NextORC: Fundamental studies on organic Rankine cycle expanders

https://researchcentres.city.ac.uk/thermo-fluids/nextorc

EPSRC (EP/P009131/1)

City, University of London

£1,450,000

May 2017/ April 2021

Commercial steam power plants pressurise and heat water to produce steam which is then expanded to produce electricity. However, using an organic fluid permits low temperature heat sources, typically between 80 and 350°C, to be converted into mechanical power more economically than steam. Organic Rankine cycles (ORC) have a great potential to contribute to the UK’s mix of low-carbon technologies with promising applications such as combined heat and power, concentrated-solar power and waste-heat recovery from reciprocating engines and other industrial processes with waste heat streams. However, despite successful commercialisation of ORCs for industrial-scale applications, more development is required at the commercial and domestic scales before its potential can be realised. More specifically, at these small-scales, the challenge lies in the design of systems that are efficient but are also low cost. One approach to achieving this is to develop systems that operate efficiently over a range of different conditions. This will enable the high-volume, low-cost production of ORC systems, enabling significant improvements in the economy-of-scale. Furthermore, at this scale, different expander technologies, such as turbo and screw expanders, and system architectures can be considered. However, it is not clear which expander technology or system architecture is the optimal choice to achieve the desired improvements in the economy-of-scale. To answer this question, it is important to improve the understanding of how different ORC expanders perform across a wide range of operating conditions, and to investigate how these systems respond to changes in the working fluid.