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Initial testing of a parallel-flow microturbine using automotive turbochargers
Dissertation (MEng (Mechanical Engineering))--University of Pretoria, 2025.
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| Format: | Thesis |
| Language: | English |
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University of Pretoria
2025
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| _version_ | 1869483914566828032 |
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| access_status_str | Open Access |
| author2 | Le Roux, Willem G. |
| author_browse | Le Roux, Willem G. |
| author_facet | Le Roux, Willem G. |
| collection | Thesis |
| dc_rights_str_mv | © 2024 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Dissertation (MEng (Mechanical Engineering))--University of Pretoria, 2025. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/107294 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-07-01T04:06:34.257Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2025 |
| publishDateRange | 2025 |
| publishDateSort | 2025 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/107294 Initial testing of a parallel-flow microturbine using automotive turbochargers Le Roux, Willem G. u18170499@tuks.co.za Humphries, Evan David UCTD Sustainable Development Goals (SDGs) Microturbine Brayton cycle Turbocharger Cogeneration Parallel-flow Dissertation (MEng (Mechanical Engineering))--University of Pretoria, 2025. Micro gas turbines have become increasingly popular for small-scale power generation. The Brayton cycle, on which micro gas turbines are based, requires a heat input – this heat can come from many sources including concentrated solar, petrol and even hydrogen. Single shaft microturbines generally have a large initial cost and a high degree of complexity. The generator is typically attached to the same shaft as the turbine and the compressor, rotating at high speeds of around 80 kRPM and upwards, which means expensive power electronics are usually required. Multi-shaft layouts, including a recently introduced low-temperature turbine (LTT) parallel-flow cycle, simplify some of these issues by using a separate power turbine for the electrical power generation. However, parallel-flow microturbines have not been tested and validated by experiments. The objective of this study was to evaluate the accuracy of analytical and simulated models of parallel-flow microturbines developed from automotive turbochargers by systematically validating them against experimental data. This dissertation is divided into three main sections which include analytical calculations, Flownex® simulations and experimental testing. The analytical approach uses the first principles of thermodynamics, heat transfer and fluid mechanics to predict performance. The simulations were used to initially determine the most promising layouts and were then validated against experimental results. The power turbine in the investigated LTT cycle was limited to a speed of below 40 kRPM, the typical limit of a standard gearbox, therefore the coupling to a generator was made simpler. The parallel-flow LTT combination of the GTX 4088 R and GT 2052 turbochargers was tested experimentally and used to improve and validate Flownex® models of parallel-flow microturbines with piping, gearbox and bearing losses included. The Flownex® model predicted the performance of the experimental setup within 10 % for all performance parameters except heat input, which was within 15.2 %. The Flownex® simulations showed that the combination of the GTX 4088 R and the GT 2052 as the power turbine could have produced 3.97 kW at 1.32 % efficiency while the power turbine is operating at 40 kRPM, but with a gasifier turbine inlet temperature above the maximum allowable temperature of 1050 ˚C. The Flownex® simulations conveyed that the parallel-flow LTT combination of the GTX 4088 R as the gasifier and the GBC 14 as the power turbine could produce 3.26 kW at 1.09 % efficiency, with the power turbine operating at a speed of 40 kRPM and with the gasifier turbine’s inlet temperature below 1050 ˚C. The results showed that this parallel-flow combination can outperform both the single shaft GTX 4088 R and the single shaft GBC 14 when operating at the same speed of 40 kRPM. The validated Flownex® model proved to be a useful tool in predicting the performance of parallel-flow microturbines and can benefit future work on parallel-flow microturbines. Department of Science, Technology and Innovation Mechanical and Aeronautical Engineering MEng (Mechanical Engineering) Restricted Faculty of Engineering, Built Environment and Information Technology SDG-07: Affordable and clean energy 2025-12-22T09:20:17Z 2025-12-22T09:20:17Z 2026-05-14 2025-12-10 Dissertation * A2026 http://hdl.handle.net/2263/107294 10.25403/UPresearchdata.30847298 en © 2024 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | UCTD Sustainable Development Goals (SDGs) Microturbine Brayton cycle Turbocharger Cogeneration Parallel-flow Initial testing of a parallel-flow microturbine using automotive turbochargers |
| title | Initial testing of a parallel-flow microturbine using automotive turbochargers |
| title_full | Initial testing of a parallel-flow microturbine using automotive turbochargers |
| title_fullStr | Initial testing of a parallel-flow microturbine using automotive turbochargers |
| title_full_unstemmed | Initial testing of a parallel-flow microturbine using automotive turbochargers |
| title_short | Initial testing of a parallel-flow microturbine using automotive turbochargers |
| title_sort | initial testing of a parallel flow microturbine using automotive turbochargers |
| topic | UCTD Sustainable Development Goals (SDGs) Microturbine Brayton cycle Turbocharger Cogeneration Parallel-flow |
| url | http://hdl.handle.net/2263/107294 |