IJIRAE Published Papers by Mihaela Constantin
The paper presents the computation method of a pump flow rate and the power required to drive a n... more The paper presents the computation method of a pump flow rate and the power required to drive a new type of rotating volumetric pump. The influence of the geometric and functional parameters of the rotating volumetric pump on the theoretical flow rate and on the power required by the machine is revealed.
The purpose of the paper is to demonstrate that the use of fine bubbles generators which are movi... more The purpose of the paper is to demonstrate that the use of fine bubbles generators which are moving into the water is more efficient than the use of fixed fine bubbles generators. The results of the theoretical and experimental researches on the oxygen transfer rate to water are presented in the case of an immobile fine bubbles generator. Keywords—Water; aeration; generating air bubbles; fine bubble generators; oxygen transfer rate; I. INTRODUCTION Oxygen transfer to water, which occurs both in aquariums, fish breeders and sewage, is an important problem in applying aeration technologies. If fine bubbles aeration [1] is used, significant energy savings are obtained, 20 ÷ 50% of the energy required for aeration [2]. Of the power consumption of a sewage plant, 67% is the energy consumption of water treatment [1] [2]. Reducing energy consumption can be done by using fine bubbles generators (FBG) where the pressure loss is low; at the same time, the efficiency of the oxygen transfer to water must be higher and the consumption of compressed air should be reduced. Air pressure at the entrance to the fine bubbles generator is a very important parameter in the selection and monitoring of fine bubbles generators, regardless of the shape or material from which they are built. It is necessary to monitor this parameter during the operation of the aeration system as it indicates the operation state of the fine bubbles generator by the fact that any clogging of the FBG orifices automatically leads to an increase in air pressure at the entrance. The size and the orifices dimensions is a major parameter of FBG, because it directly affects the working pressure of it. The working pressure of the FBG is the air pressure under the orifices plate. Using FBG which moves in water, i.e. mobile FBG has the following advantage: the trajectory of the air bubbles in water is a curve directed toward the free surface of the water; as a result the contact time between the air bubble and the water is higher, the rate of increase in the dissolved oxygen concentration in the water will be higher. As a result, the time required to aerate the water is reduced.
Papers by Mihaela Constantin
Asian Journal of Applied Science and Technology, 2021
The paper presents three types of air fine bubble generators and the micro-drilling technologies ... more The paper presents three types of air fine bubble generators and the micro-drilling technologies experimental studied in the Department of Thermotechnics, Engines, Thermic and Refrigeration Plants from Politehnica University of Bucharest. The purpose of this paper is to study the constructive factors of fine bubble generators that influence the transfer of oxygen from air to water. Fine bubble generators (FBG) were executed on micro-processing numerically controlled specialized machines: it was subjected to experimental researches; the advantages of these new types of fine bubble generators compared to the existing solutions-porous diffusers are revealed.
IOP Conference Series: Earth and Environmental Science, 2022
The paper presents experimental researches able to demonstrate that the aeration installations wi... more The paper presents experimental researches able to demonstrate that the aeration installations with mobile fine bubble generators are more efficient than the classic ones with fixed, fine bubble generators. The paper develops water aeration researches by introducing two types of fine air bubble generators: I. Fixed fine air bubble generators, which generate Ø <1 mm bubbles; II. Mobile fine air bubble generators that move in the volume of water subject to aeration. The theoretical and experimental results are presented for the two versions. According to experimental data, aeration with mobile FBG is more efficient in terms of oxygen transfer from atmospheric air to a stationary water mass.
ISSN: 2456-883X www.ajast.net 60 Experimental Researches on Measuring the Concentration of Dissol... more ISSN: 2456-883X www.ajast.net 60 Experimental Researches on Measuring the Concentration of Dissolved Oxygen in Water M. Petroșel, N. Băran & M. Constantin Ph.D. Student, Professor Dr. Eng., Sl. Dr. Eng., Faculty of Mechanical Engineering and Mechatronics, Department of Thermodynamics, Engines, Thermal and Refrigerating Equipment’s, University Politehnica of Bucharest, Romania. Email: [email protected] DOI: http://doi.org/10.38177/ajast.2021.5107 Copyright: ©2021 M. Petroșel et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Article Received: 29 October 2020 Article Accepted: 24 December 2020 Article Published: 15 February 2021
E3S Web of Conferences, 2019
The rotating machine, to which the paper relates, refers to the following: A rotating machine con... more The rotating machine, to which the paper relates, refers to the following: A rotating machine construction solution that can be used as a power machine (steam engine, pneumatic engine) The same construction solution can be used as a working machine (pump, fan, and compressor). The constructive solution and the operating principle of the rotating machine are presented, the flow rate and the machine power computation model is indicated. At the end of the paper, the machine effective efficiency is experimentally determined.
E3S Web of Conferences, 2020
Considering that in certain papers the aeration processes are confused with the oxygenation proce... more Considering that in certain papers the aeration processes are confused with the oxygenation processes, a distinction between them must be made. The paper presents modern water aeration and oxygenation installations. The experimental results obtained for the two categories of installations are highlighted. Theoretical and experimental researches aim to increase the concentration of dissolved oxygen in water; this can be done in two ways: I - by introducing atmospheric air into the water; II - by introducing a gaseous mixture consisting of atmospheric air and oxygen. Version II is better, the results being shown in Figure 11.
The paper presents the experimental model of a new type of volumetric flow meter used to measure ... more The paper presents the experimental model of a new type of volumetric flow meter used to measure the liquid volumetric flow rate. The volumetric flow meter constructive solution is presented and, for certain parameters, the liquid flow rate that passes through the flow meter is calculated. The flow meter is provided with two specially profiled rotors which rotate at the same speed but in opposite directions; each rotor is provided with two rotating pistons. The flow meter speed is measured with a tachometer with digital indication and the volumetric flow rate is read from the flow meter characteristic curve. Using the similarity theory and knowing certain parameters of the meter model, the volumetric flow meter prototype architecture is afterwards specified.
IOP Conference Series: Earth and Environmental Science
Water aeration systems are highly efficient if the dispersion of air in the water is carried out ... more Water aeration systems are highly efficient if the dispersion of air in the water is carried out in a controlled and uniform manner. The use of fine bubble generators ensures this and in addition, creates a small loss of pressure when air passes through them. The paper demonstrates that producing as few air bubbles as possible leads to a more efficient aeration process. Two water aeration installations are compared: - The first has a perforated plate with 152 orifices Ø 0.1 mm; - The second has four perforated plates, each with 113 orifices Ø 0.05 mm; Both installations are successively supplied with the same flow rate of compressed air, at the same temperature and at the same initial dissolved oxygen concentration in the water.
E3S Web of Conferences, 2021
This paper presents a way to solve the transfer rate equation of oxygen in water. After running a... more This paper presents a way to solve the transfer rate equation of oxygen in water. After running a calculation program, the graph of the function that indicates the increase of the dissolved oxygen concentration in the water as a function of time is plotted. Constructed in an original manner, the experimental installation allows the measurement of the increase of the dissolved oxygen concentration in water. The experimental obtained results are compared with the theoretically obtained data.
The paper presents the need for water aeration, increasing the dissolved oxygen content in water.... more The paper presents the need for water aeration, increasing the dissolved oxygen content in water. The formation of ozone and its use is exposed. The authors chose a TCB - 30003 ozone generator to be used in the experimental installation. Thus, atmospheric air and subsequently atmospheric air with ozone generated by CORONA type electric discharge are introduced in a water tank. At the end of the paper the experimental obtained data are compared.
The paper presents an experimental scheme performed in the laboratory of Thermotechnics, Engines,... more The paper presents an experimental scheme performed in the laboratory of Thermotechnics, Engines, Thermic and Refrigeration Plants Department of Politehnica University of Bucharest. The purpose of the installation is to specify the effective efficiency of a new type of rotating positive displacement pump rotors profiled after the conducted experimental measurements.
International Journal of Mechatronics and Applied Mechanics
The paper presents methods for measuring the dissolved oxygen concentration in water; the electri... more The paper presents methods for measuring the dissolved oxygen concentration in water; the electrical method is presented by presenting an experimental installation designed and built in the laboratories of POLITEHNICA University in Bucharest. For the creation of fine air bubbles, a bubble generator with 0.1 mm orifices processed by spark-erosion was used. The results of the experimental researches on the measurement of dissolved oxygen in water are presented.
International Journal of Mechatronics and Applied Mechanics
The paper presents an original solution of a fine air bubble generator (FBG) that is used for wat... more The paper presents an original solution of a fine air bubble generator (FBG) that is used for water aeration. The calculation of the oriffices number and their diameter is indicated, orifices appearing in the perforated plate to be mounted on the fine bubble generator. The constructive solution of the fine bubble generator is presented, and the results of the experimental researches on water aeration using this fine bubble generator are presented.
International Journal of Mechatronics and Applied Mechanics
The air filtering device allows the airflow at the exit of filter cartridge to generate very smal... more The air filtering device allows the airflow at the exit of filter cartridge to generate very small bubbles called microbubbles (Ø < 100 μm). The size of the air bubble injected into the water tank depends on the orifice size in the microbubbles generator perforated plate. The paper presents the theoretical and experimental researches results on the use of air filtration cartridges to the achievement of micro air bubbles.
Entropy
The purpose of the study is to show that two simple models that take into account only the irreve... more The purpose of the study is to show that two simple models that take into account only the irreversibility due to temperature difference in the heat exchangers and imperfect regeneration are able to indicate refrigerating machine behavior. In the present paper, the finite physical dimensions thermodynamics (FPDT) method and 0-D modeling using the Schmidt model with imperfect regeneration were applied in the study of a β type Stirling refrigeration machine.The 0-D modeling is improved by including the irreversibility caused by imperfect regeneration and the finite temperature difference between the gas and the heat exchangers wall. A flowchart of the Stirling refrigerator exergy balance is presented to show the internal and external irreversibilities. It is found that the irreversibility at the regenerator level is more important than that at the heat exchangers level. The energies exchanged by the working gas are expressed according to the practical parameters, necessary for the eng...
Entropy
The paper presents experimental tests and theoretical studies of a Stirling engine cycle applied ... more The paper presents experimental tests and theoretical studies of a Stirling engine cycle applied to a β-type machine. The finite physical dimension thermodynamics (FPDT) method and 0D modeling by the imperfectly regenerated Schmidt model are used to develop analytical models for the Stirling engine cycle. The purpose of this study is to show that two simple models that take into account only the irreversibility due to temperature difference in the heat exchangers and imperfect regeneration are able to indicate engine behavior. The share of energy loss for each is determined using these two models as well as the experimental results of a particular engine. The energies exchanged by the working gas are expressed according to the practical parameters, which are necessary for the engineer during the entire project, namely the maximum pressure, the maximum volume, the compression ratio, the temperature of the heat sources, etc. The numerical model allows for evaluation of the energy proc...
Revista de Chimie
The paper presents two constructive solutions in the field of fine bubble generators that serve t... more The paper presents two constructive solutions in the field of fine bubble generators that serve to aerate the water. Two installations for experimental researches have been designed and built in connection with the two constructive solutions. The dissolved oxygen concentration was experimentally determined. The theoretical and experimental results for the two constructive solutions are compared showing a good coincidence in relation to the results reported in the literature.
International Journal of Emerging Research in Management and Technology
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IJIRAE Published Papers by Mihaela Constantin
Papers by Mihaela Constantin