CFD analysis of combustion and emission characteristics of primary reference fuels: from transient Diesel spray to heavy-duty engine

The problem of designing robust and noise-insensitive proportional–integral (PI) controllers for pressure-sensor-based combustion-timing control was studied through simulation. Different primary reference fuels (PRF) and operating conditions were studied. The simulations were done using a physics-based, control-oriented model with an empirical ignition-delay correlation. It was found that the controllable region in between the zero-gain region for early injection timings and the misfire region for late injection timings is strongly PRF dependent. As a result, it was necessary to adjust intake temperature to compensate for the difference in fuel reactivity prior to the controller design. With adjusted intake temperature, PRF-dependent negative-temperature coefficient (NTC) behavior gave different system characteristics for the different fuels. The PI controller design was accomplished by solving the optimization problem of maximizing disturbance rejection and tracking performance subject to constraints on robustness and measurement-noise sensitivity. Optimal controller gains were found to be limited by the high system gain at late combustion timings and high-load conditions; furthermore, the measurement-noise sensitivity was found to be higher at the low-load operating points where the ignition delay is more sensitive to variations in load and intake conditions. The controller-gain restrictions were found to vary for the different PRFs; the optimal gains for higher PRFs were lower due to a higher system gain, whereas the measurement-noise sensitivity was found to be higher for lower PRFs.

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Study on fuel consumption and emission characteristics of China VI heavy duty vehicle based on vehicle specific power

E3S Web of Conferences ◽

10.1051/e3sconf/202126801055 ◽

2021 ◽

Vol 268 ◽

pp. 01055

Author(s):

Dandan Xu ◽

Zhongming Gao ◽

Yong Guo ◽

Yan Yan ◽

Fengbin Wang ◽

...

Keyword(s):

Fuel Consumption ◽

Specific Power ◽

Emission Characteristics ◽

Heavy Duty ◽

Emission Data ◽

Absolute Value ◽

Driving Time ◽

Heavy Duty Vehicle ◽

Measurement Results ◽

Pollutants Emission

This study selects a China VI heavy duty vehicle for PEMS test, and Based on the measurement results of vehicle specific power (VSP) parameters, the VSP calculation formula applicable to this study is proposed , And analyzes the distribution characteristics of VSP, and at the same time according to the fuel consumption and emission data of the actual road driving process collected by the vehicle, The effect of VSP on vehicle fuel consumption and emission characteristics and the correlation between the two are studied. Results show that VSP of the vehicle are mainly concentrated in the interval -10 ≤ VSP ≤ 10kw / t, in which the vehicle driving time accounts for about 99.3% of the total time; the correlation coefficient between VSP and average fuel consumption is about 0.93, there is a strong correlation; The changes of CO, CO2, NOX and PN with VSP all show as that under the same absolute value of VSP, the pollutants emission rate in the VSP> 0 interval is higher than the VSP <0 interval, in which the correlation between VSP and CO, CO2, PN emissions is more strong, but poorly correlated with NOX emissions.

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