Theoretical study of the effect of speed, load and fuel injection timing on a heavy-duty dl diesel engine friction losses

Theodoros Zannis, Dimitrios Hountalas, Elias Yfantis, Roussos Papagiannakis, Ioannis Katsanis, Nikolaos Xenis

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

In the present study a novel detailed friction model was developed and used to examine the generation of instantaneous friction losses in a heavy-duty (HD) direct-injection (Dl) diesel engine. The developed friction model captures effectively the physical context behind frictional losses generation in piston rings, piston skirt, loaded bearings of connecting rod and crankshaft, valve train mechanism and engine auxiliaries. The newly developed friction model was incorporated into existing diesel engine diagnostic software and upon a comprehensive calibration procedure its predictive ability was evaluated against measured data at various engine speeds and loads. Having ensured that the developed friction model predicts with sufficient accuracy the cycle-averaged friction losses of the HD Dl diesel engine examined in this study, the friction model was used to assess the individual effect of engine speed and load on the instantaneous and cycle-averaged engine friction losses. The analysis of the predictions showed that the increase of engine speed results in the increase of the percentage contribution of piston rings and valve train to total mechanical losses whereas, results in reduction of the percentage contribution of loaded bearings to total friction losses and it has imperceptible influence on piston skirt and fuel injection system mechanical losses variation. The increase of engine load results in a considerable increase of the percentage contribution of piston rings to total mechanical losses whereas, results in reduction of the percentage contribution of piston skirt, loaded bearings and valve train mechanism to total friction losses. Finally, it was examined the effect of fuel injection timing (i.e. peak combustion pressure) on indicated, mechanical and brake efficiency at three different diesel engine operating conditions since the HD Dl diesel engine examined in this study has been manufactured for operating at elevated peak cylinder pressures. The most important conclusion come up from the analysis regarding peak cylinder pressure effect on diesel engine frictional losses is that the increase of brake efficiency of a HD Dl diesel engine through high advancement of fuel injection timing (i.e. increase of peak combustion pressure) is feasible up to a certain limit of peak cylinder pressure increase (in the present study up to 220 bar). For peak pressure values higher than the aforementioned limit either the invariance or the reduction of mechanical efficiency prevents the reflection of thermal efficiency increase to corresponding brake efficiency improvement.

Original languageEnglish
Title of host publicationProceedings of the 27th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2014
EditorsRon Zevenhoven
PublisherAabo Akademi University
ISBN (Electronic)9781634391344
Publication statusPublished - 2014
Externally publishedYes
Event27th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2014 - Turku, Finland
Duration: 15 Jun 201419 Jun 2014

Publication series

NameProceedings of the 27th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2014

Conference

Conference27th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2014
Country/TerritoryFinland
CityTurku
Period15/06/1419/06/14

Keywords

  • Crankcase assembly friction
  • Diesel efficiency
  • Friction losses
  • Piston assembly friction

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