Browse Publications Technical Papers 2007-01-0180
2007-04-16

Improving the NOX-CO2 Trade-Off of an HCCI Engine Using a Multi-Hole Injector 2007-01-0180

The combustion and emission performance of two high-pressure GDI-type injectors are compared in an automotive HCCI engine during low-load, stratified operation. One of these, an 8-hole injector with 70° spray angle, provides significant reduction in NOX emissions at a given fuel-to-CO2 conversion efficiency (i.e., an improved NOX-CO2 trade-off) compared to the other, a 53° swirl injector. In contrast, attempts to enhance the NOX-CO2 trade-off using alternate charge-stratification strategies such as split injection and high intake velocity are shown to be less successful.
The 8-hole and swirl injectors are also compared using the optical techniques of Mie scattering (spray visualization), laser-induced fluorescence imaging (fuel distribution measurement), and direct combustion imaging. The resulting data suggest two possible explanations for the superior performance of the 8-hole injector. First, some fuel leaving the swirl injector at the end of injection burns as a liquid, likely contributing to NOX emissions. In contrast, no liquid burning is apparent with the 8-hole injector. Second, fuel distributions measured by fluorescence imaging show that probability density function (PDF) statistics of equivalence-ratio distribution are similar for the two injectors, but the 8-hole injector produces smaller and more numerous fuel packets that could lead to lower local peak gas temperatures and therefore lower NOX emissions.

SAE MOBILUS

Subscribers can view annotate, and download all of SAE's content. Learn More »

Access SAE MOBILUS »

Members save up to 43% off list price.
Login to see discount.
Special Offer: With TechSelect, you decide what SAE Technical Papers you need, when you need them, and how much you want to pay.
X