Fuel on a cold day

KwackerJack

So apparently with fuel being more dense on cold days in theory you should see better fuel mpg and a small saving from the pump.

Is this true and have the petrol stations 'adjusted' the pump to factor in the temperature change!

pete4130

The coefficient for expansion for petrol is about 0.0001 (.000945) for every degree C in temperature. For diesel it is 0.0008 (.000824).

So if you were to do a 100L fill of petrol with a temperature of 20C compared to a 100L fill at 0C you might get an extra 200ml of fuel.

Coefficient of expansion X temperature difference = volumetric difference
0.0001 X 20 = 0.002


0.002 X 100L = 0.2L

So if your car does 10L/100km you might get an extra 2km out of the tank.

ironclaw

Just want to say thank you pete4130 for some intelligence on the forum

Anjobe

Its the thermal expansion and contraction of air that is more significant in the difference in fuel consumption that you may observe at different ambient temperatures.

Normally fuel consumption (and engine power) are slightly decreased in hot weather. This is because the expanded air is less dense and therefore has less O2 per unit volume. The O2 sensor in the engine will detect this and less fuel will be injected into the cylinder to maintain the correct fuel/air mixture.

Wossack

lose more to evaporation filling up on a hot day vs a cold one? again though, probably miniscule

ironclaw

Wossack wrote: »

lose more to evaporation filling up on a hot day vs a cold one? again though, probably miniscule

I know State side is can be fairly significant in the warmer States as its a legal requirement for hoods over the nozzles. Then again, that's probably a safety measure first and foremost given vapor.

Bandara

Forecourt loss limits at generally deemed to be .4% unl and .2% Derv is lost on an ongoing basis. This takes into account the variance of the seasons.

Temp Comp at 15 Deg is now becoming far more widespread and is standard on any new pumps since 2012. This eliminates any loss whatsoever to the customer.

jimgoose

You'll notice more of a difference on very crisp days due to the extra density of air. It's a sort of "supercharger" effect.

Fuelwatch

Yeah all new pumps come with ATC (automatic temperature compensation)
Generally it consists of an RTD temperature probe which records the temp of fuel passing through the meter and the software adjusts the amount accordingly.
Fuel is bought from the terminal at 15 degrees, so when it is offloaded to the underground storage tanks at filling stations it usually shrinks to 10/11 degrees
Not good for station owners!!
One way if knowing if a pump has this fitted is that the display will have temperature corrected to 15 degrees written on it,
So fill up on a cold morning with an older pump!!!!

visual

What ever about the air tempture at ground level the petrol station tank is underground and the tempture range is much less than a tank over ground

KwackerJack

jimgoose wrote: »

You'll notice more of a difference on very crisp days due to the extra density of air. It's a sort of "supercharger" effect.

Well my car is Supercharged so will it be super Supercharged :-P

jimgoose

KwackerJack wrote: »

Well my car is Supercharged so will it beb super Supercharged

Precisely!

KwackerJack

jimgoose wrote: »

Precisely!

I like it :-)

Although say nothing as my insurance will most likely increase during. Winter :-o


In other news fuek will drop by 7 cent this October......apparently!!