Experimental Investigation of In-situ Oxidation of Soot

The formation of soot is common in diesel engine, and it causes environmental pollution as well as decreasing the engine performance and causes cost of maintenance to rise. However, soot can be eliminated by trapping it using soot trap element within the exhaust and burning it off to soot oxidation temperature which is around 600°C. The soot trap element is to be permanently installed at the exhaust system of the diesel engine as current off the shelf product uses filters that needs to be replaced after certain time.
To reach the high soot oxidation temperature, this research is focusing on using microwave in order to reach the soot oxidation temperature. Experiment matrix for this research has been developed, and the maximum time of exposure of the soot that is trapped within the filter element is 600 seconds. The source of soot is from the diesel engine and the soot trap is initially filled with soot as well to ensure that it is full of soot. The amount of NOx, CO, CO2 and O2 as well as the opacity of the smoke are recorded at the initial and end of the experiment by using the Anycar AutoChek gas & smoke analyzer. The decreased amount of NOx, increased amount of CO2 and a less opaque smoke emitted indicates that the soot combustion has occurred within the soot trap. The microwave generator used in this experiment can reach up to 3 kW, but it is decided to use 3 different levels of microwave energy to the soot which is at 0.5 kW, 1.0 kW & 1.5 kW. A relationship between level or intensity of the electromagnetic wave and smoke opacity, NOx and CO2 has been discovered from the results. The result has shown that the level of electromagnetic wave are increased, the amount of smoke and NOx reduction while CO2 increment are more. In-situ oxidation are very useful and has a bright future in after treatment of exhaust emissions as it ensure the vehicle to comply with the regulations in standard of gas & smoke emission and also provides a safer environment to the society as well as to the future generations.