Thread: Hotter Thread

DO YOU WANT TO KNOW SOMETHING THAT WILL MAKE EVERYONE EVEN HOTTER ???



When the ambient air temp gets hot it causes materials to expand.

When the air temp gets cold, materials contract.

All materials, with a few exceptions that vary a bit like water that has properties of gas, liquid and solids, expand and contract.

When it is hot, atoms move faster in the molecules of the material, causing the molecules to move faster, causing expansion.


Being constantly aware of the expansion and contraction properties of materials is crucial in the heavy construction business, especially in AZ where we have temp differentials of over 100 degrees F.

OK, HERE IS THE PART THAT WILL GET YOU HOT !!!

How does your gasoline pump know how many gallons of gas is being pumped into your vehicle's tank ?

I believe that these pumps are state regulated and monitored by state agencies.

Pumps in AZ are set at 60 degrees F.

I think that is also the nationwide standard.

In other words, the volume of gasoline is calculated in gallons as if it were an ambient air temp of 60 degrees.

So in the summertime, the gasoline molecules expand when the temps are very high. The higher the temp, the more the gasoline molecules expand.

The pump thinks it is 60 degrees F.

So you are getting less gas per gallon because the gasoline is expanded due to the high temps.

You still get a gallon, but it is an expanded gallon with less actual gasoline.

Most experts agree that we pay an extra dollar per gallon when fueling during high temps !

NOW DON'T THAT MAKE YOU HOT ???


*** Please refer any technical molecular physics questions to Loyal Soldier***




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I was told once to fuel up early in the mornings or the coolest part of the day, but never knew why. Thanks for the explanation!

I wonder how many will click on this thread, expecting something juicy!

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Originally Posted by Az Snake

DO YOU WANT TO KNOW SOMETHING THAT WILL MAKE EVERYONE EVEN HOTTER ???



When the ambient air temp gets hot it causes materials to expand.

When the air temp gets cold, materials contract.

All materials, with a few exceptions that vary a bit like water that has properties of gas, liquid and solids, expand and contract.

When it is hot, atoms move faster in the molecules of the material, causing the molecules to move faster, causing expansion.


Being constantly aware of the expansion and contraction properties of materials is crucial in the heavy construction business, especially in AZ where we have temp differentials of over 100 degrees F.

OK, HERE IS THE PART THAT WILL GET YOU HOT !!!

How does your gasoline pump know how many gallons of gas is being pumped into your vehicle's tank ?

I believe that these pumps are state regulated and monitored by state agencies.

Pumps in AZ are set at 60 degrees F.

I think that is also the nationwide standard.

In other words, the volume of gasoline is calculated in gallons as if it were an ambient air temp of 60 degrees.

So in the summertime, the gasoline molecules expand when the temps are very high. The higher the temp, the more the gasoline molecules expand.

The pump thinks it is 60 degrees F.

So you are getting less gas per gallon because the gasoline is expanded due to the high temps.

You still get a gallon, but it is an expanded gallon with less actual gasoline.

Most experts agree that we pay an extra dollar per gallon when fueling during high temps !

NOW DON'T THAT MAKE YOU HOT ???


*** Please refer any technical molecular physics questions to Loyal Soldier***

.

True, but it has no effect thermodynamically, since combustion occurs at a higher temperature as well. Essentially, the energy generated by the increased kinetic energy of ambient gas in the combustion chamber offsets the decreased number of hydrocarbon molecules. This is why the MPG does not vary significantly with temperature.

Originally Posted by Nomad B

I was told once to fuel up early in the mornings or the coolest part of the day, but never knew why. Thanks for the explanation!

That's good advice...I had never thought about this.

Originally Posted by Hawgdriver

True, but it has no effect thermodynamically, since combustion occurs at a higher temperature as well. Essentially, the energy generated by the increased kinetic energy of ambient gas in the combustion chamber offsets the decreased number of hydrocarbon molecules. This is why the MPG does not vary significantly with temperature.

Some have said that gas mileage actually improves during the hotter months due to better fuel combustion. Warmer fuel entering the combustion chamber allows for higher combustability leaving less unused fuel sitting in the piston valve reliefs. Some people say that in the winter months when the fuel and air are colder it is harder to combust and the fuel tends to puddle up on top of a piston.

Personally, I don't care a whole lot...if I did...I wouldn't buy cars that get 10-15 MPG...

Originally Posted by topscribe

I wonder how many will click on this thread, expecting something juicy!

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Wouldn't it be more dangerous to work with gasoline at a higher temperature?

Originally Posted by Hawgdriver

True, but it has no effect thermodynamically, since combustion occurs at a higher temperature as well. Essentially, the energy generated by the increased kinetic energy of ambient gas in the combustion chamber offsets the decreased number of hydrocarbon molecules. This is why the MPG does not vary significantly with temperature.

The mixture of fuel and oxygen are heated, caused by the compression stroke prior to ignition. The MPG does not vary but the GPM does. At the pump you are paying for expanded gasoline during high temps calculated at 60 degrees F. When the temp lowers at night, your fuel gage will too.

Thanks for the thermodynamic view Hawgdriver.




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Originally Posted by Hawgdriver

That's good advice...I had never thought about this.

If you "fill up" early, make sure you use some of it before the ambient temp heats up.

If not, your fuel in your vehicle's tank will expand and dump out of your tank's overflow, wasting dollars.

That's why it's recommended to stop fueling when the nozzle shuts off, don't try to squeeze in extra.

Here in AZ, I never fill my BBQ gas grille's propane tanks full all the way.
I usually only fill 4 gallons in a 5 gallon tank to allow for expansion from high temps. Lots of propane explosions here in AZ.




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Originally Posted by SeeingRed

Some have said that gas mileage actually improves during the hotter months due to better fuel combustion. Warmer fuel entering the combustion chamber allows for higher combustability leaving less unused fuel sitting in the piston valve reliefs. Some people say that in the winter months when the fuel and air are colder it is harder to combust and the fuel tends to puddle up on top of a piston.

Personally, I don't care a whole lot...if I did...I wouldn't buy cars that get 10-15 MPG...

I have had some problems getting older diesel equipment starting in winter conditions.

The oil is thicker, making them harder to turn over to reach optimum heat/compression to fire.

On the diesels, a little starter fluid sprayed on a rag and held around the air intake does the trick.


Older gas combustion vehicles, the same thing.
The thick, cold oil is causing the crank to turn slower.
The cold air may contribute to the problem, but not cold fuel.

When the gasoline is cold, the the hydro carbons are condensed, giving you more gas molecules per volume.

In the days before fuel injection and computers ruled your motors, we used to run our fuel line through a copper coiled line in a canister packed with dry ice.

That gave us a higher concentrate of hydro carbs to atomize with the air mixture out of the fuel jets.

Of course those were old Holley double pumpers with vacuum advance. LOL.

Ah, the good old days, just a carb, a distributor with points and a battery. LOL !!!




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Originally Posted by sneakers

Wouldn't it be more dangerous to work with gasoline at a higher temperature?

The flash point of gasoline is somewhere around -50 degrees F.

The ignition point is around 500+ degrees F.


High temps in AZ are triple digit, up to the 120s.
This year we had over 30 days 110 or more.
Almost every day in the summer is 100+.


Gasoline is always dangerous, but usually there is not a significant problem unless you decide to play with ignition sources.




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Originally Posted by Az Snake

The mixture of fuel and oxygen are heated, caused by the compression stroke prior to ignition. The MPG does not vary but the GPM does. At the pump you are paying for expanded gasoline during high temps calculated at 60 degrees F. When the temp lowers at night, your fuel gage will too.

Thanks for the thermodynamic view Hawgdriver.




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Excellent point...and I can see the flaw in my thinking...thank you. That makes sense, now that I think about why it takes more fuel sometimes to fill my tank (I'm an evil top-off-er) than other times. Great find, AZ Snake.

Originally Posted by Az Snake

I have had some problems getting older diesel equipment starting in winter conditions.

The oil is thicker, making them harder to turn over to reach optimum heat/compression to fire.

On the diesels, a little starter fluid sprayed on a rag and held around the air intake does the trick.


Older gas combustion vehicles, the same thing.
The thick, cold oil is causing the crank to turn slower.
The cold air may contribute to the problem, but not cold fuel.

When the gasoline is cold, the the hydro carbons are condensed, giving you more gas molecules per volume.

In the days before fuel injection and computers ruled your motors, we used to run our fuel line through a copper coiled line in a canister packed with dry ice.

That gave us a higher concentrate of hydro carbs to atomize with the air mixture out of the fuel jets.

Of course those were old Holley double pumpers with vacuum advance. LOL.

Ah, the good old days, just a carb, a distributor with points and a battery. LOL !!!




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Growing up, we had an old wood chipper with an inline six that was a bear to start in the cold. A little bit of ether in the air filter always got 'er going. It worked so well, we started using it on all the engines...then household appliances. We found it had limits.