Linear Modeling, Simulation and Experimental Verification of a Pressure Regulator for CNG Injection Systems

• Published in: Journal of systemics, cybernetics and informatics Vol. 6; no. 4; pp. 36 - 41
• Main Authors: Dirk Hübner, Harald Ortwig
• Format: Journal Article
• Language: English
• Published: International Institute of Informatics and Cybernetics 01-08-2008
• ISSN: 1690-4524

The number of motor vehicles powered by internal combustion engines keeps growing despite shrinking oil reserves. As a result, compressed natural gas (CNG) is gaining currency as an emerging combustion engine fuel. To this day, CNG systems – e.g., in passenger cars – are not fully integrated into the development process as conducted by vehicle or engine manufacturers. Instead, they are usually "adapted in" at a downstream stage by small, specialized companies. The present paper initially outlines the state of the art in advanced gas injection technologies. Especially the development towards sequential injection systems is described. A pressure regulator for CNG driven combustion engines is examined in detail, given its role as a highly sensitive and critical system component. Based on a precise theoretical analysis, a linear model of this pressure regulator is derived and subjected to dynamic simulation. The analytical approach is accompanied by an experimental investigation of the device. On a test rig developed at the Trier University of Applied Sciences, the static and dynamic features of the pressure regulator can be measured with the requisite precision. The comparison of measured and simulated data yields a validation of the dynamic simulation model. With the approaches developed it is now possible for the first time to model, simulate and optimize single- or multi-stage pressure regulators for CNG driven engines with less effort and higher accuracy.