NOx Emission prediction based on measurement of in-cylinder pressure for CI engine running with diesel and biodiesel

NOx is one of the major toxic emissions that needs to be regulated stringently in both EU and USA emission regulations. The engine designer is keen to get an accurate, reliable and cost effective NOx measurement system. In this paper, the application of the cylinder pressure for predicting the NOx emission of compression ignition (CI) engine fuelled with diesel and biodiesel during steady state operations is carried out. To address the problem, an experimental work was conducted on four-cylinder, turbo-charged, four-stroke and direct-injection CI engine which was fuelled with diesel and biodiesel blends. During the experiment, the main parameters consisting of in-cylinder pressure, fuel flow rate, air flow rate, and the NOx emission, were measured. The temperature within the cylinder was predicted using the cylinder pressure and air flow rate. Using the temperature values, the NOx emission was simulated in the Zeldovich extended mechanism. The simulation result was then compared with the measured one for a range of engine operating conditions. The models were shown to produce consistent results with the measured one for a range of engine working speeds and loads.