Effects of low-temperature reforming products of PRF50 on combustion and emission characteristics in an HCCI engine

Highlights: • The external fuel reforming device strategy was verified by the fuel of PRF50. • The effects of reforming temperature on reformed products were investigated. • The addition of reformed products may alter the engine combustion phasing. • The addition of reformed products can improve the engine thermal efficiency. -- Abstract: In this study, the application of external fuel reforming system in an HCCI engine has been investigated at the reforming temperature from 450 to 750 K. Experiments were conducted in a single-cylinder engine fueled with PRF50, and related simulation analysis was conducted with CHEMKIN package. The temperature of 600 K was the transition point for reformed products, and the composition of reformed products changed variously at this temperature. The results of which reveal the affection of reforming temperature of the external reformer to engine combustion phasing: When the temperature was lower than 600 K, the engine combustion phasing could be advanced by introducing reformed products, and vice versa. The combustion stability could be improved (CoV_IMEP < 5%) with reformed products when the temperature was lower than 650 K. By reasonably controlling the operating condition of external reformer, CO and UHC emissions could be reduced, and the indicated thermal efficiency could also be improved by 4% (44%).