Reduction of smoke, PM2.5, and NOX of a diesel engine integrated with methanol steam reformer recovering waste heat and cooled EGR

Abstract

Over recent years, combustion engines are effectively equipped with a waste heat recovery (WHR) system to produce power or hydrogen at less additional energy input. The WHR system in this study is partially utilized to heat reforming gas in a methanol steam reformer integrated with a diesel engine and a cooled EGR (Exhaust Gas Recirculation) device to reduce smoke, PM2.5, and NOX emissions. The test items are such as the gas pressure of cylinder, crank angle, diesel consumption rate, hydrogen-rich gas flow rate, air flow rate, and smoke, PM2.5, NOX, HC and CO emissions and the molar analysis of hydrogen-rich gas. The authors analyze how the hydrogen-rich gas addition with EGR influences smoke, PM2.5, NOX, HC and CO emissions and combustion performance. The results show that the maximum increase rate of heat recovery efficiency with respect to reaction temperature is 17.5%. The heat recovery efficiency of the reformer rises with increasing engine load up to 24.8%. Adding hydrogen-rich gas with appropriate proportion of EGR helps reduce smoke, PM2.5 and NOX from a diesel engine. In addition, the engine body is rarely changed, and it is effectively to save energy and decrease pollutants.