| Abstract:In order to further improve the thermal efficiency of low-speed engines, the improvement of the potential thermal efficiency of low-speed engines equipped with variable scavenge ports was studied based on the thermodynamic simulation model of a low-speed engine with cylinder bore of 500 mm in diameter. Parameters sucha as brake specific fuel consumption (BSFC), exhaust flow rates and exhaust temperatures of low-speed engine with variable symmetric and asymmetric scavenge ports at different engine loads and with different scavenge port heights were calculated. At the same NOx emission level, the variable scavenge ports technology can effectively improve the thermal efficiency of the low-speed engine, reducing the fuel consumption by up to about 4.3g/(kW·h). In addition, for an engine with selective catalytic reduction (SCR) system, the variable scavenge ports technology can reduce exhaust flow and increase exhaust temperature, which is beneficial to the compact design of a SCR system and reduces the cost of a SCR system. |