16 replies to this topic

[Mosquito]

The BMW / Williams story reminded me of another thing of the past.

For a certain period, some engines were equiped with a water injection system. It was offcourse in my younger days, so my memory may not be accurate, but, I think it had to do with some adiabatic principles and better controlled combustion processes.

Why isn't this used anymore in todays engines? Although the turbo era had its own problems and gadgets, i can imagine these kind of things also working out on high compression ratios...

[DangerMouse]

It's illegal these days.

[Mosquito]

Darn, could have guessed so.... Thanks for the info
I will certainly HAVE to start reading all those boring FIA material.

But, stil not resting my case : WHY is this banned? Are they afraid for fogging up the road?

Or is this included in some ~general~ rule about additives to the fuel system, etc...

[DangerMouse]

Probably got more to do with limiting power, or the possibilities of carrying "water ballast" AKA Tyrrell!

[Yelnats]

I recall that water injection was used in the eighties to cool the inlet air/fuel mixture and prevent pre-ignition in the highly turbocharged engines of the time running with two or three atmospheres of boost. This resulted in an effective compresion ratio of about 25 to 1 and pre-ignition could destroy an engine in seconds. To put this boost pressure in perspective a turbo charged road car seldom exceeds 1/2 atmosphere of boast Water injection in a properly designed non-turbo charged engine offers much smaller advantages and is seldom used today.

[Christiaan]

5.3 Engine intake air :
5.3.1 Other than injection of fuel for the normal purpose of combustion in the engine, any device, system, procedure, construction or design the purpose or effect of which is any decrease in the temperature of the engine intake air is forbidden.

As an interpretation of the rules I'd say that water injection cools the air fuel imxture after it is actually inside the chamber and hence is no longer the "intake air." More to that is what if the actuall fuel itself was cooled?

I will move this to the tech forum.

[Pioneer]

Kick on down to the next rule for something a little more applicable Christiaan...

5.3.2 Other than engine sump breather gases and fuel for the normal purpose of combustion in the engine, the spraying of any substance into the engine intake air is forbidden.

[Christiaan]

still subject to interpretation of 'intake air'. But what about the cooling of the fuel itself?

[Pioneer]

Sorry. I didn't realise that was a subject under discussion. Theres a rule for that too...

6.5.5 No fuel on board the car may be more than ten degrees centigrade below ambient temperature.

[Pioneer]

And before you ask....

6.5.6 The use of any device on board the car to decrease the temperature of the fuel is forbidden.

[Christiaan]

Wow, I should call you Pioneer Whiting! I read the section on fuel and couldn't find anything, then I read the section pn the section of engine and couldn't find anything concrete. I still have an idea but I wonder how viable it is. Anybody know what the temprature of the cylinder walls and the piston surface are after compression?

[Pioneer]

Well... I do admit I know the regulations pretty well.

Except for the bodywork dimension regulations... those are somewhat hard to picture in my head from a description so I draw pictures.

Anyone at the FIA wanna give me a job?

;)


Anyway, it seems unlikely they would ban it unless its a viable idea no? I have heard that rain entering the airbox is beneficial to horsepower production. Don't hold me to that though.

Of course the reasons for the regulations against cooling the fuel is a throwback to pre-refueling days when they would chill the fuel to reduce its volume and pack more in the tank so they could run richer mixes during the race without running dry.

[pstnspd]

Anybody know what the temprature of the cylinder walls and the piston surface are after compression?

First, my best engineering judgement tells me that the thermal inertia and heat transfer rate of the metal is far greater than the thermal inertia of the fresh charge so the gas face metal temperatures don't change an appreciable amount within one cycle. Experience tells me that production engines survive with these limits:
-Valve bridge gas face metal temperature should be less than 250°C for 4-valve aluminum alloy cylinder heads
-Block upper top ring reversal point gas face metal temperature in siamese zone of
engines may be locally up to 240°C, but 180°C elsewhere

Second, the internal surfaces of F1 engines are surely coated with something exotic to insulate from themal stresses. I would expect those coated surfaces to be much hotter and change temperature an appreciable amount within one cycle.

[Christiaan]

The reason I was asking all this is that the exhaust gases have about 4kW of power that just gets dissipated into the air. Back in the turbocharger days this would have been awesome. Without turbocharging I wondered if this power could be used to cool the air. If it could then with a turbine of 70% effeciency (typical of a turbocharger) could be used to drive a 'refrigeration system' with a coeffecient of performance of 5 (like your household refrigerator) cool the inlet gases using a heat exchanger of 80% (figures from a textbook). The inlet gases would be lowered to -3degrees. The thermal effeciency of the engine would increase , and the increased density of air would make breathing better.

Sadly I had not read all the rules, so cooling the charge or the fuel is forbidden. Also, using latent heat of vapourisation of any fluid is forbiden (which raises a question - does the water in the radiators never boil at some stage?).

Question, what is the engine was cooled this way, what if the piston surface and cylinder walls were cooled this way. What would be the benefits of running an engine thats at 0degrees? I cannot find my IC engines notes so I am relying on you guys to tell me.

[blkirk]

Don't forget that your refrigeration system would need to have its own radiator for its waste heat. Given the push to make engines run hotter so the radiators can be made smaller, I don't think you're going to convince Newey or Brawn to add an intake charge cooler next to the oil cooler.

But if you did...

I'm not sure what the effect of a 0 deg (Celcius or Farenheit?) engine would be. It would help during intake by increasing the density of the intake charge. It would help during compression by reducing the chances of detonation allowing a higher compression ratio. It would hurt during the power stroke by dropping the temperature and pressure in the cylinder faster than normal. I suspect that the power stroke effects will dominate the other two because the temperature difference is so much greater.

If you are going to actively cool something in the engine, I think the intake piping makes a better choice. Something along the lines of an intercooler might give you noticeable benefits. It may be illegal in F1, but you could have some real fun with a street car.

On this same topic, I've always wondered if you could get a useful level of cooling by putting a vortex tube in the exhaust system.

[Christiaan]

It would most certainly hurt the power stroke, but there may be ways around that, I just have to make sense of them before I post . The radiators won't be an addition, they would be a modification of the current ones. If this idea boosted effiecincy just by 5% thats an extra 40hp odd . The expense of 5kg extra weight is most certainly would worth it.

[DOHC]

Originally posted by Christiaan
the exhaust gases have about 4kW of power that just gets dissipated into the air.

That's very little.

Few ICEs have an efficiency above 35%. Given that a typical F1 engine can output 500+ kW on average, total heat losses ought to be about twice as large, maybe close to 1 MW. Most of it through the exhaust, no doubt, and the rest through heat build-up in the engine that has to be dissipated via the cooling system.