Thermal analysis of a vacuum sealed flywheel

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Journal Title

Journal ISSN

Volume Title

Insinööritieteiden korkeakoulu | Master's thesis

Date

2021-08-23

Department

Major/Subject

Sustainable Energy Conversion Processes

Mcode

ENG3069

Degree programme

Master's Programme in Advanced Energy Solutions (AAE)

Language

en

Pages

49

Series

Abstract

The purpose of this thesis is to analyse the thermal control for a flywheel energy storage system, used to harness electric energy as mechanical rotational energy. The work is to be used as reference to possible improvements to be made in the next iteration of prototyping to meliorate the efficiency of the overall system. The thermal system is designed and analyzed under vacuum conditions. The heat transfer is simulated in ANSYS Fluent and Thermal and compared to the real-world system. Additionally, the analysis compares two states of operation, under vacuum conditions and under atmospheric conditions. All losses from the motor are converted into heat, and the hollow windings are used to pump the cooling fluid in the active coils. The heat generated at the motor assembly due to copper losses and hysteresis losses as the permanent magnet machine rotates around a ferrite core, is calculated and compared to the real world heat measured by the rising temperatures at the cooling fluids. The most temperature sensitive components are the permanent magnets found at the top, center and bottom of the rotor which have a demagnetization temperature of approximately 150◦C. Additionally, the rotor is a composite of carbon fiber and resin, which has a curing temperature of around 140◦C. As the rotor operates under full levitation, the only means to dissipate heat from the rotor is via radiation to either the external housing, or the outer face of the stator. The results suggest that the overall system could experience high temperatures at longer operations, therefore improvements are required. Suggestions are proposed for future iterations of the machine to enhance the performance and efficiency of the overall system.

Description

Supervisor

Larmi, Martti

Thesis advisor

Sokolov, Maksim

Keywords

ANSYS thermal, flywheel energy storage, internal cooling, electrical machine losses

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