Combustion of simulated biogas in a dual-fuel diesel engine

Abstract

Technology related to biogas has been steadily developed over the last 50 years from small individually designed units to larger production plants. The development, however, has largely taken place on the side of biogas production and anaerobic waste treatment. Utilization of the gas produced by these methods has only recently been the subject of more scientific evaluation. The transformation of energy through biogas into the thermodynamically higher valued mechanical energy successfully and economically is now the most important research area in this field.Of the engine work already published, most concerns spark-ignited engines. The authors’ research work concerns the use of biogas in dual-fuel diesel engines. It examines engine performance using simulated biogas of varying quality representing the range of methane:carbon dioxide composition which may be encountered in gas from different sources. The total programme includes the effects of biogas quality and of the proportion of energy from pilot fuel injection over a range of speeds and loads, investigations into the performance parameters over a range of compositions of gaseous mixture. A two-cylinder, indirect-injection diesel engine of stationary type is being used as the first experimental test bed in this work and the variation of quality is provided by mixing natural gas and carbon dioxide. A data acquisition system for in-cylinder pressure and crank angle is being used successfully and some emissions measurements are also available, particularly for CO and O2.One of the authors is from India where there is thought to be considerable potential for exploiting the gaseous products from resources such as biogas, landfill and sewage gas through small stationary dual-fuel engines for irrigation and CHP applications. The nature of combustion process in the dual-fuel engine is examined by the authors through pressure-crank angle data and studies of characteristics affecting engine efficiency.