Thermodynamic Analysis of a Small-scale Biomethane Liquefaction Process

Liquid biomethane, obtained from anaerobic digestion of organic biomass, upgrading and liquefaction processes, is regarded as one of the most effective renewable biofuels to be extensively employed in the transport and power generation sectors for mitigation of greenhouse gas emissions. In this paper, a novel biomethane liquefaction process for small-scale plants is presented and thermodynamically assessed by means of a detailed thermodynamic model that employs the libraries of Fluid Prop, being very accurate for thermodynamic calculations of complex fluids. The thermodynamic model allows the heat exchanger geometry to be accurately determined and crucial parameters to be adjusted, such us the composition of the refrigerant and the operating conditions of both the biomethane and the refrigerant. The proposed model has general validity and can also be used to study the most promising biomethane liquefaction technologies for small-scale plants.