Volume of car exhaust gases
Discussion
Seems an appropriate section..
Lets say the average car in the UK has a 1.8 litre engine and cruises at say 2000 revs, and is used for 3 hours a day.
Given that there are around 30 million cars in the UK, say only half are used each day, the volume of exhaust gas emitted per day is:
1.8L x 2000 revs/minute x 180 minutes x 15m =
972,000,000,000,000 litres.
972 thousand billion litres of noxious gases. Per day.
Is that right?
I think I am off to join Greenpeace!
(feel free to point out the errors in my maths, there must be some!)
Lets say the average car in the UK has a 1.8 litre engine and cruises at say 2000 revs, and is used for 3 hours a day.
Given that there are around 30 million cars in the UK, say only half are used each day, the volume of exhaust gas emitted per day is:
1.8L x 2000 revs/minute x 180 minutes x 15m =
972,000,000,000,000 litres.
972 thousand billion litres of noxious gases. Per day.
Is that right?
I think I am off to join Greenpeace!
(feel free to point out the errors in my maths, there must be some!)
What you've calculated is the volume of air ingested by all those cars (and wrongly (most engines are 4 stoke, and don't 100% fill their cylinders at low speeds/throttle openings) not the amount of "polluting gases" (i'll leave the reader to make up their own mind if CO2 is a "pollutant".... ;-)
Max_Torque said:
What you've calculated is the volume of air ingested by all those cars (and wrongly (most engines are 4 stoke, and don't 100% fill their cylinders at low speeds/throttle openings) not the amount of "polluting gases" (i'll leave the reader to make up their own mind if CO2 is a "pollutant".... ;-)
I think this is more correct but you also have to take forced induction into account surely?1.8 litres is the maximum capacity of the engine, and being a 4 stroke, it would only do that after 2 revolutions of the engine.
The majority of the time, the throttle isn't going to be wide open, so it wouldn't be taking in the full amount either.
Then, when it burns the gasses, they expand from being hotter, and from the products of burning being larger in volume than what is put into the engine.
They also start cooling pretty quick and that means the volume shrinks too.
Diesels are also different as they aren't throttled so they take in more air than a petrol engine when compared like for like.
The majority of the time, the throttle isn't going to be wide open, so it wouldn't be taking in the full amount either.
Then, when it burns the gasses, they expand from being hotter, and from the products of burning being larger in volume than what is put into the engine.
They also start cooling pretty quick and that means the volume shrinks too.
Diesels are also different as they aren't throttled so they take in more air than a petrol engine when compared like for like.
A better way to work out exhaust gas mass, is to just look at how long it take to use a tank of fuel!
Typically you might have 50kg of fuel in a tank (~65l) and it might last you a week. On average the air to fuel ratio (by mass) of a gasoline engine is around 14.7:1. So, in a week, your engnie will ingest 14.7*50 = 735kg of air. But of course, the fuel also leaves via the tailpipe, so total exhaust flow is 785kg in a week per car.
(I'll leave you to google a typical exhaust gas density, and to turn that into a volumetric flow.)
Typically you might have 50kg of fuel in a tank (~65l) and it might last you a week. On average the air to fuel ratio (by mass) of a gasoline engine is around 14.7:1. So, in a week, your engnie will ingest 14.7*50 = 735kg of air. But of course, the fuel also leaves via the tailpipe, so total exhaust flow is 785kg in a week per car.
(I'll leave you to google a typical exhaust gas density, and to turn that into a volumetric flow.)
Ayahuasca said:
972 thousand billion litres of noxious gases. Per day.
Is that right?
(feel free to point out the errors in my maths, there must be some!)
Is that right?
(feel free to point out the errors in my maths, there must be some!)
Start by dividing by the air/fuel ratio. I'll take a wild guess at 10:1
Next bear in mind that one of the by-products of combustion is water, which is heavier than CO2.
Others will add their four penn'orth.
1kg of diesel or petrol produces c3.1kg CO2 if that helps!? Diesel, kg for kg, actually emits no less CO2 than petrol when you simplify things.
I can go through the science behind it if you'd like.
With regards volume, well it can't really be calculated as the volume changes with temperature, so it all depends how hot the exhaust gas is being emitted. Hence you'd calculate in KMol and KG.
Also don't forget a lot of what comes out of the exhaust is not noxious. Nitrogen and water aren't noxious.
I can go through the science behind it if you'd like.
With regards volume, well it can't really be calculated as the volume changes with temperature, so it all depends how hot the exhaust gas is being emitted. Hence you'd calculate in KMol and KG.
Also don't forget a lot of what comes out of the exhaust is not noxious. Nitrogen and water aren't noxious.
Edited by miniracer118 on Sunday 29th November 00:33
RizzoTheRat said:
Rovinghawk said:
Next bear in mind that one of the by-products of combustion is water, which is heavier than CO2.
Actually CO2 is about 4 times heavier than water vapour, although I have no idea how much condenses out before exiting the exhaust pipe.Gassing Station | General Gassing | Top of Page | What's New | My Stuff