Design and CFD Analysis of a Radial-Inflow Turbine for Small Scale ORC Applications

In recent years, Organic Rankine Cycle (ORC) technology has received growing interests, thanks to its high flexibility and to the capability to exploit energy sources at temperature levels difficult to be approached with conventional power cycles. These features allow exploiting renewable and renewable-equivalent energy sources, by either improving the energy conversion efficiency of existing plants or using waste heat from industrial process. As far as the expander is concerned, a high potential solution is represented by turbo-expanders, which allow reduction of plant clutter and complexity, so enhancing the potential impact on the diffusion of small power ORC-based plants. The present work concerns the design of a RadialInflow Turbine for a bottoming Organic Rankine Cycle in the tens of kW scale. Design boundary conditions are retrieved by a zero-dimensional model of a solar-assisted micro gas turbine in cogenerating mode. The design process is started by means of an in-house mean-line design code accounting for real gas properties. The code is used to carry out parametric analyses to investigate the design space for several working fluids encompassing different classes, namely refrigerants and siloxanes. The program is used to assess the effect of design variables and working fluid on the turbine performance and turbine design characteristics. Subsequently, the most promising design candidates are selected and three-dimensional first guess stator and rotor geometries are built on these preliminary designs. Stationary and rotating passages are then meshed and analyzed by means of RANS CFD based solution of the stator – rotor interaction.

[1]  Fredrik Haglind,et al.  A methodology for the preliminary design and performance prediction of high-pressure ratio radial-inflow turbines , 2018, Energy.

[2]  Markus Preißinger,et al.  Significance of loss correlations in performance prediction of small scale, highly loaded turbine stages working in Organic Rankine Cycles , 2014 .

[3]  Andrea Lazzaretto,et al.  A mean-line model to predict the design efficiency of radial inflow turbines in organic Rankine cycle (ORC) systems , 2017 .

[4]  Rodney Persky,et al.  Loss models for on and off-design performance of radial inflow turbomachinery , 2019, Applied Thermal Engineering.

[5]  Giovanni Lozza,et al.  Design Criteria and Efficiency Prediction for Radial Inflow Turbines , 1987 .

[6]  Panagiotis Giannakakis,et al.  Off-design performance prediction of radial turbines operating with ideal and real working fluids , 2018, Energy Conversion and Management.

[7]  Antti Uusitalo,et al.  Organic Rankine Cycle Power Systems: From the Concept to Current Technology, Applications, and an Outlook to the Future , 2015 .

[8]  Matteo Pini,et al.  Method for the Preliminary Fluid Dynamic Design of High-Temperature Mini-Organic Rankine Cycle Turbines , 2017 .

[9]  Ronald H. Aungier,et al.  Preliminary Aerodynamic Design of Axial-Flow Turbine Stages , 2006 .

[10]  Andrew P. S. Wheeler,et al.  The Role of Dense Gas Dynamics on Organic Rankine Cycle Turbine Performance , 2013 .

[11]  Christos N. Markides,et al.  Working fluid replacement in supersonic organic Rankine cycle turbines , 2018 .

[12]  Matteo Pini,et al.  Design Method and Performance Prediction for Radial-Inflow Turbines of High-Temperature Mini-Organic Rankine Cycle Power Systems , 2019, Journal of Engineering for Gas Turbines and Power.

[13]  Apostolos Pesyridis,et al.  Axial Flow Turbine Concept for Conventional and e-Turbocharging , 2019, SAE Technical Paper Series.

[14]  Violette Mounier,et al.  Small scale radial inflow turbine performance and pre-design maps for Organic Rankine Cycles , 2018 .

[15]  Matteo Pini,et al.  Design Methodology for Supersonic Radial Vanes Operating in Nonideal Flow Conditions , 2018, Journal of Engineering for Gas Turbines and Power.

[16]  Raya Al-Dadah,et al.  Review of organic Rankine cycle for small-scale applications , 2017 .

[17]  D. G. Ainley,et al.  A Method of Performance Estimation for Axial-Flow Turbines , 1951 .

[18]  Vincent Lemort,et al.  Pure and Pseudo-pure Fluid Thermophysical Property Evaluation and the Open-Source Thermophysical Property Library CoolProp , 2014, Industrial & engineering chemistry research.

[19]  Vincent Lemort,et al.  Techno-economic survey of Organic Rankine Cycle (ORC) systems , 2013 .

[20]  Ronald H. Aungier.  Aerodynamic Performance Analysis of Axial-Flow Turbines , 2006 .

[21]  E. Macchi,et al.  Theoretical basis of the Organic Rankine Cycle , 2017 .

[22]  Brian Argrow,et al.  Supersonic minimum length nozzle design for dense gases , 1993 .

[23]  Daniele Fiaschi,et al.  Thermo-fluid dynamics preliminary design of turbo-expanders for ORC cycles , 2012 .