New engine sends shock waves through auto industry

This is an obsolete generality based on your observations of 50 year old technology. New generations of engine are being run on the test stand that are much much better than the ones you are thinking about.

Where a gas turbine makes sense depends on the mission length and the power required, and also it is heaviliy dependent on whether or not you are a planing craft and weight is a big issue. On shorter missions (about four hours or less) there is a savings with a gas turbine. On longer missions, currently available engines would not provide a benefit.

Newer technology turbines, with a fuel consumption 10% higher than diesel would actually be more efficient in a planing craft due to the weight savings. In a patrol boat like a Mark V (50 tons displacement), the replacement of the diesels with turbines would reduce the installed propulsion system weight by approximately 20,000 pounds. This is because the diesels necessary to push a craft that big at 50+ knots get huge, and are coupled with big gearboxes. If you cruise at the same speed, the reduction in weight of nearly 20% results in a lower fuel burn and the fuel consumption is the same because of lower drag, even if the engine is a bit less efficient. If you want to go fast there are compelling reasons to go with turbines, and that carries down to boat with as little as 500 hp per engine, with these newer engines. With current available off the shelf technology, turbines make sense down to about 1200 hp per side.

That, my friend is absolutely absurd. I have been in a meeting with the man that took place about 7 years ago and I can tell you for a absolute fact that he knows more about thermodynamics that you ever will or could. The fact that he is a thermodymaics professor at a major US University has more credibility than some fool on a forum trying to shoot holes at what he is doing. Unless you understand the concept of creating constant volume combustion pressure gain by the use of detonation waves, you don't have a clue as to what makes this engine do work.

No, that is not correct. Modern car engines are 25-30% efficeint only at wide open throttle and full power. Part power efficiency is actually much lower, and does approximate 15% over a typical driving cycle. Again, if you undersood thermodynamics you might have a better appreciation for what is going on here.

First of all, it has the potential to significantly better thermal efficiency at what he has designed it for. He isn't saying it will be used in anything but hybrid vehicles, or to drive an electrical generator. It isn't intended to be used for anything else. Throttle response is not an issue. Emissions could be substantially better than a conventional engine because, as a result of the high combustion speed oxides of nitrogen production will be greatly reduced. Cost is surely going to be substantially lower than anything with pistons and valves in it. etc ect.... It isn't a marine engine, but for what they want to do with it, it appears to be ideally suited.

 

In my experience, fast spinning rotary engines like jets and turbojets are very noisy.
No reciprocal parts means no vibrations, but the turbine whine surely is undesirable in a vehicle. A turbo charger can be easily converted into an engine and could be a very compact power source for a generator, but reducing the noise to a level acceptable for passenger vehicles will also dramatically reduce the efficiency.

 

Whilst it is perfectly correct to say that BSFC does vary significantly with throttle position, due to pumping losses and poorer burn at part throttle, it doesn't, I'm afraid, reduce the average down to anything like 15%. The peak efficiency of modern lean burn engines is well over 30% and the mean efficiency is much better than 15%, closer to about 25% for normal cars and over 30% for hybrids (but only because some types of hybrid can effectively avoid partial throttle operation).

The biggest wild claim in that article, though, is the one that refers to the 1000lb weight saving in a car over a conventional engine of the same power. This is simply absurd and plain wrong or an attempt to hype up the technology.

There are some advantages to rotary engines of this type, but making exaggerated performance comparisons on the weight and BSFC points does undermine the credibility of the whole venture. In my view, making claims like this forces me to question the validity of all of their work, irrespective of the paper qualifications of the originators. I'm a retired senior principal scientist, and have seen my fair share of seemingly well-qualified and credible individuals get carried away with "over-enthusiasm" for their projects over the years.

Jeremy

 

That's true when the car is moving, but in an urban driving cycle, there is also time at stoplights to consider. Here is a link where they have measured the average thermal efficiency over an urban driving cycle to be 12%. You have to consider things like time where the engine is idling and consuming fuel but making no power in an urban driving cycle and that really kills the efficiency. So actually 15% average thermal efficiency for a conventional system is probably a good number.

http://www.heat2power.net/en__wasteheat_in_ices.php

Well, Jeremy that's not necessarily true either.

First, remember that we are talking about hybrid vehicles here, not conventional cars. In a hybrid, you have to consider the weight of the generator. That could be easily 150 to 200 pounds for a series hybrid alternator. A high speed alternator on a turbine, spinning at 75,000 rpm is very small. We designed a 30kw alternator that weighed only 22 pounds. Most reciprocating engine weights do not normally include items like the radiator, and other accessories, so when you replace the engine (that typically weighs 300 pounds) you have to account for more than the weight of the engine, you have to add the water, oil, and radiator into the equation. In a hybrid you are talking at least 550 pounds of engine, alternator and accessories.

Then, you also have to consider that if the propulsion system weight is substantially reduced, that lower weight snowballs through the car resulting in a ligher chassis and crush structure, suspension, wheels, brakes, engine mounts and other systems, and in a hybrid, lighter battery weight (which is a big deal in a hybrid). Consequently a drop in engine weight of 500 pounds could easily result in an overall vehicle weight savings of twice that amount when all of the added hardware is included and the weight of the chassis and batteries is considered. If you are comparing this to a reciprocating engine in a hybrid, it's a lot more than just the 300 or so pounds of engine weight that you would take out. Again, you have to consider that he is only talking about using this on a hybrid. Might not be 1,000 pounds, but if the engine and alternator that you took out weighed 550 pounds and you replace it with a 40 pound turbine system you are probably going to see a net hybrid vehicle weight reduction, when the batteries are considered of close to 1,000 pounds.

So the weight reduction claims aren't crazy at all, they can be accounted or and actually make sense.

 

but that's still not apples to apples. When considered turbine - in general or in original post - its assumed that it is used in constant duty generation use. But somehow the ICE its being compared to has to idle at the red light?
I totally believe that ICE in stop & Go (esp any big engine that is commonly used at 10% of peak power) is quite far below the 30% efficiency. But for technology comparisons sake you should compare a well designed system to another.

In spinning a generator I would believe a 35% efficiency on a diesel would be achievable. Original article - what did it say again 3.5x more efficient.... that's manipulation of facts at best and an outright lie at worst.

 

I should have titled this thread; "don't believe all you read".

I posted this thread for information only, not to start an argument. Wiki articles, as you should all know by now, are unlikely to be reliable sources.

Kerosene,

The exact words were "It promises to be 3.5x more efficient, etc..." Promises, not guarantees. On the evidence of your last post, I have concerns that you might believe the promises of politicians, when we all know that the lying ***kers always sell us out.

Rather than getting in a tizzy, let's wait until the end of 2011, per this link.

http://nextbigfuture.com/2011/03/wave-disk-engines-could-be-35-times.html

In #4 I also made a reference to EEstor that has been missed. It is worth reminding one and all that EEstor have, so far, failed to produce any evidence to back up their claims. That was by way of a "Caveat Emptor"

"EEstor is a company based in Cedar Park, Texas, USA. A start up company pioneering a new energy storage technology. "will change everything"

The Promise (What do we know about promises?)

The buzz was that EEStor, Inc, a secretive Texas-based company, could deliver a battery based on ultra-capacitor technology that in out-performing any battery that existed today would present electricity storage solutions that would in one stroke make a variety of alternate energy solutions suddenly very viable - an ultra efficient and long-lasting battery would make wind and solar power plants very viable, as the vagaries of production would be ironed out - even at the level of individual homes. You would see electric cars able to compete with IC-engine cars favorably in terms of range and recharge times. We would at once see a big churn in two of the biggest industries of our time - oil and automobiles. The possibilities of course are endless.

So what exactly is the claim? Sample this, "EEStor’s products, to be known as Electrical Energy Storage Units [EESU], will start coming off a production line this year. The first EESU will be a 45 kg unit that gives a car a 350 km range and can be recharged in under ten minutes. In comparison with petrofuels, a EESU cars’s running cost will be 80% cheaper." And this, "The company boldly claims that its system, a kind of battery-ultracapacitor hybrid based on barium-titanate powders, will dramatically outperform the best lithium-ion batteries on the market in terms of energy density, price, charge time, and safety. Pound for pound, it will also pack 10 times the punch of lead-acid batteries at half the cost and without the need for toxic materials or chemicals, according to the company."

Here's another new breaking news item.

http://wattsupwiththat.com/2011/04/...c-effect-of-light-into-insulators-discovered/

Cold fusion anyone?

P

 

If you say eggshells are white, someone will argue with you.

 

When someone claims a 1000lb weight reduction for a car using a new engine (note that the claim is for a reduction in weight of 1000lbs), then it's clearly wrong, no matter how you dress it up. Even if this new engine, with all its ancillaries, weighs in at, say 100 lbs, the implication is that a similar power conventional gasoline engine (with all its ancillaries) would weigh 1100lbs.

First off I don't believe that, say, a typical 100hp version of this engine, complete, would weigh only 100lbs, secondly, I know full well that a 100hp conventional gasoline engine (complete) doesn't weigh anything like 1100lbs.

The claim is plain wrong, and, in my view, throws suspicion on the veracity of every other claim made.

FWIW I am on my second hybrid car and worked on hybrid military vehicle technology research, so do know a little about the subject (although I'm by no means an expert in ICE technology). The average fuel efficiency (in terms of calorific value of fuel used vs usable motive power delivered) for my normal driving over the past 5 years of hybrid car ownership works out to an SFC of around 268g/kWh, which by my reckoning is an everyday average efficiency of about 31%. Sure my Prius is more efficient than some gasoline engined cars, but it isn't twice as efficient, by any stretch - my guess is that it might be 5 to 10% better overall, if that. To get an average efficiency of 15%, as quoted in the comparison made by the originators of this new engine, assumes that the practical SFC for normal car gasoline engines is around 550g/kWh, which is an absurdly high figure, probably higher, even, than the old gas guzzlers from 30 to 40 years ago.

Jeremy

 

Jeremy,

I'd buy a diseasel (intentional spelling) and run it on SVO with 5% unleaded. Gotta be cheaper than DERV. I'd bung in a couple of gallons of DERV from time to time, but I do enjoy the smell of a chippy. Hybrids are dysgenic.

P

 

You're letting me down, Jeremy. It was a good fight until this round, but Yellowjacket clearly explained why there is more than just engine weight involved and you didn't even try to answer his argument.

Ouch. You're not seriously expecting to counter Yellowjacket's published study with informal measurements and guestimates are you?

This round goes to Yellowjacket by a wide margin. You are going to have to come out punching hard if you want to get back in the fight.

 

Why try and argue with moot points?

The "published study" is marketing material from a company with a vested interest in showing ICE to be inefficient, so they can show enhanced performance for their heat to power technology. It's not peer reviewed and has no scientific credibility.

It's also pretty clear that there isn't the potential to make a 1000lb of weight saving by replacing the power plant of an ordinary car (which is what the originators of this engine seem to be claiming). Even allowing for the better fuel efficiency needing a small fuel tank and cooling system, you still can't save 1000lb if the original installation (complete with all ancillaries like fuel tanks and cooling system) weighs less than this to start with (which it will for the majority of ordinary cars). The heavy components, like transmissions and drive systems will be the same for both engines, so the only real weight saving is in the engine and ancillaries.

Jeremy

 

I’m sorry but this is the same old tired old argument from those who are in the aerospace industry or GT industry and are not naval architects or have any actual marine design related experience.

I shall reiterate again:

The plain facts are that a the amount of combustion air required for a GT is of the order of 5 times that for a diesel, coupled with those very large filtration units, not to mention the exhausts. This all adds weight a lot of weight!!!

Reduction in weight of 20%..where does this figure come from..reduction of what??

I think you’re forgetting to point out the ADDITIONAL weight of having to carry around so much more fuel to feed those thirsty beats.

Slight side step required here to form a better understanding. Apart from the inaccuracies just quoted , what does a patrol boat do???...it patrols….does it patrol at 50+knots day in day out…no. Does it patrol at 50+knots once a week, probably, when required.

That is the whole MO of patrol boats, they loiter, loiter for hours, days even weeks. Then when required, whooooosh, off they go in pursuit. But for short periods (may be hours maximum), never days on end either!

So, whilst in loiter mode, they carry huge reserves of fuel to feed those GTs, and consume huge amounts doing it. Just going slower doesn’t mean you pro-rata consumption like a diesel. A diesel engine SFC is significantly reduced at slower speeds, those of loitering, whereas a GTs, the reduction is marginal at best, see attached actual figures of an actual real boat using GTs which has a service speed of 45 knots compared to a diesel engine.

And unless you’re a naval architect that designs high-speed vessel and has to balance the SOR and many other conflicting issues to make the vessel a success and meet the SOR, you’ll never understand why GTs are so rarely used on high speed boats. You're not looking at the bigger picture.

my 2/c worth

 

No NA but helicopter GT.s often have low weight gearbox build in.
Air in and out dont look very heavy eighter.
Why do raceboats use them?
And at WOT GA.s run fairly economic i read.
Bit bigger boats use second drive line for slow cruising, seems to me "it all depends"
Reading up and wondering

 

Very true. I can recall really worrying about fuel burn whilst sat on the ground at ground idle waiting for people to get on board during quick turnarounds - turbo prop engines used to burn darn near as much fuel just turning and burning on the ground as they did during normal cruise flight. The same is true of pretty much any gas turbine, as you've neatly pointed out - they have a generally poor SFC when operating away from their efficiency peak, which is usually around the point where the engine is running at it's hottest allowable continuous internal temperature.

I think the only reason that race boats use them is because the high power to weight ratio is advantageous and the SFC will be acceptable because they run flat out all the time.

Jeremy

 

re race boat
they are only a little better as when you get over say 1500hp they are more reliable only beacuse there isnt a v8/v12 si engine that can do that. I dont believe weight is an issue as a percentage of all up weight, the engines builders dont even quote a weight so they are clearly not competing in that area?
They cant compete when they are say 1300hp and below
PS now that high speed diesels are getting into the high 5000hp range they are pushing the GT out also I notice