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Emissions and Efficiency Comparison of Gasoline and LPG Fuels in a 1.4 Litre Passenger Car Engine
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Abstract
This paper presents experimental results obtained from bench tests on a 1.4 litre, 4-cylinder, dual-fuel spark ignition engine, fitted with a three-way catalytic converter. Performance, fuel consumption and exhaust emissions measurements were recorded under steady state operating conditions from engine builds: (i) with multi-point gasoline liquid fuel injection, and (ii) with single-point vaporised LPG (propane). An after-market LPG conversion kit, incorporating electronic air-fuel ratio control based on exhaust oxygen concentration, was used in the latter case. Emissions were measured before and after the catalytic converter and catalyst conversion efficiency trends are presented for each fuel.
The experimental data is also compared with predictions from a thermodynamic cycle simulation and emissions prediction model which was developed with a view to gaining an improved understanding of the observed experimental trends.
CONVERSION OF light duty vehicle spark ignition engines to operation on liquefied petroleum gas (LPG) presents some difficulties in the areas of electronic engine management and control of exhaust emissions. Suppliers of after-market LPG conversion kits are faced with a very large variety of vehicle types and engine options where the size of the market for any specific combination may be small. Development of complete alternative engine management systems with fully optimised spark timing maps is not feasible and it is common practice to supply an additional electronic unit which controls fuelling only, typically using a feedback signal from an exhaust oxygen sensor. Some results [1, 2] have published from emissions oriented studies on such systems.
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Smith, W., Timoney, D., and Lynch, D., "Emissions and Efficiency Comparison of Gasoline and LPG Fuels in a 1.4 Litre Passenger Car Engine," SAE Technical Paper 972970, 1997, https://doi.org/10.4271/972970.Also In
References
- Chiu J Matthews R 1996 The Texas Project: Part 2 - Control System Characteristics of After-market CNG and LPG conversions for Light-Duty Vehicles SAE 962099
- Higinbotham E. Platz B. Clark W 1996 Effect of Selected LPG Fuel Components on Speciated Exhaust Emissions SAE 961990 1996
- Smith W.J. Lynch D.L. “Comparison of AFR calculation methods using gas analysis and mass flow measurement” SAE 971013 1997
- McEnroe, C.P “The Development of a Natural Gas Engine Simulation Model” M.Eng.Sc. Thesis Department of Mechanical Engineering, University College Dublin 1989
- Poulos, S.G. Heywood, J.B. “The Effect of Chamber Geometry on Spark-Ignition Engine Combustion” SAE 830334 1983
- Heywood, J B 1988 Internal Combustion Engine Fundamentals New York McGraw Hill Book Company