Optimized injection strategy for hydrogen-waste transformer oil biodiesel dual-fuel engines: A novel waste-to-energy solution towards environmental protection

Increasing concerns about fossil fuel exhaustion, crude price oscillations, scarcity in petroleum resources, and increased environmental concerns have prompted the attention of researchers towards alternatives for petroleum-based fuels. In this study fuel WTOB50, which is 50 % by volume of waste transformer oil biodiesel was utilized in diesel engines with hydrogen in bi-fuel mode. The experimental investigation was conducted with H<inf>2</inf> induction at 8 lpm, WTOB50 as the primary fuel, fuel injection pressures of 170, 210, and 240 bar, and fuel injection timings of 23°bTDC, 21°bTDC, and 19°bTDC, under full load conditions. Findings resulted increased thermal efficiency at a fuel injection pressure (IP) of 240 bar and an injection timing (IT) of 19°bTDC, showing a 4.08 % improvement compared to standard WTOB50 operation. BSEC was reduced by 5.23 % under the same conditions. NO<inf>x</inf> emissions were minimized at an IT of 23°bTDC, while opacity reduced at 19°bTDC with higher injection pressures. Cylinder peak pressure and heat release rate were highest at 19°bTDC, highlighting improved combustion characteristics. Additionally, dual-fuel operation exhibited delayed in ignition periods against diesel, but retarding the FIT to 19°bTDC shortened the ignition delay. Overall, bi-fuel operation with WTOB50 and hydrogen at optimized injection parameters demonstrated notable improvements in engine metrics, indicating the potential of this approach as an effective waste-to-energy solution.