Akademik Veri Yönetim Sistemi
Energy Conversion and Management, cilt.348, 2026 (SCI-Expanded, Scopus)
This study evaluates the use of waste heat from a cogeneration unit for electricity generation via an Organic Rankine Cycle (ORC) and for on-site digestate drying into fertilizer, based on real operational data from a biogas plant in Kocaeli, Türkiye. The integrated ORC-dryer system was analyzed and an electrical output of 39.10 kWe was achieved with an electrical efficiency of 15.42 % using cyclopentane as the working fluid. Cyclopentane demonstrated the highest electricity production at lower condenser temperatures, whereas at elevated condensation temperatures typical of cogenerative applications hexane and MM (hexamethyldisiloxane) showed superior cycle performance. Electrical efficiency of the plant increased from 38.63 % to 40.73 %, while its exergy efficiency improved from 37.03 % to 39.10 %. A contact-type dryer was used for digestate drying and a specific energy consumption of 3915 kJ/kg Water was observed. Considering both electricity and fertilizer sales, the maximum total daily revenue of $417.74 was achieved using cyclopentane at condenser temperature of 90 °C of which $124.74/day was attributed solely to electricity sales. In terms of environmental perspective, the analysis revealed that the highest emission savings, amounting to 18369 kg CO2/year, were achieved when cyclopentane was used as the working fluid in combination with a condenser temperature of 90 °C. By integrating novel cascade ORC and paddle dryer system into the biogas plant with design and off-design conditions, additional electricity and fertilizer is produced using waste heat. Even under off-design conditions, this integration enhances the plant’s efficiency and profitability, improves its overall feasibility and contributes to a reduction in CO2 emissions.