Title: Continuous regeneration of an electrically heated diesel particulate trap

Author(s): M. Arai, M. Saito, Y. Mitsuyama

Source: International Journal of Engine Research

Volume: 8 Number 5 Page: 477-486. November 2007

DOI: 10.1243/14680874JER01507

Publisher: Professional Engineering Publishing

Abstract: A wall-flow type diesel particulate trap using electrostatic field (E-DPT) was proposed to remove soot particles exhausted from diesel engines. This device was capable of trapping soot particles by electrostatic effect by applying a direct current electric field between two electro-plates separated by 1.5 mm. Soot trapped on the plates formed bridges of soot clusters in a narrow space between the electro-plates and it was burned by Joule heating owing to the direct electrification through the bridges. When the applied voltage to the E-DPT was lower than the critical value (Ep = 200 V), only the soot accumulation was observed. Its accumulation mechanism looked like a kind of electrostatic precipitator, and soot burning caused by the electrification through soot bridges was observed at higher applied voltages at 250-300 V. When soot accumulation and burning were balanced, a stable operation of E-DPT at 60-80 per cent removal efficiency was attained. An analysis of the experimental data on soot removal efficiency, power consumption, and heat balance during steady operation showed that the E-DPT developed is a potential system for practical application to actual diesel engines.

Title: Ion current combustion technology for controlled auto-ignition gasoline engines

Author(s): P. Attard, J. Micallef

Source: International Journal of Engine Research

Volume: 8 Number 5 Page: 429-437. September 2007

DOI: 10.1243/14680874JER03604

Publisher: Professional Engineering Publishing

Abstract: The use of ionization sensors, by means of a standard spark plug, in gasoline engines is well known. This paper focuses on the use of these sensors for controlled auto-ignition (CAI) gasoline engines, where the air-fuel mixture ignites without the need of a spark. The averaged ion current signals obtained are first observed and compared to the heat release rate and then a method to detect with accuracy the location of the 50 per cent mass fraction burned is described. The variation of emissions is studied and the effects of using a pressure sensor (to calculate the heat release rate) or an ion current sensor are portrayed. Thus it is proved possible to keep the emissions under strict control by using an ion current sensor.

Title: Artificial neural network as a predictive tool for emissions from heavy-duty diesel vehicles in Southern California

Author(s): N Hashemi, N N Clark

Source: International Journal of Engine Research

Volume: 8 No 4 Pages: 321-336. Aug 2007

DOI: 10.1243/14680874JER00807

Publisher: Professional Engineering Publishing

Abstract:
An artificial neural network (ANN) was trained on chassis dynamometer data and used to predict the oxides of nitrogen (NOx), carbon dioxide (CO2), hydrocarbons (HC), and carbon monoxide (CO) emitted from heavy-duty diesel vehicles. Axle speed, torque, their derivatives in different time steps, and two novel variables that defined speed variability over 150 seconds were defined as the inputs for the ANN. The novel variables were used to assist in predicting off-cycle emissions. Each species was considered individually as an output of the ANN. The ANN was trained on the Highway cycle and applied to the City/Suburban Heavy Vehicle Route (CSHVR) and Urban Dynamometer Driving Schedule (UDDS) with four different sets of inputs to predict the emissions for these vehicles. The research showed acceptable prediction results for the ANN, even for the one trained with only eight inputs of speed, torque, their first and second derivatives at one second, and two variables related to the speed pattern over the last 150 seconds. However, off-cycle operation (leading to high NOx emissions) was still difficult to model. The results showed an average accuracy of 0.97 for CO2, 0.89 for NOx, 0.70 for CO, and 0.48 for HC over the course of the CSHVR, Highway, and UDDS.

Title: Soot Wear in Diesel Engines

Author(s): E S Yamaguchi, M Untermann, S H Roby, P R Ryason, S W Yeh

Source: Proceedings of the I MECH E Part J Journal of Engineering Tribology

Volume: 220 No 5 Page: 463-469. Aug 2006

DOI: 10.1243/13506501J00505

Publisher: Professional Engineering Publishing

Abstract:
In response to regulatory requirements, lubricant manufacturers are seeking oils that minimize soot thickening and the accompanying soot wear. Formulation technology is being developed by additive manufacturers to satisfy these requirements. For example, such work is in progress at Chevron Oronite Company LLC, using the Cummins M-11 exhaust gas recirculation (EGR) engine test as a surrogate for the anticipated soot wear test for PC-10. Simultaneously, the authors developed bench tests to screen candidate formulations and reduce costs.

A ball-on-disc sliding wear test, using a PCS Instruments MTM® tribometer, has been investigated. Sliding conditions at high pressure are required for soot polishing wear. Conditions that correlate tribometer test results with M-11 engine results at high soot concentrations (~9 per cent) have been found. Both ball wear and Stribeck curves were determined in these tests. The high-wear oil progresses from mixed lubrication conditions to boundary lubrication at higher sliding speeds than the low-wear oil. X-ray photoelectron spectroscopy experiments were also conducted on the ball wear scars, revealing differences in the chemical constitution of the tribofilms from the two oils.

Title: Investigation of the impact of biodiesel fuelling on NOx emissions using an optical direct injection diesel engine

Author(s): A S Cheng, A Upatnieks, C J Mueller

Source: International Journal of Engine Research

Volume: 220 No 4 Pages: 297-318. Aug 2006

DOI: 10.1243/14680874JER05005

Publisher: Professional Engineering Publishing

Abstract:
The impact of biodiesel fuelling on NOx emissions was investigated using an optically accessible diesel engine. A soy-based biodiesel (B100) and three separate primary reference fuel (PRF) blends were evaluated over a range of loads at an engine speed of 800 r/min. Experimental operating conditions were carefully controlled to maintain a constant start of combustion (SOC), and a PRF blend was identified that would eliminate differences in premixed-burn fraction. A load-averaged NOx increase of ~10 per cent was observed for B100 relative to the PRF blend with matched premixed-burn fraction. The results indicate that factors other than SOC and premixed-burn fraction affect the tendency for biodiesel to increase NOx. Equilibrium calculations reveal no significant differences in stoichiometric adiabatic flame temperature between the test fuels; however, experimental data suggest that actual flame temperatures may be influenced by differences in soot radiative heat transfer. The effect of biodiesel on mixture stoichiometry at the lift-off length may also play an important role in increasing NOx emissions.

<<BACK TO PREVIOUS