Effects of the hydrogen and methane fractions in biosyngas on the stability of a small reciprocated internal combustion engine

A bio-syngas, produced from wood biomass gasification, is used with a small reciprocated spark ignition engine for higher thermal efficiency. In this experiment, as the knocking doesn’t occur even though the ignition timing is 70 deg-BTDC (before top dead center), the MBT, most-advanced for best torque ignition timing, couldn’t be determined. This phenomena, without knocking combustion, are reported by several researchers. In this report, the way to determine the ignition timing for the maximum efficiency is shown. With the cylinder pressure measurement, when the maximum heat release rate position is set near TDC, top dead center, the thermal efficiency shows the maximum and the stability shows the best in any hydrogen fraction or any methane fraction of the mixed fuel.Po. •Maximum heat release rate near top dead center gave best efficiency and stability.•Knocking did not occur when “raw” biosyngas was used.•Ignition timing needed retarding as the hydrogen fraction in the fuel increased.•Methane fraction in the fuel did not strongly affect the efficiency or stability.