Optimal design of organic rankine cycle driven by low-temperature waste heat

The exergy analysis of ORC unit driven by low-temperature waste heat was performed and an intuitive approach with simple impressions was developed to calculate the performances the ORC unit. Parameter optimization was conducted with turbine inlet temperature simplified as the variable and exergy efficiency or power output as the objective function by means of Penalty Function and Golden Section Searching algorithm based on the formulation of the optimization problem. The power generated by the optimized ORC unit can be nearly as twice as that generated by a conventional ORC unit. In addition, cycle parametric analysis was performed to examine the effects of thermodynamic parameters on the cycle performances such as thermal efficiency and exergy efficiency. It is proven that performance of ORC unit is mainly effected by the thermodynamic property of working fluid, the waste heat temperature, the pinch point temperature of the evaporator, the specific heat capacity of the heat carrier and the turbine inlet temperature under a given environment temperature.