TERS : Thermal Energy Recovery System

[wuzak]

Still don’t get it. Here’s the situation; electrical storage is maxed going into the corner. The driver is on the throttle heavy but short of flat out, i.e. feathering the power output. Exhaust heat is overdriving the turbo so the MGU-H applies a load to modulate the impeller speed. The resulting electrical energy can’t go to the charged-to-the limit battery and seemingly the driver doesn’t want the MGU-K messing with his finely balanced power output. I’ve assumed that the MGU-K would be limited to adding to crankshaft power only under full throttle which could be mistaken.

If the MGU-H is to serve as an alternative to a waste gate, it needs someplace to sink energy. Perhaps resistor banks a bit before the diffuser.

If the driver is feathering the throttle he is asking the power unit for a certain amount of power. Some of that is delivered from the ICE, some is delivered by turbocompounding (ie power being fed from MGUH directly to MGUK) and some may come from the energy store to the MGUK. If he has too much power he will ease off the throttle, and the ICE will deliver less power, there will be less exhaust energy to drive the turbine, so there will be less "modulation" of the turbo by the MGUH.

Also, I don't think there will be the situation where the energy store is full. The ES will most likely be used on acceleration from corners and to help with turbo lag.

The only way the ES will be full is if a team deliberately uses a smaller capacity, knowing that they will never need to store the full amount.

[wuzak]

If the MGU-H is to serve as an alternative to a waste gate, it needs someplace to sink energy. Perhaps resistor banks a bit before the diffuser.

I think you need to consider the turbo/MGUH and ICE as a turbocompound engine. Ignore, for the time being, that the power transfer from the turbine to the crank is through electricity.

Drawing it schematically you would have the ICE turbo and MGUH inside a box, with air and fuel as inputs and shaft power as an output, with the throttle controlling the inputs and outputs. The driver demands X load at Y rpm and the turbocompound delivers that to him.

[olefud]

Leaving a safe overhead capacity in the battery makes sense. Or perhaps providing a fixed motor baseline power and using the engine for power modulation. Still, how to prioritize the energy source while concurrently optimizing the time of available maximum motor power for speed/acceleration and controlling turbo boost is an interesting question –at least to me.

[wuzak]

I wonder if the MGUH will produce enough energy in the times where power isn't required at the crankshaft (eg, under braking, off throttle after having been at full throttle) to cover the power required to spool up the turbo at other times. That is, store the energy for later use.

Also, I would think that the MGUK would be most used for acceleration almost immediately after the enrgy is harvested and stored. That is, just after heavy braking events.

[autogyro]

Spinning up the compressor electricaly is a waste of energy.
Why not use a supercharger drive on the other end of the compressor from the crank and overrun it with the turbine when full boost is needed.
For the rest of the time at low turbo boost the turbine can drive the output, electro magneticaly.
If you combine the mgu-h and mgu-k in the gearbox everything becomes far simpler.
To start with you do away with the mgu-k on the crank nose and its silly gearset. (it becomes a supercharger drive)

[wuzak]

Spinning up the compressor electricaly is a waste of energy.
Why not use a supercharger drive on the other end of the compressor from the crank and overrun it with the turbine when full boost is needed.

Using a mechanical connection to drive the compressor will still cost energy - but this will be power taken directly from the crankshaft. So there is no actual gain in doing it this way.

Using the MGUH also gives a lot more control flexibility. To do it mechanically would require a variable speed drive and control mechanism.

For the rest of the time at low turbo boost the turbine can drive the output, electro magneticaly.

If you have a mechanical connection it would be better to use that for the compounding and compressor speed/boost control. Ideally the turbine and compressor could be separate, so each could be operated at its optimum (same goes for the MGUH system, but the FIA have not allowed this).

If you combine the mgu-h and mgu-k in the gearbox everything becomes far simpler.
To start with you do away with the mgu-k on the crank nose and its silly gearset. (it becomes a supercharger drive)

You can't have the one MGU both harvesting power from the turbine and adding power to the drivetrain. The MGU can be a generator or a motor, but not both at the same time.

If you use the mechanical supercharger drive as a compounding system you would have the MGUK as now - it could be mounted on the crank nose with its "silly" gearset, or on the gearbox as you suggest. However, mounting it on the input to the gearbox would be no different to mounting it on the crank nose. The best bet, therefore, would be to mount it on the gearbox output. In either case gearing would be required to match the motor rpm with the shaft rpm where it attaches, and a clutch system would be required to disconnect the MGU from the drivetrain when it is not harvesting power (under braking) or adding power to the system - a significant proportion of the lap time.

FWIW, having the MGUK on the gearbox output/final drive makes it more difficult to define the power unit and gearbox as separate entities.

[WhiteBlue]

Any thought as to what would be done with excess energy if electrical storage is maxed out and the turbo needed modulation to limit boost?

It would be directed into the MGUK.

Still don’t get it. Here’s the situation; electrical storage is maxed going into the corner. The driver is on the throttle heavy but short of flat out, i.e. feathering the power output. Exhaust heat is overdriving the turbo so the MGU-H applies a load to modulate the impeller speed. The resulting electrical energy can’t go to the charged-to-the limit battery and seemingly the driver doesn’t want the MGU-K messing with his finely balanced power output. I’ve assumed that the MGU-K would be limited to adding to crankshaft power only under full throttle which could be mistaken.

If the MGU-H is to serve as an alternative to a waste gate, it needs someplace to sink energy. Perhaps resistor banks a bit before the diffuser.

The meshing of electrical and ICU torque is fully automatic. There would be no situation where the power management would allow such a situation to occur. The power management would always mesh the electric and ICU torque in such a way that the ES capacity is suitably managed and excess energy can be stored away. On the other hand the system would also keep a certain level of charge in the energy storage system. Those tasks of the energy management would be permanent background tasks of which the driver is completely unaware. All he realises is the slightly different power responses on different circuits in different situations which would be very subtle but probably recognizable.

[autogyro]

You said it Wuzak.
The FIA have mandated the compressor mgu-h and turbine on the same shaft.
This prevents any useful development of the thermal energy recovery or the kinetic energy harvesting.
All it leaves is the ability to bolt on motor generators here and there.
IMO pointless.

I was not suggesting a variable drive on the supercharger crank end, only a sprag clutch that could be overrun by the turbine.
In other words the mechanical drive gives supercharging until the turbine takes over the drive to the compressor when high boost is demanded.
The supercharger drive would keep the compressor up to boost speed but allow extra from the turbine when it became spooled up.
(Hmm just thought, the turbine and compressor do remain on the same shaft with this method but they are not always connected, is that against the FIA regs?)

When not driving the compressor, the turbine drives the geartrain electromagneticaly.
(Of course this works better if the gearbox also uses electromagnetic shifting and energy harvesting )
With such a gearbox, when driver demand for drive energy from the turbine (balanced to ic torque demand) is reduced below turbine delivery, the gearbox transferes the excess electrical energy to storage along with the overrun braking energy harvested.
This will only be heat energy at low throttle off boost and most of the turbine energy in use will go through one conversion directly to drive.
With energy harvesting from deceleration still going to storage there is still a need for batteries but the storage needed would be less.

[Dragonfly]

What about a case of an electrical failure in MGUH but turbo as such, MGUK and storage operational. Retire from the race?
Or the opposite - MGUK fail, but MGUH, storage and turbo operational.

[wuzak]

You said it Wuzak.
The FIA have mandated the compressor mgu-h and turbine on the same shaft.
This prevents any useful development of the thermal energy recovery or the kinetic energy harvesting.
All it leaves is the ability to bolt on motor generators here and there.
IMO pointless.

I was not suggesting a variable drive on the supercharger crank end, only a sprag clutch that could be overrun by the turbine.
In other words the mechanical drive gives supercharging until the turbine takes over the drive to the compressor when high boost is demanded.
The supercharger drive would keep the compressor up to boost speed but allow extra from the turbine when it became spooled up.
(Hmm just thought, the turbine and compressor do remain on the same shaft with this method but they are not always connected, is that against the FIA regs?)

When not driving the compressor, the turbine drives the geartrain electromagneticaly.
(Of course this works better if the gearbox also uses electromagnetic shifting and energy harvesting )
With such a gearbox, when driver demand for drive energy from the turbine (balanced to ic torque demand) is reduced below turbine delivery, the gearbox transferes the excess electrical energy to storage along with the overrun braking energy harvested.
This will only be heat energy at low throttle off boost and most of the turbine energy in use will go through one conversion directly to drive.
With energy harvesting from deceleration still going to storage there is still a need for batteries but the storage needed would be less.

Since you are compounding the engine "electromagnetically" you still require a generator connected to the turbine. So why bother with a magnetic drive too? Why not use an MGU and use it both as a generator and to spool the turbo.

The turbine and compressor are required to be on the same shaft, but I don't believe the MGU has to be. It can be connected with gearing and a clutch. The turbine and compressor must be directly linked - ie no gearing and no decoupling, just mounted to the same shaft.

[WhiteBlue]

What about a case of an electrical failure in MGUH but turbo as such, MGUK and storage operational. Retire from the race?
Or the opposite - MGUK fail, but MGUH, storage and turbo operational.

If any component of that power train fails you are screwed. Forget about coasting home unless you are in sight of the checkered flag. You would simply loose so much performance that continuing to race would make very little sense except you are very near the end of the race. Therefore reliability becomes mission critical. Btw. this is already the case. If you loose KERS now in the opening laps of a race you have no chance to win it even from pole.

Regarding Autogyro's complaints about the TERS design limitations you should not blame the FiA. The rules simply reflect what the F1 comission wants to see. The teams did not want many opportunities for manufacturers to gain performance advantages by power train development. So they made sure that there are limited design options. It is a part of the cost containment debate. As fans we have to accept those realities. Lamenting them will not change anything.

[Tommy Cookers]

Spinning up the compressor electricaly is a waste of energy.
Why not use a supercharger drive on the other end of the compressor from the crank and overrun it with the turbine when full boost is needed.
For the rest of the time at low turbo boost the turbine can drive the output, electro magneticaly.

the supercharger is a centrifugal/radial flow blower, and has a delivery proportional to the square of its rpm
so if mechanically driven, it would need rpm assistance via overrun at low engine rpm, not at high engine rpm
(its natural characteristic ie unassisted gives insufficient boost pressure at low engine rpm if sufficient at high engine rpm)

this is a major reason why we have turbochargers on SI engines
(turbo driven) supercharger rpm (under steady running at least) is better matched to needs than if (simply) mechanically driven

planned development of the V16 BRM was boost/ rpm matching by vortex throttling of supercharger entry at high engine rpm

[autogyro]

the supercharger is a centrifugal/radial flow blower, and has a delivery proportional to the square of its rpm
so if mechanically driven, it would need rpm assistance via overrun at low engine rpm, not at high engine rpm
(its natural characteristic ie unassisted gives insufficient boost pressure at low engine rpm if sufficient at high engine rpm)

this is a major reason why we have turbochargers on SI engines
(turbo driven) supercharger rpm (under steady running at least) is better matched to needs than if (simply) mechanically driven

planned development of the V16 BRM was boost/ rpm matching by vortex throttling of supercharger entry at high engine rpm

A supercharger is a mechanicaly driven air compressor.
That compressor can be of any design and any flow type.
The rpm of the compressor would be dictated by the crank drive ratio.
The Turbine on the other end of the shaft would take over from the mechanical drive not augment it.
Before taking over from the mechanical drive of the compressor, the turbine's rpm and energy production would be as a result of the load the ic engine is working under.
Some of this load would be the energy needed to drive the compressor.
The turbine would absorb this load and apply it to the powertrain.

[Forza]

We also have to take into consideration cooling requirements/power management/ vs reliability. We could see some performance/aero compromises in order to make the package reliable. I don't recall which system F1aero is referring to but there could significant factor in overall design.

There’s a lot of difficulties with the new energy recovery systems and the cooling requirements of the whole package. ...This may lead to reliability issues coming in to play for the first couple of years too

[autogyro]

I apologise for my last few posts, you can ignore them
I have re-read the regulations and the turbine has to be connected to the compressor at all times.

So there is no real chance of any powertrain development.
F1 remains a restricted aero formula.

Sorry again.