Dimensional Variation and Parametrical Feasibility for Utilizing Aluminum Cast-House Flue Gases to Supplement Heat for the Organic Rankine Cycle (ORC)

This paper explores the industry's feasibility of using industrial exhaust gases to supplement an organic Rankine cycle (ORC) for energy harvesting and waste heat recovery. Three primary configurations were studied with six different dry and isentropic working fluids: (1) ORC driven by flue gas directly, (2) an integrated heat transfer through a thermos-oil circuit to ORC by flue gas, and (3) an enhanced heat recovery ORC drove by flue gas. The generator power output and cycle efficiencies were projected as performance indicators, while pressures, temperatures, and mass flows were altered accordingly. The results showed that adding an extra heat exchanger before the exit of the exhaust gases in Design II caused a > 14% increase in efficiency for pentane and isopentane. Design II reported a maximum power output as high as 10 MW and a first-law efficiency of 44% for isopentane. Combining the thermo-oil circuit in Design III for better heat transfer proved poor in this case and incurred a loss in efficiency and power. Co-current configured heat exchangers resulted in improved results compared with the counter-current configuration for all designs.