Thermodynamic assessment of the integration of biogas-fueled internal combustion engines and absorption refrigeration systems

• The model's power output aligns with the manufacturer's value with a 0.5% difference. • Complete combustion of the reference fuel was achieved in the reactor. • Lower thermal power (31.6%) due to non-pure CH4 biogas usage. • Major irreversibility (94%) occurs during combustion in the cogeneration cycle. • Global exergy efficiency improved by using waste heat for absorption cooling. An energy and exergy analysis of a cogeneration system integrating a biogas-fuelled Internal Combustion Engine (ICE) and an Absorption Refrigeration System (ARS) is presented, using DWSIM software for simulation. The study is based on mass and energy balances to determine the thermal efficiencies according to the first law of thermodynamics, and exergy balances to evaluate the individual efficiencies of the ICE, the ARS and the overall system. The ICE delivered a power output of 1452 kW with a thermal efficiency of 31.68%, while the ARS extracted 153.06 kW of cooling power with a coefficient of performance (COP) of 0.13 and an exergy efficiency of 31.62%. The overall energy efficiency of the system was 35.01%, with a 3.33% improvement due to heat recovery from the ICE exhaust gases. The exergy analysis showed that 75.42% of the total irreversibilities occurred during the combustion process, resulting in an exergy efficiency of 31.39% for the ICE. The overall exergy efficiency of the integrated CHP system was 36.90%, demonstrating the potential of biogas-based CHP systems to improve energy utilisation and support rural electrification strategies.