Experimental and simulation study on Fe-beta controlling of hydrocarbon emission during cold start of gasoline vehicle world light vehicle test cycle

Abstract

In order to address the extremely severe HC emissions during cold start of gasoline vehicles, a new HC trapping device was designed that can be installed in the aftertreatment system of the experimental gasoline vehicle in this study. This device has the same carrier as universal three-way catalytic converters (TWC), similar structure, and the HC trapping material was coated on the carrier of this device, the coating material used in this study was a new coating material, namely Fe-beta zeolite molecular sieve. Both vehicle experiments and molecular dynamics simulations were used in this study. The cold start experiments were carried out on the gasoline vehicle World Light Vehicle Test Cycle (WLTC). The experiments compared the differences in HC emissions from the exhaust gas of the gasoline vehicle with and without the HC trapping device. The experimental results showed that the installation of the HC trapping device significantly reduced HC emissions during the first 8 s of cold start, which was the worst phase of exhaust emissions from the gasoline vehicle. The peak value that occurred during this period was approximately tens of times greater than the peak value that occurred at later stages when HC emissions fluctuate. And the use of HC catcher resulted in a 62.34% reduction in the maximum peak value HC emissions. Then the molecular dynamics software Material studio was used to simulate the adsorption and diffusion of representative alkene molecules (butene, propene and ethene which measured from cold start test of experimental gasoline vehicle) on Fe-beta zeolite molecular sieves. The results showed that the adsorption effect was significant at low temperatures and the diffusion phenomenon was significant at high temperatures. When simulating the adsorption and diffusion of multi-component alkene molecules, there was a competitive relationship between various alkene molecules, which was greatly affected by the size of alkenes themselves. Ranking of the capture efficiency of three types of alkenes: butene > propene > ethene.