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!
Sideways To Victory!
