CFD model for tubular SOFC directly fed by biomass

The coupling between biomass gasification and Solid Oxide Fuel Cells can represent a sustainable and efficient system for electricity production. This work aims to develop a preliminary model for the operation of a tubular, electrolyte-supported fuel cell (SOFC) fed by a syngas mixture. The fuel required by the SOFC system is produced inside the energy generator box from an integrated biomass gasification system. This study stems from the European DB-SOFC project, that proposed the exploitation of the abundant biomasses deriving from agricultural residues for energetic purposes (as from olive oil and wine production). In this study, the main processes have been simulated to find a possible configuration to obtain a power value of 200 W. 25 cells were used in the model to produce the required power. The results showed that at 0.7 V it is possible to achieve 12.3 W, when the biomass gasification was integrated into the SOFC box, while it was possible to achieve 9.6 W when the system was fed by externally produced syngas.     

Design of Engineered Elastomeric Substrate for Stretchable Active Devices and Sensors

In the field of flexible electronics, emerging applications require biocompatible and unobtrusive devices, which can withstand different modes of mechanical deformation and achieve low complexity in the fabrication process. Here, the fabrication of a mesa‐shaped elastomeric substrate, supporting thin‐film transistors (TFTs) and logic circuits (inverters), is reported. High‐relief structures are designed to minimize the strain experienced by the electronics, which are fabricated directly on the pillars' surface. In this design configuration, devices based on amorphous indium‐gallium‐zinc‐oxide can withstand different modes of deformation. Bending, stretching, and twisting experiments up to 6 mm radius, 20% uniaxial strain, and 180° global twisting, respectively, are performed to show stable electrical performance of the TFTs. Similarly, a fully integrated digital inverter is tested while stretched up to 20% elongation. As a proof of the versatility of mesa‐shaped geometry, a biocompatible and stretchable sensor for temperature mapping is also realized. Using pectin, which is a temperature‐sensitive material present in plant cells, the response of the sensor shows current modulation from 13 to 28 °C and functionality up to 15% strain. These results demonstrate the performance of highly flexible electronics for a broad variety of applications, including smart skin and health monitoring.     

Principal components analysis of the photoresponse nonuniformity of a matrix detector

The principal component analysis is used to identify and quantify spatial distributions of relative photoresponse as a function of the exposure time for a visible CCD array. The analysis shows a simple way to define an invariant photoresponse nonuniformity and compare it with the definition of this invariant pattern as the one obtained for long exposure times. Experimental data of radiant exposure from levels of irradiance obtained in a stable and well-controlled environment are used.     

Predicting the emissive power of hydrocarbon pool fires

The emissive power (E) of a flame depends on the size of the fire and the type of fuel. In fact, it changes significantly over the flame surface: the zones of luminous flame have high emittance, while those covered by smoke have low E values. The emissive power of each zone (that is, the luminous or clear flame and the non-luminous or smoky flame) and the portion of total flame area they occupy must be assessed when a two-zone model is used. In this study, data obtained from an experimental set-up were used to estimate the emissive power of fires and its behaviour as a function of pool size. The experiments were performed using gasoline and diesel oil as fuel. Five concentric circular pools (1.5, 3, 4, 5 and 6m in diameter) were used. Appropriate instruments were employed to determine the main features of the fires. By superimposing IR and VHS images it was possible to accurately identify the luminous and non-luminous zones of the fire. Mathematical expressions were obtained that give a more accurate prediction of E(lum), E(soot) and the average emissive power of a fire as a function of its luminous and smoky zones. These expressions can be used in a two-zone model to obtain a better prediction of the thermal radiation. The value of the radiative fraction was determined from the thermal flux measured with radiometers. An expression is also proposed for estimating the radiative fraction.     

A correlation to estimate the velocity of convective currents in boilover

The mathematical model proposed by Kozanoglu et al. [B. Kozanoglu, F. Ferrero, M. Mu?oz, J. Arnaldos, J. Casal, Velocity of the convective currents in boilover, Chem. Eng. Sci. 61 (8) (2006) 2550-2556] for simulating heat transfer in hydrocarbon mixtures in the process that leads to boilover requires the initial value of the convective current's velocity through the fuel layer as an adjustable parameter. Here, a correlation for predicting this parameter based on the properties of the fuel (average ebullition temperature) and the initial thickness of the fuel layer is proposed.     

Synthesis of poly(propylene-glycol-diacrylates) and properties of the photocured networks

A series of poly(propylene-glycol-diacrylates) (PPGDA) having molecular weights (MW) in the range 300–3,000 and an acrylic functionality near to two were synthesized by acrylation of the corresponding hydroxy-terminated oligomers with acrylic acid in the presence of p-toluensulphonic acid as a catalyst. The M¯_n of the acrylated products was found slightly lower than that of the starting oligomers, indicating the occurrence of an acidic degradation reaction which does not influence the acrylic functionality. The acrylated oligomers were ultraviolet (UV) cured until a complete double bond disappearance was obtained: only in the presence of tripropylene-glycol-diacrylate (TPGDA) were small amounts of residual unsaturations revealed. Rubbery materials were usually obtained, with the exception of TPGDA. The properties of the cured PPGDA were investigated by means of differential scanning calorimetry, thermomechanical analysis, and dynamic mechanical thermal analysis. The T_g values were found to decrease by increasing the MW of the used oligomers, that is, by increasing the length of the chain between the two acrylic double bonds. A good agreement with the Nielsen equation was found. Moreover, the equilibrium swelling values in water were measured; the obtained values were interpreted in terms of the solubility parameters of the oligomers and of the crosslinking density of the networks. Finally, some mixtures of PPGDA oligomers with a typical epoxy-acrylate resin were UV cured; their properties confirm the high flexibilizing effect of the PPGDA oligomers. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:491–497, 1997     

Rheological and Microstructural Study of Wheat Doughs Partially Replaced with Mesquite Flour (<Emphasis Type="Italic">Prosopis alba</Emphasis>) and Added with Transglutaminase

The incorporation of different flours into wheat bread may pursue different objectives, such as increasing the nutritional quality of the products or the recovery of flour with little use in the industry. The “mesquite flour” (MF) is rich in sugar, fiber, and protein and is an interesting additive to wheat flour in baking. In this study, we used crude and thermally processed bread dough formulations of wheat flour (WF), replacing 15, 25, and 35% with mesquite flour. Furthermore, each formulation was tested for two levels (0.01 and 0.1%) of the enzyme transglutaminase (TG). Dough rheology was studied by small amplitude oscillatory compression tests, and the microstructure was analyzed by laser confocal microscopy using fluorescein isothiocyanate and rhodamine B as fluorophores. It was concluded that the incorporation of mesquite into the dough resulted in changes in the structure, as evidenced by the increase in tan δ, microscopic observations (loss of the filamentary and cross-linked gluten structure), and by the increase in the gelatinization temperature. The addition of TG led to dissimilar effects on doughs, depending on the formulation (wheat/mesquite content), but most encouraging results indicate the recovery of the structure, evidenced by a reduction in tan δ and the generation of a more filamentary structure in the dough with a higher content of mesquite flour. However, the effect of TG addition on “processed dough” was attenuated and the viscoelastic matrix of gluten did not recover.     

Antimicrobial finish of textiles by chitosan UV-curing

The purpose of this research work was to develop a textile finish based on the radical UV-curing of chitosan on textiles to confer antimicrobial properties. Chitosan is a biopolymer with unique properties such as biodegradability, non-toxicity, antimicrobial activity. In this work cotton or silk fabrics and synthetic filter fabrics were impregnated with an acid solution of chitosan added of the photoinitiator in the proper amount and cured at room temperature by exposure to UV lamp. Process conditions such as percentage add-on, dilution, chitosan-fabric contact time, irradiation time and power, were optimized. The antimicrobial activity of finished fabrics was tested according to ASTM E 2149-01 standard test performed with Escherichia Coli ATCC 8739. Moreover dyeing test with Turquoise Telon dye were carried out to evaluate the treatment homogeneity while the amino group content was determined by ninhydrin assay. Moreover on cotton and silk fabrics the treatment fastness to domestic laundering was tested, according to UNI EN ISO105-C01. Obtained results showed a strong antimicrobial activity conferred by the treatment, homogeneous on fabric surface. It is evident already at low add-on, without affecting the hand properties of natural fabrics and the filtration characteristics of the synthetic filter fabrics. Finally, washing fastness was better for samples prepared with a better penetration of chitosan inside the fibers.     

Change of Scale Strategy for the Microstructural Modelling of Polymeric Rohacell Foams

In this paper a numerical model dedicated to the simulation of the mechanical behaviour of polymeric Rohacell foams is presented. The finite elements model is developed at the scale of the microstructure idealized by a representative unit cell: the truncated octahedron. Observations made on micrographs of Rohacell lead to mesh this representative unit cell as a lattice of beam elements. Each beam is assigned a brittle linear elastic mechanical behaviour in tension and an elastoplastic behaviour in compression. The plasticity in compression is introduced as a way to mimic the buckling of the edges of the cells observed in experimental crushing tests. A contact law introduced between the beams stands for densification. A change in scale is then realized by increasing the length of the edges of the unit cell. Several computations show the ability of the proposed approach to preserve the physical degradation phenomena and the loads while drastically decreasing the computational time.