A new approach for fuel injection into a solar receiver/ reactor: Numerical and experimental investigation

An innovative and efficient design of solar receivers/reactors can enhance the production of clean fuels via concentrated solar energy. This study presents a new jet-type burner nozzle for gaseous feedstock injection into a cavity solar receiver inspired from the combustion technology. The nozzle design was adapted from a combustion burner and successfully implemented into a solar receiver and studied the influence of the nozzle design on the fluid mixing and temperature distribution inside the solar receiver using a 7 kW solar simulator and nitrogen as working fluid. Finally, a thorough computational fluid dynamics (CFD) analysis was performed and validated against the experimental results. The CFD results showed a variation of the gas flow pattern and gas mixing after the burner nozzle adaptation, which resulted an intense effect on the heat transfer inside the solar receiver.

Open image in new window

     

Antibacterial and Antifungal Activities of the Essential Oils of Two Saltcedar Species from Tunisia

The chemical composition of the volatile constituents from the flowering parts of Suaeda fructicosa and Limonium echioides were analysed by GC-FID and GC-MS. Sixty-five compounds were identified in L. echioides aerial parts. 48 out of 65 were found common to the aerial part of S. fructicosa. Palmitic acid was found as a predominant compound in both tested halophytic oils. Furthermore, the essential oil was tested against six bacteria and four fungi at different concentrations. Both oils, tested at 0.5 and 0.8 mg ml⁻¹, inhibited the visible growth of Staphylococcus aureus, Staphylococcus epidermidis, Micrococcus luteus, Escherichia coli and Salmonella typhimurium, but no antibacterial effect was detected against Pseudomonas aeruginosa. Additionally, both halophytic oils failed to show antifungal activity against all the test fungi when applied at 80, 200 and 500 μg/disc.     

Exhaust dyeing of polyester‐based textiles using high‐temperature–alkaline conditions

The factors affecting the dyeability of polyester‐based textiles with disperse dyes in an alkaline medium were studied. It was found, for a given set of dyeing conditions, that (a) the appropriate conditions for attaining a higher color yield were 45 min at 130°C with pH 9 using a material‐to‐liquor ratio of 1/10; (b) increasing the Diaserver® AD‐95 concentration to 2% ows (based on weight of substrate) as well as including triethanolamine to 2% ows in the dyeing formulations bring about a significant improvement in the dye uptake; (c) both a preheat setting from 160 to 200°C/30 s and an alkaline weight reduction have a positive impact on postdyeing with the used disperse dye; (d) the extent of dye uptake as well as the color strength are governed by the type of substrate, that is, knitted fabric > spun yarn > woven fabric, nature of the dye stabilizer, that is, EDTA > Diaserver® AD‐95 > Tinoclorite® CBB > citric acid > none, as well as kind of the disperse dye; (e) direct reuse of the disperse dyebaths, without reconstitution, in the dyeing of the used substrates was shown to be feasible in a single shade and in the reverse‐order dyeings (dark → light); (f) one‐bath, one‐step exhaust dyeing of polyester/cotton‐knitted fabric using selected disperse reactive dyes combinations under high‐temperature alkaline conditions is feasible; and (g) the color and fastness properties of the resultant dyeings depend on the type of the used auxiliaries, in addition to the nature of disperse/reactive dyes combinations as well as compatibility with other ingredients. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3563–3573, 2003     

Effect of grape variety on the evolution of sugars,hydroxymethylfurfural, polyphenols and antioxidant activity during grape must cooking

Grape must cooking is a traditional practice used for the production of foodstuff worldwide such as traditional balsamic vinegar. The aim of this work was to reveal the effect of grape variety on the evolution of the main chemical components in grape must during cooking. To this end, two grape must varieties (red Lambrusco and white Trebbiano grapes) were cooked and analysed. The monosaccharide concentration decreased because cooking resulting in the formation of 5‐hydroxymethylfurfural. At the end of cooking, the antioxidant activity and polyphenol concentration were higher and the 5‐hydroxymethylfurfural was lower in Lambrusco than in Trebbiano must. Additional changes involved degradation of monomeric anthocyanins resulting in the formation of the corresponding phenolic acids. From a health point of view, the high antioxidant activity and polyphenol concentration and the low 5‐hydroxymethylfurfural concentration make cooked red Lambrusco must a safer raw starting material for making traditional balsamic vinegar.     

The Deceleration of two hollow concentric infinite cylinders submerged in three fluids with different viscosities

In this paper, an analytical solution is presented for the angular velocities of two infinite, hollow and concentric cylinders having initial angular velocities in viscous fluid with time. The momentum equation is solved for the three regions, neglecting the inertia force because of the difficulty of the deduced equations in this case. The resulting torque affected on each cylinder surface is calculated, and the equations of motion for the two cylinders are solved using the analysis of the eigenvalue problem.     

Extracorporeal shock-wave lithotripsy in infants. Study of its repercussions on the renal parenchyma

Retinoblastoma is a childhood malignancy of the eye. Almost all patients with familial or bilateral disease suffer from the hereditary form of the disease that is caused by germline mutations in one allele of the RB1 gene. Tumor development is initiated by the loss of the second RB allele in a retinal progenitor cell. Most patients with isolated unilateral disease have nonhereditary retinoblastoma and thus do not carry a mutant allele in their germline. In no patient, the presence of a germline mutation can be excluded clinically. Consequently, relatives are at an increased risk for retinoblastoma. Molecular testing, however, enables accurate risk prediction provided that samples are available. In some relatives an increased risk can be excluded by segregation analysis. Most often, however, identification of the disease causing mutation is necessary for accurate risk prediction. Mutation analysis, which is impeded by the size and complexity of the RB gene, is facilitated by use of efficient screening methods. Using these methods, the oncogenic mutation can be identified in most patients. Therefore, predictive testing has become an integral part of contemporary management of retinoblastoma.     

Once-through and brine recirculation MSF designs — a comparative study

This study investigated the feasibility of the once-through (OT) MSF design for constructing large-capacity desalting plants rather than the conventional brine recycle (BR) MSF configuration. This was to explore the possibility of improving MSF process economics through the application of a simpler process design. It is known that the OT design is characterized by its simplicity and elimination of the brine recirculation pump as well as the rejection section. These features are expected to reduce capital and maintenance costs. The current study is based on comparing the two MSF plant configurations, OT and BR, from the standpoint of minimum heat transfer area, which is a major element in capital investment. Alternative tube layouts, long-tube (LT) and cross-tube (CT) arrangements, were considered. Design calculations were based on a plant capacity of 20 MGD, a gained output ratio of 10, a top brine temperature of 120°C, a feed temperature and concentration of 35°C and 48,000 ppm, respectively. The total number of stages was varied stepwise between 20 and 40. A rigorous mathematical model was developed to solve the optimization problem taking into consideration the nonlinearity of the thermo-physical properties of seawater and steam. The Solver tool of Microsoft Excel was used to determine the optimal solutions. Substantial savings in the heat transfer area can be realized through the application of the LT-OT design when the number of stages goes up to 40. However, comparison of the different MSF designs with the optimal number of stages and minimum heat transfer area tells us that the use of the OT designs is not likely to save more than 1% in heat transfer area relative to the conventional CT-BR configuration. Findings related to the specific chemical consumption are not in favor of OT plants where the consumption ratio varies between 1.7 and 1.9 relative to the CT-BR plants. Of course, excessive chemical consumption penalizes the operating cost of the OT plants. However, the increase in operating costs has to be weighed against the savings in capital cost and lower power consumption due to the elimination of the recycle pump and the heat rejection section. This will determine the use of the OT configuration for building MSF plants in the future. In this event, a detailed cost analysis will be needed.