Spray Pyrolysed Tin Chalcogenide Thin Films: Optimization of optoelectronic properties of SnS for possible photovoltaic application as an absorber layer

In the early 19th century, industrial revolution was fuelled mainly by the development of machine based manufacturing and the increased use of coal. Later on, the focal point shifted to oil, thanks to the mass-production technology, ease of transport/storage and also the (less) environmental issues in comparison with the coal!! By the dawn of 21st century, due to the depletion of oil reserves and pollution resulting from heavy usage of oil the demand for clean energy was on the rising edge. This ever growing demand has propelled research on photovoltaics which has emerged successful and is currently being looked up to as the only solace for meeting our present day energy requirements. The proven PV technology on commercial scale is based on silicon but the recent boom in the demand for photovoltaic modules has in turn created a shortage in supply of silicon. Also the technology is still not accessible to common man. This has onset the research and development work on moderately efficient, eco-friendly and low cost photovoltaic devices (solar cells). Thin film photovoltaic modules have made a breakthrough entry in the PV market on these grounds. Thin films have the potential to revolutionize the present cost structure of solar cells by eliminating the use of the expensive silicon wafers that alone accounts for above 50% of total module manufacturing cost.

Estudo Experimental do Tempo de Residência de Particulas em Secador "SPRAY

No presente trabalho é apresentado um estudo do tempo de resistência de partículas em um 'spray dryer' com contato ar/'spray' predominantemente co-corrente e sistema rotativo de atomização de amostra. Propõe-se aplicação de uma técnica nuclear, utilizando como traçador o radioisótopo La140.

On the modelling of fire atmosphere/sprinkler spray interacting using an Euler-Lagrange framework

An Euler-Lagrange particle tracking model, developed for simulating fire atmosphere/sprinkler spray interactions, is described. Full details of the model along with the approximations made and restrictions applying are presented. Errors commonly found in previous formulations of the source terms used in this two-phase approach are described and corrected. In order to demonstrate the capabilities of the model it is applied to the simulation of a fire in a long corridor containing a sprinkler. The simulation presented is three-dimensional and transient and considers mass, momentum and energy transfer between the gaseous atmosphere and injected liquid droplets.

Simulations of droplet dispersion in the wakes of cylinders and icing tunnel spray bars

Simulations of droplet dispersion behind cylinder wakes and downstream of icing tunnel spray bars were conducted. In both cases, a range of droplet sizes were investigated numerically with a Lagrangian particle trajectory approach while the turbulent air flow was investigated with a hybrid Reynolds-Averaged Navier-Stokes/Large-Eddy Simulations approach scheme. In the first study, droplets were injected downstream of a cylinder at sub-critical conditions (i.e. with laminar boundary layer separation). A stochastic continuous random walk (CRW) turbulence model was used to capture the effects of sub-grid turbulence. Small inertia droplets (characterized by small Stokes numbers) were affected by both the large-scale and small-scale vortex structures and closely followed the air flow, while exhibiting a dispersion consistent with that of a scalar flow field. Droplets with intermediate Stokes numbers were centrifuged by the vortices to the outer edges of the wake, yielding an increased dispersion. Large Stokes number droplets were found to be less responsive to the vortex structures and exhibited the least dispersion. Particle concentration was also correlated with vorticity distribution which yielded preferential bias effects as a function of different particle sizes. This trend was qualitatively similar to results seen in homogenous isotropic turbulence, though the influence of particle inertia was less pronounced for the cylinder wake case. A similar study was completed for droplet dispersion within the Icing Research Tunnel (IRT) at the NASA Glenn Research Center, where it is important to obtain a nearly uniform liquid water content (LWC) distribution in the test section (to recreate atmospheric icing conditions).. For this goal, droplets are diffused by the mean and turbulent flow generated from the nozzle air jets, from the upstream spray bars, and from the vertical strut wakes. To understand the influence of these three components, a set of simulations was conducted with a sequential inclusion of these components. Firstly, a jet in an otherwise quiescent airflow was simulated to capture the impact of the air jet on flow turbulence and droplet distribution, and the predictions compared well with experimental results. The effects of the spray bar wake and vertical strut wake were then included with two more simulation conditions, for which it was found that the air jets were the primary driving force for droplet dispersion, i.e. that the spray bar and vertical strut wake effects were secondary.

Regimes of spray vaporization and combustion in counterflow configurations

This article addresses the problem of spray vaporization and combustion in axisymmetric opposed-jet configurations involving a stream of hot air counterflowing against a stream of nitrogen carrying a spray of fuel droplets. The Reynolds numbers of the jets are assumed to be large, so that mixing of the two streams is restricted to a thin mixing layer that separates the counterflowing streams. The evolution of the droplets in their feed stream from the injection location is seen to depend fundamentally on the value of the droplet Stokes number, St, defined as the ratio of the droplet acceleration time to the mixing layer strain time close to the stagnation point. Two different regimes of spray vaporization and combustion can be identified depending on the value of St. For values of St below a critical value, equal to 1/4 for dilute sprays with small values of the spray liquid mass loading ratio, the droplets decelerate to approach the gas stagnation plane with a vanishing axial velocity. In this case, the droplets located initially near the axis reach the mixing layer, where they can vaporize due to the heat received from the hot air, producing fuel vapor that can burn with the oxygen in a diffusion flame located on the air side of the mixing layer. The character of the spray combustion is different for values of St of order unity, because the droplets cross the stagnation plane and move into the opposing air stream, reaching distances that are much larger than the mixing layer thickness before they turn around. The vaporization of these crossing droplets, and also the combustion of the fuel vapor generated by them, occur in the hot air stream, without significant effects of molecular diffusion, generating a vaporization-assisted nonpremixed flame that stands on the air side outside the mixing layer. Separate formulations will be given below for these two regimes of combustion, with attention restricted to the near-stagnation-point region, where the solution is self-similar and all variables are only dependent on the distance to the stagnation plane. The resulting formulations display a reduced number of controlling parameters that effectively embody dependences of the structure of the spray flame on spray dilution, droplet inertia, and fuel preferential diffusion. Sample solutions are given for the limiting cases of pure vaporization and of infinitely fast chemistry, with the latter limit formulated in terms of chemistry-free coupling functions that allow for general nonunity Lewis numbers of the fuel vapor.

Application of Lidocaine Spray for Tracheal Intubation in Neonates - A Clinical Trial Study

Background: Tracheal intubation is extremely distressing, painful, and may influence heart rate and blood pressure. Sedatives, analgesics, and muscle relaxants are not commonly used for intubation in neonates. Objectives: This study aimed to evaluate the effects of lidocaine spray as a non-intravenous drug before neonatal intubation on blood pressure, heart rate, oxygen saturation and time of intubation. Patients and Methods: In a randomized, controlled study each neonate was randomly assigned to one of the two study groups by staffs who were not involved in the infant's care. The allocation concealment was kept in an opaque sealed envelope, and the investigators, the patient care team, and the assessors were blinded to the treatment allocation. The selected setting was NICU unit of a teaching hospital in Ilam city, Iran and participants were 60 neonates with indication of tracheal intubation with gestational age >30 weeks. Patients in the treatment group received lidocaine spray and the placebo group received spray of normal saline prior to intubation. Main outcome measurements were the mean rates of blood pressure, heart rate, oxygen saturation, intubation time and lidocaine side effects were measured before and after intubation. Results: Totally 60 newborns including 31 boys and 29 girls were entered into the study (drug group n = 30; placebo group n = 30). Boy/girl ratio in treatment and placebo groups were 1.3 and 0.88, respectively. Mean age ± SD of participants was 34.1 ± 24.8 hours (treatment: 35.3 ± 25.7; placebo: 32.9 ± 24.3; P < 0.0001). Mean weight ± SD of neonates was 2012.5 ± 969 g. Application of lidocaine spray caused a significant reduction of mean intubation time among treatment group compared with placebo group (treatment: 15.03 ± 2.2 seconds; placebo: 18.3 ± 2.3 seconds; P < 0.0001). Mean blood pressure, heart rate and oxygen saturation rate, among neonates in treatment group was reduced after intubation compared with their relevant figures before intubation; however, their differences were not statistically significant except for mean oxygen saturation rate that was reduced significantly in placebo group. No side effects were observed during study. Conclusions: Though the current study revealed some promising results in the application of lidocaine spray during neonatal intubation without any considerable side effects; however, the current investigation could only be considered as a pilot study for further attempts in different locations with higher sample sizes and in different situations.

Current Legal Rules Benefit Spray Applicators When It Comes to Pesticide Drift

Homeowners, landowners, pesticide applicators, and farmers are concerned about pesticide drift. It may injure a homeowner’s garden or flowers or ruin a neighboring farmer’s crop. While no Maryland court has considered the issue of liability from pesticide drift, courts in other states have. These decisions provide some guidance on how a Maryland court might handle the issue. Depending on the facts of the drift case, pesticide applicators and farmers could owe damages for nuisance or trespass case, or for uses inconsistent with the pesticide label.

Tin Oxide Based Composites Derived Using Electrostatic Spray Deposition Technique as Anodes for Li-Ion Batteries

Recent advances in the electric & hybrid electric vehicles and rapid developments in the electronic devices have increased the demand for high power and high energy density lithium ion batteries. Graphite (theoretical specific capacity: 372 mAh/g) used in commercial anodes cannot meet these demands. Amorphous SnO2 anodes (theoretical specific capacity: 781 mAh/g) have been proposed as alternative anode materials. But these materials have poor conductivity, undergo a large volume change during charging and discharging, large irreversible capacity loss leading to poor cycle performances. To solve the issues related to SnO2 anodes, we propose to synthesize porous SnO2 composites using electrostatic spray deposition technique. First, porous SnO2/CNT composites were fabricated and the effects of the deposition temperature (200,250, 300 oC) & CNT content (10, 20, 30, 40 wt %) on the electrochemical performance of the anodes were studied. Compared to pure SnO2 and pure CNT, the composite materials as anodes showed better discharge capacity and cyclability. 30 wt% CNT content and 250 oC deposition temperature were found to be the optimal conditions with regard to energy capacity whereas the sample with 20% CNT deposited at 250 oC exhibited good capacity retention. This can be ascribed to the porous nature of the anodes and the improvement in the conductivity by the addition of CNT. Electrochemical impedance spectroscopy studies were carried out to study in detail the change in the surface film resistance with cycling. By fitting EIS data to an equivalent circuit model, the values of the circuit components, which represent surface film resistance, were obtained. The higher the CNT content in the composite, lower the change in surface film resistance at certain voltage upon cycling. The surface resistance increased with the depth of discharge and decreased slightly at fully lithiated state. Graphene was also added to improve the performance of pure SnO2 anodes. The composites heated at 280 oC showed better energy capacity and energy density. The specific capacities of as deposited and post heat-treated samples were 534 and 737 mAh/g after 70 cycles. At the 70th cycle, the energy density of the composites at 195 °C and 280 °C were 1240 and 1760 Wh/kg, respectively, which are much higher than the commercially used graphite electrodes (37.2-74.4 Wh/kg). Both SnO2/CNTand SnO2/grapheme based composites with improved energy densities and capacities than pure SnO2 can make a significant impact on the development of new batteries for electric vehicles and portable electronics applications.

Validazione di metodologie di simulazione dell’impatto a parete di spray di combustibile iniettati ad alta pressione

Il presente lavoro di tesi, svolto in collaborazione con una azienda del settore automotive, tratta lo studio di impatto di sprays combustibili su pareti calde adottando un approccio numerico CFD-3D. Viene effettuata la validazione di alcuni tra i più utilizzati modelli di interazione goccia-parete implementati nel software commerciale STAR-CD. Lo scopo principale del lavoro svolto è quello di indirizzare il lettore verso una corretta implementazione della simulazione di uno spray impattante, comprendere pregi e limiti dei modelli applicati e fornire dei criteri per effettuare la scelta tra uno di essi in funzione di condizioni di interesse motoristico.

Calibrazione e validazione di modelli per la simulazione CFD di impatto a parete di spray di combustibili

Il seguente lavoro è uno studio di iniezione (strategia, timing, spray pattern) svolto con la simulazione numerica, alle quali oggi si richiede dettaglio e accuratezza. Il lavoro si concentra sullo studio di spray multi componente, tramite la scrittura di una UDF (user define function) proprietaria, valutazione sensibilità dell'impatto a parete, film boiling a parametri modellistici influenzati dal multicomponente e scrittura di un codice per l'elaborazione delle immagini sia sperimentali che numeriche per rendere più esteso il confronto tra CFD e sperimentale, per migliorare le tarature e i modelli e comprendere meglio la fenomenologia.