Use this URL to cite or link to this record in EThOS:
Title: Diesel air-path mean-value modelling and charge properties under transient conditions
Author: Darlington, Alexander John Veale
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2007
Availability of Full Text:
Full text unavailable from EThOS.
Please contact the current institution’s library for further details.
Simple mean-value air-path models for modern diesel engines are in common use and have been reported in the literature. This thesis addresses several shortcomings in the models to improve the description of the cylinder charge properties during transient operation. During sudden increases in the demanded engine load, spikes are typically seen in both NOx and smoke emissions. The predicted cylinder charge properties during the transient are examined and compared with measurements of NOx and smoke. Together, the emissions data and charge properties paint a consistent picture of the phenomena occurring during the transient. Based on this analysis, alternative strategies for reducing emissions during load transients are developed. Experimental results show that spikes in both NOx and smoke can be avoided at the expense of some loss in torque response. Even if the torque response must be maintained, it is demonstrated that NOx spikes can still be eliminated. The air-path model is subsequently extended to include a throttle in the engine intake system. Based on this model, a feed-forward controller is designed to deliver the fastest possible reduction in the in-cylinder air-charge. This type of fast transient may be required to allow regeneration of Lean NOx Trap exhaust after-treatment systems. The performance of the model based controller is assessed experimentally using a completely novel sampling valve system to measure the in-cylinder gas properties on a cycle-by-cycle basis. When compared with a more conventional approach, the model based controller demonstrates a significantly faster change in the charge properties.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available