Assessment of Gas Injectors with the IAV Injection Analyzer pneumatic

摘要

The range of known oil deposits today amounts to only a fraction in comparison to the abundancy of natural gas deposits. With the increased exploration of shale gases, particularly in the United States via hydraulic fracturing or "fracking", the use of natural gas as a serious automotive fuel source is becoming more and more real. The use of natural gas in combustion engines has several advantages, one being the significant reduction in CO_2 emissions, by up to 20%, when compared to diesel or gasoline alone. Where natural gas injection is concerned, there are two main delivery methods for introducing the fuel source into an engine, direct or indirect. Indirect injection is conducted via the intake manifold, with gas pressures operating up to a range of 5bar. In this range, indirect gas injection is suitable for either gasoline or diesel engine configurations. Direct injection systems operating in pressure ranges of 20-30bar are currently under development and are applicable to both gasoline and diesel engines. For pressure ranges approaching 300bar, direct systems are currently available in today's market for diesel systems only. Here, the gas ignition is reliant on the diesel "jet" pre-ignition. Gas injection follows different thermodynamics when compared to fluid injection, and as such must be considered when developing the measuring techniques for analyzing and characterizing gas injectors. This article addresses the thermodynamic differences that exist between gaseous and liquid fuel injection and differentiates between the needs of the varying combustion types. The article also introduces IAV's Injection Analyzer Pneumatic, a highly accurate device that has been developed by IAV to characterize natural gas injectors for metrics such as injection rate and fuel quantity.