Re: Fuel Reformers for Home Power or Cars & Tractors

>

Nothing beats a tad of sarcasm... :-)

This is a funny one:

>>

Sarcasms? Moi?

I just think they're on the wrong track. I recover heat from my wasted engine by setting the injectors rich and toasting marshmallows on the catalytic converter. I get a 50% improvement in fuel mileage that way, and a tasty snack as a bonus.

-- Ed Huntress

The issue is that reforming always results in some loss of energy from the original fuel. You may recoup some of the loss through higher compression or other efficiencies, but you can't get more energy out than the energy that goes in.

So they're interesting, but watch for implications that they somehow get "extra" energy out of the system. It can't happen.

This appears to be quite a stream of nonsense, Naresh. What is the documentation of "much better fuel economy"?

-- Ed Huntress

OK, let's take a look at these claims. I hate wasting time like this but maybe someone will care.

I read several MIT papers on the plasmatron reformer a few years ago and my recollection is that they were all about improving exhaust emissions, particularly from larger transportation diesels in buses and trucks. I just read your references and they're mostly based on those old MIT and DOE press releases and papers.

You and your friends apparently have seized on a claim in one of the press releases, that they could reduce fuel consumption by up to 20%. That seems to be the only such claim in all of that "literature," so let's see what they're saying. You have to backtrack through the white papers to see where that claim comes from.

It's not about getting more energy out of the fuel. As the white papers make clear, these low-energy plasma reformers run at about 70% - 80% efficiency. That's impressive, but it means that the energy in the reformed fuel is

20% - 30% less than the energy of the fuel going in.

So, where is the "20% efficiency improvement"? It relates to *proposed* catalytic systems for reducing certain emissions, especially particulate emissions from diesel engines. Present diesel emission-control systems that will meet the strict US diesel emission requirements pay a hefty price in increased fuel consumption -- using diesel fuel to fire the catalytic converters to a high enough temperature to do their work. All catalytic converters pay some premium in extra fuel consumption, at least in an idealized model, because that heat has to come from somewhere. Often the "somewhere" is heat that is already lost and wasted, so practically they don't cost much of a premium. But the MIT work is all based on theoretical and lab-based models for emission control, anyway, and they're looking at the theoretical savings.

Note that there is no claim in the plasmatron literature -- at least none that I read, and I read a bunch of it -- that there is some fundamental improvement in fuel economy with existing engines. In other words, don't do this at home, kiddies, because there is no engine/emission-control system in current use that could exploit the reduced energy penalty for heating converters. Also note that there is no claim of getting more energy out of the system than you put in. The claim, theoretical as it may be, is that the plasma reformers, by increasing the hydrogen percentage in the fuel and by other means, can *reduce* the energy penalty for *emission control* systems that aren't even in use, except under lab conditions.

One bottom line is that reforming fuel still results in a loss of energy. Another bottom line is that it will mean nothing unless certain emission-control technologies are adopted, particularly for diesels.

And the big bottom line is that this is not where the action is in plasma reforming, anyway. The thing that has those MIT engineers doing the Peppermint Twist is that the plasmatron promises big energy savings in reforming hydrocarbon fuels in industrial applications, generating ethylene, hydrogen, and so on. And the big-time, long-range potential in transportation is in reforming gasoline and other fuels into hydrogen for use in fuel cells, where conversion efficiencies can run up to 90% or so. Reforming gasoline at a 20% - 30% penalty, to use in IC engines that get no more than 25% (28% if you're talking about the exotics) real-world efficiency to begin with, is not the way to save energy. d8-)

-- Ed Huntress

Rather than having a loss of energy, the energy that was previously lost as wasted heat from the engine is now used to provide the necessary energy for the endothermic reaction that cracks the fuel. Some reformers also use partial oxidation which is an exothermic reaction that gives off the heat needed by the subsequent endothermic reaction which makes hydrogen and carbon monoxide. Another slightly exothermic reaction with steam and a catalyst converts the carbon monoxide to carbon dioxide and more hydrogen. Even in the reformers that use partial oxidation there is a net savings in your pocket book.

You all are writing as if I'm talking about FREE ENERGY and OVER UNITY. This is just regular science.

http://64.233.167.104/search?q=cache:v7bxzL7s2esJ:

So what? What does cracking the fuel do for you? You put a fuel into the system that burns in an IC engine, and you get out a fuel that...burns in an IC engine. But you've paid some energy penalty for reforming the fuel.

I assume you have some objective in mind, and your frequent references to "improved fuel economy" imply that you think there's some efficiency improvement involved. What might that be?

How does it result in a net savings? The system is rife with losses. Where are the gains? Have you calculated, for example, the improved efficiency that comes from higher compression ratios possible with hydrogen fuel?

With what objective?

-- Ed Huntress

"If average fuel efficiency of US fleet of cars and light duty vehicles is increased by 20%, yearly fuel savings would be 25 billion gallons of gasoline (equivalent to 70% of oil presently imported from the Middle East)"

reference: fire.pppl.gov/fpa03_cohn.ppt

I've seen fuel savings estimates from other research projects but I didn't save the data as I was not anticipating so much skepticism about fuel reformers.

Right, especially if you are only burning the hydrogen in the engine, then all the energy in the carbon (lots!) goes to waste.

Jon

Yes, that's what I read and tracked down by reading the MIT claims that preceded it. That's where one discovers that the "savings" are totally based upon reducing the energy *penalty* incurred by catalytic conversion of the waste products of diesel combustion.

In other words, if you don't put an emission converter on the diesel, there's nothing to save. And the converter you may have on your diesel right now won't benefit from the supposed savings, either.

So the 20% claim is based on some assumptions about how much we're going to control diesel emissions, what technologies will be used to do it, and (assuming the system that Cohn assumes will be used), the relative energy costs to operate it.

You could summarize this by saying there's nothing in it for us in transportation applications now, and it's speculative if there ever will be. In any case, it won't come from improving the efficiency or power of the engine, only in *reducing* the losses in the emission control system.

That's what I found. If there's something else, it would be interesting. It is not contained in any of the references to which you posted links, to my knowledge.

You will find skepticism from anyone who has spent a significant part of a lifetime studying mechanical systems and heat engines. The free-lunch stories abound, and they're cropping up more now than ever. Scientific American published an editorial about it a few years back:

======================================

"Selling the Free Lunch" "Perpetual motion has changed its name but not its methods" By Graham P. Collins

"In recent decades crackpot inventors have focused on a variant of perpetual-motion machines known as free-energy devices or over-unity generators. These contraptions supposedly output more power than they take in, generally by drawing on an implausible font of energy hitherto unknown to science [...]"

"...The U.S. patent office may have been stung into action by recent negative publicity and complaints about ludicrous patents. Reportedly, the commissioner of patents will order a reexamination of the motionless electromagnetic generator patent. In August the office announced that patent examiners are to receive "expanded training to build and reinforce their knowledge and skills," which will be tested regularly. Patent office workers can't all be Einsteins, but perhaps now more of them will be Homer Simpsons. As he scolded his daughter Lisa when she built a perpetual-motion device: "In this house, we obey the laws of thermodynamics."

======================================

Vapor carburetors (they work; they were used in at least one production car in the 1920s; they result in no fuel savings at all), water "crackers," "fuel reformers," and various other oddities have appeared all over the crackpot literature (which is now the Web) for a century or so.

They often are based on sloppy misreadings of some scientific paper or another, combined with wishful thinking and baseless speculation. So, yes, you're likely to encounter skepticism when you move beyond the realm of the bushy-tailed enthusiasts who lack some depth in their knowledge or who willfully gloss over important details. That includes the writers of some of the press releases you linked to.

None of this should disparage the very real and interesting work being done with catalysts, plasma reformers, and so on. But they lend themselves to speculation that there is some kind of conspiracy going on to suppress their wider use, which would cure herpes, end our dependency on the Middle East, or solve the problem of gravity.

It's a technology with a lot of potential uses. Cooking one up at home to boost the efficiency of your car or truck is not among them. Further, there is nothing much for the car companies or anyone else to do with them right now, in regard to cars or trucks -- except to prove, once again, that you can turn one fuel into another, at a loss, and run an engine from the results.

-- Ed Huntress

Best way to better enonomy is to raise the compression ratio. Maybe why so many of us here drive diesel cars.... especially with fuel at 1GBP per litre.... :-(

Yes, it does boost efficiency quite a lot (although that's not the only source of efficiency from diesels -- a big part of it is that the engine is always running at its full compression ratio, and that would apply even if the CR was 7:1).

In checking those claims I noted that hydrogen has an octane equivalent of

130, but I couldn't find any data on how high you could practically run the CR with that octane rating. And the data I have on CR vs. efficiency is in a book that's buried here somewhere. So I didn't work it out.

-- Ed Huntress

Yes, and last time I drove there (June 07) I rented a turbo-diesel and it was a wonderful car. Fast, fairly powerful, and comfortable. Puegot 405 I also drove a different turbo-diesel in June 06 in Germany (World Cup) and it, too, was a great car (Opel Vectra wagon) Opel wagon got 32 mpg on the autobahn whilst going well over 140 mph.

The big problem here is that the manufacturers do not offer these types of cars in the USA. If they did, I at least, would buy them.

You may see it soon. The Europeans have designed their latest generation of diesels to meet US emissions standards, which are much higher for diesels than they are in Europe. The European manufacturers have bet on diesels to compete with the hybrids coming from Asia.

But they have a nasty legacy to overcome from two decades ago, when diesels flopped in the US. People have long memories and they carry bad impressions.

-- Ed Huntress

Somebody wrote this:: ...

I took the girl friend for a grand tour of Europe - camping overnight, around 1970. On the autobahnen, I was comfortable with 100 MPH in the E-Type (XKE), but grew resigned to being passed by a procession of Mercedes saloons going a uniform 120 mph, all day long....

Brian Whatcott Altus OK

I believe the people at MIT know what they are talking about and have more experience with it than yourself.

No offense intended Mr Huntress.

These people are getting better fuel economy with their own built devices:

No doubt about that. What the problem is that you guys have misunderstood and misrepresented what they said. What they said, if you read their white papers carefully, and not just read the press releases written by technical illiterates, is that there is a potential savings given the presumption of the use of certain anti-pollution devices. The "savings" refers to the reduced fuel cost of driving the heat-dependent converters.

That's all they said about fuel savings. But the illiterati have taken that "20% savings" and run amok with it, drawing conclusions that were neither in the MIT literature nor in the facts as they were presented. As a long-time technical writer and editor, I recognize the pattern, and it leads to a lot of gushy enthusiasms that are misplaced.

-- Ed Huntress

"Consumption data by the farmer"? "Before installation, 22 liters/hour, after installation, 6 liters/hour"?

Is this some kind of a joke? Do you have any documentation for any of this?

-- Ed Huntress