Development and Application of Catalytic Reforming System to Reduce Fuel Consumption and Pollutant Emissions for Liquefied Petroleum Gas Engine

Abstract

As technology of internal combustion engines has developed, the pollutant emissions and GHG emitted from the vehicles have been continuously reduced. Nevertheless, the fossil fuel depletion and environmental pollution have been continuously posed as issues, and the related regulations are being strengthened. To cope with such issues, powertrain electrification of automobiles is attempted all over the world, but still engines would be used in 85% of automobiles which would be sold in 2030. In addition, when GHG life cycle assessment is introduced, GHG emissions from electric vehicles, fuel cell electric vehicles, and internal combustion engine vehicles are expected to be similar depending on the level of technology development and a source of powerplant. Therefore, there is a need for immediately applicable technologies for the performance of internal combustion engines to satisfy fuel economy and pollutant emission regulations. And, rather than excessive development and dissemination of electrified powertrains, the development of renewable energy and high efficiency engines is a priority. LPG is one of the alternative fuels that can be immediately applied, and its production and transportation are quite easy. It also produces less pollutant emissions compared to the gasoline or diesel fuel. However, it has the disadvantage of fuel economy and power due to its small calorific value per unit volume. In this study, a hydrogen production system, that can be loaded on the vehicles which use reforming catalyst, was developed to overcome the drawbacks of LPG engine. It was installed on the actual engine and performance difference with the conventional engine was compared. The reforming catalyst for hydrogen production was prepared through the base engine performance test. And performance evaluation was conducted according to reactants of the reforming catalyst. The reforming catalyst performance evaluation device is used to control the reactants of the reforming catalyst, and the products of the reforming reaction (H2, CH4, CO, CO2, N2, O2) are measured using gas chromatography and exhaust gas analyzer. The performance evaluation was conducted by measuring the production rate of products. In order to implement and activate reforming catalyst in the engine, additional components such as heat exchanger for waste heat recovery and heat exchanger for product cooling were fabricated along with the catalytic reforming system. The commercial ECU (M800) was adopted to correct engine control parameters and the performance test was proceeded while varying the excess air ratio. The fuel consumption, pollutant emissions, and combustion pressure according to the operating condition were measured to obtain mechanical efficiency, volumetric efficiency, and fuel conversion efficiency and these were compared with those of conventional engines. Finally, a look-up table for various control parameter was constructed with the target of improving the fuel efficiency and reduction of NOx. In order to verify the performance of the developed catalytic reforming system for engine, a comparative experiment was conducted with conventional engine under modified FTP-72 operating conditions. Each test was repeated for three times. The results showed that NOx emission was reduced by 22.8% and fuel efficiency was improved by 3.01%.