Browse Topic: Emissions
This SAE Aerospace Information Report (AIR) describes a method for assessing size dependent particle losses in a sampling and measurement system of specified geometry utilizing the non-volatile Particulate Matter (nvPM) mass and number concentrations measured at the end of the sampling system.1 The penetration functions of the sampling and measurement system may be determined either by measurement or by analytic computational methods. Loss mechanisms including thermophoretic (which has a very weak size dependence) and size dependent losses are considered in this method2 along with the uncertainties due to both measurement error and the assumptions of the method. The results of this system loss assessment allow development of estimated correction factors for nvPM mass and number concentrations to account for the system losses facilitating estimation of the nvPM mass and number at the engine exhaust nozzle exit plane. As the particle losses are size dependent, the magnitude of correction
The automotive industry faces ongoing challenges in reducing vehicle mass and carbon emissions while ensuring structural integrity. Traditional design approaches often fail to address these issues comprehensively. This paper explores the application of generative design (GD) to optimize critical automotive components, specifically focusing on reducing mass and in turn carbon emissions. GD builds upon traditional topology optimization by employing iterative method using MELS approach to refine designs providing multiple alternative designs to choose from. MELS (Modified Extensible Lattice Sequence) specifically is used to equally spread-out points (designs) in a space by minimizing clumps and empty spaces. This property of MELS makes lattice sequences an excellent space filling DOE scheme. GD leverages the design of experiments (DOE) to vary key design variables systematically to generate and consider many potential design concepts for a given problem. It also uses artificial
Cu/zeolite selective catalytic reduction (SCR) catalysts are used globally to reduce NOx emissions from diesel engines. These catalysts can achieve high NOx conversion efficiency, and they are hydrothermally durable under real world diesel exhaust environments. However, Cu/zeolite catalysts are susceptible to sulfur poisoning and require some type of sulfur management even when used with ultra-low sulfur diesel (ULSD). In the present study, the authors seek to better illuminate the chemical processes responsible for ammonium sulfate formation and decomposition occurring in Cu/zeolite SCR catalysts. Reactor-based experiments are first conducted with a real-world concentration of SO2 (0.5 ppmv) and a typical diesel exhaust water vapor concentration (7 vol.%) to quantify progressive effects of ammonium sulfate formation. A second group of experiments probe the chemical decomposition of ammonium sulfate via NO titration. The “movement” of sulfate species during this process is monitored
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