• Energy Research
• Restricted close
• Embargo close
• other engineering and technologies close
• English close

Two studies conducted in Guadeloupe (West Indies) and Réunion (Indian Ocean) islands were designed to investigate the benefits of producing sugarcane as an energy crop and to assess the influence of agroclimatic factors on energy efficiency, respectively. In this context, it is essential to know the low heating value of the dry above-ground biomass (LHVd, MJ/kg) and its energy yield (EY, MJ/m2) in order to select the best varieties and set up a payment method for growers. Eighteen Poaceae (sugarcane and Erianthus) cultivars were compared under wet tropical environmental conditions in Guadeloupe. Three sugarcane cultivars were studied in four contrasting environments in Réunion. The partition sampling and biomass measurement procedures were identical at both locations. Low heating value (LHV) predictions were achieved using near-infrared reflectance spectroscopy (NIRS) after specific calibration (Guadeloupe), or arithmetically after lignocellulosic compound prediction (Réunion). In both studies, LHV variability was very low and slightly dependent on the site, cultivar and above-ground biomass components (millable stalks and tops, and green and dead leaves). Considering the overall dry above-ground biomass (DAB, kg/m2), the LHVd was calculated by averaging 159 samples (mean 16.65 MJ/kg) in Guadeloupe and 315 samples (mean 16.45 MJ/kg) for Réunion. An excellent linear relationship between the DAB and its EY, regardless of cultivar, age and environment, was found (n = 474 and R² = 0.99). Sugarcane energy content assessment could thus be simplified by measuring the DAB, while enabling development of a faster method of payment for growers based on the DAB measurement and the correlation between DAB and EY. Finally, the findings of this study should allow growers to rapidly determine the commercial value of their sugarcane crops, and also enable purchasers to assess the amount of recoverable energy. (Résumé d'auteur)

The research deals on the study of transonic wings whose planform shape is curved. By using Fluid Structure Interaction analyses, the dynamic instability conditions have been investigated by including the effects of the transonic flow field around oscillating wings. The results obtained confirm that for a curved planform wing, dynamic instability occurs at higher speed if compared to a traditional swept wing having similar profiles, aspect ratio, angle of sweep at root, similar structural layout and weight. The work demonstrates that a curved wing lifting system may improve the performances of future aircrafts.

The paper presents the results of a two years outdoor monitoring campaign that has been carried out on the same polycrystalline photovoltaic module at two different locations in Europe: the SUPSI-ISAAC outdoor facility in Lugano, Switzerland, from April 2006 till May 2007, and the outdoor ESTER facility in Rome, from April 2008 till May 2009. Since the same module has been tested in two places using the same testing electronic unit (MPPT 3000), the device performance differences can mainly be ascribed to the different local environmental conditions. A detailed characterization of the climatic conditions in Lugano and Rome for the periods of interest have been performed and the PV module performance comparison has been carried out in terms of module efficiency, module yield (Y) and Performance Ratio (PR). No evident influence of the PV module different mounting and monitoring management has been observed on the module performance. The PR monthly trend is mainly due to the temperature influence on the module behaviour, with lower values during summer months; for the same reason, the higher temperatures experienced in Rome penalize the performance. The monthly PR appears higher for Lugano than for Rome apart from the April 07-09 case where the performance in Rome has been higher. A 3% maximum PR deviation between the two sites has been registered during the autumn months.

Many temperate climates, like most Italian ones, are characterized by considerable daily temperature ranges. In these cases, the thermal inertia of the building has a significant influence on the management of solar and internal heat gains; then on the energy demand for HVAC, this is especially true in the cooling period. Winter and summer requirements regarding thermal inertia may be in conflict with each other, in particular when the use of the building is discontinuous, as in the case of offices. A lower thermal inertia can allow a more rapid heating in the morning and minor nocturnal losses during the winter, whereas a higher inertia may allow a slower daytime heating and a better exploitation of night free cooling during the cooling period. In this study, a typical office room has been studied by means of computer simulations. The only external wall of the room faces south and is entirely glazed; therefore, it requires the use of some device for solar control. Relatively to this room, the combined effects of some different solar control strategies and three constructive technologies, characterized by different thermal inertia, have been explored. A first strategy is based only on the use of an internal reflecting and diffusing screen, a second on the use of external movable slats, a third on the use of small slats inserted between the glasses. Strategies based on the two types of slats can be integrated with the use of an internal diffusing screen. Computer simulations were performed using a software that allows simultaneous analysis of energy and comfort issues, automatically taking into account any control action aimed at maintaining the thermal and luminous comfort. They were used climatic data of Gorizia, in the North East of Italy. Simulations results show that the thermal inertia has a great influence on energy demand and on thermal comfort. The strategy based only on the inner screen is the least advantageous from all points of view. Between the two types of slats, the external ones allow a better thermal comfort, while the others provide a better visual comfort.

Thales was born into a noble family of Phoenician origin at the time of the 25th Olympiad (floruit 585 bc; he was 40 in the year of the solar eclipse. He had no teachers but had occasion to learn from Egyptian priests. He developed into a scholar and politician very much appreciated by Heraclitus, Herodotus and Democritus, and was always considered a man of practical wisdom. He was probably the first to speak about the immortality of the soul. He is listed as the first of many unmarried men who paved the road for philosophy. For Diogenes Laertius (Lives and Opinions of Eminent Philosophers), he was the instructor of Anaximander. Thales, the man who first discovered how to draw a right-angle triangle in a circle, was the first philosopher of nature (physis). "Philosophy begins with Thales," pointed out Bertrand Russell in 1961. This honor had been conceded also by Aristotle: "Anaximander, Thales' pupil, founded the Ionian tradition of philosophy." Many explanations may be given for the importance of water, including its importance for living processes, the economic role of the Nile, the importance of the port for Miletus and the fact that Ocean and Thetys were in Homer's tradition progenitors of the world.

In order to better understand the two phase properties of the porous GDL, the liquid water pattern and local saturation in the Toray 060 gas diffusion layer (GDL) is visualized in-situ in cells close to the optimal performance point at 80°C by X-ray tomographic microscopy. A recording time of about 10 s is achieved. At the optimal performance point (dew point of reactant gases 74 °C) the water volume fraction observed depends on the rib width. A variation of ± 8 °C of the feed gas dew point leads to significant saturation and performance changes. For different current densities the water volume fraction and permeability of the liquid phase of the cathode are determined and analyzed.