Combined Influence Of Pressure Research Articles

Selection of Electrolytes for Optimal Reverse Electroactuation Energy Harvesting

A number of new developments have taken place over the years with respect to mechanical energy harvesting. However, significant progress is yet to be made to improve the energy density to sufficiently and reliably power our everyday mobile devices and other applications. Recently, a new approach in energy harvesting based on the principles of reverse electroactuation has been reported and is drawing much interest. Reverse electroactuation can be considered the opposite of electrowetting-on-dielectric, which is the manipulation of liquid droplets on dielectric with applied voltage. The reverse electroactuation approach of energy harvesting adopts a fundamental principle that the movements of liquid droplets on a dielectric film generate power by dynamically modulating the liquid-solid interfacial dielectric capacitance. The amount of power generated using this approach depends on various factors such as the type of conducting liquid used, dielectric coating type and thickness, and droplet pinning. Power densities up to 103 W/m2 have been reported using reverse electroactuation with Mercury as electrolyte, but using Mercury for real applications is not feasible due to its toxicity. In this study, we test a number of alternative conducting liquids as well as dielectric coatings in reverse electroactuation. The main objective is to observe and analyze the effect electrolyte and dielectric coatings have on power density and to compare the experimental results to previously published theoretical models. In addition to improving energy harvesting, this research contributes to fundamental understanding of how liquid movement under the combined influence of pressure, surface tension, and electric fields affect charge density. This may impact the design and development of porous materials for applications such as supercapacitors, electrodialysis, and reverse osmosis. Figure 1. In reverse electroactuation, a conducting liquid droplet is placed between two electrodes, one of which is insulated (A). A dynamic mechanical loading deflects the droplet, resulting in a modulating capacitance and therefore an electrical current (B). Figure 1

Accumulating particles at the boundaries of a laminar flow

The accumulation of small particles is analyzed in stationary flows through channels of variable width at small Reynolds number. The combined influence of pressure, viscous drag and thermal fluctuations is described by means of a Fokker–Planck equation for the particle density. It is shown that for extended spherical particles the shape of the fluid domain gives rise to inhomogeneous particle densities, thereby leading to particle accumulation and corresponding depletion. For extended spherical particles, conditions are specified that lead to inhomogeneous densities and consequently to regions with particle accumulation and depletion.

Influence of pressure on bulk density of polymer solid granules at different temperatures

Through the experimental investigation of solid granule compaction, it is demonstrated that the combined influence of pressure and temperature on the bulk density of solid polymer granules is very significant for all materials, although the effect is different for different materials, especially amorphous polymer material, such as polystyrene. A distinction is made between the effect of pressure and temperature on the bulk density for various materials and this cannot be neglected in polymer processing operations. The rheological property of solid polymer particles must be considered in the design of the plasticating extruder screw, which forms the basis of many polymer processing methods. Also, it is one of the probable reasons why extrusion using a grooved feed section in the extruder barrel can enhance the throughput of material compared with that of conventional extrusion. © 1998 John Wiley & Sons, Inc. Adv in Polymer Techn 17: 23–36, 1998

Orientation and Structure of Polyethylene Crystallized under the Orientation and Pressure Effects of a Pressure Capillary Viscometer

A commercial high-density polyethylene has been crystallized in the Instron Capillary Rheometer under the combined influence of pressure and orientation. A transparent high-modulus, and highly oriented filament structure was produced. In order to determine quantitatively the degree of orientation, azimuthal x-ray scans of the 002 reflection plane were used to obtain the orientation function of the orthorhombic unit cell relative to the flow axis in the rheometer (identified with the filament axis). A value of +0.996±0.002 was measured for this orientation function indicating that the backbones of the crystalline polyethylene chains were virtually aligned perfectly parallel to the flow axis of the rheometer. This report is concerned with the high-resolution techniques required to measure such highly oriented samples. In conjunction with the x-ray study, birefringence measurements are included which permit the determination of the orientation of the amorphous component as well as the crystalline component.