Browse Publications Technical Papers 2007-01-0324
2007-04-16

Development of an Intake Flow Based Model Calculating Real Time Exhaust Flow by Accounting for Filling and Emptying of the Engine Manifolds 2007-01-0324

According to the ISO 16183 [1] protocol for heavy-duty diesel engines, particulate matter can be determined using a partial flow dilution system (PFDS). In order to control a PFDS, it is necessary to know the exact exhaust gas mass flow rate at the sample probe of the system at any given time. For the purpose of operating a PFDS with online control, a transformation time for the entire system (exhaust mass flow determination and partial flow adjustment) of equal or less than 300 ms is specified. In order to minimize the dynamic requirements for the PFDS a fast determination of the exhaust flow rate is necessary, which can be achieved most easily by using the intake flows (air + fuel flow) into the engine.
This paper reports on the development and testing of an intake flow based model for calculating real time exhaust flow rate that accounts for the influence of the filling and emptying of the manifolds of a turbocharged diesel engine during dynamic operation. Depending on the necessary accuracy of the calculated exhaust flow, the influence of the engine manifolds, the importance of an accurate determination of the considered volumes and the influence of fast pressure, temperature and fuel flow measurement will be considered. Data will be presented to show the difference between the flow signal from intake flows, the exhaust flow from model corrected intake flow and the exhaust flow measured directly by an ultrasonic sensor system.
The influence in particulate matter (PM) results by controlling a partial flow PM sampler with different exhaust flow signals is estimated from soot and opacimetry data and verified from gravimetric PM results. Therefore tests were conducted using the intake flow, the model adjusted intake flow and a time delayed, model adjusted intake flow (which partially compensates for the transformation time of a direct measuring system) for calculating PM emission and controlling a PFDS.

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