CONCEPTS FOR THE ADAPTATION OF SI GAS-ENGINES TO CHANGING METHANE NUMBER

In a joint project of FEV Motorentechnik and Ruhrgas AG, the design of stoichiometric and lean-burn Otto engines was optimized by selective modifications to the design and operating parameters to accommodate ch anging methane numbers (LPG addition to CNG). Of particular importance was knock-free engine operation at a low NOx output to meet the requi rements of the German Clean Air Code while concurrently achieving both high efficiencies and mean effective pressures. Based upon the result s obtained concepts for the control of otto-cycle gas engines to accep t changing methane numbers were developed. The newly developed gas eng ine control device allows these concepts to meet the requirement of th e German Clean Air Code with economically viable conditions while prev enting engine knock. Furthermore, the rest results show that dedicated Otto-cycle gas engines can meet the most stringent emission limits fo r commercial vehicles while maintaining high efficiencies.