Abstract
The further thermal efficiency improvement of marine natural gas engine is constrained by a knocking phenomenon that commonly occurs in gas-fueled spark-ignited engines. It plays an important role to investigate how the knocking occurs and how to predict it based on the engine simulation model. In this paper, a two-zone model is developed to provide the prediction of knocking performance and NO emission, which is verified by engine test bed data from a transformed marine natural gas spark ignition (SI) engine. Cylindrical division theory is used to describe the shape of the two zones to decrease the computational cost, as well as a basic mechanism for NO concentration calculation. In order to solve the volume balance, three boundary parameters are introduced to determine the initial condition and mass flow between the two zones. Furthermore, boundary parameters’ variation and knocking factor (compression ratio and advanced ignition angle) will be discussed under different working conditions. Result shows that the two-zone model has sufficient accuracy in predicting engine performance, NO emission and knocking performance. Both the increasing compression ratio and advanced ignition angle have a promoting effect on knocking probability, knocking timing and knocking intensity. The knocking phenomenon can be avoided in the targeted natural gas SI engine by constraining the compression ratio smaller than 14 and advanced ignition angle later than 30° before top dead center (BTDC).
Highlights
Natural Gas (NG) is considered as an appropriate alternative for internal combustion engines due to its cleaner combustion, relative lower cost and rich reserves [1,2]
An spark ignition (SI) natural gas engine transformed from 2135 diesel engine is used in this paper to verify the
An SI natural gas engine transformed from 2135 diesel engine is used in this paper to verify the simulation model
Summary
Natural Gas (NG) is considered as an appropriate alternative for internal combustion engines due to its cleaner combustion, relative lower cost and rich reserves [1,2]. Their research integrates complex chemical kinetics with models of turbulence-based heat transfer and gas exchange processes for a four-stroke cycle It provides boundary layer thickness and mass fraction for better hydrocarbon quenching prediction. Developed a two-zone thermodynamic combustion diagnosis amodel to analyze front centered at the spark plug, and solves the intersection of the flame front with the piston, the combustion process and cycle-to-cycle variations in a spark ignition engine fueled with natural cylinder head and cylinder wall, in order to provide the avalues of the flame radius corresponding to gas/hydrogen mixtures. Most researchers put engines than in diesel engines since the basic space division theory is what happens exactly in SI engine emphasis onchambers the spherical flame and the relycylinder on complicated reaction combustion as the flamepropagation propagates process throughout and separates themechanisms combustion to obtain the emission concentration, would increase the modelflame complexity and computational chamber. Boundary parameters variation and knocking factors on engine performance will be discussed under different engine working conditions
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