Future Diesel Engines May Run On.....Gasoline

I notice that the article claims this new engine is 50% efficient, and they hope to make it reach 60% efficiency. Do the engineering types on Priuschat think this might be possible?

 

50% is extraordinary!

Most gasoline ICE are not even 20% efficient.

Most of the energy goes out the tailpipe.

 

Will gasoline and diesel technologies fully converge?

 

Not to "50%" but by 50 percent. Before making a judgement, it makes sense to find the original paper. A Google search showed:

http://feerc.ornl.gov/pdfs/Bengt_Johansson.pdf

After looking at his charts:

• PPC reads like a variation of 'lean burn', which Honda pioneered.
• The 'lean burn' problem has been NO{x}, which he reports as solved.

To achieve such efficiencies, the combustion temperature must be very high and the exhaust temperature unusually low. Page 47 shows the exhaust temperatures and those numbers look 'too good.' I think we need to see independent verification of his results.

Here is another summary from a credible source:
Green Car Congress: Lund Team Shows 57% Thermodynamic Efficiency in a Gasoline-Fueled Heavy-Duty Diesel Engine Using PPC

The comments are worth reading as they pretty well span my thoughts. I've read other super-efficient engines only to find their efficiency exists only in a narrow power band. As for solving the NO{x} problem, well I'll have to make hardcopy and reread it in a quiet place.

FYI, this looks to be a better introduction to his work:
http://www.energy.lth.se/fileadmin/energivetenskaper/Avhandlingar/Gasoline_PPC_07062010.pdf

Bob Wilson

 

Definitely possible. Peak efficiency of a normally aspirated ice is theoretically 60% IIRC, but we don't get that close, getting to about 45% in the lab. If you then recover some of the exhaust energy with a turbo charger and use that to compress air in the engine the efficiancy can go higher. Idealy you would run a compression ignition, miller cycle engine, using a tubo chager instead of a supercharger. Volvo does have some 50% efficient turbo-diesel engines. These folks say they have hit 57% in the lab, and I believe there aren't any physical laws to stop that. The problem is giving it the reliability to run in a commercial truck, not just in the lab.

Efficient gasoline engines are using more and more of ice technology for diesels - cooled egr as seen on the gen III prius, direct injection, turbo charging.

This ice uses HCCI, which is quite different technology than diesel but achieves the same thing compression ignition instead of spark ignition. Compression ignition is more efficient in terms of thermal efficiency, but spark ignition allows for more hp/liter (physically smaller and lighter engines). For heavy trucks compression ignition is better, and if you can do it with gasoline then pollution control devices will be much less expensive.

 

That might not be such a bad thing if the engine is used as a range extender in a PHEV / EREV.....it can spend most of its time in that most efficient band, with the the battery/motor picking up the rest of the load.

 

A issue with HCCI implementation mentioned in one article was that it requires higher quality fuel than what is generally available in US pumps. So if this group's work pans out, it might not work in all regions.

Which is how I pictured the Volt working when the few initial details came out.
The A1 E-tron did work this way with its rotary engine. Some drivers were unhappy with the disconnect between road speed and engine speed though. Final test fleet models had 3 speeds the engine run can run at to better match its noise to what the driver expected.

 

This may indeed require a separate pump, but given how many gallons trucks use, that may not be a problem. The other sollution proposed is lng, which is more expensive infrastructure, but the key benefit of using 0% oil instead of 10% less. This gasoline engine should be more thermally efficient if they can get it out of the lab, and once trucks have paid for the technology R&D, and fuel pumps, it may trickle down into car engines.

volt and a1 e-tron were going for low cost, not efficiency. The bmw i8 (3cyl 1.5L turbo) is the first phev that really keys on the efficiency and battery pack. The ford energi and prius phv have very efficient engines in their phevs but really sized them for hybrid not phev applications.

In a truck based phev, a truck driver is not going to worry about ice noise, simply efficiency and acceleration. If you can do a PHEV with this engine that costs less to go the same miles (including maintenance and depreciation) and gives as good or better accelleration or breaking, then it will sell.

 

Most gasoline engines can reach 30%-35%, but operate far from that BMEP - rpm area.