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The development of a recuperator for a solar hybrid micro gas turbine system
Thesis (MEng)--Stellenbosch University, 2023.
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| Format: | Thesis |
| Language: | en_ZA en_ZA |
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Stellenbosch : Stellenbosch University
2023
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| _version_ | 1867613938306252800 |
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| access_status_str | Open Access |
| author | Afeltra, M. F. |
| author2 | Van der Spuy, S. J. |
| author_browse | Afeltra, M. F. Van der Spuy, S. J. |
| author_facet | Van der Spuy, S. J. Afeltra, M. F. |
| author_sort | Afeltra, M. F. |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEng)--Stellenbosch University, 2023. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/127027 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA en_ZA |
| last_indexed | 2026-06-10T12:44:05.289Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2023 |
| publishDateRange | 2023 |
| publishDateSort | 2023 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/127027 The development of a recuperator for a solar hybrid micro gas turbine system Afeltra, M. F. Van der Spuy, S. J. Hoffmann, J. E. Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering. Counterflows (Fluid dynamics) Turbochargers Renewable energy sources Thesis (MEng)--Stellenbosch University, 2023. ENGLISH ABSTRACT: Concentrated solar power (CSP) provides a dispatchable form of electricity due to its energy storage capabilities and adds flexibility to the power network. CSP coupled with a micro gas turbine (MGT), creates a suitable technology for supplying low-carbon electricity to off-grid regions. The solar hybrid micro gas turbine (SHMGT) has the capability of replacing diesel generators, thus reducing operating costs and fuel consumption. For these reasons, Stellenbosch University is involved in the research of SHMGTs. The thermal efficiency of the current MGT system is relatively low and a method of improving this performance metric is through the implementation of a recuperator. Using a recuperator will reduce the combustion chamber’s heating requirement, reducing the fuel required to maintain combustion. Due to its simplicity and cost-effectiveness, a clamped-plate style recuperator design was selected. A significant challenge in the design of the recuperator was the balance of the thermal-hydraulic design constraints, namely the heat transfer effectiveness and the allowable pressure drop. The design was adapted to fall within the project budget by sacrificing effectiveness for pressure drop. With leakage in the system after two successive rounds of sealing the recuperator with two different high-temperature sealants, the design was concluded to be leak inherent. A different method of sealing was proposed with the use of a high-temperature gasket. Experimentation of the recuperator revealed that the MGT system could not self-sustain. This was partly due to an unexpectedly significant pressure drop over the recuperator. This was attributed to flow maldistribution within the headers, which was indicated by the thermal degradation on the recuperator when operated above the limit of 650 ◦C. An improved header design was therefore proposed. The switch-over method used to couple the MGT system was also found to be non-ideal for recuperated operation. It was found that the SHMGT combustion chamber was not suited to high temperature inlet flows due to the accompanying significant induced pressure drop. The recuperator’s effectiveness was obtained in a decoupled state of operation and was verified analytically to be in the range of 0.74 to 0.77. A validated Flownex model of the MGT system was produced, in which the recuperator was included. A case study was performed in Flownex, where the power turbine and accompanying compressor were replaced with the same turbocharger as the gas generator. It was found that the system’s power output and thermal efficiency were doubled with this replacement. AFRIKAANS OPSOMMING: Gekonsentreerde sonkrag (CSP) verskaf ’n versendingbare vorm van elektrisiteit as gevolg van sy energiebergingsvermoëns en voeg buigsaamheid by die kragnetwerk. CSP tesame met ’n mikrogasturbine (MGT), skep ’n geskikte tegnologie vir die verskaffing van laekoolstof-elektrisiteit aan streke wat buite die netwerk is. Die sonkrag-hibriede mikro-gasturbine (SHMGT) het die vermoë om dieselopwekkers te vervang en sodoende bedryfskoste en randstofverbruik te verminder. Om hierdie redes is die Universiteit Stellenbosch betrokke by die navorsing van SHMGTe. Die termiese doeltreffendheid van die huidige MGT stelsel is relatief laag en ’n metode om hierdie prestasiemaatstaf te verbeter is deur die implementering van ’n hitteherwinner. Die gebruik van ’n hitteherwinner behels ’n verminderde verwarmingsvereiste in die verbrandingskamer, wat die brandstof wat benodig word om erbranding te handhaaf, verminder. ’n Klemplaatstyl-herwinningsontwerp is gekies as gevolg van sy eenvoud en kostedoeltreffendheid. ’n Groot uitdaging in die ontwerp van die hitteherwinner was die balans van die termies-hidrouliese ontwerpbeperkings, naamlik die hitte-oordragdoeltreffendheid en die toelaatbare drukval. Die ontwerp is aangepas om binne die projekbegroting te val deur doeltreffendheid vir drukval op te offer. Met lekkasie in die stelsel na twee opeenvolgende rondtes van verseëling van die hitteherwinner met twee verskillende hoë-temperatuur-seëlmiddels, is tot die gevolgtrekking gekom dat die ontwerp inherent lek is. ’n Ander metode van verseëling is voorgestel met die gebruik van ’n hoë-temperatuur pakking. Toetse van die hitteherwinner het aan die lig gebring dat die MGT stelsel nie selfonderhoudend kan bedryf nie. Dit was deels as gevolg van ’n onverwagse groot drukval oor die hitteherwinner. Dit is aan vloei-anverspreiding binne die kopstukke, wat aangedui is deur die termiese verwering op die hitteherwinner wanneer dit bo die limiet van 650 ◦C bedryf word. ’n Verbeterde kopontwerp is dus voorgestel. Die oorskakelingsmetode wat gebruik is om die MGT stelsel te koppel, is ook nie-ideaal vir herstelwerk gevind nie. Daar is gevind dat die SHMGT verbrandingskamer nie geskik was vir hoë-temperatuur inlaatvloei nie as gevolg van die gepaardgaande groot geïnduseerde drukval. Die doeltreffendheid van die hitteherwinner kon in ’n ontkoppelde werkingstoestand verkry word en is analities geverifieer. ’n Gevalideerde Flownex model van die MGT stelsel is vervaardig, waarby die hitteherwinner ingesluit is. Hierdie model het die validering van die teoretiese drukvalberekening en hitte-oordragdoeltreffendheid moontlik gemaak. ’n Gevallestudie is in Flownex uitgevoer waar die kragturbine en gepaardgaande kompressor vervang is met dieselfde turbo-aanjaer as die gasopwekker. Daar is gevind dat die kraglewering en termiese doeltreffendheid van die stelsel met hierdie vervanging verdubbel is. Masters 2023-03-02T07:13:48Z 2023-05-18T07:00:46Z 2023-03-02T07:13:48Z 2023-05-18T07:00:46Z 2023-03 Thesis http://hdl.handle.net/10019.1/127027 en_ZA en_ZA Stellenbosch University xviii, 118 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Counterflows (Fluid dynamics) Turbochargers Renewable energy sources Afeltra, M. F. The development of a recuperator for a solar hybrid micro gas turbine system |
| title | The development of a recuperator for a solar hybrid micro gas turbine system |
| title_full | The development of a recuperator for a solar hybrid micro gas turbine system |
| title_fullStr | The development of a recuperator for a solar hybrid micro gas turbine system |
| title_full_unstemmed | The development of a recuperator for a solar hybrid micro gas turbine system |
| title_short | The development of a recuperator for a solar hybrid micro gas turbine system |
| title_sort | development of a recuperator for a solar hybrid micro gas turbine system |
| topic | Counterflows (Fluid dynamics) Turbochargers Renewable energy sources |
| url | http://hdl.handle.net/10019.1/127027 |
| work_keys_str_mv | AT afeltramf thedevelopmentofarecuperatorforasolarhybridmicrogasturbinesystem AT afeltramf developmentofarecuperatorforasolarhybridmicrogasturbinesystem |