Decreasing the Weight-Size Parameters of Gas-Steam Turbine Plant by Increasing the Efficiency of Thermodynamic Processes in the Condenser

The aim of this work is decreasing the weight-size parameters of the contact gas-steam turbine plant and contact condenser elements by increasing the efficiency of thermal-gas dynamic processes of condensation through rational irrigation of countercurrent gas-steam flow. To achieve the goal the total efficiency of water-return drops ranging from 0.1 to 1 mm at different initial velocities from 5 to 35 m/s emitted by the multi-nozzle sprinkler was determined by mathematical modeling of the liquid droplet movement processes, heat and mass transfer between the liquid droplet and gas-vapor mixture, and gas-vapor mixture pressure loss. The effect of increasing the gas-steam mixture velocity from 3.3 to 6 m/s on the overall efficiency of water return was determined. The novelty of the obtained results was defined by an increase in the water return into cycle from 12 to 13% with a droplet diameter of 0.3 -- 0.4 mm and the initial velocity from the sprinkler of 5--10 m/s. The velocity of the mixture was to 6 m/s at rational correlations of the initial velocity of the droplets’ escape, which increased the total amount of heat withdrawn to 11%. The positive effect conditions of irrigation processes on thermogasdynamic and weight-size parameters of the condenser elements for the contact gas and steam turbine plant at full pressure recovery coefficients of over 0.967 were substantiated. The most significant result was the reduction of the weight-size parameters of the marine infrastructure object power plant from 8 to 19%.

Rapid Microfluidic Mixing Method Based on Droplet Rotation Due to PDMS Deformation

Droplet-based micromixers have shown great prospects in chemical synthesis, pharmacology, biologics, and diagnostics. When compared with the active method, passive micromixer is widely used because it relies on the droplet movement in the microchannel without extra energy, which is more concise and easier to operate. Here we present a droplet rotation-based microfluidic mixer that allows rapid mixing within individual droplets efficiently. PDMS deformation is used to construct subsidence on the roof of the microchannel, which can deviate the trajectory of droplets. Thus, the droplet shows a rotation behavior due to the non-uniform distribution of the flow field, which can introduce turbulence and induce cross-flow enhancing 3D mixing inside the droplet, achieving rapid and homogenous fluid mixing. In order to evaluate the performance of the droplet rotation-based microfluidic mixer, droplets with highly viscous fluid (60% w/w PEGDA solution) were generated, half of which was seeded with fluorescent dye for imaging. Mixing efficiency was quantified using the mixing index (MI), which shows as high as 92% mixing index was achieved within 12 mm traveling. Here in this work, it has been demonstrated that the microfluidic mixing method based on the droplet rotation has shown the advantages of low-cost, easy to operate, and high mixing efficiency. It is expected to find wide applications in the field of pharmaceutics, chemical synthesis, and biologics.

Transporting Carrier With Droplets Driven by Electrowetting-on-Dielectric Effect

In the early 19th century, Thomas Young (1805) and Pierre Simon Laplace (1806) published the concept of fluid surface tension, which made great contributions to the theory of surface tension. Many scholars continued to study electrowetting-on-dielectric (EWOD) technology, hoping to effectively control the movement of droplets, to make a lot of microchannels in biomedical and life applications. The purpose of dielectric and hydrophobic layer is to prevent the droplet from short circuiting when the electrode moves, and the increase of hydrophobic layer will improve the smoothness of droplet movement. EWOD technology is used in this research as the prelude of the development of soft robot. Through the combination of finger electrode and electrowetting-on-dielectric technology, a carrier is designed. The drop is driven by Arduino and LabVIEW control software, and the carrier can be moved effectively. The effective distance between the finger electrodes was found out from the experiment to change the contact angle of the drop. Drop material will use two kinds of materials, PC and mixed liquid (PC, UV), try to change the contact angle and its strength through the voltage of 0–250V, so as to find out the maximum force and suitable contact angle, hoping to support the carrier effectively. Finally, the carrier will be transported to the designated position by using drops.

Microfluidic-based processors and circuits design

Droplets produced within microfluidics have not only attracted the attention of researchers to develop complex biological, industrial and clinical testing systems but also played a role as a bit of data. The flow of droplets within a network of microfluidic channels by stimulation of their movements, trajectories, and interaction timing, can provide an opportunity for preparation of complex and logical microfluidic circuits. Such mechanical-based circuits open up avenues to mimic the logic of electrical circuits within microfluidics. Recently, simple microfluidic-based logical elements such as AND, OR, and NOT gates have been experimentally developed and tested to model basic logic conditions in laboratory settings. In this work, we develop new microfluidic networks, control the shape of channels and speed of droplet movement, and regulate the size of bubbles in order to extend the logical elements to six new logic gates, including AND/OR type 1, AND/OR type 2, NOT type 1, NOT type 2, Flip-Flop, Synchronizer, and a parametric model of T-junction as a bubble generator. We further designed and simulated a novel microfluidic Decoder 1 to 2, a Decoder 2 to 4, and a microfluidic circuit that combines several individual logic gates into one complex circuit. Further fabrication and experimental testing of these newly introduced logic gates within microfluidics enable implementing complex circuits in high-throughput microfluidic platforms for tissue engineering, drug testing and development, and chemical synthesis and process design.

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.

Characterization of Inkjet-Printed Digital Microfluidics Devices

Digital microfluidics (DMF) devices enable precise manipulation of small liquid volumes in point-of-care testing. A printed circuit board (PCB) substrate is commonly utilized to build DMF devices. However, inkjet printing can be used to fabricate DMF circuits, providing a less expensive alternative to PCB-based DMF designs while enabling more rapid design iteration cycles. We demonstrate the cleanroom-free fabrication process of a low-cost inkjet-printed DMF circuit. We compare Kapton and polymethyl methacrylate (PMMA) as dielectric coatings by measuring the minimal droplet actuation voltage for a range of actuation frequencies. A minimum actuation voltage of 5.6 V was required for droplet movement with the PMMA layer thickness of 0.2 μm and a hydrophobic layer of 0.17 μm. Significant issues with PMMA dielectric breakdown were observed at actuation voltages above 10 V. In comparison, devices that utilized Kapton were found to be more robust, even at an actuation voltage up to 100 V.

Run-and-Halt Behavior of Motile Droplets in Response to Light

<p>We report the run-and-halt behavior of motile droplets immersed in an aqueous solution of amphiphilic molecular switch. These oil droplets move autonomously as the switch solubilizes the oil into the water. Droplet movement stops in response to UV light, and picks up again in response to visible light. This motile behavior is a consequence of the reversible <i>trans-</i>to-<i>cis</i> photo-conversion of the switch in water, because the <i>trans</i> photo-isomer stabilizes the oil droplets better than the <i>cis</i> photo-isomer, and therefore it also solubilizes the droplet more effectively. Notably, the droplets also evolve positive photokinesis under illumination with visible light, and, in patchy light environments, their complex motility pattern directs the droplets at the periphery of the illuminated areas. </p>

Run-and-Halt Behavior of Motile Droplets in Response to Light

<p>We report the run-and-halt behavior of motile droplets immersed in an aqueous solution of amphiphilic molecular switch. These oil droplets move autonomously as the switch solubilizes the oil into the water. Droplet movement stops in response to UV light, and picks up again in response to visible light. This motile behavior is a consequence of the reversible <i>trans-</i>to-<i>cis</i> photo-conversion of the switch in water, because the <i>trans</i> photo-isomer stabilizes the oil droplets better than the <i>cis</i> photo-isomer, and therefore it also solubilizes the droplet more effectively. Notably, the droplets also evolve positive photokinesis under illumination with visible light, and, in patchy light environments, their complex motility pattern directs the droplets at the periphery of the illuminated areas. </p>

Bioinspired Fog Collection Surface of Conical Brass With Gradient Wettability

How to obtain more fresh water from nature economically and efficiently is a hot issue that needs to be solved urgently. Herein, inspired by the directional fog collection ability of the surface of pine needles, a wettability-gradient-brass-cone (WGBC) was prepared through a two-step process of precision cutting and chemical etching, producing a surface with functions of fog collection and droplet movement to the root of the cone. On the other hand, through experimental exploration and optimization of taper parameters, the excellent directional collection velocity of droplets was obtained. This work may direct the design of gradient wetting surfaces by mimicking the structure of pine needles and explore potential applications in fog harvesting.