Fuel cooling

[riff_raff]

ScuderiaRuss,

.....just how does this benefit combustion exactly?

F1 engines are normally aspirated, spark ignited, otto-cycle engines. Thus, in order to produce maximum power, they must run at near stoichiometric air/fuel ratios. More specifically, their ultimate (thermodynamic) power output is limited by the mass flow of fuel they can combust efficiently. Which in turn is limited by the mass flow of oxygen the engine can trap within the cylinder during each cycle.

So the key factor for max engine power is the trapped oxygen mass fraction. And this value is helped by having a dense intake charge. The intake charge of an F1 engine is cooled (and thus densified) by the latent heat effect of the fuel evaporation. Cold liquid fuel absorbs more heat during vaporization, so the fuel latent heat effect on intake charge density is increased, thus increasing power somewhat.

It doesn't specifically benefit combustion, but it does improve intake mass flow. But not a whole lot.

[Fil]

riff_, that was actually a really good explanation.. but..

..2004 called, and it wants its thread back..

[riff_raff]

Fil,

OK. I'll try to pay more attention next time. Just giving my unsolicited opinion to posters from the year MMX.

Besides, aren't the laws of physics timeless?

[Edis]

The fuel circulate from the tank, through several fuel pumps, to the engine and most of it then back to the tank again. This can heat the fuel quite significantly, especially if a small amount of fuel is used or if no refueling is allowed. When the fuel gets warm, the cooling effect on the incoming charge decrease and there is a small loss in power. Not a big loss, a half to one percent probably if we go from say 80 degC to 40 degC but then again, there is probably also a small gain in fuel efficiency.

It should have said 40 degC to 80 degC. The numbers are from a 1989 paper by Honda, more specifically related to the RA168E F1 engine.

[archebald23]

once knew someone who ran his fuel line along the cold a/c pipe which returned the gas back to the A/C Compressor from the evaporator and wrapped it up with insulation. he experienced some improvement in engine power although not much.

fuel becomes more dense after cooling thus giving more fuel to enter combustion chamber, computer reconizes this and adjusts fuel trims, back to programmed trims, what was accomplished?

The fuel circulate from the tank, through several fuel pumps, to the engine and most of it then back to the tank again. This can heat the fuel quite significantly, especially if a small amount of fuel is used or if no refueling is allowed. When the fuel gets warm, the cooling effect on the incoming charge decrease and there is a small loss in power. Not a big loss, a half to one percent probably if we go from say 80 degC to 40 degC but then again, there is probably also a small gain in fuel efficiency.

very small or none at all. this has been on the debate table ever since f1 opened it to the public, most researches on this yield no significant results.

[Edis]

The fuel circulate from the tank, through several fuel pumps, to the engine and most of it then back to the tank again. This can heat the fuel quite significantly, especially if a small amount of fuel is used or if no refueling is allowed. When the fuel gets warm, the cooling effect on the incoming charge decrease and there is a small loss in power. Not a big loss, a half to one percent probably if we go from say 80 degC to 40 degC but then again, there is probably also a small gain in fuel efficiency.

very small or none at all. this has been on the debate table ever since f1 opened it to the public, most researches on this yield no significant results.

The paper by Honda very clearly show a difference, even if it's small.

[smbrm]

Formula One is all about the attention to detail provided by the accumulated effect of small differences! At the start fuel cooled to the allowed temperature by the rules just maximizes the mass in the tank! I am sure that if Honda found a benefit from managing fuel temperature during on-going operation it was real. It may have been small, but benefits add up!