Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
Improved modelling of a micro gas turbine for solar-hybrid application
Thesis (MEng)--Stellenbosch University, 2022.
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | en_ZA |
| Published: |
Stellenbosch : Stellenbosch University
2022
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867614101857894400 |
|---|---|
| access_status_str | Open Access |
| author | Fenner, Chaz Courtney |
| author2 | Van der Spuy, S. J. |
| author_browse | Fenner, Chaz Courtney Van der Spuy, S. J. |
| author_facet | Van der Spuy, S. J. Fenner, Chaz Courtney |
| author_sort | Fenner, Chaz Courtney |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEng)--Stellenbosch University, 2022. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/124881 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:46:41.344Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2022 |
| publishDateRange | 2022 |
| publishDateSort | 2022 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/124881 Improved modelling of a micro gas turbine for solar-hybrid application Fenner, Chaz Courtney Van der Spuy, S. J. Von Backstrom, T. W. Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering. Gas-turbines -- Combustion Heat -- Transmission Electrification Turbochargers Solar energy UCTD Thesis (MEng)--Stellenbosch University, 2022. ENGLISH SUMMARY: In the electrification of remote communities, the deployment of Concentrated Solar Power (CSP) technologies may be advantageous due to its ability to scale in size. Through hybridisation with a Brayton cycle (BC) micro gas turbine (MGT), a CSP plant’s dispatchability is improved and additionally benefited by inherent gas turbine advantages such as fuel flexibility and a high power to weight ratio. Despite the arguable advantages of a solar hybrid MGT, there has been a delay in developing MGTs for this purpose due to the cost and time associated with the process. As such, there is ongoing research at Stellenbosch University into MGTs for solar hybrid application through which a dual-shaft MGT experimental facility has been built. It was determined however, that previous work to model said MGT facility did not produce satisfactory results. Therefore, this study aims to develop an improved model to estimate the performance of the current dual-shaft facility. The dual-shaft arrangement comprises of two turbochargers, with one turbocharger representing the gas generator turbine and the other, bigger turbocharger used as the power turbine unit. The ensuing model accounted for real world phenomena that occur within the MGT and was developed to be easily computable. Enhancements to the current model included the use of a One-Dimensional Thermal Resistance Network (1-D TRN) to account for heat transfer, and the introduction of an efficiency term to adjust combustor outlet temperature estimates for the supposed incomplete levels of combustion. Overall, the model’s temperature estimations were found to be within a maximum deviation of 5 % of the measured values and, 8 % for pressure. Combustor outlet temperature estimates were substantially improved to within 4 % of the measured value, which is a 15 % improvement on previous work. Despite the increased performance, the model was only validated for the smaller gas generator turbine The larger power turbine was reasoned to have not reached thermal equilibrium and as a result temperature estimates had substantially increased levels of deviation from the measured value. A subsequent energy audit of the facility, using the 1-D TRN, showed that the power turbine is in fact operating outside of its optimal range which resulted in an increased surface area to volume flow rate ratio and indicates that the turbochargers have been improperly matched. Furthermore, the energy audit showed that over the tested range, the change in the estimated heat loss rate of the gas passing through the respective turbines is a stronger function of rotor speed than the gas mass flow rate. Scenarios of heat gain and loss by the gas working fluid also introduced a point of concern; the use of compressor and turbine experimental measurements may skew the compressor and turbine’s estimated performance when compared to the specifications of the supplier. As a result, it was found to be more reliable in estimating the current facility’s performance with the improved model developed in this study, due to it accounting for heat transfer in each of the turbochargers. AFRIKAANS OPSOMMING: Die ontplooiing van Gekonsentreerde Sonkrag (GS) tegnologieë kan voordelig wees vir die elektrifisering van afgeleë gemeenskappe as gevolg van die tegnologie se vermoë om in grootte te skaal. Deur hibridisering met ’n Braytonsiklus (BC) mikrogasturbine (MGT), word ’n GS aanleg se versendingsvermoë verbeter en bevoordeel deur inherente voordele van gasturbinessoos brandstofbuigsaamheid en ’n hoë krag-tot-gewig-verhouding. Ten spyte van die betwisbare voordele van ’n hibriede sonkrag MGT, was daar ’n vertraging in die ontwikkeling van MGTs vir hierdie doel as gevolg van die koste en tyd verbonde aan die proses. As sodanig is daar deurlopende navorsing gedoen by die Universiteit Stellenbosch in MGTs vir hibriede sonkrag toepassing waarvoor ’n dubbel-as MGT eksperimentele fasiliteit gebou is. Daar is egter vasgestel dat vorige werk om die MGT-fasiliteit te modelleer nie bevredigende resultate opgelewer het nie. Daarom het hierdie studie ten doel om ’n verbeterde model te ontwikkel om die werkverrigting van die huidige dubbelas-fasiliteit te voorspel. Die dubbelas-rangskikking bestaan uit twee turbo-aanjaers, met een turbo-aanjaer wat die gasgeneratorturbine verteenwoordig en die ander, groter turbo-aanjaer wat as die kragturbine-eenheid gebruik word. Die ontwikkelde model neem werklike verskynsels wat binne die MGT voorkom in ag en is ontwikkel om maklik berekenbaar te wees. Verbeterings aan die huidige model het die gebruik van ’n eendimensionele termiese weerstandsnetwerk (1- D TWN) ingesluit ten einde warmteoordrag in ag te neem, en die gebruik van ’n doeltreffendheidsterm om die verbrander se uitlaattemperatuur voorspelling aan te pas vir die veronderstelde onvolledige vlakke van verbranding. Oor die algemeen is gevind dat die model se temperatuurvoorspellings binne ’n maksimum afwyking van 5 % van die gemete waardes en 8 % vir druk was. Verbrander uitlaattemperatuur voorspelling is aansienlik verbeter tot binne 4 % van die gemete waarde, wat ’n 15 % verbetering is op vorige werk. Ten spyte van die verhoogde werkverrigting, is die model slegs vir die kleiner gasgeneratorturbine gevalideer. Tydens eksperimente het die groter kragturbine is nie termiese ewewig bereik het nie en gevolglik het temperatuurvoorspellings die vlakke van afwyking van die gemete waarde aansienlik verhoog. ’n Daaropvolgende energie-oudit van die fasiliteit, met behulp van die 1-D TWN, het getoon dat die kragturbine in werklikheid buite sy optimale gebied werk, wat gelei het tot ’n groter oppervlakte-tot-volume-vloeitempo-verhouding en aandui dat die turbo-aanjaers nie behoorlik by mekaar pas nie. Verder het die energie-oudit getoon dat oor die getoetste gebied, die verandering in die beraamde hitteverliestempo van die gas wat deur die onderskeie turbines gaan ’n sterker funksie van rotorspoed is as die gas se massavloeitempo. Gevalle van hittetoename en-verlies deur die gas-werkvloeistof is ook ’n bron van kommer; die gebruik van kompressor- en turbine-eksperimentele metings kan die kompressor en turbine se geskatte werkverrigting affekteer in vergelyking met die spesifikasies van die verskaffer. Gevolglik is gevind dat die verbeterde model wat in hierdie studie ontwikkel is meer betroubaar is in die skatting van die huidige fasiliteit se werkverrigting, omdat dit die warmteoordrag in elk van die turbo-aanjaers in ag neem. Masters 2022-03-01T12:51:38Z 2022-04-29T09:39:05Z 2022-03-01T12:51:38Z 2022-04-29T09:39:05Z 2022-04 Thesis http://hdl.handle.net/10019.1/124881 en_ZA Stellenbosch University xv, 103 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Gas-turbines -- Combustion Heat -- Transmission Electrification Turbochargers Solar energy UCTD Fenner, Chaz Courtney Improved modelling of a micro gas turbine for solar-hybrid application |
| title | Improved modelling of a micro gas turbine for solar-hybrid application |
| title_full | Improved modelling of a micro gas turbine for solar-hybrid application |
| title_fullStr | Improved modelling of a micro gas turbine for solar-hybrid application |
| title_full_unstemmed | Improved modelling of a micro gas turbine for solar-hybrid application |
| title_short | Improved modelling of a micro gas turbine for solar-hybrid application |
| title_sort | improved modelling of a micro gas turbine for solar hybrid application |
| topic | Gas-turbines -- Combustion Heat -- Transmission Electrification Turbochargers Solar energy UCTD |
| url | http://hdl.handle.net/10019.1/124881 |
| work_keys_str_mv | AT fennerchazcourtney improvedmodellingofamicrogasturbineforsolarhybridapplication |