Simulation-based investigation of a marine dual-fuel engine

Abstract

Recent developments have rendered the Dual Fuel (DF) engines an attractive alternative solution for achieving cost-efficient compliance to environmental regulations. The present study focuses on the safety investigation of a marine DF engine in order to identify potential safety implications. This investigation is based on an integrated engine model, which was developed in GT-ISE™ software and is capable of predicting both the engine steady-state behaviour and transient response. The model includes the engine thermodynamic simulation module as well as the engine control system functional module; the latter is responsible for implementing the ordered load changes and the operating mode switching. The developed model is first validated against available published data and subsequently used to simulate several test cases with fuel changes, from gas to diesel and diesel to gas with rapid and with delayed wastegate valve operation. The derived simulation results are used to investigate the potential safety implications that can arise during the engine operation. The results demonstrate that the engine–turbocharger matching as well as the wastegate control are critical parameters for ensuring the compressor surge free operation during gas to diesel modes transition. Abbreviations: 0D: zero-dimensional; 1D: one-dimensional; BMEP: brake mean effective pressure; CO2: carbon dioxide; DF: dual fuel; D/G: diesel generator; DTG: diesel to gas fuel modes switching; ECA: emission control area; ECS: engine control system; EEDI: energy efficiency design index; GTD: gas to diesel modes switching; HFO: heavy fuel oil; IMO: International Maritime Organization; LFO: light fuel oil; LNG: liquefied natural gas; MCR: maximum continuous rating; NOx: nitrogen oxides; PHA: preliminary hazard analysis; PI: proportional–integral; SOx: sulphur oxides; TC: turbocharger; WG: wastegate; λ: air–fuel equivalence ratio.