Fernando Neto da Silva

Technical feasibility assessment of oleic sunflower methyl ester utilisation in Diesel bus engines.

Abstract This paper describes the results obtained while testing the technical feasibility of using oleic sunflower methyl ester (SME) blended with Diesel fuel in proportions up to 30% in an unmodified Diesel bus engine. Vegetable oils methyl esters blended with Diesel oil are commonly used in compression ignition engines. However, R&D background information on the practical use of traditional sunflower oil derivatives is sparse. The present results include evaluation of the engine performance and fuel consumption and gaseous concentrations (CO and NO X ) in the exhaust gas. The exhaust gas opacity while using Diesel/SME blends and Diesel fuel was also compared. The collected data show that oleic SME utilisation did not lead to a deterioration of engine performance or to an increase in fuel consumption. Furthermore, significant increases of NO X and CO concentrations in the exhaust gas derived from SME utilisation were not detected. The smoke opacity was slightly reduced when SME was used in the proportion of 30%. The experimental testing seems to indicate that oleic SME is a suitable replacement for Diesel fuel and can be used safely in compression ignition engines in proportions as high as 30%.

Modeling of paper mill sewage sludge drying using artificial neural networks: Reduction of the training database through Taguchi’s method

ABSTRACT Drying of sewage sludge is typically modeled as simultaneous heat and mass transfer phenomena. The capability of conventional models to take into account crust formation, cracks, and shrinking is limited. Artificial neural networks (ANNs) are suitable tools for dynamic representation of drying processes; however, obtaining a suitable database is a resource consuming task. Based on the Taguchi method, nine experiments were defined to set up a training database and to develop an ANN model. A high Pearson correlation coefficient was verified when comparing the drying kinetic curve generated by the ANN model with the one obtained during the validation experiments.

An alternative approach to the inversion temperature

Abstract Above a given temperature, referred to as the inversion temperature, superheated steam is a more effective drying agent than humid air or even than dry air. However, no agreement has been reached in what concerns the definition of both the inversion temperature and its numerical value. Recent works attempted to clarify the different definitions of the inversion temperature, taking into account the obtained different numerical values. In this work, some of the ideas presented recently are developed and worked out in such a way that new graphical presentations of data are obtained, leading to a better understanding of the inversion temperature and of its value. The issues concerning the influence of the steam content of the drying agent on the evaporation rate, for different drying conditions and for a given inlet temperature of the drying agent, are clarified. The present results provide useful information on what concerns the influence of the convective drying conditions and parameters over the evaporation rate.

Exploring the Thermoelectric Performance of BaGd2NiO5 Haldane Gap Materials

One-dimensional Haldane gap materials, such as the rare earth barium chain nickelates, have received great interest due to their vibrant one-dimensional spin antiferromagnetic character and unique structure. Herein we report how these 1D structural features can also be highly beneficial for thermoelectric applications by analysis of the system CaxBaGd2-xNiO5 0 ≤ x ≤ 0.25. Attractive Seebeck coefficients of 140-280 μV K-1 at 350-1300 K are retained even at high acceptor-substitution levels, provided by the interplay of low dimensionality and electronic correlations. Furthermore, the highly anisotropic crystal structure of Haldane gap materials allows very low thermal conductivities, reaching only 1.5 W m-1 K-1 at temperatures above 1000 K, one of the lowest values currently documented for prospective oxide thermoelectrics. Although calcium substitution in BaGd2NiO5 increases the electrical conductivity up to 5-6 S cm-1 at 1150 K < T < 1300 K, this level remains insufficient for thermoelectric applications. Hence, the combination of highly promising Seebeck coefficients and low thermal conductivities offered by this 1D material type underscores a potential new structure type for thermoelectric materials, where the main challenge will be to engineer the electronic band structure and, probably, microstructural features to further enhance the mobility of the charge carriers.

Biodiesel from Lagoon Microalgae: Acceptable Alternative Fuel for the Transportation Crunch?

One main reason for the popularity of microalgae as an acceptable fuel source is their potential to maximize productivity (e.g., gallons of oil or fuel produced per acre per year) by converting the energy of solar photons during the process of carbon dioxide fixation into biomass energy, benefiting the environment. Marketing the coproducts generated (i.e., postextraction algal residue) could make transportation fuel from microalgae a viable product. The biofuel obtained from microalgae is qualitatively and quantitatively analyzed, with a focus on the energetic and environmental feasibility of this fuel for use in the transportation sector. Obstacles to and limitations of the process, in terms of energy and environmental performance, are identified. An important aspect of this issue is the need to improve product processing and recovery, which include mechanical and energy-intensive processes such as centrifugation, filtration, flocculation, and cell disruption. Results obtained so far indicate that the various strains of microalgae obtained from lagoons in Portugal and Spain offer a huge prospect for biodiesel production. However, results of life-cycle analysis with the Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation model (updated with Portuguese data) lead to the conclusion that, at this stage, biodiesel from microalgae is not a valid option for the large-scale replacement of conventional fuels. Specifically, the extraction step for biodiesel production is detrimental in terms of energy and solvent use and must be refined.

Equilibrium Moisture Content Isotherms of Codfish (Gadus morhua)

Industrial drying of salted fish is an extremely common practice in the Portuguese industry of codfish processing. The present study aims to obtain sorption isotherms of codfish, which will be useful in designing drying processes and prediction of storage conditions for this product. The equilibrium moisture contents (wet basis) were determined for salted codfish at 15, 18, 20, and 23ºC at relative humidities ranging from 40 to 70%. Experiments were also carried out for fresh codfish at the temperature of 20ºC for the same values of relative humidity. The sorption capacity of codfish decreased with an increase in temperature at constant relative humidity. Thirteen models were used to correlate the experimental data analysis of salted codfish: modified BET, Cauri, Chung-Pfost, modified Chung-Pfost, GAB, modified GAB, Halsey, modified Henderson, Kuhn, Oswin, modified Oswin, Smith, and modified Smith. Based on the mean relative percentage deviation, standard error of estimate, randomness of residual, and coefficient of determination, experimental data were well described by all the models. The equilibrium moisture content of salted codfish was best predicted using the modified GAB model, with a coefficient of determination of 0.99.

Deployment of parabolic trough concentrated solar power plants in North Africa – a case study for Libya

ABSTRACT The study addresses the potential of using concentrated solar power plants (CSPs) as a sustainable alternative of clean energy generation in the Mediterranean region and, in particular, in its North Africa shore. This location presents attractive conditions for the installation of CSPs, in particular high solar irradiation, good manpower concentration, and proximity and availability of water resources for condenser cooling. Energetic, exergetic, and economic analyses were conducted taking into consideration a particular type of CSPs - the parabolic trough concentrated solar power plant, which incorporates the most proven technology and it is already used in Southern Europe (Spain). In addition, the study considered the impact of project financing and incentives on the cost of energy. The combination of higher values for performance and potentially lower levelized cost of electricity (LCE) for the North Africa Mediterranean Rim than the South of Spain region can yield a very favorable return for the invested capital. Tripoli compared to Almeria presented superior performance and potentially lower LCE values (

Prospects for Energy Usage and Carbon Dioxide That Affect European Transportation Sector

0.18/kWh versus

High Temperature, Pressurized Wood Drying: Experimental and Simulation Results

0.22/kWh). This is significant, even when it is taken into consideration the fact that the plant in Tripoli, despite a relatively modest capacity factor of 34%, has a large gross power output of 173,886 MWhe. In addition, the implementation at the Tripoli location of a plant similar to the Anadsol plant has a slight advantage (2–3%) in terms of overall efficiency.

Predicting the drying kinetics of salted codfish (Gadus Morhua): semi-empirical, diffusive and neural network models

The objective of the reduction of greenhouse gas emissions by 2050 and the European Unions (EUs) fossil energy dependence are two factors that require political and industrial decision makers to set priorities for energy and environmental strategies. Despite the achieved efficiency in modern vehicles, increasing patterns of private car usage, together with a high dependence on oil, place transportation as the most resilient sector in this period of environmental and energy consciousness. The aim of this research was to disaggregate the existing European transportation energy data and use them to build a model of the current situation. With the model, several scenarios evaluated the well-to-wheel energy and carbon dioxide (CO2) impacts that resulted from improvements in energy efficiency, uptake of biofuels, and electric mobility, as well as a modal shift into collective modes. Analysis of the European study of the Joint Research Centre Biofuel Programme and each member states national strategy [National Renewable Energy Action Plans (NREAPs)], published in 2010, allowed characterization of the transportation energy situation by 2020 (consumption, efficiency, and new energy). The analysis of mobility surveys from major member states permitted characterization of urban areas within the passenger mobility sector, and the results were integrated into the developed model. The expected improvements in energy efficiency through the Biofuel Programme and the planned increase in biofuel blends and electrified vehicles through the NREAPs combined with an increase in passenger mobility by 2020 resulted in the following 2020 predictions: a 16% reduction in tank-to-wheel and a 12% reduction in well-to-wheel CO2 emissions in the EUs passenger mobility sector compared with 2007 levels.