A full transient three-dimensional study on the effect of pulsating exhaust flow under real running condition on the thermal and chemical behavior of closed-coupled catalyst

Jeong, Soo-Jin

doi:10.1016/j.ces.2014.06.011

Cited by 15 publications

(7 citation statements)

References 37 publications

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“…Benjamin et al (2002) and Persoons et al (2004) measured the velocity distribution within the catalyst systems. Jeong (2014) carried out a computational fluid dynamics (CFD) analysis to investigate the effect of exhaust gas pulsation on the thermal response and conversion performance of the catalytic converter. An important component is the oxygen sensor mounted in the exhaust manifold to detect the air/fuel mixture ratio.…”

Section: Introductionmentioning

confidence: 99%

Stereo and time-resolved PIV for measuring pulsatile exhaust flow from a motorized engine

Oki

Kuga

Ogata

et al. 2018

JFST

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The present experimental study deals with a pulsatile turbulent flow simulating the exhaust flow of an automotive engine. In the experiments, a four-cylinder engine is used as an exhaust-flow generator to realize flow conditions close to those in an engine environment. Particle image velocimetry (PIV) measurements visualize the flow field in an S-shaped double-bend duct at a Reynolds number of 48,000 and a Womersley number of 70.9. Stereo PIV, which is classified as a two-dimensional three-component measurement, is conducted in the duct cross sections located downstream of the bends. The stereo PIV system is synchronized with the engine operation to enable phase-locked measurements at particular phases, and the phase-averaged results show the large-scale vortical structures and the duct axial velocity distribution. Downstream of the first bend, the secondary flow consists of vortices that circulate as Dean-type vortices. Downstream of the second bend, by contrast, vortices that circulate in opposite directions to the Dean-type vortices, so-called Lyne-type vortices, form in the core of the cross section. These secondary flows persist without significant changes in their large-scale vortical structures over time. Time-resolved PIV is conducted to track the temporal evolution of the flow in the bend planes. The results show that the flow reverses locally along the inner wall of the bends during flow deceleration. Snapshot proper orthogonal decomposition (POD) is used on the time-resolved PIV data to extract the significant flow structure from the instantaneous field. We propose POD as a good post-processing tool for the instantaneous data of pulsatile cases.

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Section: Introductionmentioning

confidence: 99%

Stereo and time-resolved PIV for measuring pulsatile exhaust flow from a motorized engine

Oki

Kuga

Ogata

et al. 2018

JFST

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“…The first consists to bring the DOC or TWC more quickly to the activation temperature, using passive or active systems. These systems are − (a) electrically heated catalysts to provide a quick warm-up of the converter, (b) close-coupled catalysts (the converter is placed very close to the engine but the additional heat provided may deteriorate the catalyst with time); (c) a precatalyst, i.e., a small DOC more loaded with precious metals than the main one in order to provide an exotherm to lower the light-off temperature of the main DOC. The second and more promising solution consists in improving the design of the HC converter, by adding zeolitic materials, which act as an HC trap, to the washcoat …”

Section: Introductionmentioning

confidence: 99%

Impact of the Zeolite Structure and Acidity on the Adsorption of Unburnt Hydrocarbons Relevant to Cold Start Conditions

Westermann

Azambre

2016

J. Phys. Chem. C

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Adsorption behavior of commercial zeolites were investigated for the trapping of a hydrocarbon mixture (propene, toluene and decane) mimicking Diesel cold start exhausts under dry conditions. The studied commercial zeolites, in most cases under protonated form, (with Si/Al ratio in the range 2−15) present different structures: FAU, *BEA, MOR, MFI, FER, and LTA. Textural and structural characterizations were carried out using N 2 adsorption at −196 °C and X-ray diffraction. In situ FTIR spectroscopy of adsorbed pyridine was used to probe quantitatively the acid sites. The methodology used in this study consisted of an adsorption phase at 35 °C followed by temperature-programmed desorption (TPD) under He at 10 °C/min, and three different adsorption mechanisms were highlighted according to the pore size and the host framework. MOR and MFI structures appear to be the less selective for any type of hydrocarbon and are thus the most suitable for cold start applications. Except for these types of zeolites presenting a "single-file diffusion" mechanism, propene often desorbs at low temperatures or is adsorbed very little. By contrast, heavier hydrocarbons such as toluene and decane desorb at temperatures that match with threeway catalyst (TWC) or Diesel oxidation catalyst (DOC) light-off temperatures.

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“…Persoons et al (2006) measured the velocity distribution in the presence of reverse flow in a real exhaust manifold. Hwang et al (2007) and Jeong (2014) carried out a computational fluid dynamics (CFD) analysis to investigate flow uniformity in exhaust manifolds. However, most studies related to pulsatile exhaust flows have not considered the detailed flow characteristics, such as curvature-related secondary flow.…”

Section: Introductionmentioning

confidence: 99%

Experimental and numerical investigation of a pulsatile flow field in an S-shaped exhaust pipe of an automotive engine

Oki

Ikeguchi

Ogata

et al. 2017

JFST

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A pulsatile turbulent flow within an S-shaped double bend pipe is experimentally and numerically studied to characterize the flow field in conditions resembling an automotive engine environment. Particle image velocimetry (PIV) measurements were carried out to measure streamwise and secondary flow velocities. The flows are accelerated around the inner side walls of both bends. The secondary flow, after passing through the second bend, is directed toward the inner side in the core of the cross section, and, as a result, Lyne-type vortices, which are not consistent with the second bend curvature, are formed. A numerical simulation is performed under the same condition as the experiments with computational fluid dynamics software. The numerical simulation gives qualitative results in comparison with the experimental data though there is some deviation, and shows the cause of the Lyne-type vortex formation in the second bend. After passing through the first bend, the high-speed region appearing around the inner side shifts in accordance with the Dean-type secondary flow formed in the first bend, and thus the non-uniform flow enters the second bend. In the second bend, the low-velocity region in which the centrifugal force is not strong enough to direct the flow toward the outer side, appears in the core of the cross section. Details of the Lyne-type vortex formation are discussed by considering the driving forces of the secondary flow.

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A full transient three-dimensional study on the effect of pulsating exhaust flow under real running condition on the thermal and chemical behavior of closed-coupled catalyst

Cited by 15 publications

References 37 publications

Stereo and time-resolved PIV for measuring pulsatile exhaust flow from a motorized engine

Stereo and time-resolved PIV for measuring pulsatile exhaust flow from a motorized engine

Impact of the Zeolite Structure and Acidity on the Adsorption of Unburnt Hydrocarbons Relevant to Cold Start Conditions

Experimental and numerical investigation of a pulsatile flow field in an S-shaped exhaust pipe of an automotive engine

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