Working fluids for low-temperature waste heat from coal-fired unit for the Organic Rankine Cycle (ORC)

Abstract

Abstract With the process of industrialization, a lot of energy is consumed, and a lot of low-grade energy is produced in the process. To recover low grade heat energy from flue gas of coal-fired power plants, the organic Rankine cycle is built and improves energy utilization efficiency. Taking six working fluids, R245ca, R245fa, R123, R600, R601, and R600a, as an example, referring to the exhaust gas condition of a 300MW subcritical coal-fired unit, analysed the evaporation temperature on the net work and thermal efficiency and exergy efficiency, the influence of electricity production cost (EPC) and payback period (PBP). The results show that the net work of R123 is the largest with the same conditions, which improves the system performance. At an evaporation temperature of 400K with the objective of reaping the economic benefit, R245ca and R601 as equivalent values are able to be used in engineering.