Scavenged Pre-Chamber on a Gas Engine for Light Duty Truck

Abstract

This work presents an experimental investigation of advanced combustion of extremely lean natural gas / air mixture in a gas fueled automotive engine with a scavenged pre-chamber. The pre-chamber, which was designed and manufactured in-house, is scavenged with natural gas and is installed into a modified cylinder head of a gas fueled engine for a light duty truck. For initial pre-chamber ignition tests and optimizations, the engine is modified into a single cylinder one. The pre-chamber is equipped with a spark plug, fuel supply and a miniature pressure transducer. This arrangement allows a simultaneous crank angle resolved pressure measurement in the pre-chamber and in the main combustion chamber and provides important validation data for computational fluid dynamics (CFD) simulations. The results of the tests and initial optimizations show that the pre-chamber engine is able to operate within a significantly wider range of mixture composition than the conventional spark ignition engine. Full load operation of the pre-chamber engine is feasible with stoichiometric mixture (compatible with a three-way catalyst), without excessive thermal loading of components. At low load operation, the results show low NOx emissions with a high potential to fulfil current and future NOx limits without lean NOx exhaust gas after-treatment. The scavenged pre-chamber helps to increase the combustion rate mainly in the initial phase of combustion. However, significant unburned hydrocarbons emissions due to incomplete combustion need further optimizations. Thermal efficiency of lean operation of the engine with the pre-chamber compared to the conventional spark ignition system operated in stoichiometric conditions shows approximately 13% improvement.

Application of Advanced Combustion Models in Internal Combustion Engines Based on 3-D CFD Les Approach

“…[6,7]. More detailed information about the Engine A can be found in [18,19]. The range of operating conditions related to data presented in the paper of the Engine A are summarized in Table 3.…”

“…On the other hand, the very lean operation (subfigures on the right side of Figure 3) is correct in only qualitatively -the reason is the fact that all the fuel is burned (in CFD calculation) while it is not the case for the target engine. More information can be found in [18,19,[21][22][23].…”