Investigation of a Radial Turbine Design for a Utility-Scale Supercritical CO2 Power Cycle

Abstract

This paper presents the design procedure and analysis of a radial turbine design for a mid-scale supercritical CO 2 power cycle. Firstly, thermodynamic analysis of a mid-range utility-scale cycle, similar to that proposed by NET Power, is established while lowering the turbine inlet temperature to 900 ∘ C in order to remove cooling complexities within the radial turbine passages. The cycle conditions are then considered for the design of a 100 MW t h power scale turbine by using lower and higher fidelity methods. A 510 mm diameter radial turbine, running at 21,409 rpm, capable of operating within a 5% range of the required cycle conditions, is designed and presented. Results from computational fluid dynamics simulations indicate the loss mechanisms responsible for the low-end value of the turbine total-to-total efficiency which is 69.87%. Those include shock losses at stator outlet, incidence losses at rotor inlet, and various mixing zones within the passage. Mechanical stress calculations show that the current blade design flow path of the rotor experiences tolerable stress values, however a more detailed re-visitation of disc design is necessitated to ensure an adequate safety margin for given materials. A discussion of the enabling technologies needed for the adoption of a mid-size radial turbine is given based on current advancements in seals, bearings, and materials for supercritical CO 2 cycles.

A review of research on turbines for supercritical carbon dioxide power systems

“…The leakage flow and the limit streamline on the suction side sensitive to the turbulence model. El et al designed and introduced a radial turbine with a diameter of 510 mm and a rotational speed of 21409 rpm [81]. The results of CFD simulation show that the low end value of the turbine efficiency is 69.87%.…”

System Design and Application of Supercritical and Transcritical CO2 Power Cycles: A Review

“…A radial turbine can be used in a sCO 2 cycle owing to its low expansion ratio. El Samad et al (El Samad et al, 2020) designed a single-stage radial turbine for a 100 MW sCO 2 cycle. A total pressure of 29.7 MPa and a temperature of 1173 K were specified at the turbine inlet.…”