Need info on turbines

[Philip1]

I like the idea of a turbocompound gasoline engine after all the exhaust is wasted energy that should be put to use. Using a properly sized turbine with the appropriate gearbox one could in theory add a portion of this energy back into the system via the accesory drive. Providing there is room for an additional pulley etc...

[8307c4]

Originally Posted by 91CavGT

Rough math today yielded approximately 400 cfm available with the possibility of more depending on a couple of variables right now. I know 400 cfm is not much, but I had no idea what this device might possibly yield before, but now I know what it could do so now I have a starting point to work with.

I do not know what you intend on doing, but I know a few things about cfm's and mph because I use blowers in real life (different kind of blower, but)...

Fact is, one can increase either the cfm's OR the mph by playing with the size of the opening. Unfortunately one comes at the expense of the other but lets take two blowers that I use, yes they are strictly blowers but bear with me please:

Model bg-55
DISPLACEMENT 27.2 cc (1.66 cu. in.)
ENGINE POWER 0.7 kW (.90 bhp)
AIR VELOCITY 63 m/sec (140 mph)
AIR VOLUME 710 m3/h (417 cfm)

Model bg-65
DISPLACEMENT 27.2 cc (1.66 cu. in.)
ENGINE POWER 0.7 kW (.90 bhp)
AIR VELOCITY 78 m/sec. (174 mph)
AIR VOLUME 550 m3/h (324 cfm)

It's the same engine, same power, but the bg-55 has a round tube for an outlet where the bg-65 the same round tube has been taken down to a flat rectangular one (so it is smaller, the hole the air comes out is).
Doing so speeds up the air by giving it more mph but reduces the cfm's, in effect it's the same amount of air being pushed from the engine side but what comes out is more concentrated with one, and more diluted but over a larger area with the other.

At least in terms of blowers, the power consumed is equal. While the wider opening moves more air by volume, but the smaller opening's push is stronger (if in a smaller area). Now it all depends on the application, but there really is a noticeable difference between the two.

I would almost think, in terms of propulsion, you'd want the smaller opening.
This of course might restrict exhaust gases themselves which as likely works counter-productively, but for the purpose of experimentation I'm not sure if that helps but I thought I'd mention it.

[91CavGT]

Well, I discovered 2 auto manufactures are already in the testing phase of this idea so I'll go ahead and spill the beans on this whole thing.


It is all based on the Rankin cycle. This device starts at a water holding tank. Water then goes to a small pump of approximately 5 gallons per minute at around 20 psi. The water then travels to a diesel EGR cooler(s) (do a search on Ebay and you'll see them) where the water is super heated from the exhaust gasses. IF the EGR cooler(s) is put in place of a typical muffler then the increase in exhaust back pressure will be very minimal over what a typical stock muffler would be. I'd like to see an increase in water temp up to approximately 250-300 degrees. I know these EGR coolers are capable of these kinds of tempuratures since it is not unheard of for the coolant to flash into steam in them if the coolant passage is restricted further upstream (this is the reason why I'm thinking about running 2 or 3 large EGR coolers for a small motor).

After the heated liquid leaves the EGR coolers, it will then be routed to some sort of expansion chamber so the liquid can expand (anywhere from 1000 times to 1500 times it's original size from what I've read) before entering a turbine. I've got several ideas for a turbine, but in the end I'll just have to experiment with them until I can find one that will work right. This turbine will then be connected to the engine via an engine accessory belt. In order to prevent parasitic drag on the engine when the turbine has not gotten up to speed, a clutch, much like that is used on an A/C compressor would be used. This would allow for minimal power losses when the system is warming up (less then 1/2 of a hp is a rough guestimation), but once the system started working it should yield at least 5 hp for free.

The spent steam would then be routed through a radiator where it would condense and be sent back to the storage container where the cycle would repeat itself.


As I said earlier, BMW and Honda are already testing a more refined device that is EXACTLY like this. BMW has reported 14 hp and 15 ft lbs increase in overall power on a 1.8L 4 cylinder. BMW also claims an increase in overall engine effeciency of 15%!!!!

In an aerodynamic car just an extra 5 hp at cruising speed would equate to a very large increase in fuel economy, especially if it doesn't cost anything!! All this setup would do is take advantage of wasted energy in the form of heat. A rough guestimation of 150 pound increase in total weight of the vehicle would be seen. Most of this weight would be the weight of the water (10 - 15 gallons). I know this would be detrimental to FE, especially in hilly environemnts. So this might not be something worth while for everyone, but I will be trying it out, someday.

[dosco]

I was thinking that a bank of Peltier devices might be viable to generate additional electrical power. Not much, I'm sure, but a little bit along with a solar panel would help take some load off of the alternator.

Not sure about the steam turbine as an accessory on the engine, you need to do the thermodynamics calculations to determine the viability. I would think that it might be worthwhile to drive something other than the crank, like the A/C compressor, the alternator, etc.

[91CavGT]

Originally Posted by dosco

Not sure about the steam turbine as an accessory on the engine, you need to do the thermodynamics calculations to determine the viability. I would think that it might be worthwhile to drive something other than the crank, like the A/C compressor, the alternator, etc.

Actually, BMW and Honda are currently working on this setup with steam going back to add power to the crakshaft. Effecientcy gains of 15% to 18% have been seen.

[BamZipPow]

One could do both a steam generator as well as a seebeck electric generating device.

[mjo]

Originally Posted by 91CavGT

I know these EGR coolers are capable of these kinds of tempuratures since it is not unheard of for the coolant to flash into steam in them if the coolant passage is restricted further upstream (this is the reason why I'm thinking about running 2 or 3 large EGR coolers for a small motor).

I'm not a ME but I would be cautious of the pressures you generate in the EGR cooler. They may not be designed for the pressure buildups you will generate. Good luck.