Showing papers on "Nozzle published in 2015"

Centrifugal step emulsification applied for absolute quantification of nucleic acids by digital droplet RPA

Abstract: Aqueous microdroplets provide miniaturized reaction compartments for numerous chemical, biochemical or pharmaceutical applications. We introduce centrifugal step emulsification for the fast and easy production of monodisperse droplets. Homogenous droplets with pre-selectable diameters in a range from 120 μm to 170 μm were generated with coefficients of variation of 2–4% and zero run-in time or dead volume. The droplet diameter depends on the nozzle geometry (depth, width, and step size) and interfacial tensions only. Droplet size is demonstrated to be independent of the dispersed phase flow rate between 0.01 and 1 μl s−1, proving the robustness of the centrifugal approach. Centrifugal step emulsification can easily be combined with existing centrifugal microfluidic unit operations, is compatible to scalable manufacturing technologies such as thermoforming or injection moulding and enables fast emulsification (>500 droplets per second and nozzle) with minimal handling effort (2–3 pipetting steps). The centrifugal microfluidic droplet generation was used to perform the first digital droplet recombinase polymerase amplification (ddRPA). It was used for absolute quantification of Listeria monocytogenes DNA concentration standards with a total analysis time below 30 min. Compared to digital droplet polymerase chain reaction (ddPCR), with processing times of about 2 hours, the overall processing time of digital analysis was reduced by more than a factor of 4.

Additive manufacturing techniques and systems to form composite materials

Abstract: A printer system may include a coaxial extruder head that extrudes a core, a bulk, and/or a core and bulk cladding to form complex structures without retooling. The coaxial extruder head may include a distribution channel with an entrance and an exit, a priming chamber that surrounds the distribution channel. The priming chamber may include an outlet and a first inlet, a heating element thermally connected to the priming chamber, and a nozzle connected to the outlet of the priming chamber. Further, the nozzle may converge from the outlet of the priming chamber to an orifice of the nozzle. In addition, the exit of the distribution channel may be disposed at the orifice of the nozzle. This structure facilitates extruding a core and cladding type composite from the extruder head.

Visualization of arc and plasma flow patterns for advanced material processing

Abstract: Results are presented for physical experiments that illustrate the possibilities and efficiency of visualization for studying the effect of operating conditions (backward-facing stepped forming nozzle, exit diameter of anode, mass flow, and composition of working gas) on plasma flows at low Reynolds numbers for advanced coating and powder processing In particular, the shadow method, based on adaptive visualization transparency, is used for imaging electric arc and plasma jet flow patterns for different operating conditions Because of visualization, the optimal geometrical characteristics of the backward-facing stepped forming nozzle, mass flow rate of the working gas, and its composition were found These provide: (1) the absence of micro-shunting of the arc inside the backward-facing stepped nozzle for a transfer arc and twin arcs; and (2) compared to transient and turbulent jets, a higher density for the heat flux from a quasi-laminar flow to the surface of a flat substrate and the powder material to be treated, for nontransfer arc DC (direct current) torches and DC–RF (direct current and radio frequency) hybrid plasma flow system

Automated contact cleaning system for docking stations

Abstract: A docking station for mobile electronic devices with an automated cleaning feature is provided. The docking station includes a receiver for receiving an electronic device, a base, a piston, a nozzle, and electrical contacts for connecting to the electronic device. The piston has a plunger and an air chamber. The receiver is mounted to the plunger, such that pushing the receiver in a downward direction forces the plunger to compress air in the air chamber. The nozzle is mounted on the air chamber. Air passes through the nozzle when the air in air chamber is compressed. The electrical contacts are positioned directly under the receiver. The nozzle is directed towards the electrical contacts, whereby air is directed over the electrical contacts when the receiver is pushed in a downward direction.

Effect of Pre-Chamber Volume and Nozzle Diameter on Pre-Chamber Ignition in Heavy Duty Natural Gas Engines

Abstract: It has previously been shown by the authors that the pre-chamber ignition technique operating with fuel-rich pre-chamber combustion strategy is a very effective means of extending the lean limit of combustion with excess air in heavy duty natural gas engines in order to improve indicated efficiency and reduce emissions. This article presents a study of the influence of pre-chamber volume and nozzle diameter on the resultant ignition characteristics. The two parameters varied are the ratio of pre-chamber volume to engine's clearance volume and the ratio of total area of connecting nozzle to the pre-chamber volume. Each parameter is varied in 3 steps hence forming a 3 by 3 test matrix. The experiments are performed on a single cylinder 2L engine fitted with a custom made pre-chamber capable of spark ignition, fuel injection and pressure measurement. The measured main and pre-chamber pressure data is then used to perform heat release analysis to understand combustion phenomenon in pre-chamber and the ignition and combustion of fuel-lean charge in main chamber that follows. Within the span of parameter variation, it has been observed that a larger pre-chamber provides higher ignition energy which results in shortened flame development angle and combustion duration. It is also observed that at a given pre-chamber volume, nozzle diameter mainly affects the combustion duration which may be due to difference in penetration depths of pre-chamber jets. The varied parameters seemed to have minor effect on NOx emissions. (Less)

Large-eddy simulation of cavitating nozzle flow and primary jet break-up

Abstract: We employ a barotropic two-phase/two-fluid model to study the primary break-up of cavitating liquid jets emanating from a rectangular nozzle, which resembles a high aspect-ratio slot flow. All components (i.e., gas, liquid, and vapor) are represented by a homogeneous mixture approach. The cavitating fluid model is based on a thermodynamic-equilibrium assumption. Compressibility of all phases enables full resolution of collapse-induced pressure wave dynamics. The thermodynamic model is embedded into an implicit large-eddy simulation (LES) environment. The considered configuration follows the general setup of a reference experiment and is a generic reproduction of a scaled-up fuel injector or control valve as found in an automotive engine. Due to the experimental conditions, it operates, however, at significantly lower pressures. LES results are compared to the experimental reference for validation. Three different operating points are studied, which differ in terms of the development of cavitation regions and the jet break-up characteristics. Observed differences between experimental and numerical data in some of the investigated cases can be caused by uncertainties in meeting nominal parameters by the experiment. The investigation reveals that three main mechanisms promote primary jet break-up: collapse-induced turbulent fluctuations near the outlet, entrainment of free gas into the nozzle, and collapse events inside the jet near the liquid-gas interface.

Impaction of spray droplets on leaves: influence of formulation and leaf character on shatter, bounce and adhesion

Abstract: This paper combines experimental data with simple mathematical models to investigate the influence of spray formulation type and leaf character (wettability) on shatter, bounce and adhesion of droplets impacting with cotton, rice and wheat leaves. Impaction criteria that allow for different angles of the leaf surface and the droplet impact trajectory are presented; their predictions are based on whether combinations of droplet size and velocity lie above or below bounce and shatter boundaries. In the experimental component, real leaves are used, with all their inherent natural variability. Further, commercial agricultural spray nozzles are employed, resulting in a range of droplet characteristics. Given this natural variability, there is broad agreement between the data and predictions. As predicted, the shatter of droplets was found to increase as droplet size and velocity increased, and the surface became harder to wet. Bouncing of droplets occurred most frequently on hard-to-wet surfaces with high-surface-tension mixtures. On the other hand, a number of small droplets with low impact velocity were observed to bounce when predicted to lie well within the adhering regime. We believe this discrepancy between the predictions and experimental data could be due to air layer effects that were not taken into account in the current bounce equations. Other discrepancies between experiment and theory are thought to be due to the current assumption of a dry impact surface, whereas, in practice, the leaf surfaces became increasingly covered with fluid throughout the spray test runs.

Plasma treating apparatus, substrate treating method, and method of manufacturing a semiconductor device

Abstract: A substrate treating method may be performed by a plasma treating apparatus. The substrate treating method may include: providing a substrate on a platform in a lower portion of an inner space of a process chamber; directing a first process gas upward from a first nozzle formed at an inner wall of the process chamber into an upper portion of the inner space, the first process gas being an inert gas and wherein the first nozzle is an obliquely upward-oriented nozzle structured to direct the first process gas upward; directing a second process gas downward from a second nozzle formed at a inner wall of the process chamber into a lower portion of the inner space, the second process gas being hydrogen gas and wherein the second nozzle is an obliquely downward-oriented nozzle structured to direct the second process gas downward; and applying a microwave to the upper portion of the inner space to excite the first process gas and the second process gas into plasma, and then processing the substrate.

Quantitative analysis of surface profile in fused deposition modelling

Abstract: Fused deposition modelling (FDM) is a well-known additive manufacturing technique, which can transfer digital three-dimensional (3D) models into functional components directly. Despite many advantages FDM can offer, poor surface accuracy of fabricated objects has always been a big issue that attracts increasing attention. To study the influence on the surface profiles imposed by various process parameters effectively as well as quantitatively, the mathematical model of the surface profile need to be developed. In this work, a new surface profile model is developed to characterize the surface profile of FDM fabricated parts. The process parameters are classified into two groups (i.e. pre-process parameters and fabrication process parameters) to investigate the impacts on surface characterization. Corresponding experiments are conducted using an FDM machine to make comparison with the predicted values and to validate the reliability and effectiveness of the proposed surface models. Both the experimental results and theoretical values indicate that the surface accuracy of the top surface is mainly determined by the ratio between molten paste flowrate and the nozzle feedrate under specified layer thickness and path spacing. On the other hand, the surface quality of the side surface is primarily affected by the layer thickness and the stratification angle of the surface. At the same time, some optimization approaches for the surface improvement are presented: appropriate ratio between paste flowrate and fabrication speed are required for desirable top surface and thinner layer thickness can, to some extent, alleviate the staircase effect out of the slicing procedure and the stratification angle of the side surface should be confined to a range to avoid large geometric errors.

Rapid nozzle cooling for additive manufacturing

Abstract: Systems, devices, and methods according to the present disclosure are configured for use in additive manufacturing. Systems for additive manufacturing can include stand-alone manufacturing units, a series of units on an assembly line, or a high-capacity system with workflow automation features including a conveyor for transporting parts to or from a build area, or a robotic arm for transporting parts or adjusting a system component. An additive manufacturing system (100) can include a flow regulator (130) to change a temperature of a thermoplastic material at or in a tip (150) of a material extrusion nozzle cartridge (171), such as to enable or inhibit flow of the thermoplastic material from the tip. The flow regulator can be configured to provide a specified gas or liquid at a specified temperature, velocity, or volume.

Thin film deposition apparatus

Abstract: A thin film deposition apparatus, including a plurality of linear nozzle parts separated from each other; and an exhaust plate to which is attached the plurality of linear nozzle parts, each linear nozzle part including a linear body member; a pair of first reaction gas pipes in the linear body member and inflowing a first reaction gas; a second reaction gas pipe between the pair of first reaction gas pipes and inflowing a second reaction gas; and a pair of control gas pipes between each of the first reaction gas pipes and the second reaction gas pipe and inflowing a control gas controlling a flow of the second reaction gas

Evaluation of ultrasonic nozzle with spray-drying as a novel method for the microencapsulation of blueberry's bioactive compounds

Abstract: In this study, using an ultrasonic nozzle in the production of blueberry microspheres was investigated as a new technology by comparing with a conventional nozzle. In addition to this, ultrasonic and conventional nozzles were compared with freeze-drying method. In the first part of the study, the physicochemical properties of microspheres were examined and compared with each other. There were no significant differences ( p > 0.05) in the total phenolic content and antioxidant activity of blueberry extract microspheres produced by ultrasonic nozzle and freeze-drying. Moreover, with regard to morphological characteristics, microspheres produced by ultrasonic nozzle were observed to be more uniform in terms of size and shape. Secondly, the microspheres were evaluated for their impact on the quality of ice creams and cakes. In ice cream, the ultrasonic nozzle microspheres showed phenolics content retention ( p > 0.05) similar to freeze-dried microspheres. After baking, the ultrasonic nozzle microspheres of extract-enriched cake had the highest anthocyanin retention (79.35%). As a result, it was observed that the ultrasonic nozzle used in this study provided more protection for blueberry’s bioactive compounds compared with a conventional nozzle. Industrial Relevance The ultrasonic nozzle technology is a new atomization technology for food applications. The ultrasonic nozzle technology used in this study could lead to application in the food industry improving the stability of blueberry phenolics and other bioactive compounds.