In several areas of science and technology, there is a strong need for concentrating, separating, and sorting small particles suspended in gaseous flows. Acoustic fields can be used to accomplish this task, an approach extensively used in liquid phase microfluidics that has great potential for aerosol treatment. This paper presents an experimental investigation of acoustophoresis for very small particles in gases, with sizes ranging from tens to hundreds of nanometers. The phenomenon is studied in a rectangular channel with variable height in which a standing acoustic field is created by a broadband electrostatic transducer operated in the 50–100 kHz range. The flow can either be seeded with particles with a known size distribution or ambient laboratory air can simply be circulated in the channel. Downstream of the separation channel, the flow is separated into enriched and depleted streams with adjustable slits for analysis. The particle number density and size distribution is measured with a scanning mobility particle sizer (SMPS) as a function of position in the standing wave pattern. From these measurement, the separation efficiency is determined as a function of the particle size, excitation frequency, bulk flow velocity, and number of nodes in the channel. Further analysis yields an estimation of the force acting on the particles, which for very small particles yields novel information on the magnitude of acoustophoretic forces in the transition and molecular flow regimes.
There is potential for optimizing thermal oxidizer plants to increase industrial energy efficiency results in environmental and economic dimension of sustainability. In the present work, genetic algorithm is implemented for three thermal oxidizer cases in three different petrochemical plants to optimize the fuel cost for the three Heat Recovery Steam Generators (HRSG's) which are going to be used for the recovery of the heat from the outlet of the thermal oxidizer units. Generally, thermal oxidizers are used in petrochemical plants to burn waste gases in the plant to reduce the environmental impact of the off-gases of plant and normally the waste heat are released to the atmosphere via a s tack. The optimization results have been compared for three cases. Five decision variables have been selected and the objective function was optimized. By increasing the fuel price, the values of thermo-economical decision variables tend to those thermodynamically optimal designs.
Advanced particle manipulation techniques based on acoustophoresis have been developed in recent years, driven by biomedical applications in liquid phase microfluidics systems. The same underlying physical phenomena are also encountered in gases and hold great potential for novel particle separation and sorting techniques aimed at industrial and scientific applications. However, considering the physical properties of gases, optimizing the performance of flow-through separators unavoidably requires an understanding of the re-mixing effect of turbulence. In the work presented here we have investigated the effect of turbulence intensity on the separation efficiency of a variable frequency acoustic particle separator featuring a rectangular cross-section with adjustable height. This allows the creation of a standing wave with a variable frequency and number of nodes. The air flow is seeded with alumina particles, 300 nm nominal diameter, and the excitation source is an electrostatic transducer operated in the 50-100 kHz range. In addition to flow and acoustic parameters, the separation efficiency is investigation as a function of geometric parameters such as the parallelism of the resonator walls and the matching between the channel height and the excitation frequency. The measurements made using laser doppler anemometry and light scattering provide guidance for the design of separator configurations capable of advanced separation and sorting tasks with sub-micron particles.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.