A comparative review of ORC and R-ORC technologies in terms of energy, exergy, and economic performance

Abstract

This review examines Organic Rankine Cycle (ORC) technology, which generates electricity using organic fluids at low temperature ranges. To enhance the efficiency of basic ORC systems, they are often adapted into Regenerative Organic Rankine Cycle (R-ORC) systems. The review highlights the dimensions of economic, energy, and exergy efficiency, which are critical for practical application. Factors like the choice of working fluid, heat source temperature, and heat exchanger efficiency significantly affect economic feasibility; suboptimal choices can reduce returns and hinder project viability. Strategic decisions can improve economic outcomes and make ORC technology more appealing, as improved efficiency often leads to better economic performance through increased energy output and reduced operational costs. ORC and R-ORC systems promote sustainable energy production by enhancing energy efficiency in various applications, including geothermal power plants, industrial waste heat recovery, biomass energy production, and solar power plants. By enabling electricity generation even at low temperatures, these systems efficiently utilize existing energy sources, reduce dependence on fossil fuels, and minimize environmental impacts, thus providing both economic and ecological benefits. Additionally, when the studies conducted are examined, R-ORC exhibits higher performance than basic ORC. R-ORC is significantly superior to ORC in terms of both energy and exergy efficiency. Specifically, in terms of energy efficiency, R-ORC has been found to be 1.83 %–25.5 % more efficient. Regarding exergy efficiency, R-ORC demonstrates approximately 7.69 % better performance. Furthermore, due to these increases in efficiency, it has been determined that R-ORC also provides a more positive economic contribution compared to ORC. Thus, comparisons between ORC and R-ORC systems play a significant role in sustainable energy production and offer valuable guidance for future research. The limitations of ORC and R-ORC systems include limited efficiency due to low temperature differentials, the environmental impact of the organic fluids used, and high costs. © 2024 The Authors