Date of Publication :8th May 2024

Abstract:Biogas, increasingly utilized in recent years as a renewable energy source, is derived from the decomposition of organic materials such as manure, sewage sludge, or crop fodder in anaerobic digesters. Its primary components include methane (about 40 to 70%), carbon dioxide (CO2, approximately 15 to 60%), and trace amounts of other gases (around 1 to 3%). Typically, biogas is refined into bio-methane for commercial purposes by purifying it, a process involving the removal of carbon dioxide through various technologies like absorption, adsorption, permeation, and cryogenic methods. Among these, cryogenic technology stands out as a widely employed method, relying on the phase change properties of individual gases within the mixture. The paper investigated the impact of these phase change properties on biogas using a modified Peng-Robinson equation of state. The results successfully quantified the phase change characteristics of biogas, further validated through experiments conducted with three different biogas compositions: 50% carbon dioxide (CO2) - 50% methane (CH4), 80% CO2 - 20% CH4, and 100% CO2. The disparities between the results derived from the mixture's equation of state and the experimental findings ranged from 3.5% to 26.9%, a variance deemed acceptable considering experimental uncertainties.

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