Feasibility and Performance Analysis of Cylinder Deactivation for a Heavy-Duty Compressed Natural Gas Engine

The rising interest in the use of gaseous fuels, such as bio-methane and hydro-methane, in Heavy-Duty (HD) engines to reduce Greenhouse Gases pushed by the net-zero CO 2 emissions roadmap, introduced the need for appropriate strategies in terms of fuel economy and emissions reduction. The present work hence aims at analysing the potential benefits derived from the application of the cylinder deactivation strategy on a six-cylinder HD Natural Gas Spark Ignition (SI) engine, typically employed in buses and trucks. The activity stems from an extensive experimental characterisation of the engine, which allowed for validating a related 1D model at several Steady-State conditions over the entire engine workplan and during dynamic phases, represented by the World Harmonized Transient Cycle (WHTC) homologation cycle. The validated model was exploited to assess the feasibility of the considered strategy, with specific attention to the engine working areas at partial load and monitoring the main performance parameters. Moreover, the introduction in the model of an additional pipeline and of valves actuated by a dedicated control logic, allowed for embedding the capability of using Exhaust Gas Recirculation (EGR). In the identified operating zones, the EGR strategy has shown significant benefits in terms of fuel consumption, with a reduction of up to 10%. Simultaneously, an appreciable increase in the exhaust gas temperature was detected, which may eventually contribute to enhance the Three-Way Catalyst (TWC) conversion efficiency. Considering that few efforts are to be found in the literature but for the application of the cylinder deactivation strategy to Light-Duty or conventionally fuelled vehicles, the present work lays the foundation for a possible application of such technology in Natural Gas Heavy-Duty engines, providing important insights to maximise the efficiency of the entire system.