E3S Web Conf.
Volume 113, 2019SUPEHR19 SUstainable PolyEnergy generation and HaRvesting Volume 1
|Number of page(s)||6|
|Section||Energy Micropolygeneration and Harvesting|
|Published online||21 August 2019|
Design and off-design analysis of a Tesla Turbine utilizing CO2 as working fluid
Department of Industrial Engineering, Università degli Studi di Firenze, Viale Morgagni 40-44, 50134 Firenze (FI) Italia
* Corresponding author: email@example.com
The Tesla turbine is a bladeless expander; which principle of operation is based on the conversion of the viscous forces, developed by the flow while expanding through the rotor, in mechanical energy. It is especially suitable for small/micro size distributed energy systems (kW scale), mainly due to its very low cost, which results from the simple structure of the machine.
The Tesla turbine works well at relatively moderate expansion ratios. Therefore, it is fit for CO2 power cycles applications that are characterised by small expansion ratio, despite the high pressure involved. In this work, the design and off-design analysis of a Tesla turbine for small/micro power application utilizing CO2 cycles is proposed.
The optimized design was targeted for an inlet temperature of 150 °C and an inlet pressure of 220 bar. The final optimized geometry of the expander was defined, achieving a 23.4 W per channel power output with a 63% isentropic efficiency, when working with a 10.1 bar pressure drop at 2000 rpm. Furthermore, the turbine placement on the Baljè diagram was performed in order to understand the direct competitors of this machine.
Finally, starting from the design configuration, the maps of efficiency at variable load and flow coefficients and that of reduced mass flowrate at variable pressure ratio were realized. Through the merging of these curves, the off-design maps of the Tesla turbine were obtained, highlighting a very limited sensitivity of the efficiency to variable working conditions, if rotational speed is adequately adjusted.
© The Authors, published by EDP Sciences, 2019
This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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