SI2-3: Development and Application of Gasoline/EtOH Combustion Mechanism : Modeling of Direct Injection Ethanol Boosted Gasoline Engine(SI: Spark-Ignition Engine Combustion,General Session Papers)

The changes in thermal state, emissions and fuel economy of a 1.0-L, three-cylinder direct injection spark ignition engine when a cylinder is deactivated have been explored experimentally. Cylinder deactivation improved engine fuel economy by up to 15% at light engine loads by reducing pumping work, raising indicated thermal efficiency and raising combustion efficiency. Penalties included an increase in NOx emissions and small increases in rubbing friction and gas work losses of the deactivated cylinder. The cyclic pressure variation in the deactivated cylinder falls rapidly after deactivation through blow-by and heat transfer losses. After around seven cycles, the motoring loss is ~2 J/cycle. Engine structural temperatures settle within an 8- to 13-s interval after a switch between two- and three-cylinder operation. Engine heat rejection to coolant is reduced by ~13% by deactivating a cylinder, extending coolant warm-up time to thermostat-opening by 102 s.

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Numerical investigation of natural gas direct injection properties and mixture formation in a spark ignition engine

Thermal Science ◽

10.2298/tsci120605222y ◽

2014 ◽

Vol 18 (1) ◽

pp. 39-52

Author(s):

Bijan Yadollahi ◽

Masoud Boroomand

Keyword(s):

Numerical Model ◽

Natural Gas ◽

Internal Combustion Engines ◽

Gasoline Engine ◽

Direct Injection ◽

Spark Ignition ◽

Computational Effort ◽

Spark Ignition Engine ◽

Validity Of Results ◽

Injection Process

In this study, a numerical model has been developed in AVL FIRE software to perform investigation of Direct Natural Gas Injection into the cylinder of Spark Ignition Internal Combustion Engines. In this regard two main parts have been taken into consideration, aiming to convert an MPFI gasoline engine to direct injection NG engine. In the first part of study multi-dimensional numerical simulation of transient injection process, mixing and flow field have been performed via three different validation cases in order to assure the numerical model validity of results. Adaption of such a modeling was found to be a challenging task because of required computational effort and numerical instabilities. In all cases present results were found to have excellent agreement with experimental and numerical results from literature. In the second part, using the moving mesh capability the validated model has been applied to methane Injection into the cylinder of a Direct Injection engine. Five different piston head shapes along with two injector types have been taken into consideration in investigations. A centrally mounted injector location has been adapted to all cases. The effects of injection parameters, combustion chamber geometry, injector type and engine RPM have been studied on mixing of air-fuel inside cylinder. Based on the results, suitable geometrical configuration for a NG DI Engine has been discussed.

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