Exhaust Emission Deterioration and Combustion Chamber Deposit Composition Over the Life Cycle of Small Utility Engines

Abstract

In this study, a laboratory test procedure to mimic the life cycle of the small air-cooled engines in field operation is developed. A characterization of exhaust emissions over the life cycle of the engines is achieved with special focus given to the hydrocarbon emissions. Both Briggs and Stratton four-stroke (four-cycle) overhead-valve and side-valve engines with a nominal power output of 3.7 kW (5 hp) are used in this study. Different levels of emissions are observed for each type of engine configuration, and it is noted that the hydrocarbon emissions changed more than CO or NOx emissions. These data support the idea that combustion chamber deposits (CCD) are a significant cause of deteriorating emissions. Chemical analysis techniques are applied to the CCD, and it is found that the deposits consist primarily of polynuclear aromatic compounds and unsaturated hydrocarbons.

Catalyst Deterioration over the Lifetime of Small Utility Engines

“…As illustrated in Table 1, and as also discussed by Caceres et al 8 for similar small engines, the NO x emissions do not increase significantly, and sometimes decrease slightly, as the engines age. The HC emissions tend to increase significantly as the engines age, often as a result of increased combustion chamber deposits.…”

“…The zinc and phosphorous, along with additional elements such as calcium, were most likely from oil additives. 8 Zinc and phosphorous act as poisons for the catalyst, contributing to the decreased effectiveness of the catalysts as they age.…”

“…This method was previously found to adequately mimic the field-testing results for aging. 7,8 This method of acquiring hours on the engines requires no special parts other than the blade and inserting fuel shutoff valves. The flywheel brake is removed, and the engines are instead stopped by using the fuel shutoff valves.…”

Growth and characterization of deposits in the combustion chamber of a diesel engine fueled with B50 and Indonesian biodiesel fuel (IBF)

“…This is ascribed to the fact that biodiesel blends have less thermal stability as well as higher density and viscosity values compared with typical diesel fuel, thus increasing the possibility of deposit formation in engines (Reksowardojo et al, 2010;Liaquat et al, 2014). These deposits could negatively impact heat transfer in the combustion chamber (Yamada et al, 2002;Kalam and Masjuki, 2004), hydrocarbon emissions (Caceres et al, 2003;Gopal and Karupparaj, 2015), and the overall quality of the combustion process and the components' lifetime which could ultimately result in increased maintenance cost. It is worth highlighting that various biodiesel blends vary in terms of their physicochemical properties and consequently their combustion characteristics.…”

The influence of lubricating oil on deposits formation in a diesel engine under the operation condition of high power density

“…Deposits formation in an engine is inevitable. Its influence on power and emissions is also noticeable . Many factors may influence deposits formation, such as exhaust gas recirculation and the kind of fuel used .…”