EXPERIMENTAL AND MODELING STUDIES OF STAGED COMBUSTION USING A REACTOR ENGINEERING APPROACH

Combustion research, long dominated by mechanical engineers, is becoming increasingly a chemical engineering application. It is therefore desirable to have a well defined reactor in which to conduct combustion chemistry studies. A two zone laboratory reactor emulating a perfectly stirred reactor + plug flow reactor (PSR + PFR) sequence has been constructed and validated for use in high temperature normal and staged combustion studies. A premixed fuel/eed enters the backmixed primary zone. The effluent mixes with additional injected oxidant and/or steam, and then enters the linear flow secondary zone. Extracted gas samples from cooled probes located in each zone are subjected to several dedicated on-line stack gas analyzers, and separation/analyses by on-line gas chromatography. Detailed reaction mechanisms from the literature are incorporated into a PSR + PFR reactor engineering model. The experimental feed rates and measured temperatures are also input to the model. Good comparisons between model predictions and experimental data have been obtained for normal and air-staged combustion studies. Rate-of-prod,uction calculations from the modeling offers helpful insight into the reaction pathways responsible for important species, especially pollutants.     

Detection of expired vacuum-packed smoked salmon based on PLS-DA method using hyperspectral images

Consumers want fresh food with a long shelf-life, which in 2010, resulted in an important increase in packaged and processed food. This is especially important for fishery products due to their highly perishable nature. One problem is that it is not possible to measure freshness in packaged food only using the visible spectrum. Moreover, the detection of freshness is a complex problem as fish has different tissues with different biodegradation processes. Therefore, it would be especially interesting to have a non-destructive method to evaluate the shelf-life of packed processed fish. This paper proposes a method for detecting expired packaged salmon. Firstly, this method uses hyperspectral imaging spectroscopy (HIS) using visible and SW-NIR wavelengths. Secondly, a classification of different salmon tissues is carried out by image segmentation. Finally, classifications of expired or non expired salmon are performed with the PLS-DA statistical multivariate method due to the large amount of captured data. In a similar way, spectral data and the physicochemical, biochemical and microbiological properties of salmon are correlated using partial least squares (PLSs). The result obtained has a classification success rate of 82.7% in cross-validation from real commercial samples of salmon. Therefore, this is a promising technique for the non-destructive detection of expired packaged smoked salmon.     

Variation in Mechanical Properties and Heterogeneity in Microstructure of High-Strength Ferritic Steel During Mill Trial

HS600 and HS800 are two new generation, high-strength advanced ferritic steels that find widespread application in automobiles. During commercial production of the same grades with different thicknesses, it has been found that mechanical properties like tensile strength and stretchability varied widely and became inconsistent. In the current endeavor, two different thicknesses have been chosen from a mill trial sample of HS600 and HS800. An in-depth structural characterization was carried out for all four alloys to explain the variation in their respective mechanical and shear punch properties. The carbon content was smaller and Ti + Mo quantity was higher in case of HS800 with respect to HS600. The microstructure of both steels consisted of the dispersion of (Ti,Mo)C in a ferrite matrix. The grain size of HS800 was little larger than HS600 due to an increased coiling temperature (CT) of the former in comparison to the latter. It was found that in case of same grade of steel with a different thickness, a variation in microstructure occurred due to change in strain, CT, and cooling rate. The strength and stretch formability of these two alloys were predominantly governed by a microalloyed carbide. In this respect, carbides with a size range above 5 nm were responsible for loosing coherency with ferrite matrix. In case of HS600, both ≤5 and >5-nm size (Ti,Mo)C precipitates shared a nearly equal fraction of microalloyed precipitates. However, for HS800, >5-nm size (Ti,Mo)C carbide was substantially higher than ≤5-nm size alloy carbides. The ultimate tensile strength and yield strength of HS800 was superior to that of HS600 owing to a higher quantity of microalloyed carbide with a decreased column width and interparticle distance. A higher degree of in-coherency of HS800 made the alloy prone to crack formation with low stretchability.     

Molecular modeling of (E)-1-alkyl-4(3)-[2-(1H-azolyl)vinyl]-pyridinium salts and evaluation of their behavior towards choline acetyltransferase

A new type of extended pi-system aza-analogue of (E)-4-[2-(1-naphthylvinyl)]-1-substituted pyridinium salts (NVP+) has been designed and its inhibitory activity towards choline acetyltransferase (ChAT) has been evaluated in vitro. Among the several examples of the title quaternary salts synthesized 2 and 3, the indolylvinylpyridinium salt 2e is the only one to show a very low ChAT inhibition. The molecular modeling study is highly illustrative of their behavior towards ChAT and interaction with the recognition site. Thus, several selected cations together with the reference NVP+ compound 1a were studied at the PM3 and AM1 levels respectively. At the global minima, all the compounds are planar, which, from the electron charge distribution, shows a degree of polarization similar to the NVP+ model compound 1a. However, the fitting of all optimized structures indicated that only the indole derivative 2e showed the same aromatic fragment orientation as 1a, which allows us to define a volume that is not accessible to ligands in the enzyme and consequently to a refined model of the choline acetyltransferase recognition site.     

Numerical simulation of non-rigid landslide into reservoir with erodible sediment bed using SPH method

Bulletin of Engineering Geology and the Environment - Landslide phenomenon in accumulated erodible bed sediments in a reservoir is one of the issues in hydraulic and sedimentation sciences that has...     

Detection of frozen-thawed salmon (Salmo salar) by a rapid low-cost method

The aim of this study was to evaluate a rapid low-cost system based on impedance spectroscopy as an alternative method to differentiate between fresh and frozen-thawed salmon. Samples of fresh salmon and others submitted to freezing at −18 °C or to 2 freezing cycles, kept in frozen storage for different times, were analysed. In general, no significant differences in moisture, total volatile basic nitrogen, pH, texture parameters, K₁ value, or microbial counts between the different samples were observed. This revealed that the freezing process, storage time or number of freezing cycles did not affect the physico-chemical parameters of fish samples, except for water holding capacity, which was significantly lower in all frozen samples compared with fresh salmon. The results showed that impedance spectroscopy was unable to differentiate between different storage times under frozen conditions; however, this technique could be a useful tool to detect fish submitted to freezing process.     

Influence of brine concentration on swelling pressure of pork meat throughout salting

The influence of sodium chloride on the water holding capacity of meat is well known and described in literature. An increase in water holding capacity is associated with an increase in the swelling pressure in the protein matrix.     

Characterisation of pile salting with sodium replaced mixtures of salts in dry-cured loin manufacture

Salting, one of the fundamental operations in Spanish cured loin manufacturing, is essential to preserve the product throughout its processing and storage. However, elevated blood pressure has been identified to be the major adverse effect associated with increased sodium intake. The partial replacement of NaCl with other chloride salts such as KCl, CaCl₂ and MgCl₂ has been proposed as a possible strategy to reduce the sodium content of these products. The aim of this study was to determine the salting time needed to reach the same chloride content as commercial dry-cured loins and, to characterise the first step in dry-cured loin production (salting), in loins salted with sodium partial replaced salts. The results indicated a reduction in the salting time when using KCl as NaCl substitute and an increase in the salting time when adding CaCl₂ and MgCl₂ to the mixture. Further studies need to be done in order to fully understand the influence of these low sodium mixtures of salts on the following manufacturing steps and the final quality characteristics of the product.     

Technical comparison of a CHP using various blends of gasohol in an IC engine

The effects of bioethanol addition to gasoline on an combined heat and power with internal combustion engine (ICECHP) are investigated experimentally and theoretically. In the theoretical study, a multi-zone spark ignition (SI) engine model is developed. This model was initially developed for gasoline fueled SI engine. However, it was adapted for SI engines running on gasoline–bioethanol blend. Experimental applications have been carried out with the gasoline fuel and the model results have been validated. Using the theoretical model, effects of bioethanol addition to gasoline on output temperature, flow availability, and efficiency are investigated. The results have shown when the bioethanol blend increases, the maximum cylinder pressure and temperature increase and carbon monoxide volume percentage reduces. Also, as the bioethanol blend increases, the availability of the flue gas increases as well. It is shown that among the various blends of gasohol, E20 has the maximum availability for heat recovery. The results of the efficiency investigation have shown that the efficiency of CHP is higher than the efficiency of separate heat and power (SHP) production. In fact, if the bioethanol blend in gasohol increases, the efficiency of the CHP system increases as well. It has been shown that E20 has the largest efficiency of ICECHP using gasohol.