Energy Recovery from biogas: internal combustion engines coupled with Organic Rankine Cycle

A specific thermodynamic analysis of organic Rankine cycle, in reference to different sizes of internal combustion engines conventionally used for biogas/landfill gas, was carried out, considering several working fluids, different cycle configurations (simple cycle or regenerated cycle) and conducting a parametric analysis in order to determine optimal evaporating pressures for each fluid. The analysis demonstrates that the overall efficiency can be increased by 1,7-4,7 percentage points and the power can be incremented by 5-13% with respect to the engine without any bottoming cycle, depending on the organic fluid and the type of engine.