Performance Analysis on Low-Temperature Waste Heat Power Generation System of Aluminum Reduction Cell

The performance of an organic Rankine cycle (ORC) system to recover low-temperature waste heat from aluminum reduction cell is presented. The mass flow rate of waste heat is 69.5kg/s and minimum temperature difference between waste heat and working fluids is 10 degrees C. The results show that for the same pinch point, there is an optimal evaporating temperature for maximum net power. Among the several researched working fluids, R227ea gives highest net power for heat source temperature range of 100 degrees C-140 degrees C and R236fa produces the highest power in the range of 150-170 degrees C. When the temperature is greater than 180 degrees C, R236ea generates the maximum net power. The maximum net power for the waste heat increases from 306kW to 1425kW as heat source temperature increases from 100 degrees C to 200 degrees C. It can reduce the consumed energy for production of one ton aluminum from 0.7 to 3.3 percent.