Possible HCCI breakthrough? Calling all oppo Mech. Enginerds!

"Future next gen S2000 owner" (future-next-gen-s2000-owner) 04/13/2016 at 12:42 • Filed to: HCCI, Enginerds

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An interesting article on HCCI engines and HCCI tech being advance. This could lead to more hp and more mpg’s. Let’s all have our cake and eat it too!

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For Sweden > Future next gen S2000 owner 04/13/2016 at 12:46

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When opportunity knocks...

RamblinRover Luxury-Yacht > For Sweden 04/13/2016 at 12:51

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Aaron M - MasoFiST > Future next gen S2000 owner 04/13/2016 at 12:52

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So basically there’s a new piston design that changes mix characteristics within the combustion chamber. Unanswered questions:

How long is that nipple going to last? There’s a reason most pistons are either flat or domed, and a big protrusion isn’t going to be wonderful. Also, while the effect on intake charge seems to be positive, how does it affect exhaust flow?

I don’t believe them for a second on the NOx thing. “My computer models say so” isn’t a good reason to believe you’ve mysteriously solved an issue that affects pretty much all high-temperature internal combustion engines, whether you’re burning coal, gasoline or natural gas.

RamblinRover Luxury-Yacht > Future next gen S2000 owner 04/13/2016 at 12:53

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Claims are too vivid -reminiscent of some of the claims around alternate construction engines. I remain skeptical - of these guys at least.

DrJohannVegas > Future next gen S2000 owner 04/13/2016 at 12:55

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HCCI is tough. Real tough. I’m gonna remain skeptical until I see some proper demonstration units and durability testing.

Future next gen S2000 owner > Aaron M - MasoFiST 04/13/2016 at 12:58

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I’ve learned through my personal experiences, computer modeling and simulation is the certified fastest way to hang yourself with a design. Your output is only as good as the user is.

But I am hopeful. Anything to move IC tech forward.

Future next gen S2000 owner > RamblinRover Luxury-Yacht 04/13/2016 at 12:58

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I am skeptical but hopeful as well.

Phyrxes once again has a wagon! > Future next gen S2000 owner 04/13/2016 at 12:59

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Is he wearing a tinfoil hat and bodyarmor to protect him from big oil too?

jariten1781 > Aaron M - MasoFiST 04/13/2016 at 13:00

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Can't read the article, but I thought the dealio with HCCI is that they'd theoretically run really lean and relatively low temp hence the low NOx. It was one of the big drivers to invest in maturing the technology as far as I understood.

Aaron M - MasoFiST > Future next gen S2000 owner 04/13/2016 at 13:01

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Ultimately, we’re a lot closer to the Carnot limit for ICs then we are to the chemical capacity of ion compounds to pick up electrical charge. Fast charging technology will progress more quickly than engine technology now that DI is mainstream.

Aaron M - MasoFiST > jariten1781 04/13/2016 at 13:07

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Leaner = higher charge temperatures. Generally increasing Carnot efficiency depends on higher temperature differentials to drive higher efficiencies, and HCCI is no different. It is theoretically possible that this engine is closer to perfect homogeneity from a fluid mechanics point of view, but the engineering threshold to make a computer model that will do that is much lower than making a working engine.

Future next gen S2000 owner > jariten1781 04/13/2016 at 13:08

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The main point of the article is this particular version of HCCI has a nipple on the piston which compresses at a higher rate into a cutout in the head. This higher compression chamber ignites first, initially drives the piston down, as the nipple comes out of the chamber, the flame spread to the rest of the combustion chamber.

It operates at a temp that is higher than the point where NOx is formed. That is the claim at least, with upwards of 50% thermal efficiency.

It is all modeling and simulation at this point with a physical engine due out this summer at some point.

jimz > Future next gen S2000 owner 04/13/2016 at 13:10

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this is going to be the key. one of the big headaches with HCCI is getting the air:fuel charge to burn and not detonate.

jimz > Aaron M - MasoFiST 04/13/2016 at 13:11

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complex piston crowns hold up just fine in diesel engines:

MrDakka > Future next gen S2000 owner 04/13/2016 at 13:12

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There was a saying at my old job, modeling and simulation are always wrong. :)

That said, I’ll be keeping my eye on this

jimz > jimz 04/13/2016 at 13:15

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stupid kinja edit function is broken:

Gone > Future next gen S2000 owner 04/13/2016 at 13:36

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It fits/functions/doesn’t interfere/can be assembled on the computer though!

Future next gen S2000 owner > Gone 04/13/2016 at 13:39

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Stupid real world not being perfect.

Khalbali > Future next gen S2000 owner 04/13/2016 at 14:24

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Mazda has been working on this for a while now, not sure if it's part of skyactiv 2.0 or further down the pipeline though.

jariten1781 > Aaron M - MasoFiST 04/13/2016 at 14:24

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Hrmm...bear with me, not an engine designer. Not really talking efficiency here, just the NOx part. How one of our guys explained HCCI/NOx to me was that conditions for NOx generation in both spark ignition and traditional compression ignition were almost completely generated at the high temperature flame fronts. With the homogenous mixture HCCI would get rid of the flame front having nearly simultaneous combustion. By selecting the correct fuels, mixing strategy, and controlling charge temperature via conditioning/heating it would allow relatively low combustion temperatures even in lean air:fuel conditions. Not that that sounds easy heh.

Aaron M - MasoFiST > jimz 04/13/2016 at 14:31

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Complex piston crown =/= solid metal protrusion going up into the combustion chamber.

Aaron M - MasoFiST > Future next gen S2000 owner 04/13/2016 at 14:32

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There is no temperature point higher than when NOx is formed, only a temperature point lower than when NOx is formed. NOx formation occurs when the temperature is so high it breaks down the covalent bonds of nitrogen in the air.

Future next gen S2000 owner > Aaron M - MasoFiST 04/13/2016 at 14:38

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You are correct. I typed that a bit wrong. His HCCI leans the mix which drives up temps above the NOx producing threshold. He claims NOx isn’t an issue with his design, according to his simulations.

Aaron M - MasoFiST > jariten1781 04/13/2016 at 14:41

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And this is where the computer model crack comes in. This is not a young problem, and this is not going to be the first guy claiming to have a computer model which solves the problem. You have to remember that a typical gas turbine is operating at over 2000 degrees F, producing way higher Carnot efficiencies than any reciprocating engine ever has, and still dealing with NOx. This guy is, in essence, saying “hey guys, I out-engineered GE by putting a nipple on it.”

Aaron M - MasoFiST > Future next gen S2000 owner 04/13/2016 at 14:44

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In theory a leaner mix could produce less NOx if the excess air levels were high enough to drive down combustion temps that way, but unless a miracle occurs that also decreases your ultimate efficiency.