Calorific value of various fuels. Comparative analysis. Specific heat of combustion of fuel and combustible materials Kcal m3 in mJ

The tables show the mass specific heat of combustion of fuel (liquid, solid and gaseous) and some other combustible materials. The following fuels were considered: coal, firewood, coke, peat, kerosene, oil, alcohol, gasoline, natural gas, etc.

List of tables:

In the exothermic reaction of fuel oxidation, its chemical energy is converted into thermal energy with the release of a certain amount of heat. The emerging thermal energy it is customary to call the heat of combustion of fuel. It depends on its chemical composition, humidity and is the main one. The heat of combustion of fuel per 1 kg of mass or 1 m 3 of volume forms the mass or volumetric specific heat of combustion.

Specific heat of combustion of fuel is the amount of heat released during the complete combustion of a unit of mass or volume of solid, liquid or gaseous fuel. V The international system units, this value is measured in J / kg or J / m 3.

The specific heat of combustion of the fuel can be determined experimentally or calculated analytically. Experimental Methods Calorific value determinations are based on 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 a known chemical composition, the specific heat of combustion can be determined using the Mendeleev formula.

Distinguish between higher and lower specific heats of combustion. The highest calorific value is equal to the maximum amount of heat released during the complete combustion of the fuel, taking into account the heat spent on the evaporation of moisture contained in the fuel. The lowest heat of combustion is less than the value of the highest one 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 is converted 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 performance characteristic of the fuel and is shown 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 dimension MJ / kg. The fuel in the table is sorted alphabetically by name.

The highest calorific value of the considered solid fuels is possessed by coking coal - its specific heat of combustion is equal to 36.3 MJ / kg (or in SI units 36.3 · 10 6 J / kg). In addition, high heat of combustion is characteristic of coal, anthracite, charcoal and lignite coal.

Fuels with low energy efficiency include wood, firewood, gunpowder, milling peat, oil shale. For example, the specific heat of combustion of firewood is 8.4 ... 12.5, and gunpowder - only 3.8 MJ / kg.

Specific heat of combustion of liquid fuel (alcohol, gasoline, kerosene, oil)

The table of specific heats of combustion of liquid fuel and some other organic liquids is given. It should be noted that such fuels as gasoline, diesel fuel and oil are distinguished 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 complete combustion of 1 kg of these hydrocarbons, an amount of heat equal to 9.2 and 13.3 MJ, respectively, will be released.

Specific heat of combustion of gaseous fuel and combustible gases

The table of specific heats of combustion of gaseous fuel and some other combustible gases in terms of MJ / kg is presented. Of the gases considered, 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 - specific heat of combustion natural gas is equal to 41 ... 49 MJ / kg (for a pure 50 MJ / kg).

Specific heat of combustion of some combustible materials

There is a table of specific heats of combustion of some combustible materials (wood, paper, plastic, straw, rubber, etc.). Of note are materials with high combustion heat. These materials include: rubber different types, expanded polystyrene (polystyrene), polypropylene and polyethylene.

Sources:

1. GOST 147-2013 Solid mineral fuel. Determination of gross calorific value and calculation of net calorific value.
2. GOST 21261-91 Petroleum products. Method for determining the gross calorific value and calculating the net calorific value.
3. GOST 22667-82 Natural combustible gases. Calculation method for determining the calorific value, relative density and Wobbe number.
4. GOST 31369-2008 Natural gas. Calculation of calorific value, density, relative density and Wobbe number based on component composition.
5. Zemskiy G.T.

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1 megajoule [MJ] = 1,000,000 watt-seconds [Whs]

Initial value

Converted value

joule gigajoule megajoule kilojoule millijoule microjoule nanojoule picojoule attojoule megaelectronvolt kiloelectronvolt electron volt millielectronvolt microelectronvolt nanoelectronvolt picoelectronvolt erg gigawatt hours megawatt-hours horsepower kilowatt hours -hour international kilocalorie thermochemical kilocalorie international calorie thermochemical calorie large (food) cal. Brit. term. Unit (Int., IT) Brit. term. unit term. mega BTU (Int., IT) ton-hour (refrigeration) equivalent tonne of oil equivalent of a barrel of oil (US) gigatonne megatonne TNT kilotonne TNT tonne TNT dyne-centimeter gram-force-meter gram-force-centimeter kilogram-force-centimeter kilogram -force-meter kilopond-meter pound-force-feet pound-force inches ounce-force inches feet-pounds inch-pounds inch-ounces poundal-feet term (EEC) term (US) Hartree energy equivalent of gigatons of oil equivalent of megatons oil kilobarrel equivalent of oil billion barrels of oil equivalent kilogram of trinitrotoluene Planck energy kilogram reciprocal meter hertz gigahertz terahertz kelvin atomic mass unit

More about energy

General information

Energy is a physical quantity that has great importance in chemistry, physics, and biology. Without it, life on earth and movement are impossible. In physics, energy is a measure of the interaction of matter, as a result of which work is performed or the transition of some types of energy to others occurs. In the SI system, energy is measured in joules. One joule is equal to the energy expended when a body moves one meter by a force of one newton.

Energy in physics

Kinetic and potential energy

Kinetic energy of a body mass m moving at speed v equal to the work done by the force to give the body speed v... Work is defined here as a measure of the action of a force that moves a body a distance s... In other words, it is the energy of a moving body. If the body is at rest, then the energy of such a body is called potential energy. This is the energy required to keep the body in this state.

For example, when a tennis ball hits the racket in flight, it stops momentarily. This is because the forces of repulsion and gravity cause the ball to freeze in the air. At this moment, the ball has potential, but no kinetic energy. When the ball bounces off the racket and flies away, on the contrary, it has kinetic energy. A moving body has both potential and kinetic energy, and one type of energy is converted into another. If, for example, toss up a stone, it will begin to slow down during flight. As this slows down, kinetic energy is converted into potential energy. This transformation takes place until the supply of kinetic energy is exhausted. At this moment, the stone will stop and the potential energy will reach its maximum value. After that, it will begin to fall downward with acceleration, and the transformation of energy will occur in the reverse order. Kinetic energy will peak when the rock hits the ground.

The law of conservation of energy states that the total energy in a closed system is conserved. The energy of the stone in the previous example changes from one form to another, and therefore, despite the fact that the amount of potential and kinetic energy changes during flight and fall, the total sum of these two energies remains constant.

Energy production

People have long learned to use energy to solve labor-intensive tasks with the help of technology. Potential and kinetic energy is used to do work, such as moving objects. For example, the energy of the flow of river water has long been used to obtain flour in water mills. The more people use technology, such as cars and computers, in their daily lives, the more the need for energy increases. Most of the energy today is generated from non-renewable sources. That is, energy is obtained from the fuel extracted from the bowels of the Earth, and it is quickly used, but not renewed at the same rate. Such fuels are, for example, coal, oil and uranium, which are used in nuclear power plants. In recent years, the governments of many countries, as well as many international organizations, for example, the UN, have prioritized the study of the possibilities of obtaining renewable energy from inexhaustible sources using new technologies. Many Scientific research are aimed at obtaining such types of energy at the lowest cost. Currently, sources such as sun, wind and waves are used to obtain renewable energy.

Energy for household and industrial use is usually converted to electricity using batteries and generators. The first power plants in history generated electricity by burning coal or using the energy of water in rivers. Later, they learned to use oil, gas, sun and wind to generate energy. Some large enterprises maintain their power plants on site, but most of the energy is generated not where it will be used, but in power plants. Therefore, the main task of power engineers is to transform the generated energy into a form that allows it to easily deliver energy to the consumer. This is especially important when expensive or hazardous energy production technologies are used that require constant supervision by specialists, such as hydro and nuclear power... That is why electricity was chosen for domestic and industrial use, since it is easy to transmit it with low losses over long distances along power lines.

Electricity is converted from mechanical, thermal and other types of energy. To do this, water, steam, heated gas or air are driven by turbines that rotate generators, where mechanical energy is converted into electrical energy. Steam is produced by heating water using heat generated by nuclear reactions or by burning fossil fuels. Fossil fuels are extracted from the bowels of the earth. These are gas, oil, coal and other combustible materials formed underground. Since their number is limited, they are classified as non-renewable fuels. Renewable energy sources are sun, wind, biomass, ocean energy, and geothermal energy.

In remote areas where there are no power lines, or where due to economic or political issues they regularly cut off electricity, use portable generators and solar panels. Fossil-fueled generators are especially used both in the home and in organizations where electricity is absolutely necessary, such as hospitals. Generators usually run on reciprocating engines, in which fuel energy is converted into mechanical energy. Also popular are uninterruptible power supplies with powerful batteries that charge when power is supplied and release energy during outages.

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(fig.14.1 - Calorific value
fuel ability)

Pay attention to the calorific value (specific heat of combustion) of different fuels, compare the indicators. The calorific value of the fuel characterizes the amount of heat released during the complete combustion of fuel with a mass of 1 kg or a volume of 1 m³ (1 l). Most often, the calorific value is measured in J / kg (J / m³; J / L). The higher the specific heat of combustion of the fuel, the lower its consumption. Therefore, the calorific value is one of the most significant characteristics of the fuel.

The specific heat of combustion of each type of fuel depends on:

• From its combustible components (carbon, hydrogen, volatile combustible sulfur, etc.).
• From its moisture and ash content.

(fig.14.2 - Specific heat of combustion)

According to the table "Specific heat of combustion of various energy carriers, comparative analysis of costs", propane-butane (liquefied petroleum gas) is inferior in economic benefit and prospects of using only natural gas (methane). However, attention should be paid to the trend towards an inevitable increase in the cost of main gas, which is currently significantly underestimated. Analysts predict an imminent reorganization of the industry, which will lead to a significant rise in the price of natural gas, possibly even exceed the cost of diesel fuel.

Thus, liquefied petroleum gas, the cost of which will practically not change, remains extremely promising - the optimal solution for autonomous gasification systems.

Specific volumetric ,
she is specific volumetric heat of combustion of fuel,
she is specific volumetric calorific value of fuel.

Specific volumetric the heat of combustion of fuel is the amount of heat
which is released during the complete combustion of a volumetric unit of fuel.

Online converter for translation

Translation (conversion)
units of volumetric calorific value of fuel
(calorific value per unit volume of fuel)

The mass (weight) specific calorific value is practically the same for all types of fuels of organic origin. And a kilogram of gasoline, and a kilogram of firewood, and a kilogram coal- will give approximately the same amount of heat during their combustion.

It's a different matter - volumetric calorific value... Here, the calorific value of 1 liter of gasoline, 1 dm3 of firewood or 1 dm3 of coal will differ significantly. Therefore, it is the volumetric calorific value that is the most important characteristic of a substance as a type or grade of fuel.

Conversion (conversion) of the volumetric calorific value of fuel is used in heat engineering calculations based on comparative economic or energy characteristics for different types of fuel, or for different grades of one type of fuel. Such calculations (by comparative characteristics for dissimilar fuel) are needed when choosing it as a type or type of energy carrier for alternative heating and heating of buildings and premises. Since various regulatory and accompanying documentation for different grades and types of fuel often contains the value of the calorific value of the fuel in different volume and thermal units, then during the comparison process, when the value of the volumetric calorific value is brought to a single denominator, errors or inaccuracies can easily creep in.

For example:
- The volumetric calorific value of natural gas is measured
in MJ / m3 or kcal / m3 (by)
- The volumetric calorific value of firewood can be easily expressed
in kcal / dm3, Mcal / dm3 or in Gcal / m3

To compare heat and economic efficiency these two types of fuel must be brought to a single unit for measuring the volumetric calorific value. And for this, just such an online calculator is needed.

Calculator test:
1 MJ / m3 = 238.83 kcal / m3
1 kcal / m3 = 0.00419 MJ / m3

For online conversion (translation) of values:
- select the names of the converted values ​​at the input and output
- enter the value of the converted value

The converter gives an accuracy of four decimal places. If, after conversion, only zeros are observed in the "Result" column, then you need to choose another dimension of the converted values ​​or just click on. For, it is impossible to convert a calorie to a Gigacalorie with an accuracy of up to four decimal places.

P.S.
Converting (converting) joules and calories per unit volume is simple mathematics. However, chasing a bunch of zeros overnight is very tedious. So I made this converter to unload the creative process.

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 be calculated in kcal or kW. If the value is related to the unit of measurement of the fuel, it is called specific.

What does the calorific value of different fuels affect? 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 heats 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 during the processing of 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, the fuel is divided into liquid, solid and gas. Each group is additionally branched into a natural and artificial subgroup (+)

When 1 kg of such a "mixture" is burned, a different amount of energy is released. How much of this energy will be released depends on the proportions of these elements - combustible part, moisture, ash content and other components.

The heat of combustion of fuel (TCT) is formed from two levels - the highest and the lowest. The first indicator is obtained due to water condensation, in the second this factor is not taken into account.

The lowest TST 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 installations operating on fuel is determined.

TST can be calculated analytically or experimentally. If chemical composition fuel is known, Mendeleev's formula is applied. Experimental techniques are based on the actual measurement of the combustion heat.

In these cases, a special combustion bomb is used - a calorimetric one together with a calorimeter and a thermostat.

The calculation features are individual for each type of fuel. Example: TCT in internal combustion engines is calculated from the lowest value because no liquid condenses 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.

Internal organic ballast of the fuel is formed from oxygen and nitrogen; these components do not burn and are conditionally included in the composition. External ballast is formed from moisture and ash.

Gasoline has a high specific heat of combustion. Depending on the brand, it is 43-44 MJ.

Similar indicators of 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.

Liquid rocket fuel, ethylene glycol, is characterized by relatively low TST values. Alcohol and acetone differ in the minimum specific heat of combustion. Their performance is significantly lower than that of conventional motor fuels.

Fuel gas properties

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 calorific value. Burning, a kilogram of matter releases 119.83 MJ of heat. But it is distinguished by an increased degree of explosiveness.

Natural gas also has high heating values.

They are equal to 41-49 MJ per kg. But, for example, pure methane has a higher combustion heat - 50 MJ per kg.

Comparative table of indicators

The table shows the values ​​of the mass specific heats of combustion of liquid, solid, gaseous types of fuel.

It can be seen from the table that the highest TST indicators of all substances, and not only of gaseous ones, have hydrogen. It belongs to high-energy fuels.

The combustion product of hydrogen is ordinary water. The process does not emit furnace slags, ash, carbon monoxide and carbon dioxide, which makes the substance an environmentally friendly combustible. 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

About the calorific value of different types of wood. Comparison of indicators per m3 and kg.

TST is the most important thermal and operational characteristic of fuel. This indicator is used in various fields human activity: heat engines, power plants, industry, home heating and food preparation.

Calorific value values ​​help to compare different types of fuel in terms of the degree of energy emitted, calculate the required mass of fuel, and save on costs.

Do you have anything 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 in the lower block.