by "Herr Quattro - Has a 4-motion" (herrquattro)
Published 01/14/2017 at 11:41
by "Herr Quattro - Has a 4-motion" (herrquattro)
Published 01/14/2017 at 11:41
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STARS: 2
So, I’m in an engineering course and for my senior project my partner and I have came up with an idea to use super heated steam that’s been heated up by the exhaust system to power a steam turbine that directly powers the Turbocharger.
We haven’t been able to really find anybody doing anything similar to this. Hell, the only other steam powered application on a car was BMW turbosteamer from 2005.
any thoughts from people who probably understand this better then I do?
We literally have a crap ton of research on it, but the fact that nobody else has done anything like it a little worrying... And ignoring the issues of freezing, this is mostly a proof of concept. In any real application I figured a manufacture could use a special fluid with low boiling point and low freezing point, for more pressure. But due to the fact that we’re only in highschool, we plan on sticking to water.
My idea, in detail, is to use a heat exchanger that surrounds the exhaust pipe, exhaust manifold, and catalytic converter. This steam then powers a steam turbine that is directly linked to a turbocharger.
Then since the turbocharger doesn’t have to be near the exhaust manifold, we can have it located in a much cooler area of the engine bay.
The biggest obstacle that could be a potential issue is that of a condenser, because cooling down superheated water down to below 212 degrees is kinda hard.
But besides that, could a steam turbine realistically power a turbocharger?
Idk, this isn’t exactly formal, I’d just like to get an idea what others think before we go down this way.
"E90M3" (e90m3)
01/14/2017 at 12:00, STARS: 1
While steam could power a turbine no problem, I don’t think there’s enough heat to more efficiently use that as opposed to powering a turbo.
"facw" (facw)
01/14/2017 at 12:03, STARS: 0
I don’t know, but a single steam turbine could power this (steam turbine powering generators to power electric motors):
(not really relevant, I just really like the M-1. I guess in answer to your condensing problem the solution is obviously to just carry a bunch of water so you can skip that step and just let it off as steam :) )
"bob and john" (bobandjohn)
01/14/2017 at 12:03, STARS: 2
I mean, that’s exactly what a turbo is...a turbine. but now instead of running it on exhaust gases, you are running it on steam pressure
steam turbines are basically 1/2 a turbo but instead of a compressor wheel on the other end, you have a generator (USUALLY)
my question is this: why bother? you are taking exhaust gases to heat water, to turn to steam, and then to power a turbo...so you have energy lost in 2 energy transformations, PLUS the added weight and complexity of the steam system. instead of just driving it straight from exhaust gases
"Herr Quattro - Has a 4-motion" (herrquattro)
01/14/2017 at 12:06, STARS: 0
Well, we’ve found the catalytic converter is 1000 degrees. Even if we got only 500 degrees, we should be able to get 680PSI of steam pressure.
Its just a matter of cooling it down 300 degrees but that’s a different matter that can be solved.
"Herr Quattro - Has a 4-motion" (herrquattro)
01/14/2017 at 12:14, STARS: 0
Well from what we have found, we would be able to power a relatively massive turbocharger with a steam turbine. And we figured that the thermal heat of the exhaust system is more constant then that of the air flow of a turbocharger.
Essentially, by using a steam turbine, we would be able to have boost all the time. And no turbocharger lag.
Ignoring the obvious problems of overboosting, we would be able to harness about 700PSI if we can get the steam to 500 degrees. And considering the catalytic converter alone is 1000 * degrees that shouldn’t be an issue.
This isn’t optimal on a medium size motor (as if a 2.0L is medium) but we figured that this system, coupled with a massive turbocharger and a small ~1L engine would be highly efficient.
Due to the fact that we would have boost pressure all the time, we figured we could use a valve to vent the pressure. We would have the program-ability of the electric supercharger, and we would be able to semi realistically build this and retrofit it since it requires no modifications to the engine itself.
"thedevilinside" (thedevilinside)
01/14/2017 at 12:18, STARS: 0
So a mix of a Rankine cycle recovery and a turbo. It makes sense in some ways. You’re making the most heat under load, so it would have big lag like a turbo (I think). Sounds like a good senior design project if nothing else!
"bob and john" (bobandjohn)
01/14/2017 at 12:21, STARS: 0
ahh, okay, so you are thinking more of a boost on demand type deal?
here’s an idea: just have a small air tank (say, 2 gallons?) at high pressure (not steam, just pressure from a compressor) and when you want boost, a small valve open and bam, instant spooling of turbo and then the regular exhaust gases take over.
it gets rid of any compilations with steam, gets rid of warm up time for steam , you wont have any issues in winter (relatively speaking) and its even easier to retro fit (just tap in a small hose right before the turbo and hook it up to an air compressor.
also, slamming 700psi of steam into a turbo to get it on boost...that just sounds like a recipe for the turbo to wear out really quickly...
you still have your boost on demand, easier to make adjustments to the system (simple to swap our bigger airtank for more ‘engaing’ driving, and a smaller one for day to day or grocery getting) and you dont always want the turbo to be on boost (light loads or slowing down)
as a side note, please don’t take this as me being a dick. but your end goal sounds like you want to make the car have 0 turbo lag. having a steam system is complicated and heavy, and can be dont with smaller, easier systems. if you can do the same job with a simpler, less complicated system, why not? makes your researching easier and less places for the system to fail.
"facw" (facw)
01/14/2017 at 12:25, STARS: 0
Raises hand:
If you were running water over it, wouldn’t the catalytic converter cool down quickly? You’d essentially be water-cooling it right?
"Herr Quattro - Has a 4-motion" (herrquattro)
01/14/2017 at 12:29, STARS: 0
We have considered that, but that’d require a compressor to refill, and more importantly, the air reserves could be depleted quickly, especially in city driving or on a bunch of windy back roads that require a bunch of slowing down and accelerating.
We considered a electric motor assisted turbocharger, and using a capacitor to power it with a 48V charge. But for the reason we’re still unsure about it...
"E90M3" (e90m3)
01/14/2017 at 12:30, STARS: 0
No, it’d just take longer for it to heat up since you’ve got a constant input of heat.
Don’t ask how long because I’m not about to do math and my heat transfer class was 5 years ago.
"Herr Quattro - Has a 4-motion" (herrquattro)
01/14/2017 at 12:32, STARS: 1
That’s why we’re putting it at getting the water at 500 degrees... Plus we’d also have the exhaust manifold which will be just as hot if not hotter then the catalytic converter.
Judging by the BMW turbosteamer concept, I believe the exhaust system should be hot enough.
"E90M3" (e90m3)
01/14/2017 at 12:33, STARS: 0
While you can get steam at that pressure, that ads a lot of complexity for a problem that’s pretty much already been solved.
Also, that’s a lot of pressure, meaning a lot of stored energy. There’s a reason they use liquid when they pressure test things. I wouldn’t want to be around it if it failed.
"Bman76 (no it doesn't need a WS6 hood) M. Arch" (bman76)
01/14/2017 at 12:38, STARS: 0
Alternatively. you could just do a 6 stroke.
"JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t" (jawzx2)
01/14/2017 at 12:44, STARS: 0
if you’re talking boost on demand, as opposed to steady-state high-load, why not go direct parallel-hybrid with your steam turbine? open the flood gates on that sucker and it’d be like a huge electric motor, torque-wise anyway, you could even have a plain exhaust turbo on the engine, just a bigger one than usual because you could torque-fill with the steam and ignore the exhaust lag. You’d still have heating time requirements and weight/complexity out the wazoo, but for intermittent demand it seems plausible...? not trying to steer you away from your idea, just thinking what would be neat ;)
looks like ALMOST that has been done before...
though this is closer to a turbo-compound engine like the Napier Nomad in concept... A system like this would have an advantage over a compressed-air or hydraulic energy storing system in that it could add more heat energy tp the system on demand, rather than requiring a regenerative period... it would certainly be more complex though.
"DC3 LS, will be perpetually replacing cars until the end of time" (dc3ls-)
01/14/2017 at 12:58, STARS: 0
Just spit balling here. What if you had another turbine (in series I guess?) connected with an electric clutch (final form, wouldn’t be necessary on a proof of concept.) That was a reverse water pump? a valve opens letting coolant in and spinning it?
Edit: Wouldn’t that kind of be the best of both a supercharger and a turbo? I’d imagine because being power by the water pump, essentially belt driven, would act very much like a super charger. Then at high rpms the clutch disengages and it runs like a normal turbo.
"TheRealBicycleBuck" (therealbicyclebuck)
01/14/2017 at 13:02, STARS: 0
An electric-assist turbo is already on the market.
http://www.turbos.borgwarner.com/en/products/eBooster.aspx
"MyJeepGetsStuckInTheSnow" (myjeepgetsstuckinthesnow)
01/14/2017 at 13:18, STARS: 0
It won’t be. Do the thermodynamic calculations and you will find it will not be hot enough. Also, condensing the steam with a condenser is not a trivial matter.
Nice idea and glad you are being creative but this one is not a winner.
"Herr Quattro - Has a 4-motion" (herrquattro)
01/14/2017 at 13:32, STARS: 1
Well we’re ignoring the ‘safety aspects’ of it. This is a high school senior project, and we have only 4 months to build this thing. And as complex as a system would be, its relatively straight forward to build and test... buy a junkyard motor, exhaust, and turbocharger, throw them together and put a thermal exchanger on the exhaust. Which could be built using a junk water heater or something. This isn’t as much as putting the system on an actual car and seeing if it works, its essentially trying to prove the concept.
That being said the more thought I put into the air powered concept, the more I like it. We could simply add a 2 gallon tank at ___ PSI, that would be enough to spontaneously spool the turbocharger. Then another valve farther down the system could redirect the exhaust into that tank, recharging it instantly.
However, this steam powered system seems so great. I admit this system would be pointless on anything larger then a 2.0L, with a turbo smaller then something rated for race cars... but even for a sports car this system *could* be amazing. Hypothetically, the best place for this system would be a I4 motor on a super car, with enough instantaneous boost to make that of a V12. Of course we’re going overboard, and the practical applications are essentially null.
And besides the weight, a turbocharger adds 0 stress to an engine, which a large benefit over an electric assist.
My biggest worry is that I’ve become so focused on it, I’m making to many excuses for a system we don’t know if it will work, but when I when i weight the benefits of a system if it DID work, it seems brilliant... But I also admit this is the first ‘true’ discussion I have had about it. My partner doesn’t really understand my concepts, and while I’ve contacted several professors, they don’t seem to know, since it combines the unrelated aspects of a turbocharger and steam turbine.
But I know there is a lot of untapped thermal energy stored in the exhaust system that isn’t being used for anything. And considering most of the inefficiency of a ICE is the conversion of chemical energy in fuel to kinetic energy, but most of that energy is converted into thermal, we can recoup a lot of that energy into steam. And while we’re losing tons of energy in the form of 2 energy conversions, we’re still recouping energy that would have been lost to the exhaust anyway.
I digress haha...
"BJ" (benjamin-bignell)
01/14/2017 at 13:32, STARS: 0
I see a few problems:
* no boost until full operating temps reached
* constant boost once operating temps reached
* extra weight from the liquid reservoir (assumes the turbo and intercooler weight + plumbing is the same as an exhaust turbo)
* temp loss in vapour between boiler and turbo
* cooling challenges in hot climates and when stationary
* potential reduction of underhood safety due to risk of leaks or explosion (eg when filling washer fluid reservoir or checking oil with a hot motor)
With the exception of the first problem, I think these can be mitigated. Keep researching and digging for answers, and good luck.
"Herr Quattro - Has a 4-motion" (herrquattro)
01/14/2017 at 13:33, STARS: 0
By any chance to what thermal dynamics equations are you referencing?
"You can tell a Finn but you can't tell him much" (youcantellafinn)
01/14/2017 at 13:36, STARS: 0
The reason the catalytic converter gets as hot as it does is because it is supporting exothermic reactions. It does require high temp exhaust gasses to get going, but when operating there is a temperature rise across the catalytic converter.
You are also missing the fact that the temperature isn’t what you need to generate your steam. You need energy to generate steam, and while temperature is an indicator of energy it doesn’t give you a complete picture of the energy state of the system. To know the energy of the system you need to know the temperature of the exhaust gasses and their mass flow rate.
You need to figure out how much energy you want the turbo to put into the engine. From there you can figure out how much energy needs to go into the turbo, and from that how much energy needs to go from the exhaust to the water. Every time you convert energy or transfer it from one medium to another you need to account for that.
The reason turbos are mounted as close to the engine as possible is so that they recover the most energy possible. The exhaust energy is the highest when the exhaust gas is the hottest and fastest moving which is why turbos are being mounted closer and closer to the exhaust manifold. That obviously leads to other engineering problems in terms of developing materials and systems that can survive the extreme temperatures encountered.
TL;DR It’s probably feasible if there is enough energy in the exhaust gas to raise the mass of fluid that you intend to use to the temperature you intend to reach. You need to look at energy balance, not temperatures. Also I’m probably interchanging energy and power at various points in that stream of consciousness rambling.
"Herr Quattro - Has a 4-motion" (herrquattro)
01/14/2017 at 13:38, STARS: 0
Thanks for your feedback!
Right now, if it could work, which looks like it might, we’re mostly concerned about being able to condense it and building a turbine.
We figured that no boost for 5 minutes while the exhaust is warming up is a good trade off for being able to have access to instant boost whenever we want. (maybe just throwing a release valve until the pressure is needed.)
"Herr Quattro - Has a 4-motion" (herrquattro)
01/14/2017 at 13:50, STARS: 0
Thank you for your feedback!
I fully admit we haven’t done the calculations yet, solely to fact that we’re not sure how much energy we want, or how much energy an engine produces. As of right now, we don’t even have a donor engine to experiment with. We just don’t know enough yet.
We just want to know if this really has the chance to work before we do the math and get everything else together, as once we commit we will not have the chance to change...
Our assumptions surrounding the exhaust thermal energy being able to power the system is solely based on the BMW turbosteamer concept. We want to be able to assume that the system used by BMW is able to produce the energy levels to power a steam turbine to power a turbocharger.
I think the goal of my concept in a nutshell is to transfer the turbochargers source of power from the inconsistent energy of the exhaust flow, to the more constant thermal energy of the exhaust system.
"Herr Quattro - Has a 4-motion" (herrquattro)
01/14/2017 at 13:53, STARS: 0
Can you contact me at zack3dunn@gmail.com?
If its all right with you, I’d like to be able to reference you in my engineers notebook.
"Herr Quattro - Has a 4-motion" (herrquattro)
01/14/2017 at 14:09, STARS: 1
I like the idea, but I’ve been trying to avoid ideas that would require to modify the engine block itself.
The first iteration of our concept was exactly as you described, with the water pump pushing the coolant through the turbocharger, but I came to the conclusion that the coolant wouldn’t be able to propel it to thousands of rpm per second. And I’m not comfortable modifying an engine block...
The turbocharger/supercharger hybrid is also on our brainstorm list, but we’re both fairly certain that will work. This steam idea puts no stress on the engine, and it has the added benefit of working from a constant energy source (the thermal energy of the exhaust system)
"Herr Quattro - Has a 4-motion" (herrquattro)
01/14/2017 at 14:12, STARS: 0
I like that! I’m slightly confused how it works, but it looks interesting! Ill definitely look into that more...
"Orange Exige" (OrangeExige)
01/14/2017 at 14:29, STARS: 0
I’m no engineer but the idea seems understandable and at least somewhat feasible. (efficient may be a different story, but for a school project and not something you are being paid to do professionally, that’s not the biggest concern)
I’m interesting in seeing progress updates and hopefully a successful finish. The idea is very unique and seems promising.
I just looked up BMW’s Steamcharger and I see your inspiration but also totally see the different route you’re going to be able to do it on any old unmodified engine. I wonder if they’re still working on that concept... It seems like they’ve adjusted course a little and focused on converting the heat to electricity rather than additional power to the car - but that update was from 2011 o_O
"E90M3" (e90m3)
01/14/2017 at 15:24, STARS: 0
emailed
"MyJeepGetsStuckInTheSnow" (myjeepgetsstuckinthesnow)
01/14/2017 at 17:43, STARS: 0
For something simple at the high school level start at the heat generated from combusting the fuel at both idle and wide open throttle. Balance the equation of n-heptane + isooctane + oxygen = CO2 + Water. Then grab a chemistry book to determine the heat created per amount of gas injected (based on injector duty cycle). This heat will be transported via the volume of exhaust that can be calculated from the chemical equation above. Determine the volumetric flow rate through the exhaust by motor speed and exhaust pipe dimensions. Then based on you exhaust to water heat exchanger surface area you can determine how much of a temperature rise you can expect in the water. Then use that heat transfer rate to determine the volume of steam that can be produced at different engine speeds to calculate the dimensions of the steam turbine.
Long story short the heat exchanger would have to be impracticably huge. It wouldn’t be as simple as using a water jacket around the headers. Also to run a closed system you would need an almost equal size heat exchanger for cooling. For an open system you would have to vent the steam and replace the water. But not just any water. Distilled water so you don’t get corrosion deposits in the system.
"MyJeepGetsStuckInTheSnow" (myjeepgetsstuckinthesnow)
01/14/2017 at 17:52, STARS: 0
Thermal energy in the exhaust system is not constant though. Put your hand behind a tailpipe at WOT vs idle. Huge difference. Also see YouTube engine dyno for reference. When passively cooled by air the pipes glow red hot but with active water cooling/heat transfer the exhaust will not have thermal capacity you might be assuming is there. Put a pan on the stove burner and then put it under flowing water. It cools very quickly.
"MyJeepGetsStuckInTheSnow" (myjeepgetsstuckinthesnow)
01/14/2017 at 17:55, STARS: 0
You might also want to look into at what they are doing on semi trucks. They are using piezo electric element to transfer exhaust heat into electricity. Not sure if it would be enough to run an electric turbo (see Delphi system) but it might be able to charge batteries on a hybrid.
"bob and john" (bobandjohn)
01/14/2017 at 18:17, STARS: 0
some cars already have a air compressor for the shocks, and while yes, you would need a tank, compared to adding all of the stuff to make it steam powered? ehh.