Flow and Oxygen-Transfer Characteristics in an Aeration System Using an Annular Nozzle Ejector

Abstract

This paper is aimed at the investigation of flow and oxygen-transfer characteristics in an aeration system using an annular nozzle ejector, and the experimental evaluation of the oxygen-transfer characteristics in the ejector aeration and blower aeration. The entrainment ratio decreased with the primary water flow rate of the annular nozzle ejector, with ratios ranging between 6.8 and 0.4. It was found that the turbulence level and entrainment ratio strongly affected the air bubble size and the volumetric mass-transfer coefficient. The saturation times and volumetric mass-transfer coefficients varied with the suction air flow rate in the ejector aeration, while the times decreased and the coefficients increased with the blowing air flow rate in the blower aeration. The average mass-transfer coefficient of the ejector aeration was about 3.7 times higher than that of the blower aeration. It was found that the high turbulence level and optimum entrainment ratio were needed to increase the oxygen-transfer rate.

Numerical analysis of an annular water–air jet pump with self-induced oscillation mixing chamber

“…To validate the accuracy of the proposed numerical modelling approach, the experimental work conducted by Park and Yang 16 was used as validation target. This referred experimental study investigated the influences of both operational parameters and geometrical parameters on overall pumping performance.…”

“…The conventional AJP geometrical parameters were referred from Park and Yang. 16 As mentioned earlier, the main difference between the conventional AJP and the improved AJP design is the self-induced oscillation chamber, which is an enlarged cylindrical cavity with a cone-shaped impinge downstream sidewall, and its geometrical configuration was referred from Liao et al. 17 All basic pump parameters are listed in Table 1.…”

Performance experiments with a gas wave ejector equipped with curved channels and an analysis of the influence of channel angles

“…It primarily utilizes the turbulent diffusion of the high-speed jet created by a highpressure uid to entrain a low-pressure uid, and energy transfer between uids is completed via their direct mixing. 5,6 A static ejector has the advantages of a simple structure and low manufacturing cost, 7 but it mainly achieves energy transfer via intermolecular collisions, resulting in high levels of viscous dissipation during the transfer process. As a result, when the pressure ratio between the high-and low-pressure gases is small, the isentropic efficiency of this device is low and its pressurization capacity is severely limited.…”

Study on the Performance of Collaborative Production Mode for Gas Wave Ejector

“…Therefore, GWE has advantages of high isentropic efficiency, low rotational speed, low manufacturing and operating costs, easy disassembly and maintenance, and a strong capacity to run with liquid and solid. As a result, it has been considered for application in a variety of fields, such as the exploitation of natural gas, refrigeration cycles, and so on [16][17][18][19]. In 1960s, Spalding [20] first proposed the concept of equalizer (the initial name of GWE) and conducted preliminary theoretical researches.…”

“…Therefore, GWE has advantages of high isentropic efficiency, low rotational speed, low manufacturing and operating costs, easy disassembly and maintenance, and a strong capacity to run with liquid and solid. As a result, it has been considered for application in a variety of fields, such as the exploitation of natural gas, refrigeration cycles, and so on [16][17][18][19]. Due to the issues of both devices mentioned above, the gas wave ejector (GWE) [10] which combines the benefits of expansion-compressor units and static ejector has received more and more attention.…”