An Investigation into the Control of Startup and Shutdown Hydrocarbon Emissions in a Wankel Rotary Engine with a Novel Rotor Cooling Arrangement KAUST

Format:

Book

Conference/Event

Author/Creator:

Turner, James, author.

Contributor:

Addy, Shaun

Akehurst, Sam

Bailey, Nathan

Islam, Reza

Turner, Matthew

Vorraro, Giovanni

Conference Name:

15th International Conference on Engines & Vehicles (2021-09-12 : Capri, Italy)

Language:

English

Physical Description:

1 online resource cm

Place of Publication:

Warrendale, PA SAE International 2021

Summary:

The present work investigates a means of controlling engine hydrocarbon startup and shutdown hydrocarbon emissions in a Wankel engine which uses a novel rotor cooling method. Mechanically the engine employs a self-pressurizing air-cooled rotor system (SPARCS) to provide significantly improved cooling versus a simple air-cooled rotor arrangement. Unfortunately, the design also means that when the engine is shutdown, due to the overpressure within the engine core and the fact that fuel vapour and lubricating oil are to be found within it, unburned hydrocarbons can leak into the combustion chambers, and thence to the atmosphere via either or both of the intake and exhaust portraits As well as shutdown it also affects the startup process, where higher hydrocarbon emissions are caused due to the forced transfer of the unburned gases to the intake and exhaust ducts as the core depressurizes across the sealing grid when it is stationary. These emissions then sit in those volumes, possibly then escaping to the outside world; clearly this is also very important with respect to SHED testing of any vehicle the engine might be fitted to.The SPARCS concept is discussed with respect to how it functions versus a conventional wet sump arrangement (as employed by oil cooled rotor Wankel engines). The reasons for the engine on/off hydrocarbon issue are then readily apparent. Using a solenoid valve as a means of venting the rotor core pressure directly to the engine intake just before shutdown is introduced as a means of alleviating this problem. This approach feeds the hydrocarbon-rich gases from the core through the combustion process and out through the catalytic converter as the engine is switched off. In automotive applications this engine is to be used as a range extender and hence there is a great degree of control regarding all modes of its operation, including startup and shutdown, which is what is investigated for mitigation here.The results show that depressurizing the core in this manner results in a maximum reduction in total hydrocarbon emissions during warm shutdown and restart of 80% and 60%, respectively. However, it must be remembered that with the pressure relieved in the core, the cooling capability there is reduced, and so the approach has to be calibrated correctly to achieve the best result for the whole system

Notes:

Vendor supplied data

Publisher Number:

2021-24-0097

Access Restriction:

Restricted for use by site license