Development of a time/temperature logging device to characterise the burning characteristics of biofuels

Smit, Hendrik Christiaan (2011-03)

Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 2011.

Thesis

ENGLISH ABSTRACT: A lab scale combustion unit was designed, in order to characterise the performance of various woody and wood-based biofuels commonly used for energy production, cooking and heating. The unit was constructed in a way that it could be repeatedly reused and provide similar testing conditions, such as airflow for all samples. The requirements were that it was big enough to contain a fire large enough to yield good time/temperature profiles and at the same time easy to handle, operate and clean. It also had to allow the insertion of the thermocouples and flue gas probe. Time / temperature profiles were obtained and O2, CO2 and CO levels in the flue gas determined for each biofuel. The samples consisted of the five most commonly used fuel wood species in the Western Cape, namely Rooikrans, Camelthorn, Bluegum, Black wattle and vine stumps and five processed products, namely wood pellets, wood briquettes, commercial charcoal, commercial briquettes and handmade briquettes. Combustion time/temperature profiles were obtained for all samples and characteristic values, such as the maximum temperature and coal temperature compared. This allowed an indication of which product performed better than others in the different combustion phases and is more suitable for different requirements, such as industrial heating, or domestic cooking. Even though Bluegum and Camelthorn performed best overall they were not necessarily suited, for example, for large scale industrial use. It was found that wood pellets and charcoal were the best biofuel for industrial purposes, whereas Rooikrans was found to be the best option for small scale use.

AFRIKAANSE OPSOMMING: ‘n Laboratoriumskaal verbrandingseenheid was ontwerp vir die toets en karakterisering van verskeie houtgebaseerde biomassa soorte algemeen in gebruik vir energie opwekking, kook en verhitting. Daar was besluit om ‘n eenheid te bou vir herhaalde gebruik wat die omstandinghede vir elke toets konstant kan hou, bv. ‘n damper om lugvloei deur die sisteem the beheer. Die eenheid moet groot genoeg wees om veilig ‘n groot genoeg vuur the bevat waarmee ‘n goeie tyd/temperatuur profiel verkry kan word, maar terselfdetyd klein genoeg wees om te hanteer, operateer en skoon te maak. Die eenheid moes ook voorsiening maak vir die insteek van die termostate en gas peilstif. Tyd/temperatuur profiele is verkry en O2, CO2 en CO vlakke in die uitlaatgas is bepaal vir elke bio-brandstof. Die monsters was saamgestel uit vyf van die mees algemeen gebruikte brandhout spesies in die Wes Kaap, naamlik Rooikrans, Kameeldoring, Bloekom, Swartwattel en wingerdstompies, asook vyf geprosesseerde produkte naamlik houtpille, houtbrikette, kommersiële steenkool, kommersiële brikette and handgemaakte brikette. Verbranding tyd/temperatuur profiele is verkry vir al die monsters en verteenwoord waardes is daarvan afgelees, bv. die maksimum temperatuur wat bereik is of die temperatuur waar die vlamme uitgesterf het en slegs koolhitte gemeet word. Hierdie profiele het dit moontlik gemaak om te identifiseer watter produk het beter gevaar as ander gedurende die verskillende verbrandingsfases en is beter gepas vir verskillende gebruike, bv. huishoudelike kook en verhitting. Resultate het gedui dat die Bloekom en Kameeldoring die beste gevaar het oor all die toetse heen, maar was nie noodwendig ideaal vir elke spesifieke doel nie. Dit was bevind dat die steenkool en houtpille die beste gepas is vir industriele gebruik en dat die Rooikrans beter geskik is vir huishoudelike en kleinskaalse gebruik.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/6616
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