On the Use of Venturi Tubes in Aeration
ABSTRACT The ecological quality of water depends largely on the amount of oxygen that the water can hold. The higher the level of dissolved oxygen, the better the quality of a water system. By measuring dissolved oxygen, scientists determine the quality of water and health of an ecosystem. Oxygen enters water by entrainment of air bubbles. Many industrial and environmental processes involve the aeration of a liquid by such entrainment of air bubbles. Venturi aeration is a method of aeration that has become popular in recent years. When a minimal amount of differential pressure exists between the inlet and outlet sides of a venturi tube, a vacuum (air suction) occurs at the suction holes of the venturi tube. The present paper describes the effect of Reynolds Number, air inlet hole diameter, inlet diameter, pipe length, and angle of pipe downstream of the venturi tube, on the air injection rate. It is observed from the results that venturi tubes have high air injection efficiencies. Therefore, venturi tubes can be used as highly effective aerators in ponds, lakes, fish hatcheries, water treatment plants, etc.
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ABSTRACT: The dissolved oxygen (DO) concentration is an important index of water quality. This paper studies the dissolved oxygen recovery of the water and bubble mixture pipe flow through two sudden contractions and expansions. A 3-D computational fluid dy- namics model is established to simulate the water and bubble mixture flow with a DO transport model. An experiment is conducted to validate the mathematical model. The mathematical model is used to evaluate the effect of geometric parameters on the head loss coefficient, the relative saturation coefficient and the oxygen absorption efficiency. It is found that the contraction ratio is a signi- ficant influencing factor, other than the relative length and the relative distance. Given the same relative length and relative distance, the head loss coefficient, the relative saturation coefficient and the oxygen absorption efficiency increase with the decrease of the contraction ratio, respectively. Given the same relative length and contraction ratio, the head loss coefficient increases with the in- crease of the relative distance firstly, and then decreases gradually, in contrast, the relative saturation coefficient and the oxygen ab- sorption efficiency decrease with the increase of the relative distance firstly, and then increase gradually, the relative saturation coefficient and the oxygen absorption efficiency are inversely proportional to the head loss coefficient, respectively.Journal of Hydrodynamics 10/2014; 26(5). DOI:10.1016/S1001-6058(14)60083-4 · 0.58 Impact Factor
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ABSTRACT: A venturi pipe part (VPP) allows air bubbles to be inserted into flowing water from air inlet holes and so increases dissolved oxygen (DO) levels in irrigation water. The DO helps the roots absorb nutrients at a faster rate, and can increase a plant’s growth rate by up to 30 %. Therefore, the aim of this paper is to evaluate design considerations and experimental results related to characteristics of VPP in air vacuum and aeration process. Optimal flow velocity in venturi inlet is determined between 1 and 4 m/s for aeration process. For starting of air vacuum process, minimum flow velocity is determined as 0.80 m/s. The ratio of the throat diameter of VPP to the inlet diameter of VPP equals to 0.5. Also, the ratio of the air vent diameter of VPP to the throat diameter of VPP equals to 0.3. Volumetric air flowrate decreases with increasing pipe length. In addition, the effect of aerated water on plant growth is tested with a case study. The case study is carried out on growth of the onion (Allium cepa) samples. In result of this test, aerated water is capable for plant growth of the onion (A. cepa) samples. However, it increased the plant’s growth rate by 27 %. Thus, irrigation projects can be planned with both VPP (AirJection Irrigation) and subsurface drip irrigation systems.ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING 04/2013; 39(4):2525-2533. DOI:10.1007/s13369-013-0895-4 · 0.37 Impact Factor
Article: JOURNAL OF ENVIRONMENTAL ENGINEERING[Show abstract] [Hide abstract]
ABSTRACT: Dissolved oxygen (DO) concentration is an important water quality parameter. This paper studies the increase of DO concentration in water by air injection into a horizontal pipe flow. A 3D computational fluid dynamics model was employed to compute the water and bubble mixture flow with a DO transport model. Experiments were also conducted to validate the mathematical model. A relative saturation coefficient relationship was developed with air bubble volume fraction and travel time. An oxygen absorption efficiency is defined,and its relationship with the inlet DO concentration, air bubble volume fraction, and travel time was discussed.Journal of Environmental Engineering 06/2013; 139:908-912. DOI:10.1061/(ASCE)EE.1943-7870.0000680 · 1.22 Impact Factor