Energy and exergy analysis of the organic Rankine cycle used for recovering waste heat from the cement industry.

The limitation of global fossil fuel resources has had a significant impact in recent years. Iran wastes 570 million barrels of oil out of the allocated 1463 million barrels for the residential, industrial, and transportation sectors. The cement industry, as one of the high-energy consumers, accounts for approximately 14% of the country's industrial energy consumption, with about 40% of this energy being lost during production processes. This study aims to recover the waste heat from the cement industry using the Rankine cycle and simulate it using the Engineering Equation Solver (EES) software. Additionally, a thermal oil loop has been employed to prevent corrosion of heat exchangers and control the organic fluid evaporation process. Ethanol has been selected as the suitable working fluid, with a net power production capacity of 6213 kW, a thermal efficiency of 91.22%, and an exergy efficiency of 18.24%, outperforming R123, R1233zd(E), R1234ze(Z), and R600a. Increasing the turbine's inlet pressure by 100 kPa increases thermal and exergy efficiencies by 2.7% and 2.67%, respectively, while decreasing the mass flow rate into the evaporator by 5.6%. Increasing the condenser temperature by one degree results in approximately a 5.6% reduction in thermal efficiency and a 5.5% reduction in exergy efficiency.