How Does Gas Volume Change After Combustion in an Engine?

In summary, the conversation discusses the question of the volume relationship between unburned and final exhaust gases in an air-gasoline stoichiometric mixture. The participants consider the importance of temperature and engine conditions and suggest conducting experiments in a lab to determine the exact volume of gases produced during combustion. They also mention the gas laws and suggest doing a mass balance to calculate the volume at a specific temperature.
  • #1
CHICAGO
50
0
Hi you all

Seaching in internet, I have not found an answer to this:

In a air-gasoline stechiometric mixture, what can be the volumen relationship between the unburned (intake gas) and final exhaust gases?.

I guess temperature is important, but let's consider a normal working temperature for that engine. And let's also consider the cylinder is filled at 1 bar.

I just only want to have an idea of how much the gas is expanded after combustion.

Thanks in advance.
 
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  • #2
may i ask why this is important?
 
  • #3
Under quasi-static conditions, the ratio of volumes before and after combustion is approximately the compression ratio of the engine (since the volume is dictated by the geometry of the swept combustion chamber, not by the gases!). This is pretty meaningless. For an approximate "final" exhaust gas volume, just assume it's air at whatever temperature you're interested in. For an accurate "final" exhaust gas volume, you need to know the exact temperature, fuel type, and air-fuel ratio.
 
  • #4
Brewnog ..you are good!
wish i said that...
 
  • #5
I know what you mean, but I assume a volumen of air-gasoline stechiometric mixture at 1 bar pressure.What is the volumen at 1 bar pressure of the ignited result gases?.

We better forget this gas in a engine, and let's do the test in a lab. We have 1 cubic inch of that stech. mixture and we flame it. How many cubic inches of gas (whatever gases are those) do we get out of that combustion?

I do not know if I exposed the question properly. Sorry if it is not.

.
 
  • #6
see Post titled gas pressure in internal combustion gasoline engine
in this forum a few days ago
 
  • #7
CHICAGO said:
I know what you mean, but I assume a volumen of air-gasoline stechiometric mixture at 1 bar pressure.What is the volumen at 1 bar pressure of the ignited result gases?.

We better forget this gas in a engine, and let's do the test in a lab. We have 1 cubic inch of that stech. mixture and we flame it. How many cubic inches of gas (whatever gases are those) do we get out of that combustion?

I do not know if I exposed the question properly. Sorry if it is not.

.

It depends. Do a mass balance and then convert to volume at whatever temperature you're in. Just think back to the gas laws.
 

Related to How Does Gas Volume Change After Combustion in an Engine?

1. How does gas expansion occur in an engine?

When fuel is ignited in the engine's combustion chamber, it creates a controlled explosion. This explosion creates a rapid increase in temperature and pressure, causing the gas to expand and push against the pistons, which in turn, powers the engine.

2. What factors affect gas expansion in an engine?

The temperature and pressure of the gas, as well as the volume of the combustion chamber, can affect the expansion of gas in an engine. Other factors such as the type of fuel, air-to-fuel ratio, and engine design can also impact gas expansion.

3. How does gas expansion contribute to an engine's performance?

Gas expansion is a crucial component in an engine's performance. It provides the necessary force to move the pistons, which in turn, generates power to rotate the engine's crankshaft. The more efficient the gas expansion, the more power the engine can produce.

4. Can gas expansion be controlled in an engine?

Yes, gas expansion can be controlled in an engine through various methods. The air-to-fuel ratio, ignition timing, and turbochargers are all ways to regulate the temperature and pressure of the gas, thereby controlling its expansion and optimizing engine performance.

5. What are the potential problems with gas expansion in an engine?

If the gas expands too quickly or unevenly in the combustion chamber, it can cause knocking or detonation, which can damage the engine. In addition, if the gas expansion is not properly managed, it can lead to decreased fuel efficiency and increased emissions.

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