SIMULATION OF OXYGEN ENRICHMENT WITH CONCENTRATION ABOVE 30% ON COMBUSTION, PERFORMANCE, AND EXHAUST GAS EMISSIONS OF DIESEL ENGINE USING DIESEL FUEL AND SURROGATE BIODIESEL FUEL

• Main Author: ALMIRA GHANY, FARIZA
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/53955
• Institution: Institut Teknologi Bandung

Diesel engines have a higher thermal efficiency compared to other power generating systems, but they are also a major polluter, especially particulate emissions. One of the methods used to control exhaust gas emissions and improve the combustion of a diesel engine is by increasing the availability of oxygen in the combustion chamber. Previous studies discussed oxygen enrinchment with concentration below 30% through the intake air and oxygenated fuels. This study aims to determine the effect of oxygen enrichment through the intake air with concentration above 30% on the combustion process, performance, and exhaust gas emissions of diesel engine using diesel fuel and palm biodesel surrogate. In this study, modeling was carried out based on the results of experiment on a diesel engine, Yanmar TF 155 R-di with rotational speed of 1200 rpm, using AVL BOOST software. Data were collected for 1 case without oxygen enrichment and 4 cases of oxygen enrichment with concentration of 30.6%, 37.8%, 45%, and 54% by mass in the combustion chamber at 50%, 75%, and 100% load. Validation of the model was done by comparing the pressure data against the testing result with diesel fuel usage. Further simulations were carried out on biodiesel surrogate fuel usage. The results show that oxygen enrichment in both fuels increases the peak of heat release rate (HRR). This is due to a better combustion reaction which is also shown in the condition of 90% fuel mass fraction burned (MFB) that was reached faster. The HRR peak of biodiesel usage is lower around 6 J/degree than that of diesel usage, due to the lower calorific value of the fuel. Brake Specific Fuel Consumption (BSFC) increases by about 0.0035 kg/kWh in each case causing a decrease in thermal efficiency. The thermal efficiency and BSFC of biodiesel surrogate usage has a higher value of about 0.3% and 0.028 kg/kWh, respectively, compared to diesel fuel usage, caused by lower calorific value of the fuel. Soot emissions decreased due to the improved combustion process, but NOx emissions increased due to higher combustion temperatures and more availability of oxygen. In biodiesel usage, NOx emissions have a 50% lower value compared to diesel fuel usage, this might be caused by lower combustion temperature. Therefore, high concentration oxygen enrichment ables to improve combustion and lower the soot emissions however increase the NOx emissions.