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Previous issue date: 2015-07-24 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / A lubricidade do biodiesel interfere no funcionamento normal dos sistemas de inje??o diesel, principalmente dos bicos injetores, reduzindo o desgaste e elevando o tempo de vida da linha de alimenta??o do motor. O m?todo HFRR (High Frequency Reciprocating Rig) ? um ensaio padr?o para avalia??o da lubricidade do diesel/biodiesel (ASTM D6079), consistindo principalmente da medi??o da escara de desgaste impressa na esfera numa sonda de movimento alternado sob alta frequ?ncia. Quando o desgaste se desenvolve, algumas caracter?sticas din?micas do sistema variam, resultando em desvios significativos nos padr?es dos sinais de vibra??o, ac?sticos e de atrito. A aquisi??o e caracteriza??o das assinaturas desses sinais obtidos durante os ensaios tribol?gicos representam uma importante ferramenta n?o intrusiva de avalia??o da lubricidade desses combust?veis, cuja representa??o no dom?nio do tempo nem sempre revelam informa??es triviais, sendo necess?ria sua transforma??o para o dom?nio da frequ?ncia usando a Transformada r?pida de Fourier (FFT) do sinal. A presente tese objetivou desenvolver uma forma din?mica de avalia??o de lubricidade de combust?veis (Diesel S50, ?ster Met?lico de Soja e blendas B10 e B20) em bancada HFRR (contato esfera-disco plano), e melhoria aos referenciais metodol?gicos da ASTM D6079, aplicando t?cnicas de an?lise de sinais (vibra??o e n?vel de press?o sonora) e sua associa??o com par?metros disponibilizados pela norma ASTM D6079 (di?metro da escara de desgaste) com dura??o de 75, 120 e 180 minutos. Os perfis e par?metros de rugosidade e an?lise microsc?pica dos discos foram usados para melhor avaliar a influ?ncia do tempo e do combust?vel na evolu??o do desgaste do disco. Nesta avalia??o, a lubricidade dos combust?veis aumentou com o teor de biodiesel utilizado e diminuiu com o aumento do n?mero de ciclos aplicado. A an?lise temporal e o espectro de frequ?ncia dos sinais demonstraram sensibilidade com a mudan?a do combust?vel, o n?mero de ciclos e, consequentemente, com a evolu??o do desgaste pelo uso prolongado dos combust?veis, estando, assim, correlacionados entre si e com os resultados dispon?veis pela ASTM. / The lubricity of biodiesel interferes in the normal operation of diesel injection systems, especially in nozzles. It can reduce the wear and raise the lifetime of the engine supply line. The method HFRR (High Frequency Reciprocating Rig) is a standard test for evaluation of diesel/ biodiesel lubricity (ASTM D6079). The HFRR lubricity evaluation mainly consists of measuring the printed scar wear on the ball. When wear is developing, some dynamic features of the system vary and it results in significant changes in the patterns of vibration, sound pressure level (SPL) and friction signals. The acquisition and characterization of signatures of these signals obtained during tribological tests are an important non-intrusive tool for evaluating of the lubricity of these fuels, whose representation in the time domain not always reveals trivial information. This requires signal transformation to the frequency domain using the Fast Fourier Transform (FFT) and Short-Time Fourier Transform (STFT) analyses. This thesis aimed to develop a dynamic assessment of lubricity fuels (Diesel S50, Methyl Ester of Soybean and B10 and B20 blends) in HFRR bench (ball-on-flat disk contact), and improving the methodological framework of ASTM D6079 standard by application of signal analysis techniques (vibration and SPL) and its association with parameters provided by ASTM D6079 (wear scar diameter) lasting 75, 120 and 180 minutes. The profiles and topographic parameters of scars and their microscopic analysis were used to further evaluate the influence of the time and fuel in the wear evolution of disk. In this evaluation, the fuel lubricity was influenced by increasing of biodiesel content and decreasing of number of cycles applied. From the temporal and frequency spectrum analysis of the vibration and NPS signals it is shown that both vibration and NPS stablish a relation with fuel lubricity, biodiesel content, number of cycles and parameters of profiles from scar of discs.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/20563 |
| Date | 24 July 2015 |
| Creators | Farias, Aline Cristina Mendes de |
| Contributors | 02046752945, http://lattes.cnpq.br/8550161853747323, Souto, Ulisses Borges, 85600539649, http://lattes.cnpq.br/5255022158676985, Oliveira J?nior, Jos? Josemar de, 02261193432, http://lattes.cnpq.br/4263696954174963, Oliveira, Adelci Menezes de, 67187366434, http://lattes.cnpq.br/7673440916658787, Silva, Gilson Garcia da, 56634161453, http://lattes.cnpq.br/8681275097040450, Medeiros, Jo?o Telesforo N?brega de, Alves, Salete Martins |
| Publisher | Universidade Federal do Rio Grande do Norte, PROGRAMA DE P?S-GRADUA??O EM ENGENHARIA MEC?NICA, UFRN, Brasil |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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