Organic Rankine cycle performance evaluation and thermoeconomic assessment with various applications part II: Economic assessment aspect

Abstract

Exploration and utilization of the waste or renewable energy become more and more important for power generation in organic Rankine cycle (ORC) systems in recent decades. In this study the economic assessment under different ORC configurations has been investigated for working fluids for different applications with the assumption that the net power output remains constant. A lower condensing temperature or a higher evaporating pressure can lead to a lower specific cost per kilowatt hour. With the heat source domain increased from the geothermal application to the high temperature solar/biomass application, the operating evaporating pressure can be extended and a lower specific cost per kilowatt hour can be achieved within the appropriate pressure region. In general, the ORC with internal heat exchanger (IHX) has the close specific cost to the baseline ORC due to the additional cost of the IHX for the low heat source domains. With the heat source scale lifted to the high level, a decrease of specific cost per kilowatt hour up to 10% for the cycle with IHX compared with that of the baseline cycle. The specific cost per kilowatt hour for the reheat ORC is the highest among the current ORC configurations, while the regenerative ORC can achieve the lowest specific cost, with approximately 5–10% specific cost reduction from the baseline for various applications, whose economic benefits indicate it can be a promising alternative for ORC applications. In addition, the effect of IHX effectiveness, reheat pressure and regenerative intermediate pressure on the economic assessment has been revealed to outline the economic merits of ORC systems.