Turbo Diesel Waste Heat Steam Boost Enhancer Thread

[ConnClark]

Originally Posted by Bicycle Bob

I can't see any potential for savings here. An increase in induction pressure from an increase in backpressure sounds like tail-chasing.

The more air you pack into the cylinder of a diesel the more efficiently it operates. Turbo charging a diesel is already a proven way to improve its efficiency.

Originally Posted by Old Mechanic

I reread it Daox, and if he does that it will probably destroy the turbocharger.

regards
Mech

How?

Exhaust already has a lot of steam in it.

[user removed]

Exhaust leaving the cylinders contains a very small amount of superheated steam, that started out as atmospheric humidity. It has to be very hot for the oxygen sensor to work. The range of temperature is something like 900 degrees.

It's called dry stream. Superheated steam is dry steam and the type that does not impact the turbine blades with significant mass. Superheated steam is a different animal compared to the steam you see coming out of your tea kettle when it begins to boil.

The expansion ratio of superheated steam is something like 1000 times water in it's liquid state, while steam that has just begun to boil at 212 degrees F, is just beginning to become a vapor with a heck of a lot lower expansion ratio than the same water when it is superheated to 900 degrees under pressure then allowed to expand.

Regular steam like what you are talking about is not the same as the superheated atmospheric humidity that has passed through your combustion chamber where it has been subjected to peak combustion chamber temperatures of above 3200 degrees F.

The turbine blades spinning at say 75,000 RPM will, most likely suffer damage, from being subjected to non superheated steam. You could also create another issue by cooling down the exhaust portion of the turbine housing with the injected steam that is not superheated and completely vaporized.

It's just my opinion, and I did not research the numbers I threw out extensively, but I have no doubt that the potential for damage to the exhaust turbine blades exists.

regards
Mech

[Bicycle Bob]

The exhaust also contains a lot of steam from burning the hydrogen part of hydrocarbons. I sure wouldn't worry about the impact of any gaseous input. Big turbines are designed to survive bird strikes, rather than suck air through a grille.

[ConnClark]

Originally Posted by Old Mechanic

The expansion ratio of superheated steam is something like 1000 times water in it's liquid state, while steam that has just begun to boil at 212 degrees F, is just beginning to become a vapor with a heck of a lot lower expansion ratio than the same water when it is superheated to 900 degrees under pressure then allowed to expand.

Regular steam like what you are talking about is not the same as the superheated atmospheric humidity that has passed through your combustion chamber where it has been subjected to peak combustion chamber temperatures of above 3200 degrees F.

The turbine blades spinning at say 75,000 RPM will, most likely suffer damage, from being subjected to non superheated steam. You could also create another issue by cooling down the exhaust portion of the turbine housing with the injected steam that is not superheated and completely vaporized.

It's just my opinion, and I did not research the numbers I threw out extensively, but I have no doubt that the potential for damage to the exhaust turbine blades exists.

regards
Mech

The way I have described the design has taken into account for the water vapor in the steam. Boiling will only occur in the lower part of the tubing up to the water level in the feed tank. All tubing after that will serve to super heat the steam thus drying it. Further more once it mixes with the exhaust gasses it will be heated even more. As long as I don't try and generate as much steam as possible it will be perfectly fine.

[redpoint5]

Is the idea of injecting steam to increase the effective cylinder compression ratio? Can't that be accomplished by other means such as different bore, stroke, or combustion chamber volumes? Isn't there potential of driving the turbo at excessively high RPM?

[Christ]

Sure, any of those could work... none of those options can be achieved with $30 worth of junk, though.

[Zerohour]

I say let him try... :-p

I do have my own 2 cents to throw in here. Mechanic, have you consider store the steam in a reservoir and releasing into a 2nd turbo? Something to simply raise addition compression in the diesel engine when accelerating or pulse-gliding? Basically making a momentary boost in PSI by use of a secondary air injection. Not sure if theres any efficiency to be gained, but if you could tap a few (2-4psi) extra momentarily, it may be something worth trying as well. And you won't be blowing water vapor into your motor.

[Arragonis]

Interesting - I thought you couldn't pump steam - something I was told when onsite at a Nuclear station in the early 90s.

[ConnClark]

Originally Posted by Arragonis

Interesting - I thought you couldn't pump steam - something I was told when onsite at a Nuclear station in the early 90s.

I'm not going to pump steam (although you can just like you can pump air). I'm going to pump water that will turn into steam.

Also I might decided to go with a design change. I found I can get an electric pump that does a gallon per minute at 60 psi. I'll uses this instead of the feed tank because I can set it up to intermittently inject water into the piping. This will allow the piping to heat up more in between pulses and produce hotter steam. It also allows me to turn it off when I'm at full boost and the waste gate is open. I need to talk this over with my steam buddy to see what he thinks of this as the sudden heat changes might fatigue the piping.

EDIT: Pump http://www.northerntool.com/shop/too..._357081_357081