Mixed Flow and Oxygen Transfer Characteristics of Vertical Orifice Ejector

Abstract

The objective of this study is to experimentally investigate the mixed flow behaviors and oxygen transfer characteristics of a vertical orifice ejector. The experimental apparatus consisted of an electric motor-pump, an orifice ejector, a circulation water tank, an air compressor, a high speed camera unit and control or measurement accessories. The mass ratio was calculated using the measured primary flow rate and suction air flow rate with experimental parameters. The visualization images of vertically injected mixed jet issuing from the orifice ejector were qualitatively analyzed. The volumetric oxygen transfer coefficient was calculated using the measured dissolved oxygen concentration. At a constant primary flow rate, the mass ratio and oxygen transfer coefficient increase with the air pressure of compressor. At a constant air pressure of the compressor, the mass ratio decreases and the oxygen transfer coefficient increases as the primary flow rate increases. The residence time and dispersion of fine air bubbles and the penetration of mixed flow were found to be important parameters for the oxygen transfer rate owing to the contact area and time of two phases.

Improving oxygen dissolution and distribution in a bioreactor with enhanced simultaneous COD and nitrogen removal by simply introducing micro-pressure and swirl

“…On one hand, the enhancement of DO dissolution in the MPSR was the result of the extended residence time of the air bubbles in the slurry, which was caused by inner circulation of the bubbles in the swirl. The residence time of the bubbles was very significant for enhancing the oxygen transfer rate (Kim et al 2015). Javed also found that the gas phase mass transfer coefficient (K g a) increased when a swirl was formed in the reactor (Javed et al 2010).…”

Mass Transfer Characteristics of Vertical Two-Phase Flows with Orifice Nozzle

“…정성적 가시화 이미지는 고속 카메라(Phantom Miro eX2)와 조명장치(ARRI)를 이용하여 초당 120프레임 (120fps)의 속도로 촬영하였으며, (2,16) 이미지 분석시스템 (17) 의 영상 이원화(binarization) 기법 ) …”

“…As the primary flow pressure increases and the mass ratio decreases, the mass transfer rate increases because of the fine bubbles and wider distribution of the bubbles. (2,16) …”