Abstract
As the emission regulations are getting more stringent, engine manufacturers are continuously improving engine performance and emissions along with exploring alternative fuel options. Diesel engines dominate the current on highway heavy duty engine market. Compared with diesel, natural gas engines have many advantages like near zero soot emissions, lower CO2 emissions, lower operating cost, quieter operation, and domestic natural gas availability. Natural engines can operate at stoichiometric air fuel ratio and allow for the use of cost effective three-way catalytic converter to achieve emission targets. Moreover, Renewable Natural Gas (RNG) is the only fuel in the market with carbon negative intensity. To improve the overall engine efficiency, new engine design integrates tumble combustion, dual overhead camshaft, variable valve train system, optimized fuel system, pulse Exhaust Gas Recirculation (EGR) system and optimized turbocharger. Integration and optimization of new technologies has improved the peak Brake Thermal Efficiency (BTE) by 12% above the current Cummins heavy-duty production engine. Average transient cycle BTE is improved by 16% on Ramped Mode Cycle Supplemental Emissions Test (RMCSET) and 17% on Federal Test Procedure (FTP) cycles. Optimized architecture has demonstrated system out emission capability of 0.02 g/hp-hr. on both the FTP and RMCSET cycles.
