Quote:
Originally Posted by RH77
I agree -- and have thought quite a bit about this.
We can make engines more efficient from a consumption standpoint, but emissions nevertheless increase. A catalytic converter and EGR setup are supposed to remove most of the NOx. Newer tech (although more expensive) could be implemented.
Too bad it's one or the other right now...
RH77
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You can limit NOx by running lower combustion temps, but that generally means low compression and no lean burn. The lean burn can be overcome with EGR (inert gasses limit combustion intensity, and therefore temperature). This technology is applied to Honda's new 2nd gen. L-series engines, more efficient and cleaner than the D15z1. Traditional catalysts won't work in a lean burn environment because they require HC and the absence of O2 to transform NOx into N2 and O2.
The only legitimate technlogies that I know of right now are NOx adsorbers and Urea injection. I'm sure other stuff is in the works.
- NOx adsorbers, as used on the Insight, are merely sponges that soak up NO during lean burn operation. The Insight either purges the adsorber by running rich momentarily or just through stoichiometric burn driving.
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- Urea is commonly used by truckers in Europe, but it requires the hassle of an extra fluid and is energy intensive to make. The production of ammonia (basic component of Urea), mainly for fertilizer, is one of the most energy intensive processes in the US as far as I know (Haber Process, I believe). Not good for the holistic hypermiler I guess...
For those who care about the environment, forsaking NOx for mileage may be a bad idea. NOx is photochemical smog (Los Angeles), and a stronger greenhouse gas than CO2. It is also toxic and triggers allergies in some people...really, driving a car is like urinating in your water supply. We humans so smart.
- LostCause