Effects of operation temperature on exhaust emissions in a spark ignition system using pre-chamber stratified system 2019-36-0130

Atmospheric pollution is the major public health issue in many cities around the world. Internal combustion engines (ICE) and industries are common sources of pollutants that aggravate this situation. Aiming to overcome this problem, increasingly restrictive legislation on combustion pollutant emissions has been formulated and new technologies are being developed to ensure compliance with such restrictions. In this scenario, the lean mixtures appear as a possible alternative, but also bring some inconveniences such as combustion instabilities. Pre-chamber ignition systems (PCIS) enable a more stable combustion process due to high kinetic, thermal and chemical energy of the gases from the pre-chamber (PC), which pass through nozzles and begin the combustion process of the air-fuel mixture contained in the main combustion chamber (MC). However, some challenges still have to be overcome in the development of these systems, one of the main ones being hydrocarbon (HC) emissions. Therefore, the main goal of this investigation is to evaluate the effect of operating temperature on the pollutants emissions from an ICE with stratified pre-chamber ignition system (SPCIS) and to verify specifically the possibility of HC emissions reduction by raising the operating temperature. So, an ICE equipped with a SPCIS, operating with indirect injection of ethanol in the MC and direct injection of hydrogen in the PC, was tested under lean conditions of λ = 1.4, at 2250 rpm and indicated mean effective pressure of 5 bar. With the increase in the operating temperature of the ICE from 70 °C to 100 °C, were observed emission reductions in percentage volume of 42.4% for HC and 20.4% for CO, while NO_x emissions increased in 33.7%. These results allow to conclude that the increase in operating temperature is a viable alternative to achieve lower HC emission with PCIS.