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2 Journal of KONES

2 2006

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Influence of burn profile on the precision of 1-d engine cycle simulation

100%

Mendera K. Z. , Smereka M.

2006

tom Vol. 13, No. 2

305-314

Mass fraction burned and cumulative heat (gross and net) release curves, presenting the integrated heat release, are thought to be the approximations of the heat added to the working medium during engine cycle throughout the combustion process. Three procedures of burn profile determination are described and their specific assumptions are pointed out. These methods were applied to the cylinder pressure traces and suitable burn profiles were computed. The curves of cumulative heat release (R-W, gross and net) versus crank angle, normalized to unity, were entered to 1D Ricardo WAVE code as the user-defined cumulative burn rate profiles. The simulation results were compared and critically evaluated. Pressure traces of consecutive engine cycles and their indicate, indicated mean effective pressures are presented. Burn profiles of consecutive engine cycles, burn profiles adopted for simulation, comparison of measured and computed pressure and temperature traces, P-V diagrams of measured and simulated engine cycles exemplify results of research work.

Analysis of combustion processes in ci engine fuelled either with diesel fuel or rape oil methyl ester and additionally with ethanol

84%

Kowalewicz A.

2006

tom Vol. 13, No. 2

225-240

At the conference KONES’2005 combustion characteristics of CI engine fuelled with rape oil methyl ester (RME) and ethanol injected into inlet port have been presented. In this paper combustion processes in the engine fuelled with two base fuels: diesel oil (DF) or rapeseed oil methyl ester and additionally with ethanol have been analyzed and combustion parameters have been compared. Ethanol fraction has a serious influence on combustion. Addition of ethanol delays combustion in the initial stage but despite of that, combustion is completed earlier if the ethanol fraction is higher. This phenomenon takes place for both base fuels: RME and DF. However, for high speed (2200 rpm) and torque = 20 Nm (pe= 0,256 MPa) ignition delay of DF was so long, that ignition took place 15 CA deg ATDC. Nevertheless of that, combustion was completed only about 5 CA deg later than for neat DF. Combustion processes for both fuels are similar, but there are some differences in ignition delay. At low load and high speed for fuelling with DF combustion extends for exhaust stoke. On account on diesel – knock the engine can not be loaded by higher torque at high speed. Besides ethanol fraction, there is a strong influence of load and speed on combustion parameters. Generally increase of speed decreases maximum pressure and increase of load increases it, as well for RME as for DF. The highest pressure has been measured for DF and ethanol injection.