Enhancement of combustion characteristics of waste cooking oil biodiesel using TiO2 nanofluid blends through RSM

Growing environmental concerns and stringent emission regulations have fueled the search for an alternative fuel without engine modification that can minimize pollution from compression ignition (CI) engines. Biodiesel is a suitable alternative fuel to fossil diesel that is often made from edible or non-edible oils. The current inves-tigation is primarily concerned with the usage of waste frying oil methyl ester (WFME) as a substitute for conventional diesel with titanium oxide (TiO2) nanoparticles as additives in a CRDI diesel engine. In this work, the influence of WFME blend ratio (0-20%), injection pressure (IP) (400-600 bar) compression ratio (CR) (16-20), and concentration of TiO2 nanoparticles (60-220 ppm) on various combustion parameters such as ignition delay (ID), maximum cylinder pressure (Pmax), combustion duration (CD), and heat release rate (HRR) were studied. The investigations were constructed with the use of a statistical technique known as Design of Experiments (DoE), which is based on the central composite design (CCD) of response surface methodology (RSM). The WFME biodiesel was found to be the best blend of input parameters at a 454 bar IP and 19.4 CR with diesel at 27.7% WFME biodiesel and 201 ppm TiO2 NPs. Moreover, the desired output at aforesaid optimum combinations exhibited Pmax 67.1 bar, HRR 72.95(J/CAD), CD 42.54 (CAD), and ID 8.12 (CAD). Confirmatory tests confirmed the estimated combination, and the forecasting error was found to be within 4%. When it comes to improving the engine's performance, RSM's combination works best.