TERS : Thermal Energy Recovery System

[xpensive]

Most uninteresting, thought they left some room for innovation, how much power might such an MGUH produce anyway?

[WhiteBlue]

Most uninteresting, thought they left some room for innovation, how much power might such an MGUH produce anyway?

http://argent.fia.com/web/fia-public.ns ... _20.07.pdf

5.2.2 The maximum power used to propel or brake the car through the MGUK must not exceed 120kW.

If the max power through the MGUK is 120 kW that is also the limit for the recovery from the MGUH.

[xpensive]

120 kW from an xhaust driven turbine, is that realistic, even a 100 kRpm, that's 11.5 Nm of torque?

[noname]

120 kW from an xhaust driven turbine, is that realistic, even a 100 kRpm, that's 11.5 Nm of torque?

Yes, it is.

Does it make sense and brings benefits ? That's the questions F1 engine developers are trying to answer.

[ESPImperium]

HERS will be the next area of exploration, thats for sure, bue VERS (Vibration) and SERS (Sound) are both already being looked at. Their technology is already about 5 to 7 years away, but some things ive read say that they could be ideal top up recovery systems.

[xpensive]

120 kW from an xhaust driven turbine, is that realistic, even a 100 kRpm, that's 11.5 Nm of torque?

Yes, it is.

Does it make sense and brings benefits ? That's the questions F1 engine developers are trying to answer.

I seriously doubt the 120 kW, you need to gear the turbine speed down from some 100 kRpm to what, 3000 Rpm first?

[noname]

I seriously doubt the 120 kW, you need to gear the turbine speed down from some 100 kRpm to what, 3000 Rpm first?

Why ? You need MGU able to be revved up to ~100k RPM (not an easy thing, btw). Than feed the battery (or whatever storage system you will decide to use) and put the energy on the wheels.

The bigger problem is increased backpressure. To get 120kW from the turbine (higher PR) you will seriously compromise the engine.
And the more you are trying to extract the more you have to change turbo matching, and that means you'll be further away from turbo "sweet spot" once you are not exctracting, or extracting much less.

And that's just the few things you have to deal with.

[WhiteBlue]

I seriously doubt the 120 kW, you need to gear the turbine speed down from some 100 kRpm to what, 3000 Rpm first?

Why ? You need MGU able to be revved up to ~100k RPM (not an easy thing, btw). Than feed the battery (or whatever storage system you will decide to use) and put the energy on the wheels.

Energy from the MGUH will not go into storage. It will immediately go to the MGUK where it is fed to the rear wheels. 120 kW may be too ambitious - I agree with x here. But he asked if there is a limit in the regulations. The limit seems to be higher than what would practically be useful. Sounds like a good regulation.

[noname]

Energy from the MGUH will not go into storage. It will immediately go to the MGUK where it is fed to the rear wheels. 120 kW may be too ambitious - I agree with x here. But he asked if there is a limit in the regulations. The limit seems to be higher than what would practically be useful. Sounds like a good regulation.

You will need some kind of energy storage device to "stabilize" the system. Even if you would like to put the energy directly to the wheels.

You will not extract power all the time, it will not be continues 120kW, DC may not be 100%, etc. And, afetr all, MGU stands for Motor Generator Unit, so it is supposed to extract the power from the exhaust gases, but also to spin up the turbo (i.e. to improve transients).

[xpensive]

...
120 kW may be too ambitious - I agree with x here. But he asked if there is a limit in the regulations. The limit seems to be higher than what would practically be useful. Sounds like a good regulation.

What can we work with here, when fluid power is volumetric flow times pressure, what's the potential MGUH-power,
ball-park-wise? Please note, I'm not talking thermal power per se, just from the flow itself, regardless of temp.

Just to get started, input values picked from the top of my head; A 1.6 liter engine at 10 kRpm with 1.0 Bar boost would suck in some 250 liters per second, then xpanded ten-fold due to combustion, xiting a flow of 2.5 m^3 per second.

If the pressure drop over the turbine is 1 Bar, with a 50% efficiency, the xhaust fluid power going into the turbine shaft would be no less than 125 kW, what do you know what do you say WB?

Would some member with a better knowledge of turbocharging than me please look at the numbers above?

[noname]

If the pressure drop over the turbine is 1 Bar, with a 50% efficiency, the xhaust fluid power going into the turbine shaft would be no less than 125 kW, what do you know what do you say WB?

Pressure drop across turbine would be higher (few times) and the turbine (peak) efficiency could be well above 60%.

[WhiteBlue]

You will need some kind of energy storage device to "stabilize" the system. Even if you would like to put the energy directly to the wheels.

You will not extract power all the time, it will not be continues 120kW, DC may not be 100%, etc. And, afetr all, MGU stands for Motor Generator Unit, so it is supposed to extract the power from the exhaust gases, but also to spin up the turbo (i.e. to improve transients).

AFAIK the MGUH will mainly operate in generator mode except for spool up when there is the option to avoid the turbo lag by letting it suck energy from the battery and work in motor mode. I expect this to be the big exception. Under standard conditions there will be a surplus of enthalpy from the waste gas which can be used to drive the MGUK in motor mode.

I don't agree that the electric power from the MGUH has to be fed to a battery between the MGUH and the MGUK. Both units are fitted with a power electronic inverter which modulates the AC power to fit the unit characteristic. This technology is also used in multi axis machine tools. You typically find an intermediate circuit capacitor in such designs to do that job. I fully expect F1 to adopt that design. The electric conversion losses are much smaller compared to a battery.

Regarding the efficiency of the turbine and the compressor the rules are very free. For typical axial units as they are used in contemporary turbochargers you would expect 70%+ efficiency. Because F1 can afford to throw some money at higher efficiency I would expect the designers to use radial flow at least for the turbine which is probably transforming twice as much power as the compressor on average.

If I remember right an estimation of the total turbine power in one of the old threads came to 140 kW. After transformation losses for the turbine, the MGUH and the compressor that would probably be 100 kW net power. And the split could have been 40 kW to the compressor and 60 kW to the rear wheels. Don't nail me on the figures. They come from memory. It would be better for someone to check the old 2010 thread on the 2013 turbo unit.

Edit: found the thread viewtopic.php?p=200560#p200560

The estimated efficiencies fit, but the net power output is considered close to 200 kW. The thermodynamic computations were done by Ringo. Perhaps he can adapt the 2010 assumptions - which were done for a four cylinder engine with different fuel limit - to the current data. I expect a net value below the 200 kW.

The interesting result from the thermodynamic computation is the ratio between the turbine and the compressor power and the efficiencies, which I expect to be similar for the 2014 system. The compressor is only using 37% of the total enthalpy that the turbine is converting to power. The compressor is estimated at 76% efficiency and the turbine at 85%.

[noname]

(...)

I think we can agree there would be MGU, inverter and storage device in the system. As for the last there are few options but seems like battery-like aproach is the way to go for today, for various reason.

After all capacitor is an energy storage device (Toyota's LMP powertrain uses "batteries" build with capacitors )so, if I can ask for something, do not nail me on words, please. Power electronics is a bit outside of my comfort zone.

How the system will be designed, configured and used is not clear yet, the folks working on this have still a lot to learn. 2014 rules are defined but turbo compounding opens some new opportunities, and they are already investigated. Enough to say I expect the rules to evolve in the following years. In the sake of "road relevance" and to cope with increasing efficiency demands.

As for the turbo conigurations used today radial wheels dominate, you can find mixed sometime. I know about axial wheels being tested in prototypes. The problem with them is they will not work with single stage radial compressor, more than one is not allowed, axial of this size may suffer due low efficiency and may not give the PR required. It would make packaging difficult as well.

Extracting ~120kW (on top of the power needed to drive the compressor) is possible, but I do not expect such a big number. Definitely not in 2014.

[WhiteBlue]

I still expect them to use capacitors for the intermediate circuit. The efficiency compared to batteries is hugely better and you do not need any big capacity between the two units when they work in compounding mode. It is different in anti lag or spool up mode. In that case a huge amount of stored energy is needed. But the penalty for using a battery is loosing up to 40% of the raw energy by a twofold conversion of the battery chemistry. The capacitors also have a heat loss but it is tiny compared to batteries. Capacitors use a physical conversion not a chemical.

I have now found the difference in fuel consumption between the 2013 system assumed in the old thread and the 2014 system published in the regulations.

old 31.91 g/s
new 27.78 g/s

The ratio is 87%.

If I convert Ringo's thermodynamic calculation results by that ratio I get:

172.64 kW total energy from the turbine extracted from exhaust gas

63.88 kW total compressor requirement

108.76 kW MGUH peak power input.

100.1 kW MGUH peak electric output (92% efficiency)

98.56 kW capacitor peak output (98.5% efficiency)

90.67 kW shaft output of the MGUK to the wheels (92% efficiency)

I'm not really sure that I have considered the compressor efficiency correctly. There is also a good chance that the thermodynamics are not working linear with the fuel mass flow. We could also have further errors in the input data which I'm not aware of.

But all together I find it a reasonable assumption that you can have roughly 90-100 kW turbo compounding in a system that is allowed a total of 120 kW. The difference would be provided by the breaking power. This makes some sense if you consider the time factor between breaking and near full power demand.

Full breaking 120 kW
Full accelerating power from batteries to MGUK 20.4 kW

ratio is 17%

I think that would be sensible ratio between breaking and full throttle demand time not considering the losses in the battery. If you consider those the real time ratio is probably pushing over 20%.

[WhiteBlue]

As for the turbo conigurations used today radial wheels dominate, you can find mixed sometime. I know about axial wheels being tested in prototypes. The problem with them is they will not work with single stage radial compressor, more than one is not allowed, axial of this size may suffer due low efficiency and may not give the PR required. It would make packaging difficult as well.

Have a look at the famous Wright_R-3350 aero engine with single stage axial turbines used for turbo compounding. The efficiency of the one stage turbine was 72%. That application is now 65 years old and it probably was the commercially most successful application of turbo compounding ever done to piston engines. F1 will not be too far behind 1945 technology when they start their own lead application. This is why I'm confident that the F1 designers will at least look at axial turbines for efficiency reasons. If you set your objectives too low you will not be successful.