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Hydrogen was used to operate a single cylinder engine in homogeneous charge compression ignition (HCCI) mode. The engine was a modified 435 cm3 single cylinder air cooled Yanmar L100V direct injection (DI) compression ignition (CI) engine. The original diesel fuel injection system was removed and a hydrogen port fuel injection (PFI) system was added, along with a 1 kW intake air heater. The piston was modified from the original re-entrant bowl piston to a dish shaped piston, while maintaining the original 21.2:1 compression ratio. The engine speed was maintained at a constant 1800 RPM. Three hydrogen fueling conditions of 25, 30, and 35 slpm were investigated, which corresponded to an excess air ratio (λ) of roughly 4.38, 3.64, and 3.16, respectively The fuel conversion efficiency for the conditions tested ranged from 23% - 27%.

This study investigates the combustion and emissions of a compression ignition (CI) engine operating with mixtures of hydrogen (H₂) and carbon monoxide (CO) injected with the intake air. Hydrogen and carbon monoxide were chosen as the gaseous fuels, because they represent the main fuel component of synthesis gas, which can be produced by a variety of methods and feed stocks. However, due to varying feed stock and production mechanisms, syngas composition can vary significantly. It is currently unknown how a varying H₂/CO (syngas) ratio affects the cycle efficiency and gaseous emissions. The experiments were performed on an air-cooled, naturally aspirated, direct injection diesel engine. The engine was operated at 1800 RPM with a compression ratio of 21.2:1. Two load conditions were tested; 2 bar and 4 bar net indicated mean effective pressure (IMEPⁿ). For all test conditions the added syngas demonstrated lower cycle efficiency than the diesel fuel baseline.