Effect of direct current on gas condensate droplet immersed in brine solution

Environmentally sustainable methods of extracting hydrocarbons from the reservoir are increasingly becoming an important area of research. Several methods are being applied to mitigate condensate banking effect which occurs in gas condensate reservoirs; some of which have significant impact on the environment (subsurface and surface). Electrokinetic enhanced oil recovery (EEOR) increases oil displacement efficiency in conventional oil reservoirs while retaining beneficial properties to the environment. To successfully apply this technology on gas condensate reservoirs, the behavior of condensate droplets immersed in brine under the influence of electric current need to be understood. A laboratory experiment was designed to capture the effect of electrical current on interfacial tension and droplet movement. Pendant drop tensiometry was used to obtain the interfacial tension, while force analysis was used to analyze the effect of the electrical current on droplet trajectory. Salinity (0–23 ppt) and electric voltage (0–46.5 V) were the main variables during the entire experiment. Results from the experiment reveal an increase in IFT as the voltage is increased, while the droplet trajectory was significantly altered with an increase in voltage. This study concludes that the interfacial tension increases progressively with an increase in DC current, until its effect counteracts the benefit obtained from the preferential movement of condensate droplet.

A mask-based infection control method for screening endoscopy may prevent SARS-CoV-2 transmission and relieve staff anxiety

Objectives: Endoscopy confers high risk for acquiring coronavirus disease 2019. Although guidelines recommend that medical staff use personal protective equipment, no infection control equipment have been established for patients. This study aimed to clarify the usefulness of two face masks we had designed for transnasal and transoral endoscopy. Methods: The efficacy of the masks was evaluated by simulating coughing in a mannequin with fluorescent dyes and mapping the droplet trajectory and number. The number of aerosols generated during endoscopy was clinically evaluated in the endoscopy room. Overall, 4356 screening endoscopies were performed with the patients wearing our masks at Medcity21, a health checkup facility, between June and December 2020; the effects of the masks on the patient’s condition were evaluated retrospectively. An 11-item paper-based survey was performed by the endoscopy staff 6 months after the adoption of the mask-based infection control method. Results: Use of both masks reduced the number of droplets released during the simulation. Clinically, the use of both masks did not affect the patients’ conditions during endoscopy and prevented an increase in the aerosols in the endoscopy room. This mask-based infection control method was favorably received, and all staff indicated that understanding the efficacy of our mask-based infection control reduced their anxiety regarding infection. Until December 2020, none of our staff had contracted SARS-CoV-2. Conclusion: Our mask-based infection control method is easy to adopt, inexpensive, and effective; understanding its effectiveness may help ease the fear of infection among endoscopy staff.

Effects of Pressure and Nozzle Size on the Spray Characteristics of Low-Pressure Rotating Sprinklers

Using low-pressure sprinklers in agricultural irrigation has become an alternative way of reducing water and energy stress. To determine the applicability of the low-pressure rotating sprinkler, an experiment was conducted to evaluate the effects of working pressure and nozzle size on sprinkler rotation speed, application rate, droplet size, droplet velocity, droplet trajectory angle, and kinetic energy distribution. The results showed that the mean droplet diameter increased exponentially along with the increase in distance from the sprinkler, and a logarithmic relation was derived between droplet diameter and droplet velocity. Due to the low breakup degree of the jet under the lowest working pressure of 100 kPa, the peak values of specific power and application rate were high, which reached 0.09 W m−2 and 11.35 mm h−1, and were 3.1–5.4 times and 2.5–3.1 times those of other working conditions. Meanwhile, the peak specific power of the biggest nozzle (diameter = 5.2 mm) was 2.4–2.8 times that of smaller nozzles. With an increase in working pressure, the sprinkler time per rotation decreased and the distributions of kinetic energy and water became more uniform. Thus, it is not recommended to equip the sprinkler with a large nozzle under low working pressure.

Dynamics of a Viscous Droplet in Return Bends of Microfluidic Channels

Return bends are frequently encountered in microfluidic systems. In this study, a three-dimensional spectral boundary element method for interfacial dynamics in Stokes flow has been adopted to investigate the dynamics of viscous droplets in rectangular return bends. The droplet trajectory, deformation, and migration velocity are investigated under the influence of various fluid properties and operational conditions, which are depicted by the Capillary number, viscosity ratio, and droplet size, as well as the dimensions of the return bend. While the computational results provide information for the design of return bends in microfluidic systems in general, the computational framework shows potential to guide the design and operation of a droplet-based microfluidic delivery system for cell seeding.

Surface Tension-Based Ultra-Micro Precision Dispensing Method For Micro-Scale Manufacturing

Due to the rapid development of precision micro-manufacturing technology, it has made higher requirements for micro-connection and micro-assembly technologies. An ultra-micro-dispensing method based on the surface tension of the droplets is proposed, which can be realized on the surface of micro-components. Distribute the glue between pl. Use a pipette to pass through the capillary containing the glue, cover the tip of the pipette with glue, and then form tiny glue droplets under the action of the glue's own adhesive force and surface tension. In the experiment, the factors such as the diameter of the pipette, the speed of movement, the Cap value, and the viscosity of the glue were analyzed in detail.Fly upgrade ultra-small dispensing was achieved.The minimum glue droplet was 22.4 μm, and the droplet volume was 228 fL. The planning of the glue droplet trajectory, different plane graphics composed of uniform fl glue droplets, this method achieves precise control of the size and position accuracy of the glue droplets, the deviation of the glue spot diameter is within 2.2 μm, and the deviation of the glue droplet position is 1.58 μm Inside.

Laser-Driven Programmable Metal Transfer in GMAW

Conventional pulsed laser-enhanced gas metal arc weld-ing (GMAW) employs a single fiber laser focused and aimed on the droplet neck position to produce a laser recoil force and thus ensure the droplet detachment despite the am-perage of the welding current. One drop per laser pulse metal transfer is obtained, and the droplet deflects away from the wire axis along the laser incident direction. This implies that the droplet trajectory may also be controlled if the direction of the laser recoil force can be adjusted. Such a controllability is expected to bring an entirely new capa-bility to the GMAW process: active control on the weld beam geometry. To this end, double-sided, laser-enhanced GMAW was proposed and experimentally verified in this pa-per. The two lasers were symmetrically positioned, and both aimed at the droplet neck. The laser pulse peak power, du-ration, and pulse phase of the two lasers can all be programmed to regulate the laser recoil forces. The metal transfer under twin laser irradiations (same laser pulses and phases) was first verified. Then the effectiveness on controlling the droplet trajectory of three proposed control strategies — peak power matching, peak width matching, and phase matching of the two lasers — were evaluated. The results showed laser peak power matching is optimal for obtaining desired droplet trajectory. Since the laser can be easily controlled in real time, the transfer frequency, droplet size, and trajectory can all be adjusted in real time, and the metal transfer evolves into programmable transfer.

Visualization and Analysis Studies of Hollow Cone Spray under low Air Cross Flow Velocity under Atmospheric Condition

This study deals with the atomization of hollow cone spray water with low air cross flow. The visualization of the hollow cone spray by shadowgraphy, from the nozzle exit. The diameter of the nozzle allows to observe different modes of breakup and different structures (ligaments, helices, ...). The treatment of these images makes it possible to determine the drop size distribution of the spray droplets in function of length scales of the downstream flow. In the measurements of water hollow cone spray with injection pressures of 25kPa and air velocity of 10 m/sec. The calculations at the exit of the injector, in two planes perpendicular, and the average droplet sizes in the presence of air low cross flow conditions. The structure and characteristics of the whole and sectional body of the spray are investigated at different times. The results show the droplet trajectory profile of the liquid droplets is in a good an agreement with analytical solution.