I think that instead of producing enough steam to move the turbo, it will cool all the exhaust temperature, loosing all the power advantages of the turbocharged engine. The recirculation would include polutants that would eventually destroy/oxidize the engine.
Also increasing the pressure in the whole system is a good idea but very difficult to implement, even at 10-13 psi is difficult to maintain (in the long run).
Something similar was in the works, but instead of water it was a hydraulic system moving the turbo wheels.



just my 2 cents

 

I think you misunderstand.

How will cooling the exhaust gasses hurt performance? It will help it. Remember, the exhaust it NOT connected to the turbo at all anymore, the turbo is driven entirely by steam. The cooling of the exhaust makes it also lose volume, as it cools it contracts. This will create a scavaging effect.

I don't see how pollutants will get into the water/steam system. It's totally closed. Heat will be absorbed into the system by conduction, ie tubes wrapped around the exhaust headers, or even better, water flowing completely around the tubes within larger tubes.

I have discovered that the steam will have about 2x the density of ~1400F exhaust gases.

 

this is quite an impressive idea. the possibilites are very promising, and though they may seem a bit far-fetched at first, the ideas encompassed are basic enough to warrant some real life testing. by scavenging effect, do you mean a siphon effect? that is what i would imagine. timing could be played with if air was literally sucked out of a cylinder as it would be with a large temperature drop. maybe at low rpms. anyhow, good reading, and let me know if you need a turbo, i have 2 sitting here on a manifold (entire stock twin setup) doing nothing

my only concern would be the weight of the entire system. with all the plumbing and related accessories, it would have to weigh a good portion more than a conventional turbo setup. at least weight could be distributed a bit better in this case. the turbo could even sit right on the end of a front mount with all the water related items stored neatly in the hatch.

 

You are getting it kale.

Yes, I'd love it if I could borrow one of those turbos. You are welcome to come and witness the experiment. You got a video camera?

Weight wise, it's mostly the weight of the cylinder and water. 30-40lbs or so. But consider, as you did, that most of that weight would be in the back. Also, 40lbs is a small price to pay for 10-25% more HP, that's saved by not having to run the turbine, and the push button instant boost at any RPM. You can have 30psi at 2000RPM with this. Considering how mad people are around here for a extra 300RPM sooner spool, I'd think this would be enough to tickle everyone's fansy.

We are still paying the power to run the turbine actually, but the beauty of a steam system is we can collect and store power for later, and we also take that power from a place it's wasted anyway.

I had concerns that it may not keep up with extended WOT time. Now I'm fairly certain that there is more than enough heat released at WOT into the exhaust headers to keep it going, so long as there is enough water/exhaust contact. Some experimentation into the amount of tubing will be required.
__________________________

SMACK!!!! Just realized something, it get's better. Our turbos aren't using but about 50-75% of the mass flow coming from the engine to maintain boost. The rest get's dumped out the wastegate. So again, that means less total steam flow will be needed.

 

Dayamm! Two very interesting threads at the same time on SF? Can't be.

 

So this would use a separate water container to generate the steam? How quickly do you think this system would use it up? It would be impractical if we had to refill the water tank every so many miles

 

it would be a closed system, like your stock cooling system. water would be taken from a tank, injected into a "heating tube" heated by the exhaust which would instantly superheat it into steam, which is then run through the turbo compressor, and then through a condenser, turning it back into water and letting it swim back into the original tank. theoretically it would never have to be refilled.

 

This is a very good idea BUT there are some things to consider. First off in using the stock cooling system the temperature of the coolant throughout the whole engine will increase quite a bit causing a boosted engine to run even hotter then it would normally. I would recommend running a seperate system for the steam if this were to work for racing applications.

Next the placement of the tubes to be heated would have to be pretty efficent because the heat is not very "direct" if the tubes were only lieing on the metal pipes of the exhaust. And even still if they were run in the exhaust and the pipes were heated from the exhaust heat not near as much heat is extracted as would be from a normal turbo. So in theory its cool for the fact that you receive no backpressure BUT I dont think you would be using anywhere NEAR the thermal efficentcy of placing a turbine directly into the exhaust gases exiting the motor. So it would be nice for small boost applications but I dont see it working for anything else.

 

it would be a closed system, like your stock cooling system. water would be taken from a tank, injected into a "heating tube" heated by the exhaust which would instantly superheat it into steam, which is then run through the turbo compressor, and then through a condenser, turning it back into water and letting it swim back into the original tank. theoretically it would never have to be refilled.

ahh ok, thanks alot kale, i missed the condenser part of the whole equation.

 

ThomsonCharm: It won't use or touch the normal cooling system. I specifically mentioned that it wouldn't. This system is totally serperate from the stock cooling system. I'll looking for 350F and 100psi in the water, can't do that on the cooling system.

Why wouldn't it work for high boost applications? No offense, but are you using anything other than a feeling to make that conclusion? If you can match the mass flow rate through the turbine, you should be able to match the performance.

Also, why wouldn't the exhaust create enough heat? At 700HP, there is about 1500HP worth of wasted power in the form of heat being dumped into the cooling system, and lots left going through the exhaust. It will have a NA style exhaust, but turbo EGTs. The headers will be creating just as much heat. They won't glow or get as hot, because that heat will be getting sucked up.

So kale, when do you want to bring me that turbo?

 

i can have it for you as soon as i pull it out of my car. i can do that thursday, i think i have time then. anybody want to come help disect?

 

AnArkey,
isn't that the concept of the hydracharger that was talked about in SCC a few months (or even years) back by the in-house nerd, Dave Coleman!? Someone at Garrett had a similar concept I think. Very, very impressive nonetheless. You seem to be our SF inventor!!

-Olivier

 

Once you heated up the water and let it sit in a can waiting to be injected into the turbo it would start to cool. I would think you would need two systems, one very small closed loop directly off the exhaust system with an extremely high flash point. This would then have to be circulated into a heat exchanger keeping the potential steam water at an optimal temperature to create the instant steam. My two cents.

 

Kenlippold, you just described a good portion of the closed loop system I worked out on paper last night.

I also have a open loop systemfor drag racing, or initial experimenting. Open loop means the steam dumps after passing through turbine, rather than being recondesed. Short term use (1-3mins) only. Fine for drag cars and just some dyno testing, not so good for street cars.

To dyno this rig, just remove the turbo from the header, run a open header (yeah it will be loud during testing), and connect the turbo compressor to the intercooler, or in my nonintercooled case, the throttle. I can just have a heated tank with 350F water in it, and open a valve to a nozzle sealed in the intake to the turbine housing. Experiment with different nozzles to see what is needed for certain boost levels. Initially, running without a wastegate, it will boost most when activated, and drop down as RPMs rise. I just need to get a baseline for water mass flow vs desired boost at redline. That +10% will be the flow for the system, and the wastegate will just vent the excess like it normally does.

I don't think using the solenoid to the steam nozzle to PWM will work. Can't have the water boiling until it's in the turbine, after the nozzle. At low PWM, there will be a significant pressure drop, and steam will form between the nozzle and solenoid, and it will kill flow as the same nozzle flows a LOT less mass of water when it's steam rather than 100psi liquid. That and I'd be concerned with the pulsing that may result in the turbine from any sort of electriconic injector. Nevermind trying to find something that can handle 350F water.

Kale, you mean your stock turbos you are using? You are gonna remove them, donate them to this test, then put them back on? if so, DON'T. Not worth that much trouble.

 

This is a very interesting topic. I have worked with steam turbines before and a couple of things things come to mind. First, you need some way to ensure that the steam quality is high, i.e. low moisture content. Even superheated steam can have moisture entrained in it. Sometimes cyclonic or other types of moisture seperators are used. Second, there needs to be a very efficient way of transferring the heat from the exhaust to the water. Usually this requires lots of surface area, and especially in this case since the exhaust is moving so rapidly. This is not practical due to space considerations and due to the fact that you can't create a large resistance to flow in the exhaust or the effects of the 'free' turbocharging could be largely lost or worse. The third thing that comes to mind is the need to balance the system so that when the steam has left the turbine, it is just above the point where is changes phase back to water. Too high of a temp and it will be hard to remove more energy to get it back to water, too low and you risk impingement on the turbine blades. Also consider that most steam turbine systems use a condensor at a considerable vacuum to help complete the phase change back to water. You might be able to use a vacuum tank similar to the stock pressure tank, just reversing the operation of the check valves to try and keep a vacuum at the outlet of the turbine. I'm not knocking the idea in any way, just adding my $.02. Definately keep us informed on your findings.

 

Kale, you mean your stock turbos you are using? You are gonna remove them, donate them to this test, then put them back on? if so, DON'T. Not worth that much trouble

well, firstly my motor is dead at the moment, and i have a single kit arriving in january some time i'm not going to put the stockers back on any time soon, err, ever.

 

ThomsonCharm: It won't use or touch the normal cooling system. I specifically mentioned that it wouldn't. This system is totally serperate from the stock cooling system. I'll looking for 350F and 100psi in the water, can't do that on the cooling system.

Why wouldn't it work for high boost applications? No offense, but are you using anything other than a feeling to make that conclusion? If you can match the mass flow rate through the turbine, you should be able to match the performance.

Also, why wouldn't the exhaust create enough heat? At 700HP, there is about 1500HP worth of wasted power in the form of heat being dumped into the cooling system, and lots left going through the exhaust. It will have a NA style exhaust, but turbo EGTs. The headers will be creating just as much heat. They won't glow or get as hot, because that heat will be getting sucked up.

So kale, when do you want to bring me that turbo?

Ok I didnt see the part where you said you were not going to use the cooling system. Anyway your other two comments are an exact result of what Dave said. He said exactly what I was saying in that sure all that heat and power is coming out of the exhaust BUT its coming directly out of the exhaust. You are then trying to extract the heat from the metal the exhaust heat is touching. THAT is not efficent. Thus ensueing my assumption that it will NOT be able to match the mass flow rate of the turbine and will also not create enough heat. Because even though there is "1500 HP" of wasted energy that energy is not being used DIRECTLY like it would be on a normal turbo. Therefore making those numbers inaccurate.

Again I think you believe im knocking your idea and im not im simply trying to tell you if your want to use the exhaust heat as best as possible you going to want to use it DIRECTLY and that will probably result in backpressure of some sort. Only think I can think of that wouldnt really is by wrapping the headers in a "water jacket" that would house the water and create the steam but even still your not utilizing the exhaust heat directly. You would have to wait for the metal to heat up and then wait for the metal to heat the water.

 

Thomson makes a good point, maybe you could tap the exhaust with a very good heat conductive metal, and have that extend to where you want to heat the water. like tap into the point where the headers come together and then tap into the system with the water in it. It still wouldnt be as efficient as directly using the exhaust gases, but it would provide very minimal backpressure and be more efficient that just using the heat radiated by the metal from the headers

 

It's true, that getting enough heat out of the exhaust to CONSTANLY run the turbo may be difficult. I ask, when was the last time you were boosting for 20 minutes straight without letting off?

 

Oh well, I just shot a hole in the idea. I missed something. If I inject 350F, 100psi water into the chamber, it won't all flash to steam. It will remain mostly water. Only a little will be steam. Why? Latent heat of vaporization. The process of boiling will take so much heat energy out, it will only take less than 50% of the water boiling to cool everything off. The steam will be VERY wet, it won't work. I can't inject it as steam already, I won't be able to deliver the volume needed to run the turbo. SIGH.

Oh well, back to the simpler, easier to implement approach, injecting as steam into the exhaust header. Will help spool, but not nearly what I was hoping for.

 

It's true, that getting enough heat out of the exhaust to CONSTANLY run the turbo may be difficult. I ask, when was the last time you were boosting for 20 minutes straight without letting off?

True, but when you're idling or under light load, the power production of the engine and its associated waste heat is also rather low. Monitor your air or fuel flows at idle or in a steady state highway cruise.

Numbers I've seen indicates roughly a third of the energy from the fuel burned results in power, a third goes out the exhaust as heat and a third goes into the water jacket as heat.

Now consider how long it takes the engine to heat the coolant enough to even open the thermostat on a cool or cold day. Then consider that it takes far more heat to convert water at 212 F to steam at 212 F than to raise the temp of that water from 32 F to 212 F. I'd bet the cooling system water jacket is a lot more efficient than anything you can come up with to recover heat energy from the exhaust without introducing a huge amount of backpressure not to mention weight and plumbing complexity.

As I've said before elsewhere, it's all about the numbers, in this case the conversion efficiencies. Qualitative analysis only gets you so far.

Mike

 

OK, now I have got a real mad scientist idea. I need to stop thinking about this stuff when I'm laying in bed, it's ruining my sleep.

It's getting to be more of a drag thing at this point. Limited usage between refilling stuff. But still maybe a good plan for race cars. Anyway.....

Inject a mix of water, gasoline, and pure O2 behind the turbine, and ignite it. The ratio of gasoline:O2 will be such that it's stoich. The ratio of water:gasoline will be such that all of the insane heat that will result from gas burning in a pure O2 enviornment (which would be INSANELY hot without 80% nitrogen which normal air has), will convert all the water to steam, and leave it at about 600F.

My rough calculations are as follows. Gasoline has a heating value of about 20000 Btu/lb. Water has a specific heat of 1/Btu/Lb/F (1 BTU will raise the temp of 1lb water 1F). Water has a heat of vapoization of 970 Btu/lb. Figuring in the heat lost to vaporization, and the actual heating of the water mass from 80F to 600F, I get a ratio of water:gasoline, 13.42:1. Wow, lot's of water. This mixture would never burn in air, but in pure O2, I think it will.

Now it's just a matter of figuring out how much 600F steam it will take to power the turbine. I have no idea how to calculate that. I need just a rough idea, to figure out if the usage rate would be feasible, or just require too much water/O2 to be practical.

What REALLY determines the power the turbine absorbs? My thinking is it's mostly a matter of velocity across the fins.

Here's a question to anyone familar with steam. Does steam expand (lower density) as it get's hotter, like most gases? Is 600F steam going to have a lower density at 1BAR than 400F steam? Most info online pertains to steam being kept compressed near it's vapor pressure, which doesn't tell me anything.

Certainly, if I can get more velocity by using less water, I'll do it. I figure I can go as hot as perhaps 1000F on the steam. Any hotter might melt things (steam transfers heat to metal faster than exhaust gasses).

 

Derek,
I hope I'm not being stupid obvious, I'm not a super expert with steam but know it pretty well. Yes steam expands as it get hotter; googling for a "steam table" you will see almost all you need to know about steam; make sure you look at the right data for either saturated or superheated and like with all pressures, make sure you see if it's absolute or gage pressure. try this: http://www.connel.com/freeware/steam.shtml

Obviously 1 BAR (14.5psi) absolute is a vacuum since it's less than atm press 14.7 psi. If you mean 1 Bar gage pressure (14.5psig) saturated steam temp for that is just under 250F; any steam hotter than that is superheated and that means it is dryer, less moisture content.

Being a mekanikul ingunear (BSME Villanova '72 go Wildcats!) I've worked with steam for more than 30 years ...yikes, it's hot shit wear gloves.

Btw, this is an intersting concept. I'm in work now and haven't even read this whole thread yet but I will tonight/tomorrow and keep in the loop if I can help or add anything.

 

Thanks for the terminology clarification. Saturated means it's kept at it's vapor pressure, superheated is when it's pressure is lower than it's vapor pressure. I'm going to be using VERY superheated. 600F or so and 50-100psi.

Found the density, etc info I needed:
http://pump.net/otherdata/propsuperhsteam.htm

On second thought, it would probably work better with propane as the fuel. Already under pressure, and will convert to gas when injected. Should mix with the O2 better than liquid fuel (gas), making combustion far easier in the presense of so much water.

It still may be very workable. It seems to me it doesn't take much fuel+O2 to make superheated steam. I'm thinking that instead of trying to keep turbine inlet pressure low, and flow high, that it would work far better on less steam, fuel, O2, with a real small turbine wheel, turbine housing, and very high differntial pressures. This is not a solution that works when the turbine is running off the exhaust, as 50psi+ of backpressure does all sorts of nasty things. But with the solution above, having 50-100psi across the turbine would be fine, and should make better use of the power in the steam. Water really is great at converting thermal energy into kenetic.

It all comes down to how low I can keep the water/fuel/O2 usage. Low enough, and it's practical. If it takes 2GPM water and 10lb/min oxygen it just won't be usable for anything other than a couple minutes. I'd like to have 5-10mins of usage per refill. It would work just as well as nitrous, should give a extra 100-200HP on the top end for 600-800RWHP cars. So I can justify the usage cost of the O2, which is usually lots cheaper than nitrous anyway (thanks to it's extensive use in welding).

The intial tests of this will require a blast shield. I should produce a very imtimidating steam cannon.

Oh course, maybe it will still be too much water and the thing won't even light. I can't reduce the water much, the temps would be too high. Here's hoping the O2 does it's job of making the propane VERY easy to ignite.

 

Assuming such a system was even possible how would you avoid compressor surge. Many turbos already have this issue with a standard turbine.

Daniel