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This paper presents a methodology for a rapid determination of biogas composition using easily detectable physical properties. As biogas is mainly composed of three constituents, it is possible to determine its composition by measuring two physical properties and using specific ternary diagrams. The first part of the work deals with the selection of two physical properties, which are easy and inexpensive to measure, from a group comprising thermal conductivity, viscosity and speed of sound. Then, in the second part, a model to express these properties in terms of ternary composition is presented. It is demonstrated that the composition of a ternary gas mixture can be determined with good precision using the above. The model is applied to specific situations such as the online determination of the lower heating value of biogas without any complicated apparatus like calorimeters or batch techniques (gas chromatographs).

Performance of a compression ignition engine fuelled with animal fat and its emulsions as fuel is evaluated. A single cylinder air-cooled, direct injection diesel engine developing a power output of 2.8 kW at 1500 rev/min is used. Base data is generated with standard diesel fuel. Subsequently, animal fat is modified into its emulsions using water and methanol. Comparison is undertaken with diesel, neat animal fat and its emulsion as fuels. Results show improved performance with animal fat emulsions as compared to neat fat. Peak pressure and rate of pressure rise are increased with animal fat emulsions due to improved combustion rate. Heat release pattern shows higher premixed combustion rate with the emulsions. Higher ignition delay and lower combustion duration are found with animal fat emulsions than neat fat. Drastic reduction in black carbon smoke and NO are found with the emulsions as compared to neat animal fat and neat diesel.