4 ms·
Eventually, you'll run up against the limit defined by the Carnot efficiency. I wonder where this engine will stand in relation to that. Will they be able to bu
by theothermkn 9y ago
Eventually, you'll run up against the limit defined by the Carnot efficiency. I wonder where this engine will stand in relation to that. Will they be able to burn at a higher temperature in order to drive the raw efficiency up? Perhaps with a improved catalytic converter? Or are these all improvements in internal friction?
What does the technology actually look like? The article was frustratingly scant on details.
Ah. You can track down the video explanation: https://www.youtube.com/watch?v=N_No3KSaTrM https://www.youtube.com/watch?v=N_No3KSaTrM
Contrary to the appeal to the layperson's mechanical intuition in the video, they give away that they are apparently speeding combustion at the top of the stroke, resulting in a better approximation of "constant volume heat addition." This will result in a higher top temperature in the combustion chamber, and is the real reason for their "pushes longer and harder" explanation. This will come with added NOx production, so they'll have to have better catalytic conversion, with a couple caveats. It may be that the emissions rules are on a per-mile basis, so that the total NOx of the engine is lower per mile because less fuel is burned. They may also just be hitting markets with laxer restrictions.
- thibautg 9y agoThere was a nice explanation in an article from Ars Technica a few days ago: https://arstechnica.com/cars/2018/01/mazdas-skyactiv-x-shows-the-internal-combustion-engine-has-a-future/ https://arstechnica.com/cars/2018/01/mazdas-skyactiv-x-shows...
- aidenn0 9y agoThat's the Syactiv X which will not achieve 56%. This article is for the following generation (Skyactiv 3)
- IntronExon 9y agoIt’s probably simpler than that; “hopes” really means, “hasn’t yet, may never.”
- mastax 9y ago"Elon Musk hopes to launch Falcon Heavy in late 2012"
- tadfisher 9y agoFrom one explanation I've read [1], they actually maintain two AFR "zones" in the cylinder; one rich zone around the spark plug, with the rest of the cylinder maintained lean enough for compression ignition. Then by igniting the rich mixture via spark, little NOx and less heat is produced, while the remaining lean mixture probably producing negligent NOx as expansion occurs after TDC. If they can control it tightly enough, they can probably maintain the exact pressures and temperatures to just skirt under EPA/Euro requirements in a wide range of conditions, and switch to regular spark ignition outside of that range. [1]: http://www.enginelabs.com/news/mazdas-new-spark-controlled-compression-ignition-revealed/ http://www.enginelabs.com/news/mazdas-new-spark-controlled-c...
- credit_guy 9y agoCarnot efficiency = 1-Tcold/Thot. Tcold = room temperature ~ 300Kelvin. Thot ~ 1500 Celsius ~ 1800 Kelvin. So the theoretical Carnot efficiency is about 83%.