The effects of combustion phasing induced by water injection on deNOx performance of GDI engine at MBT ignition timing

Abstract

The call for greenhouse gas emission reduction as the result of global warming has been the main cause of the more rigorous emission legislation in the road transportation sector. In response to such requirements, car makers opt for the ‘down-sizing’ trend for engine displacement with the aim to increase brake thermal efficiency by increasing engine load (mean effective pressure). However, this leads to higher potential of engine knocking and elevated NOx emissions. This study investigates the effects of combustion phasing induced by water injection via the intake manifold of a naturally aspirated GDI engine at MBT ignition timing fuelled with E20. Water up to 30% of fuel mass is port-injected during high engine load and maximum NOx reduction of up to 82% could be achieved as the result of lower RoHR caused by vaporisation of water. Water injection prolonged the ignition delay and combustion duration (CA1090) without deterioration of combustion stability (%COV of IMEP). The optimisation of ignition timing based on MBT can improve CO emission compared to EGR systems. The proposed study demonstrates the possibility to achieve low nitrogen emissions without the need of precious metal-based catalysts.

Investigation of the parameters influence of the oxy-fuel burner and the test bench parameters on the deviation of the model similarity criterions from the full-scale values

“…The study was carried out for the model burner device capacities of 186 kW, 500 kW, 800 kW and the full-scale BD capacity of 3.5 MW. The study results showed that the criterion value does not depend on the burner device capacity, since the change in volume flow is not taken into account in the calculation formula that determines Euler's criterion values (1). Figure 5 shows the dependence of the influence of the pressure and speed of the medium in the cylindrical part of the working area on the deviation of the model Euler's criterion value from the full-scale value ΔEu, %.…”

“…Currently, the majority of electricity is generated by burning fossil fuels at thermal power plants (TPPs). Combustion products of the fuelair mixture, mainly greenhouse gases, are released into the environment during the TPP operation, thereby contributing to an increase in their concentration in the Earth's atmosphere [1] . Adoption of prior-art technologies for capturing carbon dioxide at thermal power plants means an increase in the cost of electricity generated [2][3][4] .…”