Using numerical analysis and the ANSYS Forte 19.2 package, this study investigates the performance, combustion, and emission characteristics of dual-fuel operation using ethanol as a partial substitute for diesel in a direct injection compression ignition engine. The study discovered that adding ethanol to diesel engines reduces peak cylinder pressure and temperature due to its evaporative cooling qualities, with a maximum error of only 2.5%, exhibiting remarkable alignment between simulation and experimental data. The experiment was conducted on a modified single cylinder direct injection CI engine with an ethanol port injector controlled purely by Arduino software. The tests were carried out with different Ethanol substitutions at varied engine loads (0, 20%, 40%, 60%, 80%, and 100%). The study looked at the performance and emissions of a DI CI engine with ethanol substitutes of 10%, 20%, and 30%, with E10 outperforming and E30 outperforming, but caution is urged due to increased energy degradation. E10 and E20 ethanol replacements dramatically cut CO, HC, and NO emissions in diesel engines, improving environmental performance with modest changes.