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Design of an anaerobic digester for electricity generation using a small reciprocating engine.
Mechanical and Mechatronic Engineering
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2021
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| _version_ | 1867614085913247744 |
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| access_status_str | Open Access |
| author | Sibanda, T. N. |
| author2 | Von Backstrom, T. W. |
| author_browse | Sibanda, T. N. Von Backstrom, T. W. |
| author_facet | Von Backstrom, T. W. Sibanda, T. N. |
| author_sort | Sibanda, T. N. |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Mechanical and Mechatronic Engineering |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/123612 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:46:25.318Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2021 |
| publishDateRange | 2021 |
| publishDateSort | 2021 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/123612 Design of an anaerobic digester for electricity generation using a small reciprocating engine. Sibanda, T. N. Von Backstrom, T. W. Sebitosi, A. B. Mamphweli, S. N. Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering. Biogas Reciprocating engine Digester Fuel flow-rate UCTD Mechanical and Mechatronic Engineering ENGLISH ABSTRACT: The world has an urgent need for technologies that drastically reduce greenhouse gases. Renewable gaseous fuels like biogas have shown significant growth in the market over the past couple of years. Previous studies at Stellenbosch university have converted an automotive Rover gas turbine to run on liquified petroleum gas. The final goal was to convert it to operate on biogas. Due to a ventilation issue in the test cell housing the Rover gas turbine, maintenance cost and the corrosive nature of biogas, an alternative solution was investigated. In that regard, this project saw the design and construction of a biogas digester at one of the university’s experimental farms. A test cell consisting of a production unit, a compression unit and a power generation unit were established. The production unit consisted of a biogas digester, a scrubbing unit and a preliminary storage biogas bag. The bio- digester was evaluated on performance indicators such as pH, retention time, volatile fatty acids, chemical oxygen demand and temperature. Methane content was the only performance indicator of the scrubbing system measured as a percentage per sample volume. The scrubbing unit results show that a simple system consisting of Ca(OH) (calcium hydroxide aqueous solution), Fe3+ (iron) and silica gel can reduce the undesirable gases by approximately 50% and maintain an acceptable H2S level. The production unit is completed by biogas stored up to atmospheric pressure in biogas bags. The compression unit consists of a modified single cylinder compressor and gas storage cylinders. The gas compression cycle successfully reached the rated pressure of 800 kPa using biogas. The power generation unit consisted of a small reciprocating SI engine which was utilised to prove the concept of power generation using biogas. Instead of converting the Rover gas turbine, the conversion of a small reciprocating engine was conducted. The engine was converted from a gasoline to a dual fuel-based system where the alternative fuel source is biogas.The engine had a rated power of 2 kW and a maximum power of 2.5 kW. To conduct a fair analysis, the engine was loaded with variable loads (1058 watts- base load & 1939 watts- peak load) for both fuels. After conducting several tests on the engine, it was found that biogas slightly outperformed gasoline with regards to fuel flow rate. AFRIKAANSE OPSOMMING: Die wêreld het 'n dringende behoefte aan tegnologieë wat kweekhuisgasse drasties verminder. Hernubare gasbrandstowwe soos biogas gasbrandstowwe het die afgelope paar jaar beduidende groei in die mark getoon. Vorige studies is by die Universiteit van Stellenbosch het 'n Rover-gasturbine na LPG. Die finale doel was om dit om te skakel om biogas te gebruik. As gevolg van 'n ventilasieprobleem in die toetssel vir die Rover-gasturbine, die onderhoudskoste en die korrosiewe aard van biogas, is 'n alternatiewe oplossing ondersoek. In hierdie opsig is die ontwerp en konstruksie van 'n biogasvergoder op een van die universiteitsproewe bestudeer. In 'n poging om 'n vergelyking tussen petrol en biogas te ondersoek, is die ontwerp en konstruksie van 'n biogasverteerder op een van die universiteitsproefplase ontwerp. 'n Toetssel bestaande uit 'n produksie-eenheid, 'n kompressie-eenheid en 'n kragopwekkingseenheid is dargestel. Die produksie-eenheid het bestaan uit 'n biogasverteerder, 'n skropeenheid en 'n voorlopige opberging van biogas. Die bioververteerder is geëvalueer prestasie-aanwysers soos pH, retensietyd, VFA, COD en temperatuur. Metaaninhoud was die enigste prestasie-aanwyser van die skropstelsel, gemeet as persentasie per monstervolume. Die resultate van die skropeenheid toon dat 'n eenvoudige stelsel bestaande uit Ca (OH) (kalsiumhidroksied waterige oplossing), Fe3 + (yster) en silikagel die ongewenste gasse met ongeveer 50% kan verminder en 'n aanvaarbare H2S-vlak kan handhaaf. Die produksie-eenheid is voltooi deur biogas wat tot atmosferiese druk in biogas sakke gestoor word. Die kompressie-eenheid bestaan uit 'n herontwerpte kompressor en gas stoor silinder. Die gaskompressiesiklus het met behulp van biogas die gegradeerde druk van 800 kPa suksesvol bereik. Die produksie-eenheid bestaan uit 'n klein vonkontsteekde suirenjin SI wat gebruik is om die konsep van kragopwekking met behulp van biogas te bewys. Die enjin het 'n gegradeerde drywing van 2 kW en 'n maksimum drywing van 2.5 kW. Om 'n billike ontleding te kan doen, is die enjin belas met veranderlike las (1058 watt - basislading en 1939 watt - piekbelasting) vir beide brandstowwe. Na 'n aantal toetse is gevind dat biogas beter as petrol presteer met betrekking tot brandstofvloeitempo. Masters 2021-06-23T15:16:04Z 2021-12-22T14:12:11Z 2021-06-23T15:16:04Z 2021-12-22T14:12:11Z 2021-12 Thesis http://hdl.handle.net/10019.1/123612 en_ZA Stellenbosch University 127 pages application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Biogas Reciprocating engine Digester Fuel flow-rate UCTD Sibanda, T. N. Design of an anaerobic digester for electricity generation using a small reciprocating engine. |
| title | Design of an anaerobic digester for electricity generation using a small reciprocating engine. |
| title_full | Design of an anaerobic digester for electricity generation using a small reciprocating engine. |
| title_fullStr | Design of an anaerobic digester for electricity generation using a small reciprocating engine. |
| title_full_unstemmed | Design of an anaerobic digester for electricity generation using a small reciprocating engine. |
| title_short | Design of an anaerobic digester for electricity generation using a small reciprocating engine. |
| title_sort | design of an anaerobic digester for electricity generation using a small reciprocating engine |
| topic | Biogas Reciprocating engine Digester Fuel flow-rate UCTD |
| url | http://hdl.handle.net/10019.1/123612 |
| work_keys_str_mv | AT sibandatn designofananaerobicdigesterforelectricitygenerationusingasmallreciprocatingengine |