City Research Online

Abstract

This paper presents a complete radial turbine design methodology intended for the design of a small scale organic Rankine cycle (ORC) turbo expander. The design methodology is comprised of 1D meanline design, coupled with REFPROP for real fluid properties, and 3D geometrical construction of the turbine rotor, stator and volute. A novel method to predict the rotor passage velocity distribution also enables the rotor passage to be effectively designed to ensure a smooth expansion without requiring CFD analysis. The design method is used to construct two test turbines with target isentropic total-to-static efficiencies of 85%. The first expands air from 282.3kPa and 1073K with a total-to-static pressure ratio of 3 and mass flow rate of 0.1kg/s. The ORC turbine expands R245fa from 350K and 623kPa, with a pressure ratio of 2.5 and mass flow of 0.7kg/s. Comparison with design point CFD validates the turbine design program, predicting a mass flow rate of 0.104kg/s for the air turbine at the design point with a total-to-static isentropic efficiency of 84.73%. At the design mass flow rate and rotational speed, the ORC turbine achieves a total-to-static pressure ratio of 2.51 and a total-to-static isentropic efficiency of 84.87%.

Publication Type:	Conference or Workshop Item (Paper)
Publisher Keywords:	Design, Low temperature, Turbines, Organic Rankine cycle
Subjects:	T Technology > TJ Mechanical engineering and machinery
Departments:	School of Science & Technology > Engineering

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