ADAPTATION OF AUTOMOBILE GASOLINE ENGINE FOR WORK ON MIXED FUEL WITH BIOETHANOL

Due to the introduction in Ukraine, as of May 1, 2025, of new environmental standards mandating the inclusion of at least 5% bioethanol in gasoline with an octane number below 98, the issue of adapting used automotive gasoline engines to operate on blended fuel has become increasingly relevant. Bioethanol, as a renewable energy source, possesses different physicochemical properties compared to gasoline, which affects the combustion process and, consequently, influences the engine's power output, fuel efficiency, and environmental performance. This study analyzes the impact of bioethanol addition on fuel–air mixture parameters, particularly changes in the air–fuel equivalence ratio, calorific value, and ignition boundaries. The stoichiometric ratios of gasoline–air and bioethanol–air mixtures differ, which can disrupt the quality of the prepared combustible mixture and, subsequently, alter engine performance indicators such as power and efficiency. The reduced calorific value of the bioethanol–gasoline mixture may lead to a decrease in engine power—potentially by up to 40%. When adding 25% bioethanol to gasoline, the calorific value of the fuel–air mixture decreases by 9%, which can result in a proportional reduction in engine power. At bioethanol concentrations of 30–60%, the mixture may fall outside the ignition range, rendering it ineffective without additional technical solutions. Modern approaches to engine adaptation are reviewed, including fuel delivery correction based on ethanol content sensors and oxygen sensors in the exhaust gases (closed-loop control), followed by calculations of bioethanol concentration. It is noted that most modern engines can operate on fuel containing up to 15% ethanol without modifications. However, higher ethanol concentrations require both hardware and software upgrades, such as the installation of devices like the Digital E85 Adapter or ECU software modifications. The findings emphasize the need for both theoretical and experimental research to ensure effective engine adaptation to the new fuel standards.