Post-Turbo exhaust design

[ringo]

Well water into EGR may not work if it vaporizes in the exhaust before it goes into the cylinders.
You will have dry steam by the time it goes to the cylinders.
If your exhaust temp and pressure is at a point where water does not exist as saturated steam, but basically superheated steam, it's latent heat properties will be of no use.
at around 800 to 1000 degrees C at around 10 bar, water doesn't exist in the latent temp range; it's superheated steam.

[flynfrog]

You have no evidence on such a strong position.
I was never referring to steam, and as for a polished surface not lasting long i don't know how you come to that conclusion.
If a pipe has a surface roughness, that roughness won't increase over a 2 hour period because hot air is blowing through it.
The inside of the pipe needs to be as smooth as possible.
This is the case for any diffuser system.
As for the fins, regardless of how small an advantage it is in pressure drop, it is still an option. You must take every advantage that you can get to increase turbine pressure ratio.

People don't recognize this, but the reason a steam turbine is so efficient is because the condenser operates pretty close to absolute vacuum. It does this by condensation of the steam to water. If the steam in vapour phase drops out of the atmosphere you reduce the amount of gas particles, thus reducing pressure.
Any chance of cooling exhaust after the turbine should be looked into.

what do you think the byproduct of combustion is air? Have you ever seen the hot side of a turbo?


How much do you think can passively cool a gas moving at high temps and velocity out of a meter inconel pipe. This isn't a power station where weight doesn't mater. I don't know the kg to power break of f1 car but I cant see the fins being worth the weight to lug them around the track for a fraction of a degree of temp drop.

[WhiteBlue]

Well water into EGR may not work if it vaporizes in the exhaust before it goes into the cylinders.
You will have dry steam by the time it goes to the cylinders.
If your exhaust temp and pressure is at a point where water does not exist as saturated steam, but basically superheated steam, it's latent heat properties will be of no use.
at around 800 to 1000 degrees C at around 10 bar, water doesn't exist in the latent temp range; it's superheated steam.

Fair enough. But did you consider that the EGR volume of gas will get mixed with another 97% of fresh air mass flow when it enters the compressor? The mixing will take care of the super heated steam and take it down to condensation level. Then it can evaporate again behind the compressor.

[wuzak]

Well water into EGR may not work if it vaporizes in the exhaust before it goes into the cylinders.
You will have dry steam by the time it goes to the cylinders.
If your exhaust temp and pressure is at a point where water does not exist as saturated steam, but basically superheated steam, it's latent heat properties will be of no use.
at around 800 to 1000 degrees C at around 10 bar, water doesn't exist in the latent temp range; it's superheated steam.

Fair enough. But did you consider that the EGR volume of gas will get mixed with another 97% of fresh air mass flow when it enters the compressor? The mixing will take care of the super heated steam and take it down to condensation level. Then it can evaporate again behind the compressor.

The rules allow for exhaust gas recirculation, but do they require it?

I cannot see why they would do that if they don't have to.

In road cars EGR is purely for emissions purposes.

[aussiegman]

The eventual end to the proposal is to somehow introduce water into the EGR system is it to act as a de-facto water injection system. Regardless of how it interacts or reacts post compressor, it is simply a method of water delivery to the cylinder for cooling and detonation control.

It seems that this is all hinging on reliance of a proposal that once the water is introduced and mixed with the exhaust gases, then the water is now simply part of the exhaust gas which is recirculated as permitted under 5.14.2?

Firstly, if the water vaporises in the EGR system (utilising the latent heat of vaporisation of the fluid), then it fails 7.6 which specifically prohibits making “use of the latent heat of vaporisation of any fluid with the exception of fuel…..”.

If you want to argue it’s not for cooling then what is if for? If you try to set down it’s not for cooling but for some other purpose (I have no idea what you could try and come up with), then you run into Article 5, namely 5.14.2.

Under 5.14 .2, the regs prohibit the introduction of anything other than “engine sump breather gases, exhaust gas recirculation, and fuel for the normal purpose of combustion”, being sprayed into the engine intake. If the water is not for cooling the EGR system or the exhaust gas in the EGR system or some other purpose, then it must be that the EGR system is simply a transport mechanism for the water or steam produced.

This then fails the regulation prohibiting the “spraying” water or steam into the engine intake in contravention of 5.14.2 which is essentially what you are doing by simply moving the introduction point to a point in the EGR system.

IF (and its a big "if") you could get past a first pass of 7.6 and 5.14.2, you then run back into 7.6 in that you are using the latent heat of vaporization of the water once introduced at either the EGR valve or through the intake after its been introduced into the engine as the water is not part of the exhaust gas.

Again you could try and argue you are deriving no cooling or other benefit from the water, however then the question is if it there is no benefit then why introduce it in the first place?

A third pass of 7.6 and another review of 5.14.2 basically means that if you cannot conclude that any fluid including water which is purposefully introduced into the intake either directly or indirectly through the EGR valve system fails both of these as:

a) once in cylinder the water performs a cooling function in contravention of 7.6; and
b) you can't introduce any fluid other than fuel for the purposes of combustion into the intake.

Every way I have read this, I just can;t see it as possible to use water in any way in the intake charge for detonation control, cooling or any other way.

Further to the above, there is no definition of “exhaust gas” or “exhaust gases” in the regs, however there are numerous references such as 5.1.9:

5.1.9: Engine exhaust gases may only exit the cylinder head through outlets outboard of the cylinder bore centre line and not from within the “V” centre.

Given the wording of this reg, the exhaust gases are only those that exit the cylinder head outboard of the cylinder bore centre line. As the water or other fluid does not exit from the outboard outlets of the cylinder head, but is introduced post this demarcation line of the cylinder head, then the water introduced is not part of the exhaust gases and as such fails the assumption it is simply part of the exhaust gas being recirculated once introduced.

Any way you look at it, I simply can’t see any way of getting any outright or de-facto water injection system through the regs as they stand regardless of where you introduce the water, but I am happy to be shown otherwise..

[Tommy Cookers]

The rules allow for exhaust gas recirculation, but do they require it?
I cannot see why they would do that if they don't have to.

In road cars EGR is purely for emissions purposes.

what has become called EGR is primarily as you say
but is also a 'dilution' of incoming charge, that to an extent reduces throttling for torque reduction
Mr Fiat uses this on a large scale to eliminate throttling much of the time (ok, done by varying exhaust valve timing)

2014 engines will have continuous control of exhaust pressure (and induction pressure) by the MGUH
EGR/dilution is inherently governed by exhaust pressure (and induction pressure)

when the 2014 engine is over 10500 rpm it must sacrifice boost or run lean or both, these cost crankshaft power and combined power
if we use controlled EGR/dilution power is better than the above option
the EGR/dilution will show better in-cylinder thermodynamics (ie better crankshaft power)
the raised exhaust pressure will show better out-of-cylinder thermodynamics
by reducing blowdown pressure loss and so raising turbine power recovery (as shown by NACA in 1944)

IMO if 'EGR' is allowed there's a reason for it being allowed

[WhiteBlue]

Further to the above, there is no definition of “exhaust gas” or “exhaust gases” in the regs, however there are numerous references such as 5.1.9:

5.1.9: Engine exhaust gases may only exit the cylinder head through outlets outboard of the cylinder bore centre line and not from within the “V” centre.

Given the wording of this reg, the exhaust gases are only those that exit the cylinder head outboard of the cylinder bore centre line. As the water or other fluid does not exit from the outboard outlets of the cylinder head, but is introduced post this demarcation line of the cylinder head, then the water introduced is not part of the exhaust gases and as such fails the assumption it is simply part of the exhaust gas being recirculated once introduced.

A bit of faulty logic, isn't it?

5.1.9 is there to make sure the manufacturers all use the same turbo configuration with the intake valves in the V and the exhaust valves on the outside. The same purpose as having he rotational sense of he crank shaft fixed. They want engines to be interchangeable for the teams which they are if all the plumbing is the same.

5.1.9 does not tell you where the exhaust gas goes from there. You are concluding that only exhaust gas in the composition as it comes out of the ports can be recirculated. It does not say anywhere that this is the case. If we decide to mix something into it behind the exhaust ports 5.1.9. will not stop us to do this. We are still dealing essentially with exhaust gas even if there is a bit of water in it. You will just have to use enough exhaust gas that the water mass flow does not become dominant in my view.

[dren]

We need the EGR mass flow to suppliment the A/F at RPMs above 10.5k, but how do we get it?

Where is the EGR pulled from, post turbine?
If we want exhaust pressure to be near ambient on exit of turbine, of what benefit is there to use EGR over air? If you lower boost pressure via the MGUH, you just load the motor more, which puts the load on the turbine, so we'll have higher ICE backpressure, but similar turbine exit pressure right? So the EGR will need to be pulled pre turbine.

Where is the EGR introduced, before the compressor right? If not, won't intake pressure potentially be higher than EGR pressure?

Will it need to be cooled? I'm assuming yes.

[aussiegman]

A bit of faulty logic, isn't it?

5.1.9 is there to make sure the manufacturers all use the same turbo configuration with the intake valves in the V and the exhaust valves on the outside. The same purpose as having he rotational sense of he crank shaft fixed. They want engines to be interchangeable for the teams which they are if all the plumbing is the same.

5.1.9 does not tell you where the exhaust gas goes from there. You are concluding that only exhaust gas in the composition as it comes out of the ports can be recirculated. It does not say anywhere that this is the case. If we decide to mix something into it behind the exhaust ports 5.1.9. will not stop us to do this. We are still dealing essentially with exhaust gas even if there is a bit of water in it. You will just have to use enough exhaust gas that the water mass flow does not become dominant in my view.

Have not forgotten this, however work calls but shall respond shortly..

[Tommy Cookers]

the new DI would seem capable of (timed) injection of water into each individual exhaust blowdown pulse
with droplet size suitable for effectively immediate flashing into steam within the pulse
and so boost the pulse pressure and increase the power recovered by the turbine
without particularly raising the mean exhaust pressure
ie 'amplifying' the pulses

apparently turning some of the huge amount of heat the turbine won't respond to into something (pressure) that it will respond to

[aussiegman]

the new DI would seem capable of (timed) injection of water into each individual exhaust blowdown pulse
with droplet size suitable for effectively immediate flashing into steam within the pulse
and so boost the pulse pressure and increase the power recovered by the turbine
without particularly raising the mean exhaust pressure
ie 'amplifying' the pulses

apparently turning some of the huge amount of heat the turbine won't respond to into something (pressure) that it will respond to

The DI system only allows for one (1) injector per cylinder as per 5.10.2 and no injector pre or post intake/exhaust valves.

5.10.2 There may only be one direct injector per cylinder and no injectors are permitted upstream of the intake valves or downstream of the exhaust valves. Only approved parts may be used and the list of parts approved by the FIA, and the approval procedure, may be found in the Appendix to the Technical Regulations.

So unless you can inject water and fuel through the same injector using the approved FIA injector parts to facilitate it or somehow introduce the water through some other method assuming it is not classed as injection, then I'm not sure how you could get water into the cylinder/exhaust/intake.

Further, if the system is not part of the injection system, then it could possibly fail 5.14.2 insomuch as the water is not fuel and it is being sprayed into the intake charge regardless that that this takes place in the cylinder pre-combustion.

Also a WI system would come under scrutiny on the basis of 7.6 which precludes the use of the latent heat of vaporization of any fluid other than fuel used for the normal purpose of combustion.

[WhiteBlue]

Aussiegman, you always take these regulation paragraphs out of context, which makes no sense. The rule about injectors that you mentioned is part of the regulation on the fuel system. It does not apply to water.

[dren]

Looks like the latent heat is only related to cooling the charge air. You cannot inject anything into the intake other than fuel. But this is the exhaust gas getting hit with water, timed with the exhaust valve opening and exhaust stroke. Pressure will rise slightly and temperatures will drop slightly, and you'll cool the engine. The cylinder head would be quite crowded.

But then you're stuck with having to send any water through the compressor inlet, which is illegal

5.8.1 With the exception of incidental leakage through joints (either into or out of the system), all (and only) the fluids entering the compressor inlet must exit from the engine exhaust system.

Although, that doesn't take into account the fuel...

[aussiegman]

Aussiegman, you always take these regulation paragraphs out of context, which makes no sense. The rule about injectors that you mentioned is part of the regulation on the fuel system. It does not apply to water.

I do not agree WB as I believe (and also from my experience) that you need to look at the regs holistically and account for their interactions and not only regard them as singular regulations that do not interact, reference or refer to each other. This is an accepted and oft used methodology for developing legal briefs and is also found in mathematics where axiomatic systems consisting of axioms and/or postulates are used to develop new theorems through logical processing of interrelated and interacting undefined terms.

If you have ever read a legal brief or complaint lodged against a set of technical regulations (I have read and I have also produced them), they often if not always, reference other regulation(s) for definitions of undefined terms where none exist and list past precedents to substantiate a position of belief.

Put simply:

Water injection is a method of cooling the intake charge and lowering in cylinder temperatures. It would then seem to fail 7.6 insomuch as it relies on the latent heat of vaporisation of water in contravention of the rule.

Water injection must use injector to inject the water. The regs do not define an injector as only a fuel injector, it simply says injector. As such, any injector such as an air or water injector would likely be captured and therefore prohibited.

5.10.2 that specifies “There may only be one direct injector per cylinder and no injectors are permitted upstream of the intake valves or downstream of the exhaust valves” so you cannot install a water injector pre or post cylinder.

If you tried to inject fuel and water via the one (1) permitted injector then I think it could likely fail under 5.8.1.

If you try to introduce water post exhaust valves I think it fails under 5.14.2.

I will say no more (I have 3+ pages on my thoughts) on this except that it is my belief that the is simply no way that you can install a water injection system under the 2014 technical regulations without failing against the above regulations which are strengthened by the reference rules I have previously mentioned.

[aussiegman]

The rule about injectors that you mentioned is part of the regulation on the fuel system. It does not apply to water.

This is simply not correct to my reading as Article 5 governs all aspects of the Power Unit.

5.10.2 specifies that there can be only one (1) direct injector per cylinder and no injectors pre or post cylinder.
To that point, it separates injectors from direct injectors insomuch as it clearly states that there can be only one (1) direct injector and no injectors pre or post.

Please point to where it defines injector (direct or otherwise) only as a fuel injector? The regulations do not, they only reference “injectors” and more specifically direct injectors for in cylinder use. They also define that part of technical appendix lists approved parts.

So to my read, any device that is an injector (water, air, fuel, toluene, helium3, depleted uranium) is banned under 5.10.2. If it said fuel injector, perhaps. Regardless, you fail under 5.8.1 as the fluid had not passed through the inlet and compressor first.

As such, any injector pre or post cylinder is banned under 5.10.2 and its interaction with 5.8.1.

You have yet to make a substantive argument or show how under the regs you think this or any water injection/introduction/inclusion system would be legal.

For reference:

5.10.2 There may only be one direct injector per cylinder and no injectors are permitted upstream of the intake valves or downstream of the exhaust valves. Only approved parts may be used and the list of parts approved by the FIA, and the approval procedure, may be found in the Appendix to the Technical Regulations.

Looks like the latent heat is only related to cooling the charge air.

Reg 7.6 includes systems for cooling the charge air, it does not only relate to cooling the charge air. So any system that provides cooling is covered by the ban on utilisation of the latent heat of vaporisation of a fluid.

Water injection by its very purpose and design is a method and system for cooling the intake charge and lower in cylinder temps. As such, it is covered IMHO by 7.6 as nowhere in the regulations is there a definition or demarcation as to what is and is not a cooling system.

You cannot inject anything into the intake other than fuel. But this is the exhaust gas getting hit with water, timed with the exhaust valve opening and exhaust stroke.

How do you propose to legally inject/introduce/include water into or mix it with the exhaust gases without failing under the numerously aforementioned regulations?

Pressure will rise slightly and temperatures will drop slightly, and you'll cool the engine.

In defining that the system is cooling the engine is falls under 7.6 as a cooling system and fails as it is utilizing the latent heat of vaporisation of a fluid other than fuel.

The cylinder head would be quite crowded.

And very complex if you try to route and include systems to avoid the regs.

But then you're stuck with having to send any water through the compressor inlet, which is illegal

Yes it is…

I would love for someone to make a simple and substantive case for how any of the proposed systems are legal under the currently regulations. I am very interested in the discussions of how it might work, but I just can't see you slipping one in legally.