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Researchers Find That Fuel Line Electrorheological Device Can Boost Fuel Economy

Fuel flows through two metallic meshes before it reaches the fuel injector. A voltage is applied on the two meshes to produce an electric field of about 1 kV/mm between them. Click to enlarge. Credit: ACS.

Researchers at Temple University in Pennsylvania have developed a small electrorheological device that, when inserted into the fuel line near the fuel injector, can improve fuel economy. In tests results reported in a study scheduled for the 19 November issue of the journal Energy & Fuels, they show an 18.8% increase in fuel mileage in a Mercedes-Benz diesel sedan in highway driving.

The device developed by Rongjia Tao and colleagues creates an electric field that reduces fuel viscosity, enabling the injection of smaller droplets into the engine, which, in turn, leads to more efficient and cleaner combustion than a standard fuel injector. Six months of road testing in a diesel car showed that the device increased highway fuel from 32 mpg to 38 mpg.

Because combustion starts at the interface between fuel and air and most harmful emissions are coming from incomplete burning, reducing the size of fuel droplets would increase the total surface area to start burning, leading to a cleaner and more efficient engine. This concept has been widely accepted because the discussions about the future engine for efficient and clean combustion are focused on ultra-dilute mixtures at extremely high pressure to produce much finer mist of fuel for combustion.

Here, we present our technology for efficient combustion based on the new physics principle that proper application of electrorheology can reduce the viscosity of petroleum fuels. A small device is thus introduced, producing a strong electric field to reduce the viscosity of petroleum fuels just before the fuel atomization. This viscosity reduction leads to much smaller fuel droplets and cleaner and more efficient combustion. Our device could be easily applied on current engines to improve their efficiency.

—Tao et al. (2008)

With the device, fuel flows through two metallic meshes before it reaches the fuel injector. A voltage is applied on the two meshes to produce an electric field of around 1.0 kV/mm between the two meshes. The device consumes very low electric power, lower than 0.1 W. Proper application of electrorheology or magnetorheology can reduce the viscosity of liquid suspensions.

Using the mismatch in the dielectric constant or magnetic permeability between the suspended particles and the base liquid, we can apply an electric or magnetic field to aggregate the small particles into large ones. Normally, we aggregate nanoscale or submicrometer particles into micrometer particles...The experiment with crude oil has found that this reduction can be quite significant.

...we extend the above physics principle to refinery fuels. In fact, refinery fuels, such as diesel fuel and gasoline, are made of many different molecules. They can be regarded as liquid suspensions if we take the large molecules as suspended particles, and the base liquid is made of small molecules. Under a strong electric field, the induced dipolar interaction makes the large molecules aggregate into small clusters. Similarly, this change reduces the effective viscosity of refinery fuels.

—Tao et al. (2008)

Size distribution of diesel fuel following atomization with or without an applied electric field. Click to enlarge. Credit: ACS

Applying this principle to diesel fuel, the researchers found that after application of an electric field of 1 kV/mm, the viscosity of the diesel oil was reduced by about 9%, from 4.6 to 4.18 cP. They then simulated the injection of both diesel and an E20 gasoline blend fuel into cylinders using an Accel injector and collecting the droplets on a plate. While both fuels showed good repeatable results, the results with diesel were particularly strong.

Applied to a Mercedes-Benz 300D sedan for 6 months of road testing, the device improved highway mileage by 18.8%; in city driving, the improvement was 12-15%. For the Mercedes application, the two mesh electrodes were separated by 1 cm. The diesel fuel took 5 s to pass through the 1 kV/mm electric field.

Because our technology, developed on the new physics principle, consumes very small power and improves fuel efficiency significantly, we expect it will have wide applications on all types of internal combustion engines, present ones and future ones. By adjusting the values for the electric field and time duration, we could make this technology work effectively for other fuels, such as biodiesel, kerosene, and gasoline.

—Tao et al. (2008)


  • R. Tao, K. Huang, H. Tang, and D. Bell (2008) Electrorheology Leads to Efficient Combustion. ASAP Energy Fuels, doi: 10.1021/ef8004898



The physics of this technique make a lot of sense. As long as we are going to be cavemen and get our power from burning things, might as well be high tech about it until we advance to getting energy from "non burning" sources.


That has to be a pretty clunky (and smokey) old engine to be able to benefit to the tune of 18.8% just from better atomisation.


This kind of device sounds like it could be after-market as well as new car. Can we believe the claims across a wide variety of injection engines (gas included)? If even 10% average improvement, it would be huge as the device would seem to be relatively inexpensive to make.


This kind of device sounds like it could be after-market as well as new car. Can we believe the claims across a wide variety of injection engines (gas included)? If even 10% average improvement, it would be huge as the device would seem to be relatively inexpensive to make.

Some Jerk

Old MBZ diesels have terrible atomization stock, as the fuel is being delivered by low pressure injectors driven by a rotary pump. I don't think this device would have nearly the effect on a fuel injected gas engine, and probably the atomization on newer common rail diesels is as fine as you can get.

But still, don't underestimate the number of old diesels out there. Every semi, bus and ship could potentially benefit from better atomization. Not to mention all those dirty old EU diesel cars, and the even older and dirtier ones they've exported to the third world...those things run forever. Reducing CO2 and PM in one cheap easily retrofitted stroke? Could be big.


It might not have better performance than a modern high pressure injectors, but will be cheaper and so have a large market opportunity in places like India


Sounds like snake oil. I hope it works.

Why not just heat up the fuel well above the boiling point and inject it as gas? That would be atomization at is best.


Agreed that this smells like snake oil.

The testing methodology just isn't scientific. Road tests? Oh jeez. The only way you could verify increse in mileage is to put the same car throught he same controlled lab tests with both the device and without. Just the fact that the driver doing the road tests knows that this device installed could easily account for the increase in mileage due to subconscious changes in driving patterns.

Now the concept makes sense on old-fashioned diesels, and if it really does increase mileage by even 5%, it could be a cheap and useful retrofit for older trucks. But I wouldn't hold your breath until some valid study is done.


Whatever happened to the scientific method when testing? Road tests aren't valid, this needs to be done in a lab. Changes (subconscious) in driver behaviour due to knowledge of the device being installed, plus the hundreds of other possible variables make me call BS on this. Real studies are needed.

That said, the concept itself seems logical. If it does actually work, even saving 5% fuel burn, it could be a cheap retrofit to older diesel trucks.


Computer controlled dynamometer tests with the same vehicles before and after the installation might be more convincing. The same set of cars either do or do not perform more efficiently under consistent identical tests.

Fuel atomization sounds like a good idea, but I am not sure that this is achieving the results that they say it does. It seems something like the electrolyze water to H2 and O2 schemes. It makes inefficient vehicles improve a bit, but so would a good tune up. When you tune them up the improvements due to the add on devices go away.

Bill Young

When can we expect the ads in the back of Popular Science and the half-hour infomercials?



I wonder if you get similar effect if you add detergent to the fuel. Detergent reduce surface tension.
So it might be passable to improve fuel atomization in such way.


I know some people who can do a tune up by dangling a crystal above a number plate.
OR doctoring from holding hands near the phone.
We had a famous race and rally driver promoting an energy aligning device (Needs initializing using the palms method by qualified practitioner) that attaches around the fuel line and gives more power and reduces fuel consumption when its not reducing emissions.
And many others.
So all these negative posters - the point is 'Anything' is possible.


Gas mileage is an important issue, one of the ways I have been saving money at the gas pump is with Bishop's Original- it increased my mpg by 15%.

Jim K

Holy crap! Are we talking about cow magnets taped to the fuel line?? Its been done already. It don't work


They probably did use an old Mercedes-Benz with poor atomization for testing and newer common rail system would not benefit as much. But I have to wonder how many diesel ships and locomotives would benefit from this. A 12% to 15% improvement in fuel efficiency for a ship is huge and would quickly be profitable to implement.


Is the only criteria for inclusion on this web site, that it is not yet exposed by

P Schager

Uhm, if you heat the fuel or add any of a zillion additives, you can also reduce the viscosity. Hate to spoil the excitement, but viscosity has been played with endlessly in the adaptation of SVO; it has to be sufficiently low for the engine (they typically get to within a factor of 3 of standard diesel) and beyond that if low viscosity made a world of difference on diesel efficiency we would have all heard about it. The authors dismiss additives as being inordinately expensive. You can use shorter hydrocarbon chains and alcohols--which are about the same price as diesel fuel.

Further, if incomplete combustion was leaving 19% economy on the table before this mod, you would be seeing ungodly plumes of smoke coming out of the engine. If combustion was too slow, engineers would have advanced the timing (or you'd have heard about a huge efficiency fall-off with high RPM, and fixes for that). High-pressure common rails would be discussed in the literature for fuel efficiency first, not emissions abatement.

The author dismisses high-pressure as unavailable technology--that is true of gasoline only, where it is hard to see how you can benefit. Normally there is plenty of time for gasoline fuel droplets to completely vaporize, or they would be going back to carburettors.

Also odd (back to diesel) is that the researchers are very impressed by their data which show a big boost in very small droplets, the end of the scale where I don't think there's a problem, but don't even mention that their own chart shows an increase in the larger droplets, which you'd think would be a bigger risk of incomplete combustion and particulate formation.

Small droplets aren't a panacea. They also mean that air drag will stop them before they get very far, so they'll cluster around the injector in a small cloud and produce an oxygen-poor zone. Which is why the high-pressure common rail guys need so much pressure and also have gone to multiple orifice injectors as part of the design.

I'd put my money on charged injectors (which the authors dismiss as impractical) with the voltage adjusted for conditions, maybe with an injection-cycle waveform. And then only for widening the spectrum of fuels that work well while still giving optimum emissions. Except that I don't think the engine makers care. That's a free-world public-interest versus Big Oil issue. which the lawyers in Washington don't understand.


The Mercedes 300D was last produced in 1993. So as some posters suggested, this probably only has an effect on very old diesels.


It seems like they should have ran a test with uncharged mesh screens in the fuel line. Couldn't the drag produced by these screens just being in the line have effects on the performance of the engine (although I would have assumed poorer performance)?


Reminds me of something oil companies did to prevent waxing. Anyway, they need to at least put it on a dyno and measure fuel consumption at different loads...


Why do these miracle devices always test on old s-boxes?
The average 15 year old Merc could see it's efficiency go up by double digits with a normal service (fluids, filters, air pressure and initial injection timing).
Testing over 6 months just brings in a number of other variables, such as temperature, fuel blends, traffic density, etc.

Given the results they claim, which would save shipping fleets millions upon millions of dollars (and let them retire filthy rich just as soon as the patent application clears), you would think that they would be willing to borrow a modern car and rent a dyno for a few hours...

Don't they teach any scientific methodology at Temple University?

Roger Pham

Thanks, P Schager, for many good points.

Indeed, with the low-pressure old dielsel injector, the smaller droplets will not have enough velocity to penetrate the thick compressed air in large-bore truck engines sufficiently to promote good combustion. Larger droplets have more penetration at lower velocity, due to the lower surface to mass ratio.

Until they have tested this device in larger truck diesel engines, their claim of efficiency gain will not be of significance.


Alas, this idea won't work with a modern gasoline engine. The reason is simple: modern gasoline engines already have fuel injectors that atomize the fuel very finely, so adding this device won't provide any more improvements in fuel atomization.

Henry Gibson

You might be able to retrofit such a unit into standard carburetors for finer spray. It is best to put an engine on a test block and generate a known amount of power over a period of hours with and without the device in operation. It is very easy to increase mileage in a car by careful control so driving is not the way to test such a device. Almost every modern car could be programmed to limit acceleration and speed to give substantial mileage increse. ..HG..

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