LiquidPiston rotary, claims 75% thermal efficiency. The next quasiturbine?

[dalcazar]

[URL unfurl="true"]http://www.gizmag.com/liquidpistol-rotary/24623/[/url]

I couldn't find any previous mention of this on here, it seems to be brand new news. What do you think, bull or not? I'm inclined towards bull. I haven't done thermodynamics in so long that the charts don't mean much to me anymore.

There are a few things I don't like about it, they talk about over-expansion (which to me says creation of a vacuum) and somehow think that moving the apex seals from the rotor to the housing makes a difference in the need for lubrication. It almost seems like this thing is a scam for dumb investors, but I could be wrong (I really hope I am).

 

[GregLocock]

Over expanded is a term used in Atkinson style motors, it basically means you run a very long exhaust duration compared with intake, this can boost efficiency but hurts bmep. the PV loops in the article look like 50% efficiency not 75.





Cheers

Greg Locock


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[BigClive]

GL - I would have thought that you would have very long intake duration - not exhaust? The intake opening at the normal point but closing very late so a lot of the air/fuel mixture is pushed back out of the cylinder - LIVC style.

The new engine probably is an attempt at another scam.

 

[hydroman247]

This seems too good to be true.

I saw this posted on Reddit in the engineering section and it got an iffy appraisal by members there. Will still keep an eye on it, but it would be good if they showed a full working diagram.

 

[Marquis]

Bit worrying. Lets break it down:

"The truth is that if you had both engines at the same compression ratio, the spark-ignited engine has a faster combustion process and a more efficient process. In practice, it’s limited to a lower compression ratio otherwise you get spontaneous ignition.”

It is true that a spark ignition typically has a very fast 10-90 burn duration compared to a diffusion flame combustion engine but the diesel engine combustion is usually intentionally slowed down by the use of pilots for NVH reasons and the effect this has on efficiency isn't that high.
What has been totally avoided is the biggest reason for diesel engines efficiency over petrol- the fact that the diesel engine doesn't need to be throttled- lower pumping losses.

"The internal combustion engine (ICE) has had a remarkably successful century and a half. Unfortunately, it’s notoriously inefficient, wasting anywhere from 30 to 99 percent of the energy it produces and spewing unburned fuel into the air"

Absolutely not true- 'combustion efficiency' is often used as a measure of how completely an engine burns by post processing the CO, CO2, HC and Nox emissions and looking at how much fuel was injected. Modern emissions compliant engines all fall to 99.9% with no exceptions or else they wouldn't meet emissions regulations. I've seen an engine achieve only in the low to mid nineties in the laboratory and these are gross poluters that belch out black smoke. Energy is lost in terms of sound and heat but this isn't unburned fuel. This makes the subsequent arguments lose credibility.


"In this way, all the fuel is burned and almost all of the energy released is captured as work. Shkolnik calls this use of constant volume combustion “the holy grail of automotive engineering.”

Constant volume combustion is definately beneficial but to selectively focus on this aspect...

The Ecomotors OPOC engine achieves or approaches constant volume combustion because of the crank/piston motion kinematics but it doesnt achieve anywhere near this kind of 75% Break thermal efficiency.It also has a longer expansion stroke than the compression.

His cycle analysis is a good start but assumes adiabatic efficiency and is very accademic. Even INDICATED Thermal efficiencies must factor in heat losses. This is where the poor surface to volume ratio of the rotary engine will certainly be a hurdle.

Nope- this is a parallel, I'm finding- start ups often have very opinionated very accademic head strong people.

Its no different to Lemke of Achates Power claiming ring less piston operation for engines is the future and claiming ultra low friction due to loss of valvetrain while totally ignoring another set of pistons , a savagely long stroke and another crank, or Hofbauer claiming 100mpg for his engine when mounted in a vehicle.
These claims will be what enables generous funding from venture capitalist companies. Down the line the seasoned and really experienced engineers will be employed by these start ups- the claims will become more realistic. The original accademic CEO will usually do the dignified thing and take a supporting role if his ego allows it and a deal may be struck with an OEM. Either that or the no measured results will come anywhere near to the original claims and the funding will stop!

http://www.auto-scape.com

Sideways To Victory!

 

[dicer]

So where is the dynamometer print out and fuel consumption figures? Just more fancy CAD designs, and nothing in hard metal that is running, nothing that really runs or works. Just someones dream in animation. And pictures.