COMPARATIVE PERFORMANCE STUDY OF A MODIFIED GASOLINE ENGINE WITH THROTTLE-VALVE-DRIVEN MECHANICAL HYDROGEN INJECTOR

In this study, a single-cylinder, air-cooled, 4-stroke, spark-ignited internal combustion engine was modified to operate with both gasoline and gas-phase hydrogen. The engine cylinder cover was redesigned, and an enhanced mechanical hydrogen injector was attached to it. Measurement devices capable of capturing all critical test parameters for comparison purposes were integrated into the test engine. Additionally, all necessary safety equipment was adapted to ensure the safe delivery of hydrogen to the engine. The engine was initially tested with gasoline, and values for engine torque, brake power, specific fuel consumption, TE, and VE were recorded at air throttle openings of 20º to 90º in 10º increments and speeds ranging from 1000 to 3900 rpm. The same parameters were then measured using gas-phase hydrogen. In the experiments conducted with gasoline, optimal performance was achieved at air throttle openings of 60º to 90º and engine speeds of 2350 to 3400 rpm. In the experiments using hydrogen, the most favorable values were observed between 1300 and 1775 rpm at a 30º air throttle opening. When comparing the performance of gasoline and hydrogen in the same engine, results indicated that using gaseous hydrogen led to a 79.54% reduction in engine power and a 73.44% decrease in engine torque. This reduction is considered typical, given that the lower calorific value of hydrogen in the gas phase, at the same pressure and temperature (1 bar, 20 ºC), is approximately 0.010 MJ/l, compared to around 34 MJ/l for gasoline. During testing, issues such as knocking, pre-ignition, and backfire typically associated with intake manifold injection did not occur. No prior studies have employed a direct hydrogen injection method into the combustion chamber with a mechanically activated Hydrogen Injector driven by the intake valve.