جستجوی مقالات مرتبط با کلیدواژه « pressure drop » در نشریات گروه « شیمی »

Production of a homogeneous solution is of great interest for Lab-on-a-Chip (LOC) applications. Since the fluid flow in microchannels is laminar, the LOC devices have low mixing efficiency in passive mixers. The present study proposes a novel electroosmotic micromixer in which the electrodes have a fin-shaped structure in the mixing chamber. In other words, the combined effect of obstacle and electro-osmosis is evaluated. The effect of various parameters such as electrode angle, electrode height, inlet velocity, alternating current, and frequency on mixing index and pressure drop is investigated. Vortices are formed around the electrodes due to the applied electric field and their fin-shaped structure. It is revealed that the mixing index is an increasing function of applied voltage. The results demonstrate that there is an optimal value for the parameters, including frequency, electrode height, inlet velocity, and electrode angle. An increase in the mixing efficiency is accompanied by an enhancement in the pressure drop. It is revealed that the maximum efficiency is achieved when the electrode height is 5 μm and the electrode angle is 60°. The coefficient of performance of the proposed micromixer is more than that of the reference mixer when the electrode height is 2.5 μm and the electrode angle is 90°.

Persistent efforts were made by various researchers to improve the quality of gas-solid fluidized bed by means of hindering the bubble formation, avoiding the coalescence of bubbles through bubble breakage, thereby exhibiting a meticulous bed expansion and fluctuation. To conquer these difficulties and to achieve a better fluidization quality use of distributor, turbulence and promoter has been recommended and emerged as an alternative and effective technique.  The introduction of promoters performs well in smoothening the fluidization operation in terms of infringement of bubbles, and regulating the bubble size through inhibiting their growth. A better fluidization quality is achieved by various fluidization characteristics such as bed expansion, fluctuation, mixing index and minimum fluidization velocity. Therefore, various researchers investigated the usage of different types of promoters and distributors and recommended that by using a suitably designed promoter and distributor possess an improved fluidization quality with marginal fabrication cost, however the operational cost remains unchanged. Most of the literature studies are dealt with the qualitative effect of the usage of promoters and distributors in a gas-solid fluidized  bed though investigation of various hydrodynamics characteristics viz. bed expansion ratio, bed fluctuation ratio, bed pressure drop ratio.

The influence of Sodium dodecyl sulfate and Triton X-100 surfactants on the two-phase pressure drop and two phase flow regime of water-air and gas condensate-air in upward vertical pipe were investigated for various gas/liquid flow rates. Sodium dodecyl sulfate and Triton X-100 reduced the pressure drop of single phase water flow by 11% and 29% compared with that of pure water single phase flow at water velocity of 13 m/s. For condensate single phase flow, Sodium dodecyl sulfate and Triton X-100 reduced the pressure drop by 9% and 17% compared with that of condensate single phase flow with no surfactant at gas condensate velocity of 13 m/s. The maximum efficiency of Sodium dodecyl sulfate and Triton X-100 in reducing the pressure drop of water-air system were 67.1% and 79.8%, respectively, compared with that of pure water-air two-phase flow. For gas condensate-air system, the maximum efficiency of Sodium dodecyl sulfate and Triton X-100 in reducing the pressure drop was 57.1% and 36.7%, respectively, compared to that of pure condensate-air two-phase flow.