Talking to a turbo expert

[WhiteBlue]

Your fuel flow rate must be an error. You probably meant exhaust flow rate. It is still way excessive in that case.

By a napkin style calculation I arrive at 2.34 bar inlet pressure although they have mentioned that 3 bars would be allowed. At three bars an 1,6L engine with similar efficiency as the existing F1 engine and working at 10,000 rpm would produce 833 bhp. The plan is obviously to cut down fuel use from today's 150 kg to 115 kg to limit the engine to the lower power figure. The obvious way for the users not to exceed the max fuel flow is limiting the turbo pressure to the 2.34 bar I figured. So it would make sense to use that figure for a calculation.

Regarding the likely AFR of the engine I would assume that the spray guided direct injection will achieve a 5% higher AFR than the port injected engine. The engine will be able to run AFR >16 for low rpm and very close to 14.7 at full power. So using 14.6 is probably not a bad assumption. This would bring the exhaust factor to 15.6 and generate 1794 kg of exhaust gas respectively an average of 0.374 g/s in an 80 min race. These figures would put the current 2.4L NA engine at an AFR of 13.9. That is probably not such a bad assumption.

[ringo]

Your inlet pressure has to be boost pressure + atmospheric pressure.
My flow rate is fuel+air not fuel alone. Fuel alone is 0.03kg/s
I hope you read my last post and not the first one. The first post is not accurate.

I am working with equations. The only thing i am skeptical of is the flame temp and pressure and friction power.
friction power has to be tested. My power value is indicated power not brake.
other than that, it looks pretty sound. from the excel file i have an exhuast temperature of 1204K or 931 degrees.
I'm working with 10,500 rpm, this way i get 670hp of work.
fuel is 48,000kJ/kg. air temp 30 degrees, manifold air temp 40 degrees.

[WhiteBlue]

You are probably using a peak mass flow rate where I was using the average flow rate. Average is probably 25% under peak which means your figure of 0.5 kg/s is correct. The specific energy of petrol is probably a bit lower around 46 or 46.8 MJ/kg. So can you just list the complete final data for easy consumption?

engine power
rpm
inlet pressure
compressor power requirement
compressor efficiency
turbine efficiency
turbine p1, p2, T1, T2
turbine power output

All data under the assumptions that the turbine and the compressor are not coupled.

[ringo]

10,000rpm at 2.34 bar at 14.6 a:f

i get:
496hp ,

keep in mind i haven't lowered my cylinder pressure or temp. I could with the flame program, but i'm feeling to lazy. lowering the pressure would lower everything though.

air + fuel flowing out the engine comes to 0.37kg/s

clearly there is something different to what you are doing. 833hp is pretty high.
how did you get that value exactly?

I am playing by the thermodynamic rules so I can't argue with what I get.

Let me use the values from the Honda Ra18 1.5lt engine, to see how accurate my calculations are.
it uses 2.5bar of boost with a 1.494 lt engine, 9.4 compression ratio, equivalence ratio of 1.15.
it makes 504kW at 12,500rpm.

When i put these numbers in and mimick this engine, i get a result of 640kW 858hp, compared to honda's 504kW. This sounds realistic and i havent taken into account friction power, which should lower my 640kW value.

so it's safe to assume your 800hp value has some discrepancy. Maybe the efficiency is higher than can be expected.
the boost and flow rate is too low to produce that much power, so is the engine speed.

[ringo]

You are probably using a peak mass flow rate where I was using the average flow rate. Average is probably 25% under peak which means your figure of 0.5 kg/s is correct. The specific energy of petrol is probably a bit lower around 46 or 46.8 MJ/kg. So can you just list the complete final data for easy consumption?

engine power
rpm
inlet pressure
compressor power requirement
compressor efficiency
turbine efficiency
turbine p1, p2, T1, T2
turbine power output

All data under the assumptions that the turbine and the compressor are not coupled.

gimme a sec,

FUEL
fuel heating value (MJ/L): 46.8
fuel density (kg/m3) 917.9
equivalence ratio: 1

AIR
Atmospheric temp (*C) 30
atmospheric pres. (kPa) 101
intercooled temp (*C) 40
specific heat Cp (kJ/kgK) 1.005
gas constant air, R (kJ/kgK) 0.287


ENGINE
# of cylinders, N 4
engine speed, n (rpm) 10500
displacement, Ve (L) 1.6
compression ratio (r): 9.4
volumetric efficiency: 1

TURBO
turbine efficiency ŋT 0.85
compressor efficiency ŋC 0.76
boost guage pres. (Bar) 2
-------------------------------------------------------------------------------
results:

FUEL
flow rate V (m3/s) 0.14
air mass flow, ma (Kg/s) 0.469103094 lb/min 61.92160835
fuel flow rate mf (kg/s) 0.031911775 air and fuel, ma+f 0.501014869

COMPRESSOR
compressor enthalpy kJ/kg 146.6234318
compressor power kW 73.46051943 horsepower 98.51217269
outlet temp, K 413.8794111 *C 140.8794111
intercooler ΔT -100.8794111

ENGINE
P2 (bar), 69.29061634 <---- T.D.C.
T2 (Kelvin) 766.521627
adiabatic pressure bar: 277.1546454 <----- ignition
adiabatic flame temp K: 3066
Exhaust pres P4 (bar) 12.0396603
Exhaust temp, T4 (K) 1251.964676
indicated power kJ/kg 976.8488348
Indicated power kW: 489.4157907 horsepower: 656.3173424

TURBINE using adiabatic flame values
turbine available enthalpy: 542.4820954
turbine available power kW: 271.7915958 horsepower: 364.4785093
full load exh. temp K: 616.9256409 degrees C: 343.9256409
compressor load exh temp 1011.716549 degrees C 738.7165487
useful power kW: 198.3310763 horsepower: 265.9663366

turbine p2 is exhaust, atmospheric pressure. 343 degrees is very cool.
Note the total output is usable work. this is it's full capability (compressor power isn't subtracted as yet).
But remember 343 is when you add all your fandangles on the turbo, this is when it is fully loaded. It wont run cooler.

With the compressor alone, it exhuasts at 738 degrees.

[WhiteBlue]

your figures seem to be all right. The mass flow figure that you are using is for 25% reduced power or fuel consumption.

My power calculation was very simplistic.

An 18,000 rpm NA 2.4L engine produces 750 bhp peak power and uses 150 kg fuel during a race while the average power output is 75% of 750 bhp.

If I simply divide power by 2.4 and multiply with 1.6 and multiply with 2.34 bar and divide by 1.8 for rpm I get 650 bhp. When I multiply with 3 bar I get 833 bhp. Very simplistic.

[ringo]

oh , the engine exhaust temp and pressure is the turbine inlet temp and pressure, since the gases is straight out of the exhaust manifold and into the turbo.

I noticed, i accidentally left the compression ratio at 9.4. Oh well.

What's interesting is that the turbo generator or TERS has a lot of power it can scavenge. 250hp at least.

To explain the data above.
It's the same engine, the first set is the input data. The second set of data is the result.

[WhiteBlue]

It is interesting to see the mismatch of the turbine power with the compressor power. The factor is 2.7. Or in other words you waste 63% of the exhaust gas energy if you only run a turbocharger and do no turbo compounding.

I would think that we have 198.3 kW at full peak power of the engine. The engine would run only at 75% effective power which would also reduce our turbine power to 148.7 kW.

If we push that through a generator and the inverter to a battery we still have 133.9 kW. We need 75% of 73.5 kW for the compressor which is 55.1 kW or 61.3 kW of electric power due to losses in the motor and inverter.

This leaves us 72.6 kW on battery level. If we use it to drive the wheels we must convert another time and keep 65.3 kW mechanical power. As this power has to be compared to average engine power we get another 13.4% of the engine power without any fuel use. This is 0.314 GJ race energy. A massive amount compared to KERS.

If we permanently feed the electric energy from the hybrid compounder to the front wheels we do not even need to install battery capacity. We just have a weight penalty for the generator, the motor and the two inverters.

Regarding the weight penalty we are not talking peanuts here. We have to install MGU and inverter capacity of 271.8 kW. I reckon that my two stage turbine design with mechanical compounder would be a lot more weight efficient.

[xpensive]

...
An 18,000 rpm NA 2.4L engine produces 750 bhp peak power and uses 150 kg fuel during a race while the average power output is 75% of 750 bhp.

If I simply divide power by 2.4 and multiply with 1.6 and multiply with 2.34 bar and divide by 1.8 for rpm I get 650 bhp. When I multiply with 3 bar I get 833 bhp. Very simplistic.

Gosh WB, that's 17.4 Hp per liter, Bar and kRpm, wonder where you learned that formula, from another member perhaps?

[ACRO]

If I simply divide power by 2.4 and multiply with 1.6 and multiply with 2.34 bar and divide by 1.8 for rpm I get 650 bhp. When I multiply with 3 bar I get 833 bhp. Very simplistic.

i feel the calculation will be more accurate when you put in this formula the square root of YOUR piston stroke. can you provide us with numbers?

[WhiteBlue]

If I simply divide power by 2.4 and multiply with 1.6 and multiply with 2.34 bar and divide by 1.8 for rpm I get 650 bhp. When I multiply with 3 bar I get 833 bhp. Very simplistic.

i feel the calculation will be more accurate when you put in this formula the square root of YOUR piston stroke. can you provide us with numbers?

not my cup of tea.

[ACRO]

a superb answer for the request of implementing the maximum stroke of YOUR piston to the formula WB ...

[ringo]

interesting article on turbo compunding.
System looks huge:

http://www.mhi.co.jp/technology/review/ ... 441049.pdf

It weighs in at 130kg, one thing to note is that it runs on 5% bleed off from the exhuast manifold. They claim it's 200kW, so this diesel engine must be a very huge unit for that much power to be contained in only 5% of the gas.

As riff raff said, the size of the unit is a very important consideration.

Now that i read this article, and looking at my engine calculation, 200kW of energy cannot simply be collected from a turbine spinning at 100,000 rpm.
I don't know if there is a generator out there that runs at that speed or if 200kW can be collected from a tiny unit. The cooling requirements must be huge.
A planetary gear set could help though, with a 5:1 ratio. 20,000 rpm seems to be possible with the additional weight of a gear set, with gear oil cooler for the high speeds.

It's best this generator takes a % of the exhuast from the exhuast manifold, at least at a power level that can be handle by a shoe box sized motor/generator.

Maybe 80hp KERS unit on the secondary turbine?

[WhiteBlue]

interesting article on turbo compunding.
System looks huge:

http://www.mhi.co.jp/technology/review/ ... 441049.pdfIt weighs in at 130kg, one thing to note is that it runs on 5% bleed off from the exhuast manifold. They claim it's 200kW, so this diesel engine must be a very huge unit for that much power to be contained in only 5% of the gas.

This is a 5000 kW engine and Mitsubishi are probably experimenting in order to find the best way to turbo compound slow running generator and ship diesels. A completely different application. I also have my problems to understand the total system design. The diagram of the steam turbine they show is not compatible with the hybrid turbo charger they show later. So I see the hybrid turbo charger as an alternative to the steam turbo compounder which seems to be in use for other applications and was previously considered.

http://www.alibaba.com/product-free/112 ... RATOR.html

These monsters run on 700 rpm and have huge displacement compared to an F1 engine.

EDIT: Further news show I was right about the ship diesels.

http://www.greencarcongress.com/2010/08 ... 00826.html

The next unit has 754 kW electricity generating power and will drive a ship diesel next year.

[WhiteBlue]

An interesting turbo compounding idea comes from Torotrak

http://www.torotrak.com/pdfs/tech_paper ... System.pdf

Therefore, by modulating the loads on the Variator, the turbocharger can :-
1. Operate as a supercharger at low exhaust gas flows.
2. Operate as a standard turbocharger at “medium” exhaust gas flow with the Variator unloaded.
3. Load the turbocharger to recover energy to the crank at high exhaust energy gas flows.
4. Enhance engine braking by increasing cylinder pressure (supercharging) in overrun.

The system sounds very feasible for F1. The additional weight for the variable drive would be 8 kg. Perhaps the asymmetric turbo charger with the over sized turbine would weight 3 kg more than the simple turbo charger. So a team can have something like 100 hp more brake power without additional fuel use and 11 kg weight penalty. The weight is even competitive with the weight of the engine and beats it if you consider the fuel the engine has to carry. F1 would be foolish not do do such a system.