Limitation 70 km / h on the device

[delnoram]

the more we go slowly and the more the consumption decreases, and not the opposite ...
It's not "religious", it's mathematical ...
If a vehicle consumes 2 liters per hour in slow motion, I do not see how he could consume less while driving ...

I have a doubt about your mathematical demonstration, what is the speed of the vehicle in slow motion for you?

[I Citro]

My demonstration disregarded speed, precisely to show that the engine consumes no less by driving faster.

It is therefore assumed that there is a consumption "heel" to run the engine at its idle speed, to which we add the consumption to move the vehicle forward.
This "rolling" consumption increases with speed, and not the opposite as some claim.

Then, there is bottling or running consumption becomes lower than heel consumption and or heel consumption increases (to evacuate the calories mechanically). In this case, it is the idling time that accounts for the bulk of the total consumption and not the kilometers traveled, although they are in particularly unfavorable conditions (as acceleration phases without level of control). ).

[danielj]

Hello, I did some research and a little study to understand the evolution of the conso of a thermal vehicle. Well I simplified a little (very little) ...

Public chat http://www.ecolo.org/documents/document ... -elect.htm
We write:
One liter of gasoline can provide 10 thermal kWh. One could believe that a liter of gasoline would travel 100 km 100 km / h. But ... the maximum yields are from 23% (gasoline) to 28% (diesel). These yields are rarely achieved: cold engines, non-optimized diets. For urban driving, it is estimated that the actual yield is around 10%. The weakness of this real return is mainly due to accelerations. In addition, the consumption stops decreasing below 60 km / h (because it is necessary that the engine turns ..). As a result, few vehicles consume less than 5 l / 100 km at 100 km / h and less than 7.5 l / 100 km in the city. The air conditioning is added to that (1 / 3 consumption in town, 1 / 6 on the road).
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Sure :
http://philippe.boursin.perso.sfr.fr/pdgmoteu.htm

We read: -Consumption specific:
The Cse is the mass of fuel (in grams) that the engine would consume to deliver a power of 1 kW for one hour (ie a job of 3600 kJ).
The specific consumption is calculated by dividing the hourly consumption by the effective power.
Cse (g / kW.h) = mc (g) / (P (kW) * t (hour))
with fuel density ρ (740 kg / m3) and volume of fuel consumed V
Cse (g / kW.h) = V (cm3) * ρ (g / cm3) * 3600 / (P (kW) * t (s))
Cse (g / ch.h) = V (cm3) * ρ (g / cm3) * 3600 / (P (ch) * t (s))


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Sure :
http://insee.fr/fr/themes/document.asp? ... f_id=18067
We read :
The graphical representation of kilometric consumption (L / 100km) as a function of speed is not a straight line, but a U-shaped curve, which has a minimum around 80 km / h for a light vehicle (70 km / h for a heavy weight). This speed of 80 km / h at which the kilometer consumption is minimal is therefore the energy optimum.



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The expertise of "danielj" :

Consumption in liters per hundred kilometers and liters per hour of a thermal engine vehicle.

As soon as a heat engine is running, with the vehicle stationary in neutral, it consumes fuel. This is the minimum consumption for the engine to work and overcome its own friction, maintain its temperature, drive accessories, camshaft, water pumps, oil pump, alternator, etc. It is not possible to go below this minimum consumption in liters per hour.

This results in consumption in liters to the hundred kilometers goes through a minimum when the stabilized speed varies from zero to maximum!

I show it to you for a particular case (but extensible in all the cases):

I start from two measures:
1) The consumption of the vehicle 90km / h (stabilized) is 5.5 liters / 100km (C).
2) Measured consumption of engine idling (vehicle stationary in neutral), 2 liters per hour. (measure of 0,5 l in 15mn)

1 ° - to 90km / hto make a hundred km, we put (60 / 90) x100 = 66,66 mn.
I use for the minimum operation of the out-of-the-money engine to move the car forward: (2 / 60) x66,66 =2,2 liters. (A)

The rest of consumption is therefore used to advance the vehicle
either: 5,5 - 2,2 =3,28 liters. (B)
This consumption is mainly used to overcome the resistance of the air (and friction proportional to the speed who are very weak and that I integrate with the resistance of the air as a first approximation).

The resistance of the air is proportional to the square of the speed.


2 ° - to 70km / h, To know the consumption due to resistance of the air at another speed it suffices to make the ratio of the squares of the velocities; for 70 km / h one will have: conso 2 / conso 1 = 70 squared / 90 squared = 4900 / 8100 = 0,605. Let 3,28 x 0,605 = 1,984 liters (B ')

Consumption for the minimum operation of the engine out of expense to move the car (A ') is calculated as before, time to make 100km = (60 / 70) x 100 = 85,71 mn; min conso x time per hundred km, that is (2 / 60) x 85,71 = 2,857 liters (A ').

Hence the consumption at 70 km / h of 1,984 + 2,857 = 4,841 liters per hundred km (C ').


3 ° - at 50 km / hwe find in the same way: 4 liters (A '') and 1,010 liters (B '') {50 squared divided by 90 squared = 0,308 of coef x 3,28 = 1,010}.
the conso to 50 km / h is 1,010 + 4 = 5,010 liters to the hundred km (C '').
So higher than 70 km / h! ! !


4 ° - at 30 km / hwe find in the same way: 6,666 liters (A '' ') and 0,364 liters (B '' ') {30 squared divided by 90 squared = 0,111 coef x 3,28 = 0,364}.
the conso to 30 km / h is 0,364 + 6,666 = 7,030 liters to the hundred km (C '' ').
So higher than 50 km / h! ! !
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Allure of the consumption curve in liters per hour (fcV):



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Allure of the consumption curve in liters per hundred kilometers (fcV):


WE HAVE A CONSO MINI FOR SOME SPEED (60 ... 80 km / h + -). CONSOTING IN LITERS PER HOUR INCREASES ABOVE AND INCREASES BELOW!

Other times the autojournal gave consumption tables 100km and I saw that there was this optimal speed!

a+

[I Citro]

All these data date a little and allow to better understand the current evolutions to decrease this consumption heel:
- Downsizing: reducing engine displacement reduces idle fuel consumption
- Direct injection and stratified charge: make it possible to reduce the consumption even more during the phases of operation under low load in lean mixture. For simplicity, we create an area near the spark plug where the mixture will ignite properly and a more distant area that will behave a bit like a pneumatic engine or air depleted or without fuel but overheated by the combustion of the explosion will expand and exert pressure on the piston.
- Micro hybridization and freewheel mode: will cause the motor to be cut off in the phases where it is not used to propel the vehicle (from 30 to 55% of the journey time).

In short, by reducing "heel consumption", the optimum consumption speed will be lowered. For information, we consider that the aerodynamic losses were negligible and were part of the "heel consumption" up to about 70kmh, beyond that, the aerodynamic losses become predominant.

Finally, if all these remarks become more and more false with the changes that I have just described, they no longer apply as soon as the automobile is electric, because it then only expends the energy necessary for movement and does not know plus this notion of "heel consumption".
Thanks to this, my old electric cars that run mainly below 70kmh, consume 20kWh of energy at 100km, which is less than 2 km at 100km

This is why the petrol car will be electrified more and more to become a generator powering an electric car ...

[Flytox]

Let's be clear: all the accessory parts of an automobile are worth to be electrified despite the multiplication of electric motors.
The result is a gain on all the tables;
Energy consumption, gain in weight, gain in size, gain in ease of integration, and, if one takes the trouble, gain in reliability.
List of bodies already electrified and which were driven mechanically in the past; Cooling fan, fuel pump, power steering (electro-hydraulic then "full" electric), injectors, headlight height adjustment, intake air compressors, idle speed regulator, ...

List of organs that are beginning to be electrified and will be generalized; water pump, air conditioning, clutch, shift control, traction motor for hybrid operation, brake system ...

In aeronautics, it is clear that the trend is towards the electrification of all the "accessories" around the engine and cabin. The specifications in relation to the weight and the price of the parts are not at all the same, but this electrification is supposed to provide better reliability, simplification, weight gain, overall size, maintenance cost, etc.



http://www.safran-group.com/IMG/pdf/saf ... ook_FR.pdf

DEVELOP AN AIRCRAFT
OPTIMIZED ENERGY

Compared to the current architecture, the advantages of a
100% electric energy chain are potentially
very important for the entire aviation industry
and its economy. First, at equivalent performance,
electrical and electronic systems are renowned more
reliable as complex hydraulic mechanisms or
tires.

Then, the coexistence of heterogeneous circuits impose
today a partitioning and multiplication of
embedded equipment. With a single energy vector
- electrical, in this case - we can consider a
mutualisation and a better distribution of the different
systems. For example, several applications so far
totally separated could eventually share a
same electronic or the same calculator. It will result from
this rationalization of significant weight gains, synonyms
for the operator of the aircraft fuel economy and / or
increase the payload.



Towards a significant reduction in operating costs

Similarly, the prospects opened up by electricity grids
"Intelligent" make possible an overall optimization of the
energy consumption, with a more precise allocation of
resources limited to "just need" and less wastage.
This will lead to a net reduction of energy needs
auxiliary networks. Like most of this energy
is taken from the main engines, this would allow
reduce the fuel consumption needed to generate
this so-called non-propulsive energy - again opening the way to
better performance and fuel savings.
Finally, electrical systems have an advantage
certain in terms of maintenance and repair. Outraged
an intrinsic robustness which gives these equipments a
long life "under the wing", their removal is revealed in
general simpler and faster than an equipment
hydraulic or pneumatic that often requires - for
treat one piece - to intervene on an important part
network (pressurization, emptying ...). This property
electrical systems is therefore also likely to
generate a reduction in maintenance costs for the operator,
as well as an increase in the operational availability of
his plane.

[dede2002]

Hello,

The consumption of 2 liters / hour in slow motion seems exaggerated.

On the technical data of carbureted cars, we find for example 0.6 l / h for an opel kadett 1000 and 1.3 l / h for a Commodore 2.5 6 cylinders.
0.38 l / h for an 2cv6 and 0.45 l / h for an 4L.

Modern cars probably consume less, and diesel even less, idle.

edit: Unless the accessories have increased, the idle consumption of modern engines would have increased?

[Macro]

0.9l / h for a trendy 140 vw tdi

[Did67]

The consumption of 2 liters / hour in slow motion seems exaggerated.
?

I recall a "measurement" that I made. It's not theory:

I made a "descent" with my C5 petrol 2.0 with on-board computer (converted to LPG):

- slow motion ; no gear engaged
- freewheel at exactly 90 km / h
- consumption displayed: 1 l at 100 !!!

So 1 l at 100 km. At 90 km / h. Either way, 1 h = 100 km ...

So given the uncertainty about the measurement, I could have written about 1 l per hour.

For a 4 petrol engine to cycle 2.0 l.

[louis40]

It will be a great idea the day our cars will be stuck at 130 km / h.
Lighter engines, less powerful brakes and therefore lighter ...
Everything will be lightened because the maximum shock will be 130 and therefore minimal consumption!

In fact, the consumption of a camoin corresponds to that how many cars?
And if we saved on that side too?

[dede2002]

A big truck that consumes less than 1l / 100 per ton ...

Did 67 I also tried, with a small 3 cylinders, 1.7 l / 100 to 50 km / h (0.85 l / h). But it was raining ropes, I had lighthouses. windscreen wipers, heating and defrosting switched on.
It would be interesting to try with and without electrical consumers (or with and without air conditioning).