Thermo-economic optimization of small-scale organic Rankine cycle: a case study for low-grade industrial waste heat recovery

Abstract

This work is focused on a case study of a small-scale Organic Rankine Cycle (ORC) adopted for electricityproduction from low-grade industrial waste heat recovery. This kind of applications raises a great in-terest due to the high amount of low-grade waste heat recoverable within industrial processes, but lacksof in-depth experimental investigations on the topic. The main reason is the difficulty to reach profitablesmall-scale projects, so more cost-effective solutions are being explored in the literature throughthermo-economic optimizations. Nonetheless, the results obtained cannot be discussed with respect toactual operating data. In light of this, this paper proposes to conduct the thermo-economic optimizationon the basis of an experimental application. In this manner, a comprehensive model of the facility isdeveloped, calibrated, and validated from actual operating data. The model is used to conduct thethermo-economic optimization, revealing the influence of the organicfluid, cycle architecture, geometricparameters of main components, or control strategy used to obtain the best cost-effective solution. Themain results show that, by means of a multivariable optimization using cost-effective ratios as objectivefunction, a cheaper and powerful solution adapted to each specific project may be designed.