Optimization of combustion and performance parameters by intake-charge conditions in a small-scale air-cooled hydrogen fuelled SI engine suitable for use in piston-prop aircraft

Abstract

Purpose Spark ignition (SI) engines are used in a wide area in the transportation industry, from road vehicles to piston-prop aircraft. On the other hand, the decrease in reserves of fossil fuels used in SI engines and the increase in greenhouse gas emissions makes the use of alternative fuels inevitable. In this paper, optimization of in-cylinder combustion and engine performance parameters by intake-charge conditions [i.e. intake-air temperature, injection timing and exhaust gas recirculation (EGR)] in a hydrogen (H2)-fueled small SI engine is performed. Design/methodology/approach Experimental studies were performed at a 1,600 rpm engine speed of a single-cylinder, air-cooled engine having a stroke volume of 476.5 cm3, maximum output power of 13 HP and torque of 25 Nm. The hydrogen-fueled SI engine was operated by a lean air-fuel mixture (ϕ = 0.6) under wide-open throttle (WOT) conditions. Findings The findings of the paper show that improvements can be achieved in in-cylinder combustion, indicated engine performance, exhaust NOx emissions with optimum intake-air temperature, the start of H2 injection and the ERG rate. Practical Implications It has been determined that a 32°C intake-air temperature, 395°C (bTDC) start of H2 injection, and 5%–10% EGR rates are the most suitable values for the examined hydrogen fueled SI engine. Originality Value Hydrogen is a usable alternative fuel for SI engines used in a wide area from road vehicles to piston-prop aircraft engines. However, a number of problems remain that limit hydrogen fueled SI engines to some extent, such as backfire, a decrease of engine power, and high NOx emissions. Therefore, it is appropriate to examine the effects of intake-charge conditions on in-cylinder combustion, engine performance, and NOx emissions parameters in a hydrogen fuelled SI engine.