Low-Energy Synthesis Gases from Waste as Energy Source for Internal Combustion Engine

The aim of this article is to analyze the energy recovery of synthesis gases in an internal combustion engine, in terms of both their general behavior and recommendations for their future composition in production. This article presents an experimental analysis of power and economical parameters of internal combustion engine as a source of propulsion for a cogeneration unit. The power parameters were measured using 13 various low-energy synthesis gases as fuels. Most of them are methane-free synthesis gases. The main components of these synthesis gases were hydrogen, carbon monoxide, methane, carbon dioxide, and nitrogen. The composition of the synthesis gases responded to various waste gasification technologies. The mass lower heating value of the selected synthesis gases ranged from 4 to 8 MJ/kg. The combination of these gases in stoichiometric mixture with air gives an idea of the effect of the combustible components in the mixture on the overall engine parameters achieved. The results were compared with the reference fuel methane. For the measured group of synthesis gases, at full load of the naturally aspirated spark-ignition engine (swept volume 686 cm³), at set optimum angle of ignition advance and revolutions at 1500 1/min, the drop in power parameters, compared to methane, was between 18 and 40%; the increase of the hourly fuel consumption was higher by 550%, up to 900%. The decrease of the overall effective efficiency ranged between 2.2 and 4.5%. The combustion of the measured synthesis gases had similar characteristics as were the characteristics of natural gas combustion, or methane, that was without signs of abnormal combustion. The conclusions of the experiments point out that at revolutions 1500 1/min, the power parameters of a combustion engine, or a cogeneration unit, burning stoichiometric mixture, rise approximately linearly, with rising lower volumetric heating value of the mixture. On the other hand, with rising mass lower heating value of the fuel the hourly consumption of the synthesis gases approximately linearly decreases. Recommendations are given for the composition of synthesis gases as to their production, which are directly applicable in practice. The presented results can help to understand how to set waste gasification processes in order to influence and achieve optimum power and economical parameters of combustion engines or cogeneration units.