TERS : Thermal Energy Recovery System

All that has to do with the power train, gearbox, clutch, fuels and lubricants, etc. Generally the mechanical side of Formula One.
gruntguru
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Re: TERS : Thermal Energy Recovery System

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At 80% compressor and turbine efficiency, recovery does not improve appreciably with increasing PR. At higher efficiencies recovery will increase with PR.

Let's assume 80% efficiencies. The fact that recovery is independant of PR allows PR and CAT to be optimised for combustion efficiency. (We did have several posters here claiming that high PR's would rob energy from the MGUH because of high compressor work.) Combustion efficiency will be optimal at AFR around 1.2 for homogeneous charge and higher if stratified. So PR at all rpm will be determined primarily by best AFR for combustion. Next priority is most likely compressor and turbine efficiency. Staying close to the peak efficiency island benefits recovery, pressures and temps applied to the piston engine etc.

Air massflows in the examples are approximate. Don't forget that massflow also depends on CAT, VE etc.

Higher CR is only a secondary benefit of lean mixture. 1.2 would be a ballpark optimal mixture with CR held constant.
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Tommy Cookers
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Re: TERS : Thermal Energy Recovery System

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this essay linked below (and its source material) seems to tell us that ......

treating the compounding as a Brayton cycle (so ignoring blowdown) substantially underestimates the exhaust energy recovery
Brayton cycle predictions regarding various PRs and related AFRs are thus misleading or worse
(in the Wright TurboCompound, Brayton predicts negative recovery ? but actual recovery (net of compressor) is positive 5 - 12%)

in choosing Brayton we assume pressure turbine working, but our F1 engines conserve and use exhaust pulses ie blowdown
the peak pressure seen by F1 turbines is far higher than the steady mean pressure used in Brayton

posted here as the (big) engine thread seems to be focussed on other aspects currently
http://www.ukessays.com/services/exampl ... engine.php


btw - lean mixture means more charge heating by compressor, so higher CR will only be available if more charge cooling is done ?

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Blackout
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Re: TERS : Thermal Energy Recovery System

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Have some dumb questions about KERS, engine braking, clutch etc:
In an interview with Vettel where he talked about 'lift and coast' and many other things, he said something like: 'it's simple, when I come of the gas, gearbox goes to neutral and i let the car roll..."

Does the car really goes to neutral? or is it just declutched?
How many times per lap (in Spa for example) does the MGUK harvest energy (and produce engine braking) while the engine is clutched to the rear wheels? KERS can harvest energy when gear box is declutched: cant'it?

bergie88
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Re: TERS : Thermal Energy Recovery System

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In my opinion the powertrain setup is like a pre-transmission parallel hybrid drivetrain:
Image
The advantage of this setup is that the ICE can be decoupled from the rest of the drivetrain, such that the friction and pumping losses of the ICE are eliminated. I think this is what Vettel means, so when the car is decelerating the MGU-K is harvesting energy, which is optimized by opening the clucth so decoupling the ICE.

wuzak
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Re: TERS : Thermal Energy Recovery System

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The MGUK is connected to the ICE, before the clutch.

tuj
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Re: TERS : Thermal Energy Recovery System

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yeah Wuzak is right, the MGU-K is driven off the front or rear of the crank-shaft and sits nestled to the side of the ICE in most configs.

Image

bergie88
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Re: TERS : Thermal Energy Recovery System

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I see, so it is not positioned between the engine and the gearbox as in a passenger car parallel hybrid configuration. I am curious about the benefits of this, because in this setup the MGU-K also has to overcome the engine's drag and pumping losses before it can regenerate kinetic energy. Is there maybe an extra mechanical connection between the gearbox and the MGU-K which can be decoupled from the engine?

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aleks_ader
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Re: TERS : Thermal Energy Recovery System

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bergie88 wrote:I see, so it is not positioned between the engine and the gearbox as in a passenger car parallel hybrid configuration. I am curious about the benefits of this, because in this setup the MGU-K also has to overcome the engine's drag and pumping losses before it can regenerate kinetic energy. Is there maybe an extra mechanical connection between the gearbox and the MGU-K which can be decoupled from the engine?
No if remember right all is the rules: Mechanical link to mainshaft only (ICE crankshaft). So no clucted elemnt between. Only spring dampers alowed etc.
"And if you no longer go for a gap that exists, you're no longer a racing driver..." Ayrton Senna

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godlameroso
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Re: TERS : Thermal Energy Recovery System

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How exactly does the MGU-K transfer power to the cranshaft? Is it gear driven, chain, electric motor attached to the crank pulley? Maybe like a starter on the flywheel?
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wuzak
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Re: TERS : Thermal Energy Recovery System

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godlameroso wrote:How exactly does the MGU-K transfer power to the cranshaft? Is it gear driven, chain, electric motor attached to the crank pulley? Maybe like a starter on the flywheel?
It's geared to the crankshaft.

I'm not sure that there are any chain or belt driven accessories on a formula 1 engine.

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Blackout
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Re: TERS : Thermal Energy Recovery System

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I'll reformulate my questions:
Does Kers harvest energy when the engine is declutched from the rear axle?
Does the engine get declutched from the rear axhle during braking in F1 in the first place?

Because AFAIK, Kers has no physical connections with the rear axle brakes. It doesnt harvest rear axle braking energy, it 'just' harvest energy during braking; it harvests engine brake energy.

Kers workes in fact IMO like the Ters, sometimes it brakes the engine (the turbo for Ters) and harvests energy in the same time, and sometimes it accelerates it.
(and it seems that Kers since 2014 car harvest during acceleration too... just like Ters)

Edit: didnt notice this thread is about Ters not ERS nor KERS. Sorry.

Jolle
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Re: TERS : Thermal Energy Recovery System

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Blackout wrote:I'll reformulate my questions:
Does Kers harvest energy when the engine is declutched from the rear axle?
Does the engine get declutched from the rear axhle during braking in F1 in the first place?

Because AFAIK, Kers has no physical connections with the rear axle brakes. It doesnt harvest rear axle braking energy, it 'just' harvest energy during braking; it harvests engine brake energy.

Kers workes in fact IMO like the Ters, sometimes it brakes the engine (the turbo for Ters) and harvests energy in the same time, and sometimes it accelerates it.
(and it seems that Kers since 2014 car harvest during acceleration too... just like Ters)

Edit: didnt notice this thread is about Ters not ERS nor KERS. Sorry.
The KERS unit is connected to the crankshaft, and is decluched from the rear axel when the clutch is pulled. However, a (racing) car is only decluched while stationary. Under braking there are three forces working on the rear axle: the brakes, the ICE and the KERS unit. A system works out how much each of these is being used depending on how much pressure the driver puts on the brake paddle or how much engine brake he wants (with a switch on the dash for corner entry).

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Blackout
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Re: TERS : Thermal Energy Recovery System

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Thank you.
(I was led to believe the engine is declutched during some brakings for a short time... which made me ask my self so many baffling questions..) :oops: :lol:
Last edited by Blackout on Fri Sep 11, 2015 12:19 pm, edited 1 time in total.

Tommy Cookers
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Re: TERS : Thermal Energy Recovery System

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when the driver is on the brake pedal (if he is off-accelerator) the engine is allowed to run at eg 120 kW with gu-k action at 120 kW
ie the PU output ('overrun push') cannot exceed zero but electricity is being generated real-time from the combustion of fuel
generated by the system named after the recovery of KE
this option occurs in what is often and quaintly described as the engine braking phase

gruntguru
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Re: TERS : Thermal Energy Recovery System

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Fuel would only be added (wasted) when the power available from braking the rear wheels is less than the power required to "motor" the crankshaft + 120 kW (max MGUK harvest). Even then, fuel would only be added during braking if the full 120 kW available from MGUK to the ES was deemed "high priority" and the race fuel allowance was "low priority".

Using fuel in this way (purely to charge the battery) is much less efficient than fuel used at max power:
1. The thermal efficiency at circa 120 kW crankshaft will be much lower.
2. Inefficiencies in the "GUK harvest - ES charging - ES discharging - MUK drive to wheels" cycle will further reduce the fuel energy -> wheel energy conversion efficiency.
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