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Post by Cybermortis on Jun 26, 2013 16:42:23 GMT
*Nods*
The questions that could be asked and tested would be;
A; Is the temperature of gasoline in fuel tanks constant, or does it fluctuate? As I noted not everyone uses tanks buried at the same depth and of course you can find above ground tanks (although this seems very rare these days, at least for commercial stations.) I'd guess that above ground tanks will show temperature variations while below ground tanks won't.
B; Does cold gasoline contain more energy (ie is it denser) than warm gasoline? Logic would say yes, although it is open to debate as to if this is going to give any noticeable difference in MPG in the real world.
C: Could any reported difference in MPG from filling your car up in the morning really be connected to the air temperature/humidity ect rather than the temperature of the fuel? (For that matter could this simply be a case of filling up early in the morning means you tend to miss the worst of the rush hour traffic?)
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Post by the light works on Jun 26, 2013 16:47:15 GMT
*Nods* The questions that could be asked and tested would be; A; Is the temperature of gasoline in fuel tanks constant, or does it fluctuate? As I noted not everyone uses tanks buried at the same depth and of course you can find above ground tanks (although this seems very rare these days, at least for commercial stations.) I'd guess that above ground tanks will show temperature variations while below ground tanks won't. B; Does cold gasoline contain more energy (ie is it denser) than warm gasoline? Logic would say yes, although it is open to debate as to if this is going to give any noticeable difference in MPG in the real world. C: Could any reported difference in MPG from filling your car up in the morning really be connected to the air temperature/humidity ect rather than the temperature of the fuel? (For that matter could this simply be a case of filling up early in the morning means you tend to miss the worst of the rush hour traffic?) or do the cooler temperatures just mean you get the same air-fuel mixture at a lower throttle setting, but the same overall fuel efficiency? |
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Post by silverdragon on Jun 27, 2013 6:13:20 GMT
You could ask anyone who goes racing... especially, like F1, those who do it for a living...
Where is SR when you need him?...
I know already that colder denser air is a different jet than warmer air when setting up a race vehicle carburettor, colder air needs a finer spray, will compress more on a normally aspirated engine, will give you more bang for your buck, as you have more grams of Oxygen per litre to burn fuel with...
The litres-per-second you can scoop into a race engine at full chatter are important for how much fuel you can burn, and colder air temps will give a much better rate of combustion, purely because you get more in....
The air is warmed by exhaust gas under "Outside air" pressure, injected with fuel, force-fed into the engine, and goes bang....
In a warmer climate, there is less air density.
That is almost the equivalent of taking an engine up a mountain....
Less dense air, less air pressure, less litres-per-second compared to sea level cold air...
And less efficient.
The vehicle will try to burn more fuel.
Most fuel injected engines are set up to run on an "Average" outside air temp, that is pre-set, and does not vary. to speed up, you increase fuel flow.
If you dont have enough air to burn that fuel, it just gets wasted....
If its a Carb, the air will draw its own fuel in.
Density matters...
Again, average cars are set up to that magic 14-1 ratio of air to fuel.
When bike racing, on a cold day, I would set my carb to burn a 14.1 to 1.....
On a warm day, I would change the jet to one that would burn 13.9 to 1.
Its the same reasons why Humans cant breath up high mountains, lack of oxygen...?...
The lungs have to work harder to get that oxygen into the system.
However, an engine on "Idle", you may find takes longer to react.
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Post by privatepaddy on Jun 27, 2013 15:22:20 GMT
*Nods* The questions that could be asked and tested would be; A; Is the temperature of gasoline in fuel tanks constant, or does it fluctuate? As I noted not everyone uses tanks buried at the same depth and of course you can find above ground tanks (although this seems very rare these days, at least for commercial stations.) I'd guess that above ground tanks will show temperature variations while below ground tanks won't. B; Does cold gasoline contain more energy (ie is it denser) than warm gasoline? Logic would say yes, although it is open to debate as to if this is going to give any noticeable difference in MPG in the real world. C: Could any reported difference in MPG from filling your car up in the morning really be connected to the air temperature/humidity ect rather than the temperature of the fuel? (For that matter could this simply be a case of filling up early in the morning means you tend to miss the worst of the rush hour traffic?) A/ The subterranean temperatures appear to be most stable at a level of 25 feet. They appear to be stable around the average locations yearly average temperature ie there was discussion that in the UK that temperature would be around 6C. Underground fuel tanks do not appear to be buried at that level, to the top of the tank a maximum depth of a certain Brand (in Aus) is around 10 feet including the forecourt cement surface. The tank is installed on a concrete slab which depending on the tank diameter is around 20 feet. The tank installation is backfilled with soil. Once the underground tank contains fuel it becomes a hazardous area where special instrumentation must be used in measuring the temperature. Perhaps measuring the temperature of fuel pumped into a suitable container will provide suitable data. Above ground tanks will as you say follow ambient air temperature. B/ Cold petrol/gasoline is more dense, Some interesting numbers via an online calculator which should be viewed with A in mind. At 0C density is 751.92 g/L At 14C density is 738.82 g/L At 16C density is 737.00 g/L At 18C density is 735.19 g/L At 25C density is 728.94 g/L C/ As a vehicle moves around in an average day ambient temperature will change and hence the fuel density, while air pressure affects density relative humidity will affect the fuel/air saturation point (?) Since you pay per litre/gallon of fuel the actual delivery temperature would be more important to me. |
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Post by Cybermortis on Jun 27, 2013 15:40:08 GMT
*Nods* In both cases that was why I thought a good test to do would be to create their own tanks. This allows them to cover any differences in tank designs (including insulation) and installed depths in different areas and from different dates - it is possible that the related laws and practices have changed.
It may not be practical to use gasoline for such small scale testing, as they would probably need countless permits and have to follow existing rules due to environmental concerns. I have little doubt they could probably get around these problems, but it could be expensive and time consuming for something that isn't really needed. We are after all simply interested in the temperature and any variations within the tanks over a period of time, and we don't need to use gasoline to do this. Water will give us the same information and is unlikely to require more than the permission of whoever owns the land. For the effect of temperature on gasoline we can do small scale in-shop tests.
While I suspect that above ground tanks will show temperature variations, I'm unclear as to how much insulation they may have. After all an above ground tank is presumably designed to be much stronger than a tank installed below ground. You don't really need to worry about a tank that is below ground being hit by a vehicle or falling over.
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Post by silverdragon on Jun 28, 2013 6:49:12 GMT
The main design feature of an above ground tank these days is that it is placed in an enclosure designed to prevent the tank getting hit....
The tank will be mildly insulated and fit for purpose, but most of its added strength would have been put there to prevent us lot damaging it whilst in transport?....
The tanks themselves are normally well ventilated should the need arise...
This is what I was told, the designers of those tanks know the term "BLEVE", they have something akin to the burst-disks MB's used to use in vent pipes, should the inside air pressure increase, those disks will burst, and allow emergency ventilation.
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Post by privatepaddy on Jul 9, 2013 13:37:07 GMT
1 Litre of petrol is defined at 60 deg F or around 15/16 deg C. Apparently with modern pumps the electronics compensate for temperature differences so the litre of fuel you buy is the equivalent of a litre at 60 deg F. This is jurisdiction/country dependant.
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Post by jedimaster on Jan 4, 2014 18:02:13 GMT
The only place that I have ever seen above ground fuel storage is on an Army Base in our region. All the Civilian Gas stations use underground storage.
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Post by the light works on Jan 4, 2014 18:39:32 GMT
The only place that I have ever seen above ground fuel storage is on an Army Base in our region. All the Civilian Gas stations use underground storage. my fuel depot has abovegeround tanks. they are double walled and insulated, as well as essentially being installed inside an empty pond. |
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