engleski

Numerical Investigation of Influence of Injection Timing and Knock on Dual Fuel Engine

Compressed natural gas (CNG) can be used in diesel engine with great benefits, but because of its low reactivity it is usually used in a so called Dual Fuel combustion (DF). Optimal parameters for DF engines are not yet investigated thoroughly which is the motivation for this work. The main objective of the investigation is to show the influence of different injection timings and influence of knock phenomena on characteristics of port injected DF engine. The introduction of CNG into the intake port of diesel engine usually results with some CNG slipping into the exhaust port due to valve overlap. By analysing the simulation results, the injection strategy that significantly decreases the CNG slip is defined. The study of knock occurrence showed the highest allowed compression ratio that will result in knock free operation of the presented engine. It has been shown that for ambient conditions at the intake port the compression ratio of 18 could be used, while in charged conditions the compression ratio should be lowered to 16. The research was performed numerically by using a cycle simulation tool (AVL Boost v2013).

Dual Fuel ; Injection timing ; Knock ; CNG ; Methane

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