How does the BMW turbosteamer concept work and what challenges does it face?

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In summary, a new design for a power generation system involves using exhaust gases to instantly boil water and spin a turbine. There are some questions about the design, such as how to prevent liquid from entering the turbine and how to regulate steam flow to the turbine. Some suggestions for a homemade version include using a radiator or wrapping copper tubes around the exhaust pipe for heat transfer, and using a half a turbocharger as the basis for the turbine. There may be concerns about leaks and wear on the plumbing of this system.
  • #1
Ayrity
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http://www.gizmag.com/go/4936/

theres the link in case anyone hasnt seen it already. pretty simple concept, and it sounds like a great idea to me, but I don't quite understand 2 areas of the specific design, maybe somone can help.

Firstly, is the heat from the exhaust gasses really enough to instantaniouslly boil water? and in that same light, how is the water not pumped through the turbine? in other words, how can they make sure that only steam is used to spin the turbine? do they use gravity in their setup so that the turbine just sits higher?

secondly, in the article they say that the turbine will be connected directly to the crankshaft. I do not understand how this would be possible, won't the turbine be spinning at a variety of different speeds and be somewhat unpredictable in RPM because of the dramatic lag that the heat transfer and spin up in the turbine would cause? so even if it was geared down, you wouldn't know what ratio to have put inbetween the turbine shaft and the crank. the only solution i could think of (since i have been researching them recently) is to put a type of CVT (continuously variable transmission) between the two so that the gear could be selected depending on what speed the crank was turning at.

thanks for any help guys
 
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  • #2
Ayrity said:
Firstly, is the heat from the exhaust gasses really enough to instantaniouslly boil water? and in that same light, how is the water not pumped through the turbine? in other words, how can they make sure that only steam is used to spin the turbine? do they use gravity in their setup so that the turbine just sits higher?
Well, take a feel of a catalytic converter next time you've been driving for a while. I would venture a guess that there is, but not instantaneously. As far as the liquid/stem goes, what you're thinking is exactly what I would expect them to do. There is most likely a liquid trap somewhere in line to prevent liquid phase ingestion into the turbine.

Ayrity said:
secondly, in the article they say that the turbine will be connected directly to the crankshaft. I do not understand how this would be possible, won't the turbine be spinning at a variety of different speeds and be somewhat unpredictable in RPM because of the dramatic lag that the heat transfer and spin up in the turbine would cause? so even if it was geared down, you wouldn't know what ratio to have put inbetween the turbine shaft and the crank. the only solution i could think of (since i have been researching them recently) is to put a type of CVT (continuously variable transmission) between the two so that the gear could be selected depending on what speed the crank was turning at.
Or they plan on somehow regulating steam flow based on crank speed/turbine speed. I am sure that this would be one of the big issues that would be worked out on the test rig.
 
  • #3
ya i thought about a steam regulator, but maybe a cvt could do 2 things at once, that way you wouldn't need separate valves and a teperature switch etc etc. (in terms of what i could replicate at home at least haha) what do you think would be more efficent for heating water by exhaust for a teat at home? wrapping some copper tubes around the exhaust pipe? a radiator?, and also for the turbine, would half a turbocharger work well?
 
  • #4
Ayrity said:
ya i thought about a steam regulator, but maybe a cvt could do 2 things at once, that way you wouldn't need separate valves and a teperature switch etc etc. (in terms of what i could replicate at home at least haha) what do you think would be more efficent for heating water by exhaust for a teat at home? wrapping some copper tubes around the exhaust pipe? a radiator?, and also for the turbine, would half a turbocharger work well?
I would think that the radiator would be the better bet since it would maximize the surface area that is responsible for the heat transfer. You could try the coil, but there would definitely gaps, etc that would reduce the effectiveness. It would be very easy to make a coil though. So I would, if I were to try to replicate this, try the coil first.

The turbo is the basis for many a home made turbines. You have to get them turning at very high speeds though. That may be an issue. I'm not quite sure of the size they're using on the BMW. I only skimmed the article.
 
  • #5
ya, i would have to give some thought to it as well, the size i mean. obviously i should use the exhaust turbine part of the turbo right? so its good for high temperatures etc. and also (ive never worked with a turbo beofre) is it possible to take off the other turbine blade? or separate the housing halfs? because i wouldn't need it to pump air, only have one turbine wheel spin on an extended axis
 
  • #6
What are they using for makeup water? There are always leaks.

Basically looks to be a waste heat boiler powering a turbine. Look up some of the marine engine/turbine sites.
 
  • #7
i have no idea, that's why i put it to everyone here, the details on this thing are missing ha. maybe they routed the condensation of the A/C unit into the lines, that's the only place i could think of where you could get some extra water without thinking about refilling it. why are there always leaks? plumbing isn't that hard is it?
 
  • #8
Generally leaks a little around the shaft seals on the turbine, not much but does add up. Also, eventually, through valve spindles and so on. Plumbing does eventually wear out, breakdown. For steam systems usually by erosion, scale and expansion contraction. In a vehicle vibration/shock would be an issue as well.

If you're interested, Lee Valley has some good reprints of old tech from about the 1890s. Or you could check out Lindsey(Lindsay?) books, the build your own smelter/lathe people. The catalog is a hoot.
 
  • #9
haha sounds interesting, i love that old technology stuff.
 
  • #10
Old technology doesn't equal bad. You can learn a lot from that. I know I have. Plumbing does eventually leak, that's true, but a properly designed system can go for a whole lot of years before that happens. That usually get's hot to hell when someone decides to take something apart.

I would imagine that they'd have to have another tank, similar to the windshield wiper fluid tank that you'd have to refill every so often. A low level on that tank prohibits that system's usage. You will get a small amount from the exhaust products as well. But I don't know how much the system would require.
 
  • #11
I think it would be more logical to use power produced by steam turbine to recharge battery and to provide energy to other components. This way all the power produced by ICE can be dedicated to providing torque to the wheels. Using this design problem of torque synchronization can be avoided.
Also this hybrid is not practical in countries where temperature falls below 0C in a winter time. Unless they are planning to use some kind of water substitute.
 
  • #12
Dmitri said:
I think it would be more logical to use power produced by steam turbine to recharge battery and to provide energy to other components. This way all the power produced by ICE can be dedicated to providing torque to the wheels. Using this design problem of torque synchronization can be avoided.

As it stands, not all the power produced by the engine is dedicated to providing torque to the wheels. A good 65-70% is just wasted. A fair proportion is used to drive ancilliary systems, - oil, water and power steering pumps, fans, ignition, lighting, and then all the driver comforts. This is just a way of utilising more of the wasted energy.

Also this hybrid is not practical in countries where temperature falls below 0C in a winter time. Unless they are planning to use some kind of water substitute.

This logic holds for conventional cars too, - what goes in your cooling system? :smile:
 
  • #13
brewnog said:
... A fair proportion is used to drive ancilliary systems, - oil, water and power steering pumps, fans, ignition, lighting, and then all the driver comforts. This is just a way of utilising more of the wasted energy.
Does not portion of engine's torque has to be used to generate power for these systems? All I am saying is why not to use thermal energy to provide power for this systems. So engine itself does not have to lose some of its power.

This logic holds for conventional cars too, - what goes in your cooling system? :smile:
Can you really use antifreeze in steam engines?
 
  • #14
Dmitri said:
Can you really use antifreeze in steam engines?
Sure, but it raises the boiling point and would, most likely, leave a residue over all of the components. Plus, that stuff just smells bad when it's vaporized. Pretty nasty smell.
 
  • #15
FredGarvin said:
Plumbing does eventually leak, that's true, but a properly designed system can go for a whole lot of years before that happens. That usually get's hot to hell when someone decides to take something apart.

I would imagine that they'd have to have another tank, similar to the windshield wiper fluid tank that you'd have to refill every so often. A low level on that tank prohibits that system's usage. You will get a small amount from the exhaust products as well. But I don't know how much the system would require.
Yeah, if they can keep the leakage to a few pints per thousand miles, then it isn't a big deal to just refill it at the same time as your windshield washer fluid every time you get an oil change.

I'm a big fan of trying to recover and use waste heat for other purposes. It's easy money.
 
  • #16
Dmitri said:
Does not portion of engine's torque has to be used to generate power for these systems? All I am saying is why not to use thermal energy to provide power for this systems. So engine itself does not have to lose some of its power.
Sure, but one way or another, the system produces some total amount of power and the accessories use some total amount of power. It doesn't matter where exactly you take off the accessory power, you get the same amount at the wheels.

One good reason to not tie the turbine to the accessories is that the accessory power varies widely and the turbine power varies widely - and the two don't correlate. But the turbine power varies with engine output, so the turbine puts power down to your wheels exactly when you want it.
 
  • #17
The system is under really high pressure and temperature (about 40bar and 400 degrees) the pressure is dropped in the turbine to atmospheric, which causes the pressurised hot water to change into steam, thus no water. Also steam engines have purge valves for any condensation build up.

The pressure supplied to the system will be controlled under load dependent criteria. The problem with this system is it is only good on long runs, and when the vehicle is turned off all that heat energy is lost.

The steam needs to generate electricity which can be stored, also this way even when the vehicle is stationary or switched off it still can reclaim the lost heat energy.
 
  • #18
guys ,i'm working on this project for my senior project , the tempreture is high enough to generate steam , however I'm facing a problem :
according to my design , the water flow rate is very low (0.54 l/min) and the pressure is up to 7 bars , so I'm finding it hard to allow water to be distributed equally in the 250 tubes tube side of the shell and tube heat exchanger , and i don't know how to do that or if it's possible or not can anyone help ? thank you :)
 
  • #19
I'm doing a similar kind of project, why does the water not distribute evenly? Could you turn the exchanger 90 degrees so the water fills the tubes and flows up, the water level will be equal in each tube . Why can you not increase the water flow rate?
 
  • #20
Is the pressure drop high? Then you have too few/too small tubes.
 
  • #21
guys, imagine a flow rate of 9 ml/s and of pressure 7 bars going out of a pump, this flow will look like a thread ( very thin line ) , and it enters directly to the shell and tube exchanger that has 250 tubes , how will this flow be distributed equally in the tubes ?
i think i need a certain design of a distributor or a collector but i got no experience in that , i need help!
and i can't really increase the flow rate since water will not be superheated to steam then .
 
  • #22
By my very rough calculation, that's about 20kW to vaporize the water at your pressure and flow rate.

So the "common sense" question might be, why do you need as many as 250 tubes to handle that power level?

20kW is roughly equivalent to about 10 electric kettles. So how much length of tubing does your 9ml of water need to flow through, in the 1s it takes to vaporize it? About 1m of 3mm diameter tube is the right sort of volume. Your heat exchanger doesn't need to be 1m long, you can coil the tube into a helix if you want...

That's about as far as I'm going to get "designing" this without using a calculator, so I'll stop there - it's your project not mine.
 
  • #23
as u know in heat transfer , Q depends on cross section aread and delta T mean, yes i need

to take around 26 kw heat , but since the maximum temp of hot fluid is 650 C , and i need

to heat water to around 400 C , then delta T mean is small , that's why i need big cross

area, based on HTRI exchanger program , this is the best design , to have 230 tubes of 6.4

mm diameter. the problem is stil ther, how to distribute the small flow to all those tubes ,

can you help ? thank you
 
  • #24
Those numbers don't make "common sense" to me.
230 tubes 6.3mm diameter have a total area of 7400mm^2.
You have 9000mm^3 /s of fluid flow
That is a flow velocity of about 1.2mm/sec. How long is your fluid going to take to pass through the exchanger ?

For good heat transfer you don't need a big cross section area. You need a big surface area. I would forget about round tubes and start brainstorming for a completely different geometry of heat exchanger.
 
  • #25
fluid velocity is around 0.11 m/s , what do you by other design? can you help me in that ? so far i got no experience except in the normal round design of tubes , thank you
 
  • #26
boudzmawed said:
fluid velocity is around 0.11 m/s

Are you sure?
0.0064^2 * pi/4 * 230 * 0.11 = 8*10^-4 m^3/s = 0.8 l/s
Previously you said 9 ml/s :confused:

Of course the steam velocity will be higher because of the greater volume, but I'm talking about the water velocity.
 
  • #27
My data is taken from the HTRI exchanger program , for a flow of water of 9 ml/s and diameter of tubes of 6.4 mm and tube length of 0.5 meters , and number of tubes of 215 tubes , the tube velocity is around 0.11 m/s . my question is , how to make that very low flow get equally distributed for all the tubes, or is there any other better design to allow me to take the 26 kw of heat from the exhause gases of the car? thank you
 
  • #28
I'm trying to do the concept of a turbosteamer that the bmw is workking on but I'm facing few problems :
the flow rate of water will be 9 ml/s and of pressure 6 bars . based on htri xchanger program , the best design of my shell and tube heat xchanger will be of 22 cm diameter and 6.4 mm tube diameter where number of tubes will be 215 and the length will be around 0.5 meters.

my problem is how to allow this very low flow rater ( 9 ml/s) enter the 215 tubes equally ?

my 2nd problems is that i have no experience with microturbines , i need to know how to design that turbine, ihope you can help guys

thank you
 
  • #29
Mount the heat exchanger vertically. Put the exhaust through the tubes (hot at the top and cooled exhaust leaving from the bottom). The water to be boiled is on the shell side. The upper portion of the heat exchanger will act like a superheater, and the water 'distribution' problem is solved. Put baffles in there so the water doesn't slosh around when you take a corner.

edit -- by the way I don't think that HRTI program is really for designing boilers.
 
  • #30
having the exhaust on tube side means huge pressure drop which means a back pressure. ur sure it wil work ?
 
  • #31
plus it's a bit difficult to place the hex vertical on the exhaust pipe of the care don't u think ?
 
  • #32
boudzmawed said:
having the exhaust on tube side means huge pressure drop which means a back pressure.
What's the pressure loss from pushing the exhaust through the shell side of your tube bundle? That's not a free ride either. By the way, how much backpressure is acceptable? I think you need to know that before you can decide what your boiler should look like.

ur sure it wil work ?

No, but it's not my project. I'm just throwing ideas at you.

PS: You should get into the habit of typing out real words. Once you're out of school nobody wants to read text-speak.
 

1. How does the BMW turbosteamer concept work?

The BMW turbosteamer concept works by using the exhaust gases from the car's engine to power a steam turbine. The steam produced by the turbine is then used to generate additional power for the car's engine, increasing its overall efficiency and reducing fuel consumption.

2. What are the main benefits of the BMW turbosteamer concept?

The main benefits of the BMW turbosteamer concept include improved fuel efficiency, reduced emissions, and increased power output. It also allows for a smaller, more efficient engine to be used, resulting in lighter weight and better performance.

3. What challenges does the BMW turbosteamer concept face?

One of the main challenges of the BMW turbosteamer concept is the complexity of the system, which can make it more expensive to produce and maintain. There are also challenges in integrating the system into existing car designs and ensuring its reliability and durability.

4. Is the BMW turbosteamer concept currently being used in production cars?

No, the BMW turbosteamer concept is not currently being used in production cars. It has been tested in prototype vehicles, but has not yet been implemented in mass-produced cars. However, some of the technology and principles used in the concept have been incorporated into other hybrid and fuel-efficient vehicles.

5. How does the BMW turbosteamer concept compare to other hybrid technologies?

The BMW turbosteamer concept is unique in that it uses exhaust gases to power a steam turbine, rather than relying solely on battery power like most other hybrid technologies. This allows for more efficient use of energy and can potentially result in greater fuel savings. However, the complexity and cost of the system may make it less practical for widespread use compared to other hybrid technologies.

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