Percorrer por autor "Gameiro da Silva, M."
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- Emissions characterization from EURO 5 diesel/biodiesel passenger car operating under the new European driving cyclePublication . Lopes, M.; Serrano, L.; Ribeiro, I.; Cascão, P.; Pires, N.; Rafael, S.; Tarelho, L.; Monteiro, A.; Nunes, T.; Evtyugina, M.; Nielsen, O.J.; Gameiro da Silva, M.; Miranda, A.I.; Borrego, C.The increasing demand of petroleum based fuels and their use in internal combustion engines have adverse effect on air quality and climate change. Production of biofuels promises substantial improvement in air quality through reducing emission from biofuel operated vehicles. In this study the influence of the fuel mixture on EURO 5 vehicle exhaust emissions operating under the New European Driving Cycle (NEDC) and in hot operating conditions was analysed. Distinct diesel/biodiesel ratios (B0 (100%/0%), B7 (93%/7%) and B20 (80%/20%), volume basis) were considered. Experiments were conducted on a chassis dynamometer examining several pollutants, namely: carbon dioxide (CO2), carbon monoxide (CO), nitrogen oxides (NO and NO2), particulate matter (PM10 and PM2.5) and total volatile organic compounds (VOC). Moreover, a VOC speciation analysis by gas chromatography was performed to explore the emission variations regarding a set of seventeen VOC.The biodiesel fuel blends showed significant differences in combustion efficiency. An increasing amount of biodiesel in the fuel results in decreasing trends regarding NO, and particulate matter emissions. However, nitrogen dioxide and total VOC emissions increase with the biofuel content in the fuel. Moreover, the VOC speciation analysis suggests that the set of VOC present in exhausted gases is clearly fuel dependent.
- Evaluation of errors on the CFD computation of air flow and heat transfer around the human bodyPublication . Martinho, Nuno; Lopes, A.; Gameiro da Silva, M.A detailed computer aided design model representing a female human body was created from a 3-D scan of a full scale thermal manikin. The sensible heat losses due to convection and radiation for a person seated in a rectangular room were calculated using CFD simulations, as well as the parameters characterizing the flow around the body including air velocity and temperature. The accuracy of numerical results was evaluated in terms of the physical approximation errors, namely inlet boundary conditions and turbulence models, and spatial discretization errors due to the number of grid elements and grid refinement near solid surfaces. Results were compared to published data from two tests performed in conditions that portrayed the CFD simulations. The use of: a mixed turbulence model between k-e{open}, for zones away from solid surfaces, and k-ω, for zones close to solid surfaces; values of the dimensionless y + parameter inferior to 5 jointly with a low-Reynolds method to model the flow in the near-wall region of the human surface and inlet non-uniform boundary profiles for temperature, velocity and turbulence intensity, leaded to good agreement with experimental results, with a global mean relative error of the order of 7%, with a standard deviation of 4%, in terms of convective and radiative heat flux between the human body and the thermal environment.
- On-road performance comparison of two identical cars consuming petrodiesel and biodieselPublication . Serrano, L.; Carreira, V.; Câmara, R.; Gameiro da Silva, M.The present work studies the impact on vehicle performance and fuel consumption when using 100% diesel with petroleum origin (fossil diesel), compared to a mixture of 20% biodiesel in 80% of fossil diesel fuel (B20). For the accomplishment of this work an assessment was made using some primary tests on a chassis dynamometer, measuring vehicle performance and consumption. Subsequently a methodology was developed to conduct road tests. These considered the simultaneous circulation of two identical vehicles, fed with the two different fuels, but running on the same traffic and road conditions. Both vehicles were equippedwith geo-referencing systems (GPS) and datameasured by the Electronic Control Unit (ECU) were acquired. A precision balance was used in fuel consumption measurements of an auxiliary reservoir. The results demonstrate that the use of biodiesel has a penalizing effect on themass fuel consumption and on vehicle's performance, but this is largely dependent on the type of circuit used. One can also conclude that the methodology implemented on the study of fuel alternatives is extremely important. It is noticeable that for different route needs, different energetic solutions are more suitable than others, which can only be properly assessed by conducting road tests.