Quote:
Originally Posted by Isaac Zachary
So compared with what we've been doing, heating the fuel reduces fuel use by 50%? I'm sorry but that doesn't sound correct. For one, there's still not that much difference between spraying in fuel without heating it to 300°C and not heating it. Most of it evaporates already, which is why it's called "gasoline." And if fully evaporating all of it produced such great results, then fuels like natural gas should produce similar efficiencies when comparing energy to energy.
|
Modern engines burn pretty much all the fuel dispensed, within the power stroke. Simply vaporizing the fuel before it enters the engine does not gain you any additional efficiency unless your fuel system was primitive.
However, as mentioned in another Ecomodder Thread, HOW the fuel burns has tremendous room for improvement. The work that people such as Ivey and pfgPro have done show that there is room to improve thermal efficiency via the addition of energy to the fuel mix. Heating is just one variable. Tumble and swirl is another. Addition of oxidative or reactive elements or compounds is worth a closer look.
I mentioned the work by Transonic Combustion Technology because it does NOT make sense to most people on a simple precursory viewing. Their advertised gains are valid, however. Injection of gasoline heated to 300 degrees C while at 8000 psi puts it in a super-critical state whereas the fluid/gas has unusually high diffusion rate (something like three orders of magnitude greater than standard state) resulting in deep penetration into the combustion chamber BEFORE auto ignition can occur. When auto ignition does occur, the mixture is fully gaseous and HCCI (homogeneous charge compression ignition) comes into play. Their engine was tested by the Society of Automobile Engineers in Detroit and the fuel efficiency gains as well as the emission claims were validated and awards were given thus this technology is not snake oil. The engine ran as a throttle-less engine. Mazda's HCCI capable SkyActive engine can only use HCCI in a narrow band. The beauty of Transonic's Technology is the ability to run HCCI in the ENTIRE power band! The problem of their technology they were unable to overcome was that: a few psi extra pressure or a few degrees extra temperature and carbon would form. And not just soft fluffy carbon, but something akin to industrial diamonds. You can imagine the effect on injector longevity.
All this being said, the work of Ivey and pfgPro is sneaking up on the fabled Smokey Yunick Adiabatic Engine. From everything I can glean, his engine was on the threshold of HCCI combustion but, not quite. I think pfgPro's engine is leveraging the above discussed principles to approach the HCCI regime creating a faster burn than normal resulting in far less need for ignition lead time and wasted burn in the lagging portion of the power stroke. This is especially evident in the fact that when he is running 30:1 air/fuel ratios (AFR), his ignition lead is reasonable and his combustion stability is good.
Smokey used carburetors and eschewed electronics. pfgPro is leveraging modern electronic controls. We can see how advantageous that is. I think we can create a near HCCI engine that runs in a much broader range than Mazda's SkyActive system.