I just wanted to know what you guys thought of this. I few years ago when I was getting my engineering degree, a professor of mine was working on this new type of engine.

The engine is called a Star Rotor engine, much much different than any engine you might know of. Up front, this is NOT like the rotory engines you might know of like the Wankel rotory engines used in some Mazda's cars today.

This engine uses the Brayton Thermodynamic cycle, which is much more efficient than the Otto thermodymanic cycle used in internal combustion engines today. The thermodynamic cycle is 45-60% efficient, compared to conventional engines of 15-20%. This means that this engine will effectively triple the gas mileage of conventional engines with similar power ratings.

The design of this engine is quite genius. The compression, ignition, power, and exhaust stages are broken up into seperate parts which can be done with more efficiency because each part of the engine can specialize in what it does. In addition, all moving parts rotate around a single axis. This means almost NO wear and tear on your engine. All parts considered high-wear in the compressor and the expander don't even touch, so there is literally no wear at all. The only part of the engine which would require oil, is near the power shaft which is seperate from the rest of the engine and will stay relatively cool. That means the oil will never heat up and break down, meaning very very few oil changes.

The engine has a tenth the moving parts of a conventional engine, thus it will be cheap to mass produce. Because the engine is much more efficient, the engine will also be alot smaller. A 130hp engine will have the volume of 2 cubic feet. Other positive things this engine will boast are: Low pollution, multi-fuel capability, no vibrations, quiet (not always a good thing if you ask me ;-)), long life, high turn-down ratio, scalability.

This engine is exactly what we need with fuel prices going the way they are going today. This would revolutionize the way we know engines today. These engines will easily go into the millions of miles. You would literally never have to buy a new engine again.

Check out the website http://www.starrotor.com and you can view the data that they have just gathered on their latest 3rd generation compressor. Check out how flat the torque curve is. Check out the efficiencies topping out at over 70-80%. That is awesome!

One early question I had was how speed will be regulated. The speed will be regulated by changing the compression ratio in the compressor. This can be easily done by changing when the air is allowed to leave the compressor. The earlier, the less pressure, the later, the more pressure.

Also, check out some of the animations that show how the engine will run. It should give you a better idea of how the engine works. It's hard to think of at first because you expect there be a cycle of some sort, meaning, compression, expansion, exhaust, intake repeat....You have to get over this. In the combustion chamber there is a CONSTANT combustion! It is always expanding. I have a fairly good understanding of this engine. If you have any questions, you can PM me, or e-mail me at maxoctane@gmail.com

 

seems real interesting but when are we realistically going to see this is a car?? how fast can it really go?

 

wow, sounds impressive! That really is a simple design and looks promising.

 

Hmm. I like.

 

very interesting indeed.

Unfortunately this engine is not anywhere close to being made yet. The problem is funding. The last I heard about funding was a couple years ago and the guy was having a hard time getting the proper funding. He is currently being funded by the university, but that is hardly enough to develop this quickly. I know he was hoping by end of this decade, but that was 5-6 years ago and I don't think he has gotten as far as he hoped. What is more interesting is that he tried to sell his idea to several automotive companies, none of which agreed to help fund his research. I do know at the time the compressor was not working and one company said they would re-evaluate when he go the compressor working. Since then he does have a working compressor, but I have not talked with him so I do not know of any news that has not been updated on the website.

To answer your second question: It can go VERY fast. In conventional engines, you have to worry about timing. The speed of the engine is limited by airflow, valve movement and timing. On top of that, you have pistons slamming up and down. (Can you see how this new engine will be so efficient?). This new engine will spin on a relative axis. Essentially nothing mechanical limiting it's ability to spin, and thus will have the potential to spin crazy fast. I would guess easily 3-4 times that of a conventional engine, maybe even faster. I do not think enough is known about this engine to where we know for sure. Since the inner and outer rotors do not touch, leakage is expected, and thus the engine will be more efficient at higher rpm's. Most of the testing it looks like they have done so far have been <10K rpm's so I figure that will most likely be the operating range of the engine, although I could be wrong...

 

I read bout this engine on the website you provided but I see one problem- automotive manufacturers will not employ such designs in their cars as it will make the car too reliable for them. They make a TON of $$$ from selling parts etc and dealerships stay in bussiness thanx to unreliable engines that ALL manufacturers make today ( 03 Pathfinder got towed in to my dealership today with a need for a new motor for instance). Simple and EZ to fix cars are a thing of the past nowa days. Today you need to have a zillion gadgets inside the car, so when they break down you will be forced to spend thousands of dollars on repairs to fix it. Manufacturers could make a car that would not break- but that would not be smart for them. If the car ran great for 10 years of ownership, manufacturers would loose $$$ on parts and sales would be down, since not many people would be buying new cars. I personally keep cars for a long time, and would love to see new ideas like this being applied to keep the technology moving. Internal combustion engines are old tech, 100+ years we been spining pistons up n down making power, its time for something new.

 

a few words...

modern IC piston engines are about 33% efficient, not 15-20...



and...


ANYTHING that generates heat or has moving parts is prone to failure. when the leakage becomes too great, or the combustor becomes carboned up, or the recuperator becomes inecfficient.

not only that, but theres still an entire car to break, even if the engine did hold up forever.

it is time for something new, but whatever direction they take it, ill always have a job.

 

and some more looking at it... looks pretty good and flow remains relatively the same for a slight PR variation, which seems to suggest that leakage past the compressor gaps isnt all that much of a problem, however, he isnt running it at the 6 ATM that it was set for.

also, torque curves arent output, theyre input. the compressor is being driven by an outside source, since the compressor alone is being tested, without the rest of the engine...

 

The first thing that comes to mind for me is repair costs.
The second thing that comes to mind for me is heat dissipation.


Oh, yeah. Why are we wasting time trying to improve the efficiency of something that consumes a finite resource?

 

The standard otto thermodynamic cycle is 15-20%. Modern advances in the combustion engine such as turbo's, and hybrids do get better efficiencies, however think of the complications as opposed to this Star Rotor Engine. A hybrid engine is thousands times more complex and expensive when compared to the Star Rotor engine. Also, it is only a matter of time for new advances to the Star Rotor engine will emerge to increase its efficiences as well.

True, but when standard engines might last 200K miles, or even 300K if taken care of, the Star Rotor Engine will last in the millions of miles. The cost to replace one will not matter anyway because they will be much cheaper to manufacture.

Very true. The guy who is developing this engine hopes that one day cars will be sold without engines. Instead, when buying a car, you will swap out the engine in your current car with the new "shell" car.

True, but the compressor is the same thing as the expander just in reverse. Compressor data will reflect (somewhat) the data gathered from the expander . Output from the expander will look like relatively like the data from the compressor in reverse

Thats the idea, the repair costs will be negligible. MUCH less than any internal combustion engine. If Mark has his way, engines will be leased. If anything goes wrong, take your car back, and swap out the engine with a different one. These engines will be much less complex and repair will be much easier. Repair will also be much less necessary because these engines will fail much less and will require much less maintenance and thus not prone to error because of negelegent owners.

As for heat dissipation, I am sure something will be incorporated. Because of the higher efficiency, there will be less heat to dissipate in the first place. Maybe a pseudo-radiator like device? I do not know what he plans to do with heat dissipation, or whether or not it will even be a problem.

Finally, this is not wasting time. Think about it. This engine is multi-fuel. If we could essentially double or triple the efficiency of the engines we could use alcohol to run these engines - alcohol can be grown from corn, ie not a limited resource. Talk about a limited resource... everybody is talking about hydrogen cells. Where the hell does hydrogen come from? Hydrogen uses electricity to generate and electricity mostly comes from burned coal - a limited resource.

This is the perfect answer that our planet needs right now. Unfortunately BlackBirdVQ is right. The problems is there is more money in expensive, inefficient engines that break down and require thousands of dollars to fix. What we need is one small company to jump on board to steal the market share that all of the other automotive companies hold. Then all of the other automotive companies will be forced to comply or otherwise go out of business. I sure hope this happens.

 

sounds nice maxoctane were in dallas u at im in garland
<~~~~

 

You Engineers never cease to amaze me! That sounds wild man, with gas the price it is I'm sure he's really trying to expedite this now! Good luck guys, very interesting.

 

no, not hybrid, just a regular n/a gasoline piston engine... 33% thermal efficiency. about 33% into the cooling system, and the remaining into the exhaust


doubtful. if he can attain the 70-80% figures his site boasts consistantly, without any side effects, the energy (read: heat) will be consumed in driving the output shaft rather that being dissipated. id guess about ~30%, part of which is recuperated in the ...recuperator ( ), and i wonder if this thing will need much more than a cool breeze for a cooling system


not only that, but the penny pinchers will like it, auto MFGs will be able to put more money into QC on other parts of the car, etc...


i think this has potential...

lets build a drag car using one, as a model/demonstration. get one of the big three to donate a chassis... if they do it for electric car builders, theyll do it for him. if not funding, then throw him a rolling chassis...

 

You sound doubtful about the recuperator. The nice thing is that this technology is not entirely new and an efficient engine with recuperator that uses the Brayton cycle already does exist...ie jet engines. Taken from the white paper on the page:

Brayton cycle engines have a high power density, which is why they are used to propel jet aircraft. In contrast, Otto and Diesel engines have a lower power density. Further, because Otto and Diesel engines release high-pressure air to the environment, the throttling noise is very loud. In contrast, the Brayton cycle releases the exhaust gas at 1
atm, offering the potential to be quiet, provided mechanical noises are minimized.

The major challenge in implementing Brayton cycle engines is to find a means to process large volumes of air to achieve a desired power output. Traditionally, this is accomplished using dynamic (i.e., axial or centrifugal) compressors and expanders. Unfortunately, these devices require very high speeds – 100,000 rpm for a 30-kW unit sold by Capstone – to develop the desired pressure and flow. Also, they do not have a large “turn-down” ratio, meaning they operate efficiently only at one speed. Further, they
are affected by changes in air density, which can result from varying humidity or altitude. Positive displacement compressors and expanders overcome this problem; however, most conventional approaches have severe problems (e.g., low power density, imbalance), making them unacceptable.

 

not at all, maybe a bit modest about its power returns, i still think that he should consider the possibility of it collecting exhaust carbon and losing efficiency.


also, i wonder what a refrigerant cycle heat exchanger would do cooling the incoming air, to boost efficiency, since this whole engine is based on compression and expansion, and not so much explosion (as all 'external combustion' engines are.

do you talk to the professor regularly?

 

The recuperator is already proven, along with its added efficiency and it's already engineered so that exhaust carbon will not be a problem in current Brayton cycle jet engines. I am not an expert when it comes to jet engines, nor am I am expert when it comes to the recuperators that will be designed for this engine... but I do believe it will not be a problem. If and when this engine is used, who knows how much carbon exhaust it will give off anyway. If alcohol is used it most definitely won't be a problem.

I do not know what you mean by a refrigerant cycle heat exchanger. I do not know where you picked that up from. On the webpage, you might notice that he has the refrigerant cycle, but that is for use for an air conditioner, and has nothing to do with the engine.

However, it is mentioned that atomized water could be sprayed into the compressor to increase efficiency. Taken from the white paper: To improve the efficiency of the Brayton cycle engine, atomized liquid water can be sprayed into the compressor inlet. As the liquid water evaporates during the
compression, it keeps the compressed gas cool, which lowers the required compression work. Because the compressor exhaust is cool, it allows the exhaust from the heat exchanger to be cool as well, thereby reducing the thermal signature.

Technically, this engine is about explosion. The gas in the combustor is constantly exploding and expanding and thus driving the expandor. Just like in regular engines, the cooler the air, the more dense it is and thus the less compression the compressor has to do to obtain the desired airflow.

Unfortunately, no, i do not talk with this guy anymore. I am hardly in town anymore and I don't want to bother him with e-mail when I am sure he is busy with his research.

 

alcohol will require a bit of 'phasing in' before its available in mass quantities. you cant even buy M85/E85 in florida. if this is introdiced in the next 10 or so years, and plans to be used in production cars, itll likely be gasoline powered. not only that but automakers have penny-pinchers working for them, would rather use existing fuel supply units, lines, tanks, etc...

go figure.

never mind, if you get a chance you can pass that on to the professor. or maybe ill 'bother' him with an email

yes, i read all that already. unfortunately water displaces oxygen, and therefore reducing the incoming charge. there are other ways to cool the charge.

exploding? are there really explosion events? i though it was just one big expansion, constant fuel introduction... like a jet engine.

 

Agreed. I assume the alcohol will be slowly introduced as a mixture with the gasoline. There are already parts of the US that mix a certain percentage of alcohol generated from corn in with their gasoline.

After reading your post again, I had not realized that the refrigerant cycle heat exchanger was actually your idea. I assumed that you had read it somewhere on the website. My apologies.

Anyway, I too wonder if adding another thermodynamic cycle will increase the overall efficiencies of the engine - or if it will be like building an air-conditioner to cool the incoming air of my second air-conditioner, for my third...and so forth. By introducing cold air into the compressor, you are simply reducing the amount of work that the compressor has to do. The compressor will require 33% of the total work output to run. Increasing the compressor efficiency by 20% which is quite a bit, will only effect the total engine efficiency by ~6%.

I had not thought of this, however I am confident that Dr. Holtzapple and his team already has. I am curious to see where their research goes.


I guess this last comment train is all relative. How do you define exploding? Technically explode means to expand rapidly, and that is what the gas in the combustor is doing....constantly expanding, or exploding, with constant fuel introduction... like a jet engine. You mentioned that this engine was all about compression and expansion and not so much about explosion, however without the explosion there would be no work done. But of course you already know that. Regardless I am sure if this technology takes off, alot of new ideas will emerge to increase efficiency.

 

without expansion there would be no work done. explosion is a rapid expansion, rapid enough to create a pressure spike, wave, etc.

a consistant fuel flow and burn isnt really an explosion... meh.. lets not get into semantics


yes, the heat exchanger would be in the intake tract, cooling the charge. i understand about 60ºF is about ideal for a gasoline piston engine, id bet the cooler the better with a brayton.

 

In a competitive free market, this doesn't happen. Competition encourages advances in technology and quality. 50 years ago, cars required much more maintainance and didn't last 50k. The model T's engine would only last a few thousand miles. Today, even most Fords last 100-150k miles. The VQ didn't come about as an accident, it came about because Nissan wanted to make a better V6 than anyone else.

The market for cars and trucks is huge and there's 45 brands currently selling cars. If there was a proven super dooper engine that got double or triple the gas mileage and longetivity of current engines, GM (or fill in the blank) would adopt the technology, make a killing, and put everyone else out of business.

This engine may be the future, but it needs to be proven first.

 

or at least come up with something to compete.

 

Regardless, when this engine comes out, it is going to kick so much ***

 

So how does this engine like running at varied speeds? (sorry, didnt get too far into the website)

A gas turbine engine would be fun to put in a car, but they tend to like to run at a consistant speed.

 

I hope so. It looks like it will have the efficiency of a turbine engine without it's drawbacks.

 

thats why i suggested the drag car thing... to get teh 'word out'


with a decal or something of the sort that says 'this car gets 60 MPG in the CITY!'

and obviously it would sound completely different, it would definately get attention.

the general public tends to shy away from 'gas savers' because they want something that can merge onto the freeway with no problem, and get around that semi quickly on a 2 lane highway.

what size would the engine have to be to produce 300HP?

if you get a car that weighs in like an insight, metro, etc... you could be doing 12s or better.

 

I tend to think that an engine like this wouldn't be very rev-happy and would work best when at a constant speed. Something like this in a hybrid type vehicle would overcome that potential downside.

 

Interesting, the star rotor compressor shown on the website looks and works just like the oil pump on my old 1984 Subaru GL 1800cc. Except it had 4 points. Man, that takes me back

 

yes, thats a gerotor type compressor, and SEVERAL fluid pumps are designed around the concept.

foobeca, the compressor has a high turn down ratio, meaning it operates well at more than one speed, im guessing this is due to the pressure ratio maintained between the compressor and turbine...

 

Yup, thats where Dr. Holtzapple got the idea from. The star rotor was used in small and larger oil pumps... however it had never been attempted in this type of application before.

 

StarRotor makes the news:

http://www.starrotor.com/images/Starrotor.wmv