Oil - Eating a C4

[Elec]

Following a conversation launched here:
https://www.econologie.com/forums/post119080.html#119080

[...]
Back on topic and I submit to your sagacity measurement and calculation that I just made.
my C4 consumption measurement (110 HDI with FP) at a steady speed of 113 km / h on 50 km (4 Nantes-Cholet channels). A day without wind, temp ext 10 °, QNH 1010, altitude 25 75 to m.

Input data: mass 1400 kg (with me in it)
front surface: 2,24 m2
Cx (reported) to the front surface: 0,31
The calculation of the required energy is made starting from the present information on this site:
http://users.jyu.fi/~mweber/consommation/

The calculated energy requirement is 19 kWh / 100 km
Consumption measured with the on-board computer is 4,9 L / 100 (Diesel)

X = 4,9 10,2 50 kWh content in diesel.

reservoir performance at the wheel 19 / 50 or 38%
If one admits a yield of the engine to the wheel of 10% (transmission) the output of the engine would be 38 / 0,9 = 42% !!!

FYI average power on the course is 21,4 kW (29 CV) or 1 / 4 of maximum power! The engine was 2500 t / min) [...]

[RIAZ]

For one who would pass there by chance ...

This topic was created by Elec that does not support that we can see things other than through the distorting prism that strikes via hundreds of fiery post ......

Since it has no arguments, he prefers to eliminate his opponents ....

Chistophe would do well to remove this topic .....

[Christophe]

Remove non, ca will interest all C4 drivers to compare their consumption not?

Besides all those who have an onboard computer could estimate the return on their vehicle as they know:

a) the average speed
b) average consumption

Only "unknown" = SCx but that's easy to find on the net ...

[RIAZ]

Only "unknown" = SCx but that's easy to find on the net ...

The CdA is known, I indicated in the input data.

The unknown is the energy needed for the wheel to advance the C4 on the flat and without wind at 113 km / h.

I made the calculation on the basis of this information on this site:
http://users.jyu.fi/~mweber/consommation/

That's what he should validate ......

[Christophe]

You yes but not others who would assess the overall performance of their car.

This site is good I do similar calculations during my studies ...

The trickier point is to accurately estimate the rolling resistance (depends on the road, the type of tire, width and wear ... in short, a nice "mess" !!)

It is considered that size is negligible compared to another if the second is at least ten times the first. We see that the air resistance can be neglected if the speed is less than 20 km / h. However, the speed limits allowed on roads and motorways in Europe, the resistance of the bearing is not negligible (it is 33 90% of the total in km / h and 20 130% of the total in km / h).

[RIAZ]

Using the curve expressing the ratio Fx / Fr (aerodynamic / rolling resistance), I found an inconsistency in my result and I looked for my mistake.
By really using (!) The following calculation as described here
http://users.jyu.fi/~mweber/consommation/
and also there
http://sfp.in2p3.fr/Debat/debat_energie/websfp/Livet-elect.htm
detailed below:
Force of air resistance = 1 / 2 * k * S * Cx * V2 (square)
et
rolling resistance force = M * g * k (my error was there!)
where M is the mass of the vehicle and a dimensionless coefficient k estimated at 0,015.

-> we find for 113 km / h, 17,1 kWh / 100km which compared to the 50 kWh contained in the fuel, gives an efficiency of 34,2% from the tank to the wheel.
If we admit 90% yield for the transmission it gives 38% yield for one engine.

Let the very educational table Dirck Pitt which details the performance of the well to the wheel, to the thermal solution and power solution. If we assign a yield of 38% to the engine, consider that the average yield of electric current must be 58% for the same overall result.



This is strictly impossible if we consider the current available on the network, which is at least one European mix.

Of course this does not deny that the engine can have a catastrophic performance in certain conditions and these conditions are common today.

Of course the comparison is made in the case of optimum use of the engine.

But the first way to go, perhaps this is to stop doing anything and only use the car when its use is optimum.
Luckily, it is in this case it is difficult to replace .....

Using the same calculation, if instead of rolling in C4 we drive with Loremo, the need for energy passes 7,5 kWh / km 100 be a fuel consumption of L 2,15 / 100 !!!!

And passing from 4,9 to 2,15 L / 100, we are sure that we have made a real progress .....