Submitted by [deleted] t3_z7iqnq in explainlikeimfive
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Submitted by [deleted] t3_z7iqnq in explainlikeimfive
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Didn't ask the question but love this answer, thanks for simplifying that process for me
When gas burns in air, it becomes a gas and gets hot. When a gas gets hot it expands. When a gas expands, it can push things.
So we trap it in a tube, burn it, and when the gas in the tub expands it pushes on a 'cap'. When the cap moves it pushes the wheels forward. Do this a thousand times a minute and you've got a decent amount of energy for a car.
"when gas burns in air, it becomes a gas" 😂
Gasoline does not refer to a gas, ironically
The fuel is pumped into the engine as an atomized mist. The perfect ratio is 1 part of fuel to 14.7 parts air.
So that air fuel mixture (the fuel is atomized, so it’s even distributed) then gets compressed by the engine to roundabout 1/10th of it’s original volume. For example, if each cylinder in the engine is 0.5 Liters, then that 0.5 L gets compressed 10x to fit into 0.05 L.
That’s when the spark plug creates an electric arc, igniting the compressed air/fuel mixture. Now, this is where all the chemistry comes to bear. The oxygen in the 14.7 parts of air is what actually burns. But the 1 part of fuel mixed evenly throughout the air is what spreads the flame quickly and evenly throughout the air. It works like an accelerant, kind of like lighter fluid on a barbecue.
The spark lights the fuel on fire, which then burns all the air… this creates a violent explosion and rapid expansion of hot gases that force the engine to spin and create usable power.
It is flammable. If you put it in a squirter bottle and sprayed some in a metal cup, put the cup upside down, and lit it, the cup would be pushed up. Engines basically do this specially designed metal cups called pistons. The pistons are aligned in a way where each time they are pushed up they spin a shaft. Then fancy engineering makes it so these explosions that push the pistons up can happen 1000s of times per second.
It gets mixed with air just before going into the engine, once it's mixed with air and is no longer a liquid, it's pretty flammable.. at a certain time a sparkplug creates a spark that sets off the burning (about the highest point in the pistons motion so the expanding flames help push the piston down with extra force, enough to rotate a shaft attached to the tires)
The thing mixing the liquid with air is called a carburetor, there's plenty of videos about them on YouTube for free, a channel called smarter every day did a whole deep dive and built a clear one that he shows working up close and in slow motion and I think it'd answer all questions about them
your engine is made up from a bunch of pistons in a chamber which go up and down. all the pistons connect to a rod which they spin when they go up and down. gasoline is a liquid that can catch on fire and explode very easily. a spark plug is a device at the top of the chamber which creates sparks.
when a piston goes down, gasoline and air are sucked in to the chamber. then when it goes back up the spark plug makes a little spark that makes the gasoline explode. this explosion pushes the piston back down and makes the rod spin. the rod that they spin is connected to the wheels which makes the car move. these explosions happen thousands of times per minute and keep the engine spinning
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Typical gasoline readily ignites when aerosolized, but is very stable as a liquid (Makes it relatively easy and safe to transport). You could throw a lit match into a barrel of gas and it would most likely just go out, assuming there were no gas vapors present.
A car uses devices such as a carburetor or fuel injectors to purposely aerosolize the liquid gasoline in tiny, tiny spurts, mix it with air and then ignite it using the spark plugs. This creates a small explosion. The power of the explosion in the engine moves a piston. The piston movement turns other stuff and yada yada ultimately powers the car.
So a whole match ON FIRE can fail to ignite a barrel of gasoline, but a teeny tiny spark (from the spark plugs), under the right circumstances, can light a tiny aeresolized and oxygen-rich charge of fuel, and turn that into energy.
As you say it's just a liquid, it doesn't 'work' at all, and it certainly doesn't power cars. The burning of gasoline, really the exploding of gasoline, is what powers internal combustion engines.
Gasoline is ignited with a spark, inside a container, where the only escape route for the explosion is the direction we need to apply force.
Moskau50 t1_iy6swfk wrote
Gasoline liquid evaporates very easily to gasoline vapor. Gasoline vapor is highly flammable. So if you take gasoline vapor, mix it with air, and then cause a spark, it will burst into flames. If you put that explosion into a sealed container, that burst of flame becomes an explosion. If you only partially seal the container, plugging one side with a movable piston, the explosion will push the piston outwards. If you hook up that piston to a rotating crankshaft, the motion of the piston blowing outwards from the cylinder can be used to turn the crankshaft.
If you use some mechanical or electronic systems to regularly put gasoline vapor and air into the cylinder, spark it to ignite it, and then open a vent to get rid of the combustion gases, then you can turn that gasoline liquid/vapor into steady rotational energy in the crankshaft. You can hook the crankshaft up to whatever you want; a transmission to power a car, or an alternator to generate electrical power.