ / kg.
| Fuel | |
|---|---|
| Anthracite | 26,8…34,8 |
| Wood pellets (pillets) | 18,5 |
| Firewood dry | 8,4…11 |
| Dry birch firewood | 12,5 |
| gas coke | 26,9 |
| blast-furnace coke | 30,4 |
| semi-coke | 27,3 |
| Powder | 3,8 |
| Slate | 4,6…9 |
| Oil shale | 5,9…15 |
| Solid propellant | 4,2…10,5 |
| Peat | 16,3 |
| fibrous peat | 21,8 |
| Milling peat | 8,1…10,5 |
| Peat crumb | 10,8 |
| Brown coal | 13…25 |
| Brown coal (briquettes) | 20,2 |
| Brown coal (dust) | 25 |
| Donetsk coal | 19,7…24 |
| Charcoal | 31,5…34,4 |
| Coal | 27 |
| Coking coal | 36,3 |
| Kuznetsk coal | 22,8…25,1 |
| Chelyabinsk coal | 12,8 |
| Ekibastuz coal | 16,7 |
| freztorf | 8,1 |
| Slag | 27,5 |
Specific heat of combustion of liquid fuel (alcohol, gasoline, kerosene, oil)
The table of specific heat of combustion of liquid fuel and some other organic liquids is given. It should be noted that fuels such as gasoline, diesel fuel and oil are characterized by high heat release during combustion.
The specific heat of combustion of alcohol and acetone is significantly lower than traditional motor fuels. In addition, liquid rocket fuel has a relatively low calorific value and, with the complete combustion of 1 kg of these hydrocarbons, an amount of heat equal to 9.2 and 13.3 MJ, respectively, will be released.
| Fuel | Specific heat of combustion, MJ/kg |
|---|---|
| Acetone | 31,4 |
| Gasoline A-72 (GOST 2084-67) | 44,2 |
| Aviation gasoline B-70 (GOST 1012-72) | 44,1 |
| Gasoline AI-93 (GOST 2084-67) | 43,6 |
| Benzene | 40,6 |
| Winter diesel fuel (GOST 305-73) | 43,6 |
| Summer diesel fuel (GOST 305-73) | 43,4 |
| Liquid propellant (kerosene + liquid oxygen) | 9,2 |
| Aviation kerosene | 42,9 |
| Lighting kerosene (GOST 4753-68) | 43,7 |
| xylene | 43,2 |
| High sulfur fuel oil | 39 |
| Low-sulfur fuel oil | 40,5 |
| Low sulfur fuel oil | 41,7 |
| Sulphurous fuel oil | 39,6 |
| Methyl alcohol (methanol) | 21,1 |
| n-Butyl alcohol | 36,8 |
| Oil | 43,5…46 |
| Oil methane | 21,5 |
| Toluene | 40,9 |
| White spirit (GOST 313452) | 44 |
| ethylene glycol | 13,3 |
| Ethyl alcohol (ethanol) | 30,6 |
Specific heat of combustion of gaseous fuel and combustible gases
A table of the specific heat of combustion of gaseous fuel and some other combustible gases in the dimension of MJ/kg is presented. Of the considered gases, the largest mass specific heat of combustion differs. With the complete combustion of one kilogram of this gas, 119.83 MJ of heat will be released. Also, a fuel such as natural gas has a high calorific value - the specific heat of combustion of natural gas is 41 ... 49 MJ / kg (for pure 50 MJ / kg).
| Fuel | Specific heat of combustion, MJ/kg |
|---|---|
| 1-Butene | 45,3 |
| Ammonia | 18,6 |
| Acetylene | 48,3 |
| Hydrogen | 119,83 |
| Hydrogen, mixture with methane (50% H 2 and 50% CH 4 by mass) | 85 |
| Hydrogen, mixture with methane and carbon monoxide (33-33-33% by weight) | 60 |
| Hydrogen, mixture with carbon monoxide (50% H 2 50% CO 2 by mass) | 65 |
| Blast Furnace Gas | 3 |
| coke oven gas | 38,5 |
| LPG liquefied hydrocarbon gas (propane-butane) | 43,8 |
| Isobutane | 45,6 |
| Methane | 50 |
| n-butane | 45,7 |
| n-Hexane | 45,1 |
| n-Pentane | 45,4 |
| Associated gas | 40,6…43 |
| Natural gas | 41…49 |
| Propadien | 46,3 |
| Propane | 46,3 |
| Propylene | 45,8 |
| Propylene, mixture with hydrogen and carbon monoxide (90%-9%-1% by weight) | 52 |
| Ethane | 47,5 |
| Ethylene | 47,2 |
Specific heat of combustion of some combustible materials
A table is given of the specific heat of combustion of some combustible materials (, wood, paper, plastic, straw, rubber, etc.). It should be noted materials with high heat release during combustion. Such materials include: rubber of various types, expanded polystyrene (polystyrene), polypropylene and polyethylene.
| Fuel | Specific heat of combustion, MJ/kg |
|---|---|
| Paper | 17,6 |
| Leatherette | 21,5 |
| Wood (bars with a moisture content of 14%) | 13,8 |
| Wood in stacks | 16,6 |
| Oak wood | 19,9 |
| Spruce wood | 20,3 |
| wood green | 6,3 |
| Pine wood | 20,9 |
| Kapron | 31,1 |
| Carbolite products | 26,9 |
| Cardboard | 16,5 |
| Styrene-butadiene rubber SKS-30AR | 43,9 |
| Natural rubber | 44,8 |
| Synthetic rubber | 40,2 |
| Rubber SCS | 43,9 |
| Chloroprene rubber | 28 |
| Polyvinyl chloride linoleum | 14,3 |
| Two-layer polyvinyl chloride linoleum | 17,9 |
| Linoleum polyvinylchloride on a felt basis | 16,6 |
| Linoleum polyvinyl chloride on a warm basis | 17,6 |
| Linoleum polyvinylchloride on a fabric basis | 20,3 |
| Linoleum rubber (relin) | 27,2 |
| Paraffin solid | 11,2 |
| Polyfoam PVC-1 | 19,5 |
| Polyfoam FS-7 | 24,4 |
| Polyfoam FF | 31,4 |
| Expanded polystyrene PSB-S | 41,6 |
| polyurethane foam | 24,3 |
| fibreboard | 20,9 |
| Polyvinyl chloride (PVC) | 20,7 |
| Polycarbonate | 31 |
| Polypropylene | 45,7 |
| Polystyrene | 39 |
| High density polyethylene | 47 |
| Low-pressure polyethylene | 46,7 |
| Rubber | 33,5 |
| Ruberoid | 29,5 |
| Soot channel | 28,3 |
| Hay | 16,7 |
| Straw | 17 |
| Organic glass (plexiglass) | 27,7 |
| Textolite | 20,9 |
| Tol | 16 |
| TNT | 15 |
| Cotton | 17,5 |
| Cellulose | 16,4 |
| Wool and wool fibers | 23,1 |
Sources:
- GOST 147-2013 Solid mineral fuel. Determination of the higher calorific value and calculation of the lower calorific value.
- GOST 21261-91 Petroleum products. Method for determining the gross calorific value and calculating the net calorific value.
- GOST 22667-82 Combustible natural gases. Calculation method for determining the calorific value, relative density and Wobbe number.
- GOST 31369-2008 Natural gas. Calculation of calorific value, density, relative density and Wobbe number based on component composition.
- Zemsky G. T. Flammable properties of inorganic and organic materials: reference book M.: VNIIPO, 2016 - 970 p.