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Generally an ICE engine has poor efficiency. Gasoline engines have about 25% efficiency. To increase the efficiency, you need to burn hotter (the ideal Carnot e

Generally an ICE engine has poor efficiency. Gasoline engines have about 25% efficiency. To increase the efficiency, you need to burn hotter (the ideal Carnot engine has an efficiency of 1- T-hot/T-cold; there’s not much you can do about T-cold -> it’s just the ambient temperature, so you need to increase T-hot). Diesel engines do just that; despite the fact they are further away from the ideal engine than their Otto cousins, they burn so much hotter that they have a much better efficiency (up to 45%). But now they have another problem: they burn so hot that they burn part of the nitrogen in the air. That produces nitrogen oxides. Popularly known ad Diselgate, or the Volkswagen emissions scandal. So with am ICE, you either have poor efficiency, or you produce NO_x pollution. Which one is it?

foxyv 5y ago
This is why modern diesels use DEF. It's just hot Urea solution that is sprayed through the diesel exhaust stream which reacts with the NOX after the first pass through the diesel oxidation catalyst. Urea and the nitrous oxide become nitrogen, water, and CO2. Hydrogen engines may need to use a DEF process like diesels eventually. Especially since hydrogen combustion is really good at making NOX. https://www.autoserviceprofessional.com/articles/7257-diesel-exhaust-fluid-fluid-injection-for-nox-reduction https://www.autoserviceprofessional.com/articles/7257-diesel... https://www.capitalremanexchange.com/20-facts-you-need-to-know-about-diesel-exhaust-fluid-def/ https://www.capitalremanexchange.com/20-facts-you-need-to-kn...