Waste to fuel: Pyrolysis of waste transformer oil and its evaluation as alternative fuel along with different nanoparticles in CI engine with exhaust gas recirculation

The present research aims to produce the alternative fuel from waste electric transformer oil through two levels pyrolysis process with potassium hydroxide catalyst, enhance it by 150 ppm of 30–50 nm sized Zinc oxide and Cerium oxide nanoparticles and then tested with/without EGR method to achieve low exhaust emissions. The experiments were performed on a single-cylinder, four-stroke CI engine at varying engine loads from 0 to 100% with an increment of 25% at a fixed engine speed of 1500 rpm. The results obtained from the combined test fuels have been compared with reference (conventional) diesel fuel. The performance of fuels like Diesel, PBWTO, PBWTO/ZnO, PBWTO/CeO₂, and with working conditions like PBWTO/ZnO +20% EGR and PBWTO/CeO₂ +20% EGR were recorded respectively at full load conditions in which HC emission as 11, 19, 14, 13, 15 and 15 ppm, 32.9%, smoke opacity as 32.9%, 39.5%, 16.6%, 19.3%, 20.1%. WTO addition into diesel fuel increased the CO emission; however, it is reduced with the nanoparticle addition. That is, PBWTO/ZnO, PBWTO/CeO₂, PBWTO/ZnO +20% EGR and PBWTO/CeO₂ +20% EGR have produced 0.058%, 0.046%, 0.056%, and 0.043% of lesser CO emission than PBWTO fuel respectively. In particular, EGR ensured noteworthy NOx emissions. For example, D, PBWTO, PBWTO/ZnO, PBWTO/CeO2, PBWTO/ZnO +20% EGR and PBWTO/CeO₂ +20% EGR have emitted 1248 ppm, 1427 ppm, 1484 ppm, 1156 ppm, 831 ppm and 821 ppm of NOx emission, respectively. Due to the lower calorific value, higher viscosity, and poor atomization of WTO-added test fuels, the engine performance worsened. Accordingly, under full load condition, BTE was found to be 30.12%, 27.35%, 25.44%, 26.04%, 24.67%, and 25.26%, and BSFC was calculated to be 342, 410, 456, 450, 470, and 459 g/kWh for D, PBWTO, PBWTO/ZnO, PBWTO/CeO₂, PBWTO/ZnO +20% EGR and PBWTO/CeO₂ +20% EGR, respectively. In the conclusion, it is well-noticed that waste transformer oil can be used as a fuel substitute in CI engines with no modification on the vehicular system, and the addition of nanoparticles is a very good solution to mitigate the high exhaust pollutants arising from the use of WTO substitutes.