Numerical and experimental evaluation on the pooled effect of waste cooking oil biodiesel/diesel blends and exhaust gas recirculation in a twin-cylinder diesel engine

Nowadays, worldwide, many countries are engaged in reducing the vehicular exhaust emissions from diesel engines as diesel engines are the main source of power in various transport applications. Biofuels obtained from various feedstocks serve as a better alternative fuel in CI engines because of its emission reducing capabilities. The major drawback in the usage of biofuels in CI engine is the rise in the formation of nitrogen oxides which would be harmful to human health. WCO biofuel was processed using trans-esterification technique and the contents available were analyzed using gas chromatography mass .spectroscopy (GCMS). Four different blends, namly B100, B60, B40, and B20 were made. The physio-chemical properties of the prepared test fuels were identified using ASTM standards. The investigation on the characterisation of performance, combustion, sound and emission of the test engine was done. Fuel combustion modeling was done using ANSYS Fluent for diesel, WCO biofuel and best suited blend obtained from experimental results. From both the simulated and the experimental results, it was found that B20 blend fuel would be best suited to the test engine with a maximum reduction of 17% in unburned hydrocarbon (HC), 30% in carbonmonooxide (CO), 14.08% in smoke, 7.35% in carbondioxide (CO2) and 16.46% increase in NOx emission respectively. With an intention to reduce NOx emission in the selected B20 blend fuel, EGR at three rates, namely (5%, 10%, and 15%) were utilized. Again, the experiments were conducted with varying EGR rates for B20 blend fuel. A good percentage of reduction in NOx was obtained with increase in EGR rates. But other emissions like CO, HC, smoke, and CO2 emissions were found to increase with rise in EGR rates. Thus, a comparison was made with three rates of EGR emission values with all types of test fuels to optimize the EGR rate leading into the inlet charge. 10% EGR rate gave a maximum reduction of 16.34% in NOx emission without affecting much in the emissions like HC, CO, Smoke, and CO2 along with a small drop in performance.

Automated summary

With the increasing global concern on diesel engine exhaust emissions, biofuels serve as a better alternative for compression ignition engines, but may lead to increased nitrogen oxide emissions which are harmful to human health. Research found that B20 blend fuel is the most effective in reducing emissions, particularly with a maximum reduction of unburned hydrocarbon, carbon monoxide, smoke, and carbon dioxide emissions. Increasing exhaust gas recirculation (EGR) rates can effectively reduce NOx emissions but may result in higher emissions of other pollutants.