Improvement in Thermal Efficiency of Lean Burn Pre-Chamber Natural Gas Engine by Optimization of Combustion System

2017 ◽  
Author(s):  
Qian xiong ◽  
Yasuo Moriyoshi ◽  
Koji Morikawa ◽  
Yasushi takahashi ◽  
Tatsuya Kuboyama ◽  
...  
Keyword(s):  
Natural Gas ◽  
Thermal Efficiency ◽  
Combustion System ◽  
Lean Burn ◽  
Gas Engine ◽  
Natural Gas Engine

Effect of Port Gas Injection on the Combustion Instabilities in a Spark-Ignition Lean-Burn Natural Gas Engine

2018 ◽  
Vol 28 (10) ◽  
pp. 1850124
Author(s):  
Li-Yuan Wang ◽  
Li-Ping Yang ◽  
En-Zhe Song ◽  
Chong Yao ◽  
Xiu-Zhen Ma
Keyword(s):  
Natural Gas ◽  
High Frequency ◽  
Gas Injection ◽  
Low Frequency ◽  
Combustion System ◽  
Combustion Instabilities ◽  
Lean Burn ◽  
Engine Load ◽  
Gas Engine ◽  
Natural Gas Engine

The combustion instabilities in a lean-burn natural gas engine have been studied. Using statistical analysis, phase-space reconstruction, and wavelet transforms, the effect of port gas injection on the dynamics of the indicated mean effective pressure (IMEP) fluctuations have been examined at a speed of 800[Formula: see text]rpm and engine load rates of 25% and 50%. The excessive air coefficient is 1.6 for each engine load, and the port gas injection timing (PGIT) ranges from 1 to 120 degrees of crankshaft angle ([Formula: see text]CA) after top dead center (ATDC) of the intake process. The results show that the PGIT has a significant effect on cyclic combustion fluctuations and the dynamics of the combustion system for all studied engine loads. An unreasonable PGIT leads to increased combustion fluctuations, and loosened and bifurcated structures of combustion system attractors. Furthermore, for both low and medium engine loads, the IMEP time series at earlier gas injections ([Formula: see text]CA and [Formula: see text]CA ATDC) undergoes low-frequency fluctuation together with high-frequency fluctuations in an intermittent fashion. For other PGITs, high-frequency intermittent fluctuations become persistent combined with weak low-frequency oscillations. Our results can be used to understand the oscillation characteristics and the complex dynamics of combustion system in a lean-burn natural gas engine. In addition, they may also be beneficial to the development of more sophisticated engine control strategies.

Measurements and Modelling of a Lean Burn Gas Engine

1996 ◽  
Vol 210 (6) ◽  
pp. 449-462 ◽  
Author(s):  
C R Stone ◽  
K J S Mentis ◽  
M Daragheh
Keyword(s):  
Natural Gas ◽  
High Efficiency ◽  
Combustion Model ◽  
Hydrocarbon Emissions ◽  
Combustion System ◽  
Lean Burn ◽  
Gas Engine ◽  
Natural Gas Engine ◽  
Brake Mean Effective Pressure ◽  
Pressure Maximum

Natural gas is an alternative fuel that has potential for low emissions and a high efficiency. This paper presents the experimental results and predictions from a computer simulation of a fast burn high compression ratio (FBHCR) combustion system intended for use in a lean burn natural gas engine. Comparisons are made between the FBHCR combustion system at two compression ratios, predictions made by a two-zone combustion model and measurements from the original combustion system, for the brake efficiency, brake mean effective pressure, maximum cylinder pressure and the brake specific NOx emissions. Experimental measurements of the unburnt hydrocarbon emissions, the burn duration and the cycle-by-cycle variations in combustion are also discussed from the original and fast burn combustion systems. The results show how the conflicting aims of low emissions and low fuel consumption can be satisfied using a lean burn combustion system. The computer predictions are shown to be reliable, and thus suitable for estimating the performance of other engine builds.

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