Rotary Diesel ??
02-11-07, 10:40 PM
#28
Soft & Wooly
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Yeah I figured they meant a thermal reactor, but still, the difference in terminology is amusing.
Considering how much fire you can shoot out of the tailpipe on an unconvertered rotary an afterburner isn't really that far out of the question...
Considering how much fire you can shoot out of the tailpipe on an unconvertered rotary an afterburner isn't really that far out of the question...
02-12-07, 08:56 AM
#29
The General RE
Originally Posted by z-beater
I just wanted to say that there is some very well written responses in this thread. I had an oppurtunity to see some pictures of diesel rotary engines. There were some that were in the 2500hp range. Remember that these were massive though. I believe that it was the old John Deere warehouse.
Z
Z
02-12-07, 07:51 PM
#30
the main advantage a diesel has over gasoline is the higher compression ratio. higher compression= higher thermodynamic efficency, which is why diesels get better fuel mileage.
The problem with a diesel rotary is that wankel engine geometry does not allow very high compression. The problem has nothing to do with apex seals or anything like that, it is a simple matter of having room for the intake charge. See, to increase the compression on a wankel, at least with all current designs, what you have to do is reduce the size of the 'pocket' in the rotor face. Thats all good, but what you find is that in reducing that size, you lose a lot of flow, because the intake charge has to flow through that pocket. Mazda did a lot of testing and found that there was almost no difference in output between a 9.0 and 11.0:1 compression ratio engine for that very reason. I think there is a SAE paper about it somewhere...
I believe the rx8 has 10.0 compression, so maybe the side port configuration helps, or they found another way around the problem. It is also possible that a totally different geometry might help, such as wider rotors.
For those that arent familiar with compression ratios, gasoline engines usually fall within about 8:1 to 12:1, with most being around 8-9. at anything over 10:1 you start having to worry about major detonation problems, so those are genrally only used on exotics or on engines with advanced efi systems and/or variable valve timing. Diesel engines on the other hand, are generally 15:1 to 25:1. Newer models are mostly towards the upper end of that range, because they are using better injection systems, and it helps with efficiency and versatility. low compression diesels like 15:1 sometimes have a lot more trouble with cold starts and stuff, since they dont heat the air as much.
The problem with a diesel rotary is that wankel engine geometry does not allow very high compression. The problem has nothing to do with apex seals or anything like that, it is a simple matter of having room for the intake charge. See, to increase the compression on a wankel, at least with all current designs, what you have to do is reduce the size of the 'pocket' in the rotor face. Thats all good, but what you find is that in reducing that size, you lose a lot of flow, because the intake charge has to flow through that pocket. Mazda did a lot of testing and found that there was almost no difference in output between a 9.0 and 11.0:1 compression ratio engine for that very reason. I think there is a SAE paper about it somewhere...
I believe the rx8 has 10.0 compression, so maybe the side port configuration helps, or they found another way around the problem. It is also possible that a totally different geometry might help, such as wider rotors.
For those that arent familiar with compression ratios, gasoline engines usually fall within about 8:1 to 12:1, with most being around 8-9. at anything over 10:1 you start having to worry about major detonation problems, so those are genrally only used on exotics or on engines with advanced efi systems and/or variable valve timing. Diesel engines on the other hand, are generally 15:1 to 25:1. Newer models are mostly towards the upper end of that range, because they are using better injection systems, and it helps with efficiency and versatility. low compression diesels like 15:1 sometimes have a lot more trouble with cold starts and stuff, since they dont heat the air as much.
11-14-07, 01:07 AM
#31
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Dr. wankel and Curtis Wright made a lot of the different concepts, one of my favorite was his KKM 125 and the DKM 250 which were the 125cc rotary engines. Said to spin at an economical rate at 12-14,000 rpms, but could reach 25,000 rpms safely. Since they didn't have turbo's back then, what kind of power could be reached with modern day machining, direct injection, and a lil help of a turbo on something that small. It only weight 30 lbs with cast iron housings and 23 with aluminum.. the picture i saw was him holding it in his hands..
What kind of power numbers/ power band could be found in say a 1 liter 4 rotor? and what would that sound like?
i was looking at their power band for the different amount of rotors, and the difference between a 2 and 3 rotors is huge, and from 3 to 4 wasnt nearly as big of a leap but still large difference in power.
I Think mazda is going backwards with increasing the displacement. I want to see smaller rotors and cheaper to replace engines,
I know we only use a small percentage of the energy exerted from gasoline, most of the energy being lost is heat i thought, what kind of ways could we utilize the energy being produced? weather we use the heat transfer to power a electric motor, or to recurculate the exhuast gases if we can find a way to have more use to them?
My learnings of how all this stuff works is still very limited, it try to read as much as i can but with working full time and school full time its damn near impossible.
but What i want to do in my life is make this rotary engine more useful, efficient, and better on gas. I know for a fact in the world we have people with ideas that could revolutionize the rotary engine and i want to hear some ideas!!
What kind of power numbers/ power band could be found in say a 1 liter 4 rotor? and what would that sound like?
i was looking at their power band for the different amount of rotors, and the difference between a 2 and 3 rotors is huge, and from 3 to 4 wasnt nearly as big of a leap but still large difference in power.
I Think mazda is going backwards with increasing the displacement. I want to see smaller rotors and cheaper to replace engines,
I know we only use a small percentage of the energy exerted from gasoline, most of the energy being lost is heat i thought, what kind of ways could we utilize the energy being produced? weather we use the heat transfer to power a electric motor, or to recurculate the exhuast gases if we can find a way to have more use to them?
My learnings of how all this stuff works is still very limited, it try to read as much as i can but with working full time and school full time its damn near impossible.
but What i want to do in my life is make this rotary engine more useful, efficient, and better on gas. I know for a fact in the world we have people with ideas that could revolutionize the rotary engine and i want to hear some ideas!!
11-14-07, 04:53 PM
#32
I know some stuff
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Yes, but diesels also run on very lean burn situations. 50:1 at idle! and remember that diesel has more energy per unit than gasoline. high compression has somthing to do with it also. but its the by product of high compression that gives the diesel its efficiency, cylinder pressure! which is also related with boost pressure and injection timming.
personaly i think the hardest part with a diesel rotary would be getting the compression ratio high enough, and the combustion pocket designed right for efficiant burn. i think the rotor tub or quench area just plane sucks on a rotary engine. this is an area that needs to be developed big time! jmho
personaly i think the hardest part with a diesel rotary would be getting the compression ratio high enough, and the combustion pocket designed right for efficiant burn. i think the rotor tub or quench area just plane sucks on a rotary engine. this is an area that needs to be developed big time! jmho
11-15-07, 04:01 AM
#33
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The rest of the facts are very interesting.
Thanks for the input everyone,very interesting topic
Karis
11-20-07, 01:04 AM
#34
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Please someone correct me if I'm wrong, I thought that the efficiency of a diesel comes from the heat generated by the pressure created in the compression ratio, and the higher the compression ratio the more injector nozzle pressure you need to get past the pressures and still have good atomization. For example: if you have a compression ratio of 9to1 and atmospheric pressure is 11psi that would convert to 99 psi in the highest point of compression, so if a diesel is 25to1 then you have to spray past the 275psi plus some to get good atomization. this all has to do with direct injection of course because in the old days diesel had a pre-chamber ignition.
12-03-07, 11:21 AM
#35
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Combustion chamber pressure (Compressed) is no match against a common rail system. As stated, compression ratio is commonly 18:1 which gives a pressure for about 18 bar (261psi) and common rail are up towards 2000+ bar (29007psi).
12-03-07, 11:49 AM
#36
It's OK. I'm not the be all end all of anything and I don't claim to be. Questioning things is human and perfectly normal.
Everyone else here disagrees with me anyways even when I put disclaimers and am very clear about how I use a certain word. They don't read. People even disagree with things when you provide direct proof when they have zero experience. This is why I'm slowly leaving this forum for good. It's why I don't post much anymore and why I will never again start another thread here. I'm no longer even contributing towards technical topics anymore. I'm done with this forum. Let the others debate everything and let those who know nothing be considered the experts as they usually are. I am only sticking around because a few people talk to me through PM's but that's it.
Everyone else here disagrees with me anyways even when I put disclaimers and am very clear about how I use a certain word. They don't read. People even disagree with things when you provide direct proof when they have zero experience. This is why I'm slowly leaving this forum for good. It's why I don't post much anymore and why I will never again start another thread here. I'm no longer even contributing towards technical topics anymore. I'm done with this forum. Let the others debate everything and let those who know nothing be considered the experts as they usually are. I am only sticking around because a few people talk to me through PM's but that's it.
12-03-07, 02:53 PM
#37
there is truth to what you say, but I think there is at least one silent ignorant person who reads good posts and learns the information for every outspoken idiot who posts up bullshit. I post less lately than I used to for the same reasons, but when people ask a question like this that actually has more to it than the usual 'why won't my car run' stuff, I like to speak up and help out, even if I'm not always 100% correct I think I help at least a few people to learn something, and every once in a while I post up my own questions when i wonder about something. Don't give up on us rotards quite yet.
03-16-08, 12:36 AM
#38
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wow... no offense but it looks like (most) of you dont know jack about diesels...
diesels engine speed is controlled by the amount of fuel injected not by a throttle plate. because of this at low speeds if a diesel wasnt directly injected (at the very minimum into a prechamber) the diesel fuel would knock long before TDC. this is also why at low rpms the older diesels when given too much throttle they would have large clouds of black smoke (prior to computer controlled and more complex mechanical injection systems). Black smoke is almost always unburnt fuel in diesels (because too much is being injected for the amount of air). because factory computers dont maximize performance in diesels ridiculous amounts of power can be gained with an aftermarket controller without losing gas mileage.
the reason for the high compression ratio on diesels is so when the fuel is injected it will immediately ignite.
The glow plugs are used to heat the air that enters the cylinder before the engine heats up so the diesel fuel will ignite.
Also the main reason why diesel engines are so heavy is because the block itself has to be built alot thicker to prevent it from cracking under the immense pressure and temperatures in a diesel engine. this is also why the early duramax (GM) diesels which were under built used to end up with cracked blocks if pushed too hard.
I could post more information if anyone would like.
diesels engine speed is controlled by the amount of fuel injected not by a throttle plate. because of this at low speeds if a diesel wasnt directly injected (at the very minimum into a prechamber) the diesel fuel would knock long before TDC. this is also why at low rpms the older diesels when given too much throttle they would have large clouds of black smoke (prior to computer controlled and more complex mechanical injection systems). Black smoke is almost always unburnt fuel in diesels (because too much is being injected for the amount of air). because factory computers dont maximize performance in diesels ridiculous amounts of power can be gained with an aftermarket controller without losing gas mileage.
the reason for the high compression ratio on diesels is so when the fuel is injected it will immediately ignite.
The glow plugs are used to heat the air that enters the cylinder before the engine heats up so the diesel fuel will ignite.
Also the main reason why diesel engines are so heavy is because the block itself has to be built alot thicker to prevent it from cracking under the immense pressure and temperatures in a diesel engine. this is also why the early duramax (GM) diesels which were under built used to end up with cracked blocks if pushed too hard.
I could post more information if anyone would like.
03-16-08, 01:20 AM
#39
rx7 killer
It's OK. I'm not the be all end all of anything and I don't claim to be. Questioning things is human and perfectly normal.
Everyone else here disagrees with me anyways even when I put disclaimers and am very clear about how I use a certain word. They don't read. People even disagree with things when you provide direct proof when they have zero experience. This is why I'm slowly leaving this forum for good. It's why I don't post much anymore and why I will never again start another thread here. I'm no longer even contributing towards technical topics anymore. I'm done with this forum. Let the others debate everything and let those who know nothing be considered the experts as they usually are. I am only sticking around because a few people talk to me through PM's but that's it.
Everyone else here disagrees with me anyways even when I put disclaimers and am very clear about how I use a certain word. They don't read. People even disagree with things when you provide direct proof when they have zero experience. This is why I'm slowly leaving this forum for good. It's why I don't post much anymore and why I will never again start another thread here. I'm no longer even contributing towards technical topics anymore. I'm done with this forum. Let the others debate everything and let those who know nothing be considered the experts as they usually are. I am only sticking around because a few people talk to me through PM's but that's it.
03-16-08, 06:04 PM
#41
^ bwahahaha.
NO. it wont.
There are a whole host of reasons that hydrogen will never work as a fuel for IC engines. The two biggest ones are energy density and availability.
Since hydrogen is really only plentiful and obtainable either in fossil fuels or water, and it takes lots of energy and causes pollution to get it from either one, there is really no basis for the so called 'hydrogen economy' because while burning hydrogen is efficient and causes no pollution, obtaining it makes up for all that and more.
The other thing is that hydrogen has very little energy density. Even at 700bar it still has only 1/8 the energy per unit volume of diesel fuel.
I wrote a paper on this for my IC engines class when I was an undergrad, the upshot was that if one had a diesel car that got 50mpg (which there are many available nowadays), it would (obviously) travel 50 miles on a gallon of diesel. If one were to convert that car to hydrogen, and use the gallon diesel to produce the hydrogen, compress it, put it in the car, and drive it, it would only go 14 miles (about 30% of the diesel). Not only that, but it would have reduced interior area due to the huge tank, and would be extremely unsafe due to the high pressure needed to store the hydrogen, and the extreme flammability of hydrogen. If you would like I can try to post the whole paper, or email it.
The whole idea of hydrogen as a fuel is ridiculous. It is merely a ploy by the government and the oil and car companies to make people think that there is some kind of progress going on, when in reality, not much is being done to combat the fuel and pollution problems.
Heres another thing to think about: You could make an electric car, right now with no new technology, that had all the performance and luxury of modern cars, and had a range of 250+ miles. There are also new battery charging technologies out there that could charge the batteries in a matter of 10 minutes or so. The efficiency of batteries is much higher than hydrogen, and electricity is comparatively clean and available. Another interesting point is that theoretically, the whole world could run on electricity obtained from renewable sources such as wind and solar. In fact wind alone contains 9 times the TOTAL amount of energy used in the world.
NO. it wont.
There are a whole host of reasons that hydrogen will never work as a fuel for IC engines. The two biggest ones are energy density and availability.
Since hydrogen is really only plentiful and obtainable either in fossil fuels or water, and it takes lots of energy and causes pollution to get it from either one, there is really no basis for the so called 'hydrogen economy' because while burning hydrogen is efficient and causes no pollution, obtaining it makes up for all that and more.
The other thing is that hydrogen has very little energy density. Even at 700bar it still has only 1/8 the energy per unit volume of diesel fuel.
I wrote a paper on this for my IC engines class when I was an undergrad, the upshot was that if one had a diesel car that got 50mpg (which there are many available nowadays), it would (obviously) travel 50 miles on a gallon of diesel. If one were to convert that car to hydrogen, and use the gallon diesel to produce the hydrogen, compress it, put it in the car, and drive it, it would only go 14 miles (about 30% of the diesel). Not only that, but it would have reduced interior area due to the huge tank, and would be extremely unsafe due to the high pressure needed to store the hydrogen, and the extreme flammability of hydrogen. If you would like I can try to post the whole paper, or email it.
The whole idea of hydrogen as a fuel is ridiculous. It is merely a ploy by the government and the oil and car companies to make people think that there is some kind of progress going on, when in reality, not much is being done to combat the fuel and pollution problems.
Heres another thing to think about: You could make an electric car, right now with no new technology, that had all the performance and luxury of modern cars, and had a range of 250+ miles. There are also new battery charging technologies out there that could charge the batteries in a matter of 10 minutes or so. The efficiency of batteries is much higher than hydrogen, and electricity is comparatively clean and available. Another interesting point is that theoretically, the whole world could run on electricity obtained from renewable sources such as wind and solar. In fact wind alone contains 9 times the TOTAL amount of energy used in the world.
Last edited by patman; 03-16-08 at 06:11 PM.
07-04-09, 10:47 PM
#44
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Rotary Diesel ?
A rotary diesel engine comprising a casing which forms a working space composed of intersecting cylindrical chambers. A rotor is rotatably positioned in at least one of the chambers and a rotary sealing member is positioned at least in one of the other of the chambers, the rotor having a plurality of radially extending lobes and the rotary sealing member having a plurality of radially extending grooves intermeshing with the lobes. A fuel injection assembly is cooperatively carried by the rotary sealing member and is made up of a manifold, a fuel entry port, fuel injection chambers, and pressure building and metering components for each of the fuel injection chambers. An appropriate actuating device, stationarily located external to the rotary sealing member, provides control for the complete fuel injection assembly.
07-06-09, 03:11 AM
#45
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Here's a company that's working on a diesel rotary.
http://www.l3com.com/products-servic...?type=p&id=124
http://www.l3com.com/products-servic...?type=p&id=124
07-14-09, 10:06 AM
#46
I was talkin to a engineer friend last year, he works for a company here in ohio and said they are developing a rotary diesel engine for the military....he is suppose to keep me posted when they get it going.........i cant say what company of course but i ever hear more I will let you guys know..
ohh the engine will be used in a UAV military use...
When I graduated in England I almost landed a engineering job working on single rotor engines for the same company
ohh the engine will be used in a UAV military use...
When I graduated in England I almost landed a engineering job working on single rotor engines for the same company
07-14-09, 10:32 AM
#48
HEY PATMAN...google hydrogen rx8...you may be in for a rude awakening!!!!
MAZDA (not shouting) introduced 9 rx8 to a company in Japan which have been so successful in the 2 yrs or so, that they ordered a few more....Europe got wind and now Norway just recievd their first of a number on order...so check over your paper dude....if it was engnieering you may want to rethink your degree or at least your paper.......
Hydrogen is possible and it does work for both emmision and milage
MAZDA (not shouting) introduced 9 rx8 to a company in Japan which have been so successful in the 2 yrs or so, that they ordered a few more....Europe got wind and now Norway just recievd their first of a number on order...so check over your paper dude....if it was engnieering you may want to rethink your degree or at least your paper.......
Hydrogen is possible and it does work for both emmision and milage
07-14-09, 12:43 PM
#49
haha, yes ive known about that since they came out a couple of years ago. look at the specs on reduced range and power output when running on H2 (~100bhp IIRC).
Ford and GM also both have hydrogen prototypes that they drive around. Several major automakers also have hydrogen fuel cell vehicles driving around, not to mention probably hundreds of privately owned hydrogen vehicles (Schwarzenegger has a hydrogen humvee, for example). I've seen several of these various vehicles in person at conferences and things- never once have I met anyone presenting one who can answer my questions when I ask about leakage rates or mainstream hydrogen sources.
I never said you couldn't make a hydrogen car. I just said it will never be mainstream. Just because there are a few driving around doesn't change that a bit. Hydrogen is a hot topic because it sounds so good to the uninformed - no emissions, comes from water, all that- which makes all the politicians cream their pants, hence huge government incentives for R+D, etc. It is basically a research movement based on a PR campaign, anyone who knows what they are talking about will tell you that without several MAJOR breakthroughs in technology it won't work for public use.
You need to mind your manners a little- read the information I posted and attempt to refute if you want, but try not to make rash comments without doing any research. Making insulting comments about my degree (finished- now working on a MS and Ph.D) or paper (96% grade given by one of the nation's leading engines and emissions experts) just makes you look like a twerp.
Pat
Ford and GM also both have hydrogen prototypes that they drive around. Several major automakers also have hydrogen fuel cell vehicles driving around, not to mention probably hundreds of privately owned hydrogen vehicles (Schwarzenegger has a hydrogen humvee, for example). I've seen several of these various vehicles in person at conferences and things- never once have I met anyone presenting one who can answer my questions when I ask about leakage rates or mainstream hydrogen sources.
I never said you couldn't make a hydrogen car. I just said it will never be mainstream. Just because there are a few driving around doesn't change that a bit. Hydrogen is a hot topic because it sounds so good to the uninformed - no emissions, comes from water, all that- which makes all the politicians cream their pants, hence huge government incentives for R+D, etc. It is basically a research movement based on a PR campaign, anyone who knows what they are talking about will tell you that without several MAJOR breakthroughs in technology it won't work for public use.
You need to mind your manners a little- read the information I posted and attempt to refute if you want, but try not to make rash comments without doing any research. Making insulting comments about my degree (finished- now working on a MS and Ph.D) or paper (96% grade given by one of the nation's leading engines and emissions experts) just makes you look like a twerp.
Pat
07-16-09, 12:25 PM
#50
Old [Sch|F]ool
I'm somewhat interested in spark-ignition "heavy fuel" (kerosene/Diesel/jet fuel) rotaries, leading up to a dual-fuel conversion of a Mazda.
There's a company with a bunch of videos on YouTube who has a heavy fuel Wankel for UAVs. In one of the videos they take a room temperature engine and pull-start it on Jet A with one pull...
There's a company with a bunch of videos on YouTube who has a heavy fuel Wankel for UAVs. In one of the videos they take a room temperature engine and pull-start it on Jet A with one pull...