Using Divided Exhaust Period to Improve Fuel Economy and Aftertreatment Thermal Management in a Turbocharged Multi-cylinder Light-duty Engine running on Dual Fuel Reactivity Controlled Compression Ignition – A Simulation Study
Although turbocharging can extend the high load limit of Low Temperature Combustion (LTC) strategies such as Reactivity Controlled Compression Ignition (RCCI), the low exhaust enthalpy prevalent in these strategies necessitates the use of high exhaust pressures for improving turbocharger efficiency, causing high pumping losses and poor fuel economy. To mitigate these pumping losses, the Divided Exhaust Period (DEP) concept is proposed. In this concept, the exhaust gas is directed to two separate manifolds: the blowdown manifold which is connected to the turbocharger, and the scavenging manifold that bypasses the turbocharger. By separately actuating the exhaust valves using variable valve actuation, the exhaust flow is split between two manifolds, thereby reducing overall engine backpressure and lowering pumping losses. In this paper, results from zero-dimensional and one-dimensional simulations of a multi-cylinder RCCI light-duty engine equipped with DEP are presented.