Investigation of CO2 and PN emission characteristics according to the propane content for a LPG engine

Abstract

Many countries of the world aim to achieve carbon neutrality by 2050 and has a set goal for carbon reduction in 2030. Among eco-friendly alternative fuels, engines using liquefied petroleum gas (LPG) have been developed to address regulations. LPG fuel, consisting of a mixture of butane and propane, is currently under investigation to assess how altering the propane content influences fuel atomization, injection quantity, and exhaust gas. This study analyzes the effect of propane content on the engine control strategy and exhaust gas emissions (CO2, particle number (PN)) from LPG fuel based on engine experiments, chassis experiments, and Real-world Driving Emission (RDE) tests. The results indicated that with increased propane content, the injection duration and quantity increased, resulting in increased CO2 emissions but decreased PN emissions. The differences in emission increased according to propane content. Across chassis and RDE tests, higher propane content consistently associated with increased emissions (CO2), while PN consistently stayed at lower levels. The study results offer insights into potential research directions proposed at determining the optimal propane content for minimizing CO2 and PN emissions.