STUDY OF OXYGEN ENRICHED AIR WITH CONCENTRATION ABOVE 30% ON COMBUSTION , PERFORMANCE , AND EXHAUST EMISSION OF DIESEL ENGINE

• Main Author: TRIANANDARI WINANTO AYU PUTRI, ADINDA
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/53952
• Institution: Institut Teknologi Bandung

Diesel engines have a potential of causing adverse health impacts, because they are contributing in up to 88% of total carbon emissions in the transportation sector. Increasing the amount of oxygen in the combustion chamber, also known as oxygen enrichment, is one of the methods used to reduce exhaust emissions and improve the combustion quality of diesel engines. Complete combustion occurs when the engine is operated in conditions of sufficient air passing through the inlet. This process ensures that nearly all of the fuel molecules react with oxygen, resulted in complete combustion, which means that all the hydrocarbon components of the fuel can be completely oxidized. Many studies have been carried out for the oxygen enrichment with oxygen concentrations below 30% in diesel fuel usage. Therefore, this research aims to study the effect of oxygen enrichment with concentration above 30% on combustion, engine performance and exhaust gas emissions. Tests were carried out on Yanmar TF R-di diesel engine with single cylinder, a direct fuel injection system, a compression ratio of 17.8 and a constant rotation speed of 1200 rpm. Data were collected at 4 oxygen enrichment conditions, namely 32.22%; 39.71%; 47.38%; and 56.32% with 3 load variations, namely 50%, 75%, and 100%. Combustion process analysis is based on heat release rate of the diesel engine, which is derivatives of combustion chamber pressure. The results show that along with oxygen enrichment the start of combustion time shifts away from the TDC. This causes the ignition delay time to be shorter and resulted in a decreased peak heat release rate. There is an increase in the reaction between the fuel and oxygen, which is indicated by the 90% fuel mass fraction burnt moving up to 4o of the crank angle, showed that the combustion reaction is faster along with oxygen enrichment. Under all oxygen enrichment conditions, brake specific fuel consumption (BSFC) increased by an average of 0.01517 kg / kWh. The increasement in BSFC indicates a decreasement in thermal efficiency, where the thermal efficiency decreased by 4% due to the shift in start of combustion time and incomplete combustion as indicated by a decrease in the cumulative heat release value. It can not be denied that the oxygen enrichment method has one drawback in NOx emission, this is shown in the test results where NOx emissions increase significantly up to 3 times compared to conditions without oxygen enrichment caused by high combustion temperatures and excess oxygen. On the other hand, the smoke opacity decreased significantly up to 70% indicating an increase in the degree of soot oxidation inside the combustion chamber.