It is certainly recognised that cavitation is an important factor when injecting diesel into the engine and the injectors are designed with this in mind.  The normal assumption is that it helps air/fuel mixing but there may well be more to it than that.

I think the arguments that there are significant potential gradients within cavitation bubbles as they collapse(e.g. https://link.springer.com/article/10.1134/1.567892) are pretty convincing, and the mechanism is essentially fluid independent, ie it is not dependent on the polarised nature of water molecules. It would therefore be present when cavitation bubbles in diesel collapse and may well be a factor in igniting the diesel.


Nigel

On 28/09/2017 18:41, JonesBeene wrote:

The history/science of efficient fuel combustion in the ICE is almost completely understood, right? Any previously unknown gain in efficiency would be a surprise. However, “cavitation” in the sense of a mechanism for a net energy gain –is one feature/parameter which is not well understood. Brian Ahern has been involved for years with a technology of simply adding HV electrons to a diesel, which sounds easy but in practice is not simple. Cavitation could improve that task.

In general when a gasoline powered ICE is converted from carburetion to manifold fuel injection, there is a 2-3% efficiency gain. And if converted to direct injection (GDI) like a diesel, then the efficiency gain is closer to 5%, regardless of any change in compression ratio. Therefore it is reasonable to suggest net gain is coming from the higher pressure cavitation of the injector in GDI. This could be optimized by even higher pressure injection (Mercedes has actually patented this process). If increased cavitation were to be combined with a source of HV electrons then the net gain could be forthcoming beyond any expectations.

To backtrack, the higher efficiency of diesel engines is normally considered to be related to increased compression ratio – and no doubt most of it is. Diesel fuel has slightly more energy content but that is negated by higher unburnt particulates. Higher compression ratio is the biggest contributor to diesel efficiency, but we need to ask: is cavitation responsible for any of the diesel efficiency gain? If so, can this finding be used with gasoline too? Can direct injection be used to add electrical charge (at the injector)?

In principle, it seems likely that cavitation bubbles would be an easier way to channel electrical charge into an engine since bubbles would protect against grounding. CES apparently demonstrate that ions are gainful, even with no net polarity imbalance, and their work may have implications for hydrocarbons. Given new findings about cavitation in general, it is possible that a part of the extra efficiency of the diesel configuration relates to cavitation, even using the standard diesel. This could be optimized for the GDI configuration (gasoline direct injection) once it is better understood. Moreover, since the cavitation route itself has been previously unrecognized as gainful in itself, there may be additional ways to make it even better (assuming it is gainful on its own accord).

In cavitation and sonoluminescence  the extra energy content  is said to relate to “bubble collapse” and shock waves - with the Casimir effect possibly entering into the mix. Nigel has suggested LENR possibly catalyzed by the neutrino flux. A “dense hydrogen” or hydrino route is also possible and Casimir+UDH would be a hybrid suggestion. This niche begs for more study since every 1% gain – when multiplied by several hundred million vehicle driven daily is likely to be worth about $10 billion to society yearly, not to mention less pollution. Even this week, a News story exposes the fact that most SUVs and light trucks are getting less than 20 mpg in the 2017 model year. That is unacceptable and way too low - we have been lulled into thinking gasoline will not surge in price soon, but it will.

Perhaps all of this will be made moot by the upcoming switch to battery powered hybrids. That could take years.

We seem to be way too complacent in not providing better fuel economy NOW, even if battery power arrives sooner than expected.


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