2014 intercooling

[gruntguru]

http://www.stealth316.com/2-turbotemp.htm
Here is another calculator - in psi and *F unfortunately but there is a F -> C converter lower on the page. Use 14.5 psi (abs) inlet 38.3 psi (gauge) boost to get a pressure ratio of 3.5 Use whatever compressor efficiency you like. 100% gives an outlet temp of 339*F (170.6*C) . 82% gives an outlet temp of 391 *F (199.4*C). 82% is very high. I wonder if the F1 compressors are that high?

[ringo]

The compressors would be about that with the current technology. But as said earlier, the engines dont operate at 3.5 bar. I thknk you will see that at lower rpms like 5000, but that depends on the compressor map. With a high compression ratio that these engines have you would probably see maybe 0.5 bar at full power. And wont have 200 degree c air. Anyhow the current cars would probably see the same 40 degree or so air into the intake. Im not sure of the intercooler requirements so cannot speak to that.

[wuzak]

The boost pressure depends on the air flow required to support burning the 100kh/hr fuel flow rate.

For a 1.6l engine, assuming volumetric efficiency of 100%, the air passed per revolution is 0.8l.

At 10,500rpm that equates to 8400l/min = 8.4m³/min = 0.14m³/s.

Fuel flow is 100kg/hr = 0.0278kg/s.

Assuming an AFR of 14.7:1, the air flow required is 0.408kg/s. Air density is ~1.2kg/m³ (changes with temp and pressure, so just a guide), meaning that the volumetric air flow required is 0.34m³/s.

To get that 0.34m³/s in the space of 0.14m³/s requires a pressure ratio of 2:43:1 from the compressor. Ie 2.43atm ABS or 1.43atm boost. That is at stoichiometric AFR.

WIth AFR = 20:1 the pressure ratio required would be 3.3.

All vvery rough calcs. But it is certainly going to be more than 0.5bar boost.

[gruntguru]

The compressors would be about that with the current technology. But as said earlier, the engines dont operate at 3.5 bar. I thknk you will see that at lower rpms like 5000, but that depends on the compressor map. With a high compression ratio that these engines have you would probably see maybe 0.5 bar at full power. And wont have 200 degree c air. Anyhow the current cars would probably see the same 40 degree or so air into the intake. Im not sure of the intercooler requirements so cannot speak to that.

These graphs give you some idea of how much boost is required to burn the allocated fuel at Lambda = 1.0 and 1.3 respectively. Full explanation in the "Formula One 1.6l V6 turbo engine formula" thread.

[ringo]

That's fine, I have my simulator. ha ha.
It sizes intercoolers as well, however it sizes based on what temperature drop I want across it, at certain air flows.

Currently it's set with a 13:1 compression ratio. This is very high. If there was more date on pumping losses and other frictional losses, I would be able to determine the best compromise between boost pressure ratio and compression ratio for overall cylinder pressures.

[ringo]

The boost pressure depends on the air flow required to support burning the 100kh/hr fuel flow rate.

For a 1.6l engine, assuming volumetric efficiency of 100%, the air passed per revolution is 0.8l.

At 10,500rpm that equates to 8400l/min = 8.4m³/min = 0.14m³/s.

Fuel flow is 100kg/hr = 0.0278kg/s.

Assuming an AFR of 14.7:1, the air flow required is 0.408kg/s. Air density is ~1.2kg/m³ (changes with temp and pressure, so just a guide), meaning that the volumetric air flow required is 0.34m³/s.

To get that 0.34m³/s in the space of 0.14m³/s requires a pressure ratio of 2:43:1 from the compressor. Ie 2.43atm ABS or 1.43atm boost. That is at stoichiometric AFR.

WIth AFR = 20:1 the pressure ratio required would be 3.3.

All vvery rough calcs. But it is certainly going to be more than 0.5bar boost.

Not really. It depends. I think I've posted some graphs in the other thread. the boost pressure is very much dependent on your compression ratio and engine speed, and air temperatures. But it's nowhere at 3.3 bars at 10,500 rpm.

[wuzak]

The boost pressure depends on the air flow required to support burning the 100kh/hr fuel flow rate.

For a 1.6l engine, assuming volumetric efficiency of 100%, the air passed per revolution is 0.8l.

At 10,500rpm that equates to 8400l/min = 8.4m³/min = 0.14m³/s.

Fuel flow is 100kg/hr = 0.0278kg/s.

Assuming an AFR of 14.7:1, the air flow required is 0.408kg/s. Air density is ~1.2kg/m³ (changes with temp and pressure, so just a guide), meaning that the volumetric air flow required is 0.34m³/s.

To get that 0.34m³/s in the space of 0.14m³/s requires a pressure ratio of 2:43:1 from the compressor. Ie 2.43atm ABS or 1.43atm boost. That is at stoichiometric AFR.

WIth AFR = 20:1 the pressure ratio required would be 3.3.

All vvery rough calcs. But it is certainly going to be more than 0.5bar boost.

Not really. It depends. I think I've posted some graphs in the other thread. the boost pressure is very much dependent on your compression ratio and engine speed, and air temperatures. But it's nowhere at 3.3 bars at 10,500 rpm.

Which comes first - boost or compression ratio?

The defining factor is the fuel flow rate. From that you work out how much air (mass) you need.

The RPM, capacity and VE define how much air (volume) gets into the engine, so from that you can work out what pressure that air needs to be to get the required mass flow rate.

Then you would worry about the CR.

[ringo]

How will you know your volumetric effficiency?
These are not things you can answer without empirical evidence.
As i say 3.3 is not seen at 10,500 rpm. You guys can do your calculations and check it.
For 3.3 bar your probably at some ridiculously low compression ratio.

[wuzak]

How will you know your volumetric effficiency?
These are not things you can answer without empirical evidence.
As i say 3.3 is not seen at 10,500 rpm. You guys can do your calculations and check it.
For 3.3 bar your probably at some ridiculously low compression ratio.

I don't know the volumetric efficiency. I used 100% for simplicity in a simple calculation.

It is going to be above 100% - even the NA engines had VE above 100%.

Compression ratio is likely lower than your target, whch i sbasically for a non supercharged application.

[gruntguru]

Wuzak is spot on with his analysis. CR is the last thing chosen in this application.

Your simulator is probably not going to be very useful. The current formula poses a completely new design challenge. Getting enough air into the engine is no longer the challenge. A 1.6 with unlimited boost and 15,000 rpm could be designed to flow enough air to burn at least double the fuel flow allowed under the rules. So the design challenge becomes "how do you get the most energy out of each drop of fuel?"

[gruntguru]

How will you know your volumetric effficiency?
These are not things you can answer without empirical evidence.
As i say 3.3 is not seen at 10,500 rpm. You guys can do your calculations and check it.
For 3.3 bar your probably at some ridiculously low compression ratio.

Volumetric efficiency is typically 110%+ for this category of engine. (That is 110% of pressurised charge air not intake air.)
I have done my calculations (which you would know if you had read and understood the posts and graphs). To burn the allocated fuel at 10,500 and AFR of 1.0 would require intake pressure of about 2.3 bar abs. At AFR = 0.85 the pressure required is about 2 bar abs, but as explained elsewhere, there is no way the engines are run at 0.85 (or even 1.0 for that matter)

My guess on CR would be 10 or 11.

[ringo]

Your's are built around a quotation from renault about using 3.5 bar of boost. And it seems you have molded and shaped around that figure, and that's where i find issue.

Here is my boost chart:



This is for peak horsepower of about 615hp and keeping with fuel flow rate limits my VE is at 1.2
. It's gauge pressure. No sign of 3.5bar absolute or 2.5 gauge anywhere at 10,500rpm.

As for the fuel, this is not special toluene fuel that needs to be heated up. It's ordinary fuel for the most part.
Honda used 40 degree air for full power, and only used 70 degree air for fuel efficiency at a reduced power; with their toluene fuel. This high temperature operation simply wont apply to these new engines.
15 to 20 degrees above ambient is a reasonable guess for intake air temperatures.

[wuzak]

Your's are built around a quotation from renault about using 3.5 bar of boost. And it seems you have molded and shaped around that figure, and that's where i find issue.

Here is my boost chart:

http://s1010.photobucket.com/user/ducka ... d.png.html

This is for peak horsepower of about 615hp and keeping with fuel flow rate limits my VE is at 1.2
. It's gauge pressure. No sign of 3.5bar absolute or 2.5 gauge anywhere at 10,500rpm.

As for the fuel, this is not special toluene fuel that needs to be heated up. It's ordinary fuel for the most part.
Honda used 40 degree air for full power, and only used 70 degree air for fuel efficiency at a reduced power; with their toluene fuel. This high temperature operation simply wont apply to these new engines.
15 to 20 degrees above ambient is a reasonable guess for intake air temperatures.

That doesn't quite agree with what you said earlier.

The compressors would be about that with the current technology. But as said earlier, the engines dont operate at 3.5 bar. I thknk you will see that at lower rpms like 5000, but that depends on the compressor map. With a high compression ratio that these engines have you would probably see maybe 0.5 bar at full power. And wont have 200 degree c air. Anyhow the current cars would probably see the same 40 degree or so air into the intake. Im not sure of the intercooler requirements so cannot speak to that.

1.17 bar boost equals an approximate (rough calc) AFR of 15.7:1.. It's certainly not the same as the 0.5bar boost you said earlier.

Perhaps when you said 0.5 bar boost at "full power" you meant "at max rpms"?

[ringo]

Yea max rpm, that was a typing error.

My A:F is set at 13.6:1 at all times in my calcs. boost is just pressure, it doesn't speak to the mass flow of the air. My intake temps are set at 40 degrees C. I don't buy into the learn burning gig as a performance advantage really. I don't really see where it will be used at racing speeds. Maybe in a situation where fuel is critical, or where engine push affects handling under braking or something.

[gruntguru]

Your boost chart looks about right for 13.6 (you should use lambda - 13.6 is meaningless unless the fuel type is known) assuming 14.7 is stoich for the fuel used i.e. 0.925. I repeat "there is no way these engines are running 0.925". At that AFR 7.5% of the fuel is going out the exhaust and contributing nothing to the power.

Honda RA128E in economy trim ran 0.98 and saw 32.2% thermal efficiency (272 g/kW.hr). If this engine was allowed to run in the current series with 100 kg/hr max fuel flow, it would make 368 kW or 490 bhp.

When run in its max power mode with lambda = 0.87 and intake air temp 40*C it's thermal efficiency was about 28.4% (307 g/kW.hr). With 100 kg/hr max fuel flow the "high power" version would make 324 kW or 432 bhp.

Which version would you run?