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Post by Antigone68104 on Jun 23, 2013 3:13:30 GMT
That silly e-mail about only buying gasoline when it's cool so you get more for your buck is going around again, possibly because it's stinky hot around here right now.
I know this was posted regularly on the old Disco boards, but I think this would work for either another minimyth special or "filler" for another episode on fuel mileage.
Testing: Find a gas station owner who will let the guys lower a thermometer into the underground fuel tanks. Once they have an average temperature for gas waiting to be bought, chill a measured amount of gas by 15-20 degrees or so and see if the amount "shrinks". If there's no difference, ramp it up -- see just how cold they can get gas without freezing it, and see if that has a measurable effect on how much fuel is in the container.
I'd like to also test warmer temperatures, but I can't come up with a way to keep the gas from evaporating in the process, giving a false result. And depending on just how the gas is being warmed, those tests come with a chance of missing eyebrows.
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Post by Cybermortis on Jun 23, 2013 12:52:51 GMT
Here's something you might not know - There are two types of gasoline sold at the pump, 'winter' and 'summer'. These have different vaporisation temperatures.
Evaporation should not be a problem in this case, since gasoline is usually stored in sealed containers (including the fuel tank of a car). So they could just put the gasoline in sealed containers to be chilled and warmed as needed. As long as they don't try to heat the gasoline to the point where the pressure rises more than the limits of the container this should be safe enough - and doing this in the small scale would allow them to run any tests safely in the bunker anyway.
Heating the gasoline safely should be simple. Instead of having a heating element in the container, you place the container in a pan of water and heat the water - the heating element for a fish-tank might be ideal for this - cheap, safe and provides gentle heating. Chilling might be more of a problem, but maybe they could get an old refrigerator and run up something that can cool the water accurately enough for their needs? The science and build are technically simple, although I suspect that the execution is a different matter...
The containers would need to be clear so the level of the gasoline can be seen with ease. I'm thinking that heavy duty test tubes with a cap would be perfect for this. They are cheap and easy to get hold of, can show what is or is not going on without having to use dangerous amounts of gasoline, are small enough that the rig needed should be small and easy to set up - especially when it comes to heating/chilling as this could be done in a beaker of water rather than a pan or bucket. Add a little dye to the gasoline so you can see it more clearly on film and...done.
I'd say that they should test 'average' temperatures between 0-40 degrees centigrade in either five or ten degrees increments.
I'm also thinking that putting temperature probes into a real fuel tank might be difficult to arrange. But there is a simple way around this. What they are looking for is the temperatures underground tanks reach, which doesn't automatically mean 'gas tank'. MB could create a number of small tanks and bury them at the correct depth - I *think* that different locations have different laws/rules for how deep tanks need to be and of course you can get above ground tanks too. So if they build several small tanks they can bury them at the most common depths and have one above ground, fit them with temperature gages, fill them with water and then collect data over the course of a week or two - they should look for the difference between air and ground temperatures which might allow them to make an educated guess as to the temperatures tanks may reach in different conditions.
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Post by OziRiS on Jun 23, 2013 16:24:20 GMT
Other than the small addition that they should remember to find out how actual underground gas tanks are insulated, I think you've pretty much covered all the aspects of this one. Let's see if they pick it up
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Post by Cybermortis on Jun 23, 2013 17:10:43 GMT
Other than the small addition that they should remember to find out how actual underground gas tanks are insulated, I think you've pretty much covered all the aspects of this one. Let's see if they pick it up I thought that I'd noted that their small tanks should be constructed (and of course installed) exactly like existing fuel tanks are - and as they are making their own they should be able to create 'older' style tanks should their be any significant difference in construction/design. Of course I THOUGHT this...and forgot to actually SAY it...DOH!
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Post by the light works on Jun 23, 2013 21:49:41 GMT
I think modern fuel tank monitors include a thermal transducer for monitoring the temperature.
modern underground tanks have the fuel tank, then a layer of supporting media, then the external containment tank. then a minimum of 3 feet of soil, if the tank is buried under the lot, where cars will be driving over it.
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Post by Antigone68104 on Jun 23, 2013 23:31:53 GMT
That empty lot beside M5 got sold and developed, didn't it? Pity, because they would have had no problem digging a deep enough hole for test tanks there.
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Post by silverdragon on Jun 24, 2013 8:53:39 GMT
There is this thing about layering in ponds that can be helpful.
In any large body of water, the surface ill heat up, but only to a certain depth..... lakes, ponds, and the rest...
That certain depth is 8ft, or as near as makes no difference.
Therefore, when considering filtration for a Koi pond, as I did, you have to make the decision to separate the filtration to allow this layering or not, and what depth your pond will be, may alter things.
So, in an open pond, the sun will only warm the top 8ft.
I think most below ground gas tanks are below that depth anyway?...
I therefore say that if the weather will affect the density of petrol in underground tanks, it will depend on the trend of degree-day weather warming the ground.... As in, a few hot days continuously may warm the ground up, and that heat MAY transfer to the petrol in the tank.... But changes in weather will take a few days to make any difference, and one cold night will not.
Pumping Petrol on a cold morning will not affect how MUCH petrol you get, when compared to a warm afternoon... Of if it does, I would say precious few millilitres or cc's difference?...(Per [x] number of gallons... I like to mix up my volumes between Imp and metric to confuse.....)
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Post by silverdragon on Jun 24, 2013 9:02:04 GMT
Idea..... Can they go back to where they did that full scale test on exploding sewers.... Can they install a sizeable tank in the hole?... and bury it?... Filled with Water.... reason is one of safety, and I dont think it actually matters if its water or petrol?.... Can they monitor the temp of that tank?... as various depths?.. (see above post "Layering")
If the tank does not warm up or cool significantly, do we get an answer?...
BTW, pump heads above ground, and temperature of.... The bit that counts how much fuel you have will be cooled by the liquid being pumped through it. Therefore, I suggest testing that in case someone claims sun-strike on the pump changes the monitoring ability?....
Otherwise.....
Are there any abandoned fuel stations that MB;s can get access to to "Monitor" tanks?... Can those tanks be water filled (Flushed if need be...) and continuous monitoring be done over a couple of days....
Will an ACTUAL fuel station of fuel company be interested in this type of monitoring, would they allow it?... would they be part of the test?...
ALSO. When driving the silver bullet myself, I draw a tanker full from ABOVE ground storage units.... I am not aware of any "Sun-strike" issues on the tanks?...
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Post by Cybermortis on Jun 24, 2013 11:47:57 GMT
I suspect that the logic is that cold liquids are denser than warm liquids. Therefore cold gasoline would contain more energy per volume than warm gasoline.
Well, the real logic is that people will believe anything you tell them if they think they will get something for nothing.
I think that tanks are removed when stations are closed down, both for safety and environmental reasons.
Building their own 'mini' tanks would be good enough, and as I noted would allow them to look at different designs and depths - for example they can check above ground tanks or much older designs.
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Post by Antigone68104 on Jun 24, 2013 14:15:55 GMT
The reasoning (using that term very loosely) in the e-mails I've seen is that cold liquids are denser than warm liquids, therefore if you buy gas when it's cold you're packing more gas into that gallon. Not that this would work even if gasoline does "shrink" a measurable amount when cold.
Every time I've seen a gas station close down, they've immediately pulled the tanks before putting the "For Rent" sign up.
(Edit to fix markup, I'm used to sites that use < > for their HTML)
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Post by the light works on Jun 24, 2013 14:23:22 GMT
as I already said - as I recall the tank monitor they installed when they upgraded the station I worked at included temperature in the three-times-a-day printout. if my memory is correct, I can't imagine their favorite station would be averse to pulling a few extra printouts (they may like a few bucks to cover costs, or they may not)
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Post by silverdragon on Jun 25, 2013 8:57:45 GMT
Eventually?... but can MB's get to one between closing and decommissioning?... Do they always remove tanks right after closing?... I think I know one or two that may still have the underground tanks in place?....
Or, as suggested, can they be allowed to monitor a gas station "In use".....
EDIT, I just remembered, one place, removal of tanks was not possible, so they flushed, then pumped them full of concrete.....
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Post by privatepaddy on Jun 25, 2013 12:13:07 GMT
It is my understanding that at x depth temperature remains virtually constant year round, so at a given depth the temperature of the contents of the tank will stabilise with the surrounding soil temperature.
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Post by Cybermortis on Jun 25, 2013 13:03:07 GMT
It is my understanding that at x depth temperature remains virtually constant year round, so at a given depth the temperature of the contents of the tank will stabilise with the surrounding soil temperature. This was my thinking - that the temperature in underground tanks would remain fairly stable. That said having looked at the entry for permafrost on wilkipedia it seems that while ground temperature doesn't change as much or as fast as air temperature. You do get temperature variations to a depth of some 15 feet - although against this is the fact that the fuel is unlikely to be sitting there for more than a week before new fuel is added. Above ground tanks are a different matter entirely.
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Post by privatepaddy on Jun 25, 2013 13:47:48 GMT
It is my understanding that at x depth temperature remains virtually constant year round, so at a given depth the temperature of the contents of the tank will stabilise with the surrounding soil temperature. This was my thinking - that the temperature in underground tanks would remain fairly stable. That said having looked at the entry for permafrost on wilkipedia it seems that while ground temperature doesn't change as much or as fast as air temperature. You do get temperature variations to a depth of some 15 feet - although against this is the fact that the fuel is unlikely to be sitting there for more than a week before new fuel is added. Above ground tanks are a different matter entirely. Given a statistically constant ground temperature at the subsurface level X of the tank, delivery temperature of the fuel will stabilise with ground temperature. It is a matter of relevant mass the fuel being the lesser mass. The energy content of a substance is dependant on the number of moles of the substance available for the chemical reaction, if I remember correctly. If you are delivering the same volume and hence "moles" of a chemical reactant both in summer and winter then there should be no difference in the energy produced. But since engine efficiencies vary (I think?>) with the differing seasons, some natural variations will occur. How to tell what is causing the differences?
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Post by Cybermortis on Jun 25, 2013 15:39:56 GMT
Humm.
You know there may be a way to see if any apparent changes in fuel efficiency might be down to air temperature when the engine is running.
Get a couple of small ICE engines used for RC cars and place them in boxes that are maintained at different temperatures (or at least make sure that the air being used is at a particular temperature. They can run the engines to see if there is any difference in fuel efficiency, both using electric monitoring equipment that measures MPG and emissions and by simply using the exact same amount of fuel and seeing if one engine cuts out earlier than the other.
They could use the same set-up to measure the energy content of gasoline at different temperatures, this time by keeping the air temperature constant but using fuel that is at different temperatures.
They might even be able to rig up the engines to a light, which might give an idea as to how much power is being produced at a particular RPM visually by the intensity of the light produced.
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Post by the light works on Jun 25, 2013 15:52:02 GMT
Humm. You know there may be a way to see if any apparent changes in fuel efficiency might be down to air temperature when the engine is running. Get a couple of small ICE engines used for RC cars and place them in boxes that are maintained at different temperatures (or at least make sure that the air being used is at a particular temperature. They can run the engines to see if there is any difference in fuel efficiency, both using electric monitoring equipment that measures MPG and emissions and by simply using the exact same amount of fuel and seeing if one engine cuts out earlier than the other. They could use the same set-up to measure the energy content of gasoline at different temperatures, this time by keeping the air temperature constant but using fuel that is at different temperatures. They might even be able to rig up the engines to a light, which might give an idea as to how much power is being produced at a particular RPM visually by the intensity of the light produced. would it not be better to use small water cooled motorcycle engines for this? my thinking in this is that they are probably going to have fewer variables within the engine, itself, as well as the option of fuel injection. it would also be interesting to play with atmospheric pressure, if you are using a climate controlled enclosure. Alternately, you could make a temperature controlled air intake to eliminate other issues that might occur from having the engine inside a box. would it be worth spawning this into its own thread?
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Post by privatepaddy on Jun 25, 2013 16:25:04 GMT
Humm. You know there may be a way to see if any apparent changes in fuel efficiency might be down to air temperature when the engine is running. Get a couple of small ICE engines used for RC cars and place them in boxes that are maintained at different temperatures (or at least make sure that the air being used is at a particular temperature. They can run the engines to see if there is any difference in fuel efficiency, both using electric monitoring equipment that measures MPG and emissions and by simply using the exact same amount of fuel and seeing if one engine cuts out earlier than the other. They could use the same set-up to measure the energy content of gasoline at different temperatures, this time by keeping the air temperature constant but using fuel that is at different temperatures. They might even be able to rig up the engines to a light, which might give an idea as to how much power is being produced at a particular RPM visually by the intensity of the light produced. Most modern engine combustion management systems use air warmed in the vapourisation of petrol/gas before it is burnt in an engines cylinder. Fuel temperature and air temperature are independent of the buried fuel tank and its contents temperature. Petrol/gasoline burns more efficiently as a gaseous mixture in air than vapour "droplets". Ambient air temperature can and is increased to obtain the optimum air temperature for combustion. Chemical speaking the calorific content of burning petrol/gasoline can be and has been derived by burning it and heating water. Much more accurate than generating electricity to produce light.
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Post by the light works on Jun 25, 2013 16:45:59 GMT
Humm. You know there may be a way to see if any apparent changes in fuel efficiency might be down to air temperature when the engine is running. Get a couple of small ICE engines used for RC cars and place them in boxes that are maintained at different temperatures (or at least make sure that the air being used is at a particular temperature. They can run the engines to see if there is any difference in fuel efficiency, both using electric monitoring equipment that measures MPG and emissions and by simply using the exact same amount of fuel and seeing if one engine cuts out earlier than the other. They could use the same set-up to measure the energy content of gasoline at different temperatures, this time by keeping the air temperature constant but using fuel that is at different temperatures. They might even be able to rig up the engines to a light, which might give an idea as to how much power is being produced at a particular RPM visually by the intensity of the light produced. Most modern engine combustion management systems use air warmed in the vapourisation of petrol/gas before it is burnt in an engines cylinder. Fuel temperature and air temperature are independent of the buried fuel tank and its contents temperature. Petrol/gasoline burns more efficiently as a gaseous mixture in air than vapour "droplets". Ambient air temperature can and is increased to obtain the optimum air temperature for combustion. Chemical speaking the calorific content of burning petrol/gasoline can be and has been derived by burning it and heating water. Much more accurate than generating electricity to produce light. sometimes accuracy needs to be tempered with viewer friendliness, though.
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Post by privatepaddy on Jun 25, 2013 17:01:30 GMT
Lets remember that Mythbusters use science in their show, they can if they wish chose to use a vehicle filled with fuel of differing temperatures to see if there is a difference, much like the tailgate up or down episode. Chemically X grams of petrol/gasoline has a certain calorific content, its science.
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