Thermodynamic performance analysis of power, heating, cooling and hydrogen production in a factory waste heat-supported combined cycle

As energy demand increases with population growth and technological advancement, fossil fuel consumption and greenhouse gas emissions rise, intensifying global warming. Improving energy efficiency and integrating renewable sources have become critical. According to IEA data, a significant portion of Turkey's emissions originates from the industrial sector, highlighting the importance of utilizing waste heat to enhance energy and exergy efficiency. This thesis presents a multigeneration energy system designed to utilize factory flue gas waste heat for power generation, heating, cooling, and hydrogen production. The system incorporates an Organic Rankine Cycle (ORC), an Absorption Cooling System (ACS), photovoltaic panels, and a Proton Exchange Membrane (PEM) electrolyzer. Thermodynamic analyses were conducted, including energy and exergy efficiency calculations, mass and energy balance equations for each component, and exergy destruction assessments. Key parameters such as waste heat flow rate and temperature, heat exchanger contact temperature, turbine isentropic efficiency, and evaporator temperature were investigated. Results showed ORC energy efficiencies of 38.91% and 9.33%, with exergy efficiencies of 16.73% and 29.77%. The ACS yielded energetic and exergetic performance coefficients of 0.2785 and 0.13, respectively. Heating and cooling loads, net power output, and hydrogen production were 360.4 kW, 143.8 kW, 57.79 kW, and 0.00007348 kg/s. The system's sustainability index was calculated as 1.29. These findings demonstrate that the proposed multigeneration system offers notable advantages in industrial energy recovery and efficiency.