Parametric study in a stoichiometric diesel micro-pilot natural gas engine for efficiency optimization
2022-01-0558
03/29/2022
- Event
- Content
- Diesel piloted natural gas engine's performance varies depending on operating conditions and has shown to perform best under medium to high load. It can often be equal to or better the fuel efficiency of a diesel-only engine in this operating range. In this paper, a multi-cylinder multi-cylinder diesel 6.7L engine was converted to run stoichiometric natural gas /diesel micro-pilot combustion with a maximum diesel contribution of 10%. The effects of combustion controling parameters, including the pilot start of injection, pilot injection pressure, pilot injection quantity, EGR, and global equivalence ratio were experimentally studied using the Taguchi Orthogonal Matrix approach while operating at stoichiometric conditions. Furthermore, a 1-D simulation model was calibrated with the experimental data to assess further efficiency improvement by optimizing the turbocharger and combustion chamber geometry. It was observed that EQR and the diesel pilot SOI are primary factors impacting thermal efficiency. The numerical analysis made it possible to improve 0.4% additional to demonstrated base 40% BTE by optimizing the turbocharger, including increasing turbine size and reducing back pressure. Reducing combustion chamber adds another 1.1% BTE by reducing piston surface area to decrease heat loss and centralizing pilot diesel ignition. A final 2.0% can be done with base friction reduction, reduced fuel pump work, Miller cycle LIVC with increased CR and improved micro-pilot injection and combustion, resulting in a final 43.5% brake thermal efficiency.
- Citation
- Bonfochi Vinhaes, V., Yang, X., Eggart, B., McTaggart-Cowan, G. et al., "Parametric study in a stoichiometric diesel micro-pilot natural gas engine for efficiency optimization," SAE Technical Paper 2022-01-0558, 2022, .