Avaliação do equilíbrio de fases de misturas biodiesel e álcoois de cadeia curta com aplicação em motores ciclo diesel
The production and indiscriminate use of fossil fuels should decline in future decades because of global warming caused by the emission of gases that cause the greenhouse effect, which cause various climate dysfunctions. The diversification of the world's energy matrix involves the expansion...
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| Formato: | doctoralThesis |
| Idioma: | pt_BR |
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Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/handle/123456789/52445 |
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| Resumo: | The production and indiscriminate use of fossil fuels should decline in future
decades because of global warming caused by the emission of gases that cause the
greenhouse effect, which cause various climate dysfunctions. The diversification of the
world's energy matrix involves the expansion and strengthening of renewable energy and
biofuels in order to combine energy security with sustainable development. Biodiesel is
a viable alternative to the use of diesel due to the similarity between its properties and
applications, without requiring any modification to internal combustion engines.
Biodiesel overlaps with fossil fuels due to its biodegradable, sustainable and
environmentally friendly character. This work presents the production of methyl biodiesel
using commercial soybean oil in a route operating with potassium hydroxide (KOH) in
order to obtain liquid-liquid balance (ELL) data and its applicability in a diesel cycle
engine. Initially, a comparison of equilibrium diagrams and an evaluation of
thermodynamic models were carried out between biodiesel (biodiesel + glycerol +
methanol) and methyl palmitate, an isolated biodiesel ester (methyl palmitate + glycerol
+ methanol). The results showed good dynamics for the UNIQUAC and NRTL models,
in addition to showing a diagram with an extensive biphasic region. In order to propose
new biofuel formulations, ELL studies in ternary systems were carried out containing
Alcohols + Biodiesel + Diesel, focusing on the use of biodiesel as a stabilizing additive
for alcohols in diesel mixtures, in other words, the miscibility of ternary systems was
investigated. Compliance of the phase equilibrium data was validated by the OthmerTobias and Hand anxieties. The distribution and selectivity coefficients calculated for the
immiscibility regions indicated that the increase in the carbon chain strengthens the
biodiesel solubility. The experimental data also correlated with the UNIQUAC and NRTL
thermodynamic models. Both models showed high agreement with the experimental data,
with deviation values (RMSD) lower than 1.78%. The liquid-liquid equilibrium data
obtained for the studied systems made it possible to obtain binary interaction parameters,
through the thermodynamic compatibility of equilibrium data using the UNIQUAC and
NRTL models. The obtained parameters can be applied to evaluate the conditions of
processes involving liquid liquidity through process simulators. Finally, a diesel engine
fed with fuel blended with biodiesel/methanol/n-butanol was employed to investigate the
effects of differences in fuel blend ratios and engine load on combustion characteristics
in terms of specific fuel consumption and thermal efficiency of the brake. Two 2³
experimental designs with the addition of three central points were carried out, evaluating
the effect of the variables, concentration of additives (methanol and n-butanol), molar
ratio (B/M) and potency. Load is the main factor affecting the specific fuel consumption
and thermal efficiency of the brake. |
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