F1technical.net

tomislavp4 wrote: How about using the heat from the brakes to drive a turbine? Or to heat water and use the steam to drive a turbine? How feasible is it?

It is much more efficient to transfer the kinetic energy of the vehicle directly to electrical energy then to transfer it to heat(via the brakes) and then try to harness it from there. Usually the less energy is transferred from one form to another the more efficient the system as a whole. Waste heat, such as from the engine exhaust, is transferred via a turbine in a turbocharger, but does not utilize all of the available energy in the exhaust, thus the search for a more efficient HERS system.

So while your idea is feasible, it is not the most efficient option currently available.

flynfrog,

It's like the old drag racer's joke: "Gasoline is for washing parts. Alcohol is for drinking. But nitro is for racing!"

Best regards,
Terry

I think we should be reminded of what sort of power we are talking about here, if the engine has a 20% efficiency, an F1 engine on full song is giving away 2000 kW through exhaust and cooling system.

That's 160 000 kJ over an 80 seconds lap if you never lift off. Find a way to recover 10% of that (16 000 kJ) and you make KERS look rather stupid.

How about a 6 stroke engine?

1-2-3-4
Suck-Squeeze-Bang-Blow
(All petrol)


5-6
Bang*-Blow**


*Inject water after stroke 4 - the heat of the cylinder combined with perfect gas law results in massive change in temperature = massive change in pressure & density = increase in cylinder volume = another powered stroke.

**Vent the steam in to the exhaust system (also helping to cool it somewhat compared to the petrol exhaust gases)




This also re-uses alot of the thermal energy that would otherwise be lost (or worse further reduces performance through aerodynamic radiator drag).



I know there are issues with 6 stroke engines - regarding materials mostly. But no better proving ground than F1 for a technology with real world connotations (as opposed to the FUD of KERS).

If I get you right Paddy, you are suggesting using the engine as a steam generator? Interesting, never thought about it that way.

Lars

I believe you've just described Bruce Crower's 6-stroke engine:

http://www.autoweek.com/apps/pbcs.dll/a ... WEEKSISSUE

joseff wrote:I believe you've just described Bruce Crower's 6-stroke engine:

http://www.autoweek.com/apps/pbcs.dll/a ... WEEKSISSUE

Exactly!


Read about it many moons ago.

A good engineer is always eager to learn. Thanks a lot guys!

It should be possible to calculate how much power can be recovered by the water For the turbo-steamer example

You can estimate the mass flow of the exhaust (velocity etc)
Get the temperature of the gases.
Get the emissivity of the gasses.
Get the surface area of the exhaust pipes.
Get the thickness of the pipes.
You know about the flow of water..
Set up a heat transfer equation..(Or use some CFD program) and you get the Input power to the water.

Afterward you can just treat it like a regular Steam turbine cycle.
So your F1 engine would be a combined cycle engine

One More radiator is going to be needed though.. the condenser.

viewtopic.php?f=4&t=3619&start=390

There are tons of links and info in this thread. So I hope that perhaps the two threads get integrated under a new title.

I think HERS and KERS threads should be different threads, as they are quite different topic.

Anyway, @n smikle, thanks for the info.

Some way I can take a sort way to it? I mean, for this first stage I don't need a very detailed analysis, but I do need it to do it quite soon. I mean, I was thinking of doing it basically with enthalpies graphs for overheated water steam and that stuff, as well as assuming the Renault's article figure (680hp for exhaust, 150KW for water refrigeration, 120KW for oil) as approximately valid.

If, as suggested, we use just a single circuit, which while not recovering as much energy would be certainly lighter and smaller hence more interesting for F1 application, and with just a single expander/turbine followed by a small radiator for condensing back the fluid, what % of those 680hp exhaust loss power + the other two sources, could be recovered?

Given BMW achieved 80% of the exhaust's, with the single circuit one, would 60% be close to reality?

As for the steam cycle, I guess you mean the best should be Rankine's?
Sorry for not being so accurate. Despite being from the engineering camp, thermodynamics wasn't ever one of my strongest's points, and have forgotten quite a lot about it

By the way, in case HERS arrives to F1 (or FOTA series) in 2013 or so, how do you think the system will be? What would you guys suggest?

I hope I'm not being to simplistic but the heat in the exhaust and the relatively low temps elsewhere in a race car seem ideal for using an external combustion engine such as the Stirling, which uses the temperature differnce to generate power.

redcat wrote:I hope I'm not being to simplistic but the heat in the exhaust and the relatively low temps elsewhere in a race car seem ideal for using an external combustion engine such as the Stirling, which uses the temperature differnce to generate power.

now if tht could be sized down to nanotechnology I think you've got something there

J-Raid wrote:I think HERS and KERS threads should be different threads, as they are quite different topic.

Anyway, @n smikle, thanks for the info.

Some way I can take a sort way to it? I mean, for this first stage I don't need a very detailed analysis, but I do need it to do it quite soon. I mean, I was thinking of doing it basically with enthalpies graphs for overheated water steam and that stuff, as well as assuming the Renault's article figure (680hp for exhaust, 150KW for water refrigeration, 120KW for oil) as approximately valid.

If, as suggested, we use just a single circuit, which while not recovering as much energy would be certainly lighter and smaller hence more interesting for F1 application, and with just a single expander/turbine followed by a small radiator for condensing back the fluid, what % of those 680hp exhaust loss power + the other two sources, could be recovered?

Given BMW achieved 80% of the exhaust's, with the single circuit one, would 60% be close to reality?

As for the steam cycle, I guess you mean the best should be Rankine's?
Sorry for not being so accurate. Despite being from the engineering camp, thermodynamics wasn't ever one of my strongest's points, and have forgotten quite a lot about it

By the way, in case HERS arrives to F1 (or FOTA series) in 2013 or so, how do you think the system will be? What would you guys suggest?

You might get 40% of the exhaust energy . That is about 0.4 * 680hp = 272 hp extra.

I think the design of heat exchanger for the exhaust, will affect it. Because the more Fins and (or) tubes in the exhaust can cause the engine to loose some power. So it will be a trade off.