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But why are we discussing HHO without first challenging the "35-50% more efficient than gasoline engine" claim? Can we ask for specific reasons why this is possible with Scorpion? What are the energies involved in dissociation and recombination and how does it help up the efficiency THAT much? Or it is just a claim without substantiation, that has got a discussion jump-started here?
Diesel direct injection combustion is pretty complicated, and I don't understand it fully. The fuel starts to burn up as it exits the injector nozzle after a short ignition delay. So there's tiny burning fuel droplets swirling in the piston's bowl. When you add propane, which is injected upstream in the intake, you get an additional homogeneous mixture adding a whole new dimension to the combustion.
Diesels have injection throughout the powerstroke, the way I understand it, which is why they have so much more available torque. The "combustion" as it were, never occurs at one solid point in the piston's travel, only the ignition part of it.
In a properly tuned diesel, the AF ratio at almost any given moment (not counting moments before or after the one you're looking at) is lean. The overall combustion process, when measured on the exhaust stroke, shows "not-so-lean", but probably still not stoich.
IOW - Since the fuel is injected throughout the power stroke, from TDC to BDC (not really, but bare with me), and there is (let's say) 1L of air in the cylinder, considering stoich to be 15:1 (for easier figuring), there are now 1000mL of air, and to create a stoich mixture, you'd need 66.67mL of fuel.
So, now you take that 66.67mL of fuel, and inject it over the 90* of power stroke, and you end up with a mixture that starts out extremely lean, and as it burns up the air, it becomes less lean.
Assuming that fuel is injected from TDC to BDC (90*, but it's really not), that would be 66.7/90 = .75mL of fuel injected per degree of crankshaft rotation.
This results in the first degree of crankshaft rotation having a 750:1 AF ratio, and each subsequent degree being closer to stoich mixture, until the "total burn" AF ratio has become 15:1, as measured by the exhaust gasses.
Someone, please correct me if I'm wrong about this!
But why are we discussing HHO without first challenging the "35-50% more efficient than gasoline engine" claim? Can we ask for specific reasons why this is possible with Scorpion? What are the energies involved in dissociation and recombination and how does it help up the efficiency THAT much? Or it is just a claim without substantiation, that has got a discussion jump-started here?
I think it's best to wait and see if the Scorpion makes it to market. We need to see someone driving it around and see what they say. It seems like their gizmo is way different than the homemade stuff. I think they are claiming that they are displacing 30%-40% of the gasoline fuel. This is a "supercar" implementation, i.e. Tesla for HHO. It wouldn't be cost-effective for the rest of us.
Christ, that is right. It's not a bang, it's a burn throughout injection. Although generally the injection duration is only a couple crank angles. The more fuel you want to inject the longer the injection duration will be, as injection pressure and nozzle orifice size are fixed. That's why people end up putting larger nozzles to make more power, since they want all their fuel injected as close to TDC as possible, because late injection is inefficient and finish burning down in the exhaust (that's how the new CR TDI does it to burn off the DPF, late injection events, as the CR system has the capability to manage multiple injections events per cycle). I don't really see how varying AF ratio is relevant to the discussion though.
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