Understanding Combustion Energy: Types, Distribution, and Details

In summary: Then the heat is converted to other forms, depending on what we want (pressure, mechanical, light), depending on the type of engine.
  • #1
physior
182
1
hello!

I tried to find online but no luck

can you tell me please what is exactly the energy from a combustion? let's say of 1 mole of gasoline

is it mechanical waves? it is light? is it temperature?

I need to know the details, how much of it in the various types of energy, and what exactly type of energy

any hint?

thanks!
 
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  • #2
It is thermal energy (heat). Depending on the method of combustion it may be released without light(radiation), but typically a significant fraction is radiation. The rest is released through conduction/convection from the exhaust gases (in a heater) or pressure drop (in a piston).
 
  • #3
Like russ said, what you get from combustion is heat. The fuel is said to posses chemical energy. On combustion, it releases heat or thermal energy. This heat can be converted to various forms based on our requirements.
 
  • #4
but it's not heat that drives a piston, but mechanical waves because of the rapid expansion of air due to the rapid production of many gases
what is this percentage?

also, what is the amount/percentage of light energy?
 
  • #5
physior said:
but it's not heat that drives a piston, but mechanical waves because of the rapid expansion of air due to the rapid production of many gases
what is this percentage?

also, what is the amount/percentage of light energy?
In the combustion chamber, the temperature of the working fluid goes as high as 2000 °C. This causes the pressure of the gases in the combustion chamber to increase to a great extent. This high pressure pushes down the piston. So basically, heat is converted to mechanical energy.
 
  • #6
The heat of combustion is a precisely defined quantity. It assumes that you start out with 1 mole of the material being combusted (say gasoline) and a stoichiometric quantity of oxygen, both at 25 C and 1 atm, and you end up, after complete reaction, with the reaction products at 25 C and 1 atm in your calorimeter. The heat of combustion is the amount of heat you need to remove from the calorimeter to achieve this final state.

Chet
 
  • #7
physior said:
but it's not heat that drives a piston, but mechanical waves because of the rapid expansion of air due to the rapid production of many gases
what is this percentage?
Not "waves", just pressure. But yes, that's what I said. Recognize though that pressure energy and thermal energy are related and the release of pressure energy also releases thermal energy. So it is both that are driving the piston (and the thermal energy created most of the pressure energy anyway).

As I said, the ratio varies, but in a car about 30% is converted in that way.
also, what is the amount/percentage of light energy?
Again it varies, but in a car it is pretty small: a fraction of the heat loss in the engine block. Maybe 5-10% of the total.
 
  • #8
siddharth23 said:
In the combustion chamber, the temperature of the working fluid goes as high as 2000 °C. This causes the pressure of the gases in the combustion chamber to increase to a great extent. This high pressure pushes down the piston. So basically, heat is converted to mechanical energy.
Thats a good way to put it: chemical energy is converted to heat a
 
Last edited by a moderator:

1. What is combustion energy?

Combustion energy is the energy released when a substance reacts with oxygen, resulting in the production of heat and light.

2. What are the different types of combustion?

The three main types of combustion are complete, incomplete, and spontaneous. Complete combustion occurs when there is a sufficient supply of oxygen and results in the production of carbon dioxide and water. Incomplete combustion occurs when there is a limited supply of oxygen and results in the production of carbon monoxide and/or soot. Spontaneous combustion occurs when a substance ignites without an external source of heat.

3. How is combustion energy distributed?

Combustion energy is typically distributed through the transfer of heat. This can occur through conduction, convection, or radiation. Conduction is the transfer of heat through direct contact, convection is the transfer of heat through the movement of fluids, and radiation is the transfer of heat through electromagnetic waves.

4. What factors affect combustion energy?

The amount of oxygen available, the type of fuel being burned, and the temperature of the reaction are all factors that can affect combustion energy. In addition, the presence of impurities or inhibitors in the fuel can also impact the energy released during combustion.

5. Why is understanding combustion energy important?

Understanding combustion energy is crucial for a variety of industries, including energy production, transportation, and manufacturing. It also plays a significant role in environmental impacts, as combustion is a major source of air pollution and greenhouse gas emissions. By understanding the different types, distribution, and details of combustion energy, scientists can work towards more efficient and sustainable energy solutions.

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