Combustion characterization of natural gas in a lean burn spark-ignition engine

Abstract

International audienceLean burn natural gas fuelled spark-ignition engines are particularly attractive regarding environmental performance. Nevertheless, few data exist concerning lean combustion in gas engines in terms of ignition delay, combustion duration and combustion rate. Such data are necessary when using thermodynamic models to predict energy and environmental performance. The present study proposes a contribution to such combustion characterization as a function of spark timing, air excess and engine load. This work is based on experimental cylinder pressure measurements in an open chamber engine on the one hand, and on a one-zone thermodynamic model used as a heat release analysis tool on the other hand. Results obtained, such as mass fraction burned, ignition delay and combustion duration, allow identification of the parameters used in the Wiebe function, a semi-empirical law that is frequently used to describe the combustion in predictive models

Dynamics of cycle-to-cycle variations in a natural gas direct-injection spark-ignition engine

“…Lean mixtures of alternative fuels such as natural gas, biofuels and fuel-blends, with operational modes such as direct injection (DI) and homogeneous charge compression ignition (HCCI) have been realized in recent years, with improved performance over the conventional gasoline and diesel engines [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. However, internal combustion engines suffer from cycle-to-cycle variations (CCV) in combustion variables such as pressure, and these cyclic variations may become severe under lean burn conditions or for highly dilute mixtures with exhaust gas recirculation (EGR) [16][17][18][19][20].…”

Experimental study on the laminar flame speed of hydrogen/natural gas/air mixtures

“…In China, the use of natural gas as fuels for taxis has been widely applied. However, due to the slow burning velocity of natural gas and its poor lean-burn ability, the natural gas spark-ignited engine has the disadvantages of low thermal efficiency, large cycleby-cycle variation, and poor lean-burn capability, and these will decrease the engine power output and increase fuel consumption 1) [2]. Mixing the natural gas with a fuel that possesses high laminar flame speed is an effective method to solve the problem of the slow laminar flame speed of natural gas.…”

Measurements of laminar burning velocities for natural gas–hydrogen–air mixtures

“…Natural gas is considered to be one of the favorable fuels for engines and natural-gas-fuelled engines have been realized in both spark-ignited and the compression-ignited engines. However, due to the slow burning velocity of natural gas and its poor lean-burn ability, the natural gas spark-ignited engine has the disadvantages of low thermal efficiency, large cycle-by-cycle variation, and poor lean-burn capability, and these will decrease the engine power output and increase fuel consumption [1,2]. Due to these restrictions, natural gas engines are usually operated at stoichiometric equivalence ratio with relative low thermal efficiency.…”