Natural Gas for High Load Dual Fuel Reactivity Controlled Compression Ignition in Heavy Duty Engines

Abstract

Reactivity controlled compression ignition (RCCI) has been shown to be capable of providing improved engine efficiencies coupled with the benefit of low emissions via incylinder fuel blending. Much of the previous body of work has studied the use of gasoline as the premixed lowreactivity fuel. However, there is interest in exploring the use of alternative fuels in advanced combustion strategies. Due to the strong market growth of natural gas as a fuel in both mobile and stationary applications, a study on the use of methane for RCCI combustion was performed. Single cylinder heavyduty engine experiments were undertaken to examine the operating range of the RCCI combustion strategy with methane/diesel fueling and were compared against gasoline/diesel RCCI operation. The experimental results show a significant load extension of RCCI engine operation with methane/diesel fueling compared to gasoline/diesel fueling. For gasoline/diesel fueling, a maximum load of 6.9 bar gross indicated mean effective pressure (IMEPg) at CA50 = 0 deg aTDC (after top dead center) and 7.0 bar IMEPg at CA50 = 4 deg aTDC was obtained without use of exhaust gas recirculation (EGR). For methane/diesel fueling, a maximum load of 15.4 bar IMEPg at CA50 = 0 deg aTDC and 17.3 bar IMEPg at CA50 = 4 deg aTDC was achieved, showing the effectiveness of the use of methane in extending the load limit for RCCI engine operation.