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1
Huo, Fei Yang, Jia Hui Sun, Wei Li Li, and Yi Huang Zhang. "Influence of Large Turbo-Generator Stator Ventilation Ducts Structural Changes on Stator Temperature." Advanced Materials Research 462 (February 2012): 318–26. http://dx.doi.org/10.4028/www.scientific.net/amr.462.318.
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For the complex status of fluid flow in stator radial ventilation ducts of large turbo-generator, the temperature distribution of stator is dramatically affected by the flow status of cooling medium in stator ventilating ducts. In this paper, a new ventilating ducts structure in stator is investigated. According to fixing a wind deflector on the stator teeth adjacent to the ventilation ducts, the fluid flow status of cooling air is changed flowing in stator ventilation ducts. For this reason, the effect of heat transfer in stator is changed. Taking an air-cooled turbo-generator as an example, considering the characteristics of fluid flow and heat transfer in turbo-generator ventilation system, the three-dimensional fluid flow and heat transfer coupling model is established. Using finite volume method, three-dimensional fluid field and temperature field control equations are coupling solved. Based on this, the velocity distribution in ventilating ducts is obtained. Besides that, the velocity distribution is studied with the cooling air flows into radial ventilation ducts at different incident angles. The influences of wind deflector and incident angles on the fluid velocity and temperature distribution are analyzed. Based on that, some useful conclusions are obtained.
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Gaczoł, Tomasz. "Natural balanced ventilation. Simulations part 2." E3S Web of Conferences 49 (2018): 00026. http://dx.doi.org/10.1051/e3sconf/20184900026.
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The paper is devoted to test results of air flow through natural ventilation supply-exhaust ducts in the rooms located on the upper floor of the building that were conducted in ANSYS Fluent software. Three types of solutions were selected for the tests: air inflow into the room through the air intake located at the basement level, air inflow through the window ventilator (although no longer used, this solution can be found in many existing residential buildings) and the natural ventilation system supported with the so-called “solar chimney” that is usually a glass superstructure, located on the roof of the building above the ventilation ducts. All simulations were conducted with an outdoor temperature of +3 degrees C. The indoor temperature is + 20 degrees C, considered to be the minimum thermal comfort level. The simulations concerned such issues as: pressure system inside the room and in the exhaust duct, distribution of air temperatures in the room, vector direction of air flow through supply and exhaust ducts and in the room. Tests conducted using a computer method of air flow analysis in ducts and in the analysed room indicate that the developed natural balanced ventilation system is a good solution, especially when building sealing is so common. In all cases presented, it meets the normative regulations and requirements for the ventilation air stream and the air exchange rate in the room. The paper (second part) describes test results concerning the room located on the upper floor of the building, i.e. with a long 9-meter long supply duct and a short 3-meter long exhaust duct.
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Gaczoł, Tomasz. "Living quarters. A natural balanced ventilation system. Simulations part 1." E3S Web of Conferences 49 (2018): 00025. http://dx.doi.org/10.1051/e3sconf/20184900025.
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In the following article the author proposes the solution for a properly functioning natural ventilation system based on the use of supply and exhaust ducts, i.e. by designing a natural balanced ventilation system. The paper is devoted to test results of air flow through natural ventilation supply-exhaust ducts in the rooms located on the lower floor of the building. The simulations conducted in ANSYS Fluent software relate to such issues as: pressure system inside the room and in the exhaust duct, distribution of air temperatures in the room, vector direction of airflow through supplyexhaust ducts and in the analysed room. Three types of solutions were selected for the tests: air inflow into the room through the air intake located at the basement level, air inflow through the window ventilator (although no longer used, this solution can be found in many existing residential buildings) and the natural ventilation system supported with the so-called “solar chimney”. All simulations were conducted with an outdoor temperature of +3 degrees C. The indoor temperature is + 20 degrees C, considered to be the minimum thermal comfort level. In the era of common building sealing, the presented ventilation system may be a good solution that guarantees proper functioning of natural ventilation. In all cases presented, it meets the normative regulations and requirements for the ventilation air stream and the air exchange rate in the room. The paper (first part) describes test results concerning the room located on the lower floor of the building, i.e. with a short supply duct and a 12-meter long exhaust duct.
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Li, Yong, Weili Li, and Ying Su. "Sensitivity of Axial Velocity at the Air Gap Entrance to Flow Rate Distribution at Stator Radial Ventilation Ducts of Air-Cooled Turbo-Generator with Single-Channel Ventilation." Energies 12, no. 18 (September 6, 2019): 3442. http://dx.doi.org/10.3390/en12183442.
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In the design and calculation of a 330 MW water-water-air cooling turbo-generator, it was found that the flow direction of the fluid in the local stator radial ventilation duct is opposite to the design direction. In order to study what physical quantities are associated with the formation of this unusual fluid flow phenomenon, in this paper, a 100 MW air-cooled turbo-generator with the same ventilation structure as the abovementioned models is selected as the research object. The distribution law and pressure of the fluid in the stator radial ventilation duct and axial flow velocity at the air gap entrance are obtained by the test method. After the calculation method is proved correct by experimental results, this calculation method is used to calculate the flow velocity distribution of the outlets of multiple radial ventilation ducts at various flow velocities at air gap inlets. The relationship between the flow distribution law of the stator ventilation ducts and the inlet velocity of the air gap is studied. The phenomenon of backflow of fluid in the radial ventilation duct of the stator is found, and then the influence of backflow on the temperature distribution of stator core and winding is studied. It is found that the flow phenomenon can cause local overheating of the stator core.
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Lu, Yi Ping, Qing Hui Pan, Hui Lan Li, and Jia De Han. "Experimental Study of Flow Field of Large Air-Cooled Turbine Generator for Multi-Ventilation Ducts of Stator." Applied Mechanics and Materials 644-650 (September 2014): 377–80. http://dx.doi.org/10.4028/www.scientific.net/amm.644-650.377.
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To study rotational air flow field of rotor and complicated flow distinction owing to multi-ventilation ducts of stator in a large air-cooled turbine generator, considering axial symmetry of air supply, an experiment setup of ventilation system of semi-machine configuration was built in this paper. At condition of rotating, ventilation is measured by hot-wire anemometer. Firstly, ventilation in 16 different semi-circle radius is got. Measurement shows that ventilation in different radius varies much. Then ventilation of outlet of stator ducts is measured. The result shows that ventilation which is affected by flow back and jet less is higher. The conclusion will provide theoretical references for ventilation cooling of rotor ducts in large air-cooled turbine generators.
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Gaj, Patryk, and Joanna Kopania. "Influence of Geometry of Channel on the Flow Noise Parameters." Mechanics and Mechanical Engineering 22, no. 2 (August 24, 2020): 541–52. http://dx.doi.org/10.2478/mme-2018-0043.
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AbstractAcoustic emission through duct walls is an important problem in engineering acoustics. This phenomenon most commonly occurs in heating, ventilating and air-conditioning (HVAC) and other gas flow ducting (large industrial silencers). Many works focus on elaboration of more exact description of the acoustic field phenomena reflecting the real conditions in which these appliances operate. As a standard, circle or rectangular ducts are used in ventilation systems. However, technical conditions during the installation of the HVAC system, due to the limitation of the assembly space, require often the use of channels with other geometries. This paper presents aeroacoustical parameters of three most common cross-sectional shapes of air-moving ductwork. The rectangular, square with roundedcorners and circular ducts were studied. The “natural” duct attenuation, which is a consequence of duct shape or noise breakout and involves a diminution of the internally propagated sound power was observed. Natural duct attenuation can be a useful way of reducing sound power levels in long runs of duct.
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Gherghe, Ion, Doru Cioclea, Florin Rădoi, Adrian Matei, and Răzvan Drăgoescu. "Notions regarding the design of suction systems for industrial ventilation." MATEC Web of Conferences 342 (2021): 02006. http://dx.doi.org/10.1051/matecconf/202134202006.
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Air flow in ducts is one of the basic processes of ventilation and air conditioning. Knowledge of this phenomenon and the laws according to it is indispensable for drawing up the sizing calculations of the duct networks, for determining the energy needed to move the air as well as for determining the aerodynamic parameters related to the ventilation ducts. Industrial buildings include large spaces with various sources of releases of harmful substances. Type of these sources and their location depends on the technological process in each section or room.The main role of industrial ventilation systems is to provide a continuous source of fresh air supply from the outside, to keep the temperature and humidity at comfortable levels, to maintain an adequate supply of oxygen in the work area, to control concentrations of hazardous explosive and / or toxic gases in the air and at work, to remove unwanted odors from a particular area and to remove and dilute airborne contaminants. The paper presents the design of exhaust systems, the calculation of suction ventilation systems and the choice of ducts with higher aerodynamic parameters in the choice of fans, using nomograms.
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Sulin, A. B., A. A. Nikitin, T. V. Ryabova, S. S. Muraveinikov, and I. N. Sankina. "Energy-efficient outdoor air flow control in ventilation systems." Omsk Scientific Bulletin. Series Aviation-Rocket and Power Engineering 5, no. 2 (2021): 18–24. http://dx.doi.org/10.25206/2588-0373-2021-5-2-18-24.
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A method for controlling the ventilation system flow characteristics is considered based on the forming principle an air temperature and carbon dioxide concentration predicted estimate in a room based on the changes dynamics analysis in these parameters in the supply and exhaust ducts. The expected microclimate parameters predicted assessment in real time opens up the possibility of using such elements and algorithms for controlling the ventilation and air conditioning system, which provide the required air quality with minimal energy consumption. The analysis calculates the finding probability the measured parameter inside or outside the control zone after a specified time interval. The algorithm for the control system actuators actuation for the channels of temperature and carbon dioxide concentration is presented in the block diagram form. The decision-making logic for actuating the actuators is based on the changes direction and intensity analysis in temperature and carbon dioxide concentration in the exhaust duct and the temperature difference between the supply and exhaust
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Renz, Andreas, Julian Praß, Johannes Weber, and Stefan Becker. "Experimental Investigation of a Friction Ventilator." Advanced Engineering Forum 19 (October 2016): 43–49. http://dx.doi.org/10.4028/www.scientific.net/aef.19.43.
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Standard decentralized ventilation systems typically consist of two ventilators for inlet and exhaust air and a heat exchanger for the heat recovery. A recently developed device, a so called friction ventilator, combines these three elements into a single functional element. The ventilator consists of circular plates which are rotating centrally in between the inlet and the outlet duct of a ventilation system and generate a countercurrent flow in the two ducts. Furthermore, the discs act as a rotating heat exchanger between the two air flows. To increase understanding of the energy transfer from the rotating discs to the flow an experimental investigation on the effect of different rotor geometries was conducted. The study showed an interesting influence of the hub diameter on the characteristic curves with a higher pressure difference for an increase in diameter. The results of the heat recovery measurement however were only mildly affected by the hub geometry. Here the distance between the discs, the rotational speed of the discs and the volumetric flow seemed to have the greatest effect on heat recovery.
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El Moueddeb, K., S. Barrington, and N. Barthakur. "Perforated Ventilation Ducts: Part 1, A Model for Air Flow Distribution." Journal of Agricultural Engineering Research 68, no. 1 (September 1997): 21–27. http://dx.doi.org/10.1006/jaer.1997.0176.
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Tsakanian, Oleh S., and Serhii V. Koshel. "Integral Thermo-Anemometers for Average Temperature and Airflow Measurement in Ducts, at Anemostat Outlets and in Ventilation Grilles." Journal of Mechanical Engineering 23, no. 4 (December 30, 2020): 14–21. http://dx.doi.org/10.15407/pmach2020.04.014.
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When creating ventilation systems, it is important to correctly calculate the volumes of air inflow and outflow. If an error is made in the calculation or a redistribution of air flows is required, measurements are indispensable. The existing methods for determining the air flow rate by using point measurements in the cross-section are laborious and time-consuming, and taking readings at different time points introduces a significant error into the result. A. M. Pidhornyi Institute of Mechanical Engineering Problems of the National Academy of Sciences of Ukraine has developed a new hot-wire anemometer whose use greatly simplifies the measuring process. This device allows one to measure the average values of temperature and air velocity (flow rate) in the cross-section of air ducts or at the inlets and outlets of grilles and anemostats, and can be used in real time to monitor and control air flow rate and temperature in ventilation systems. The probe of the hot-wire anemometer is a metal shell with guides on which a sensitive element is laid. Its principle of operation is to change the heat transfer coefficient at different air leakage velocities. The anemometer is preliminarily calibrated in laboratory conditions at various velocities. There has been obtained a calibration dependence that can be used to measure the air flow rate at the inlets and outlets of air distribution devices and directly in the air ducts. To improve the measurement accuracy, it is necessary to provide the 90° angle of airflow leakage on the hot-wire anemometer probe. For this, special air collectors and air flow rectifiers are used.
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Zhang, Qun Feng, Jin Li Yan, Min Wang, and Zhi Xiang Chen. "CFD Application on Ventilation System of Hydro-Generator." Advanced Materials Research 383-390 (November 2011): 3561–65. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.3561.
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Averaged 3D N-S equations and RNG k-ε equations were solved with parallel computing CFD code on the flow field of dual radial ventilation system without fan for a hydro-generator. The MRF(multiple implicit rotating frame) method was used to simulated the rotating motion of the generator and porous media model were used to simulate the pressure loss of air cooler. Rational tactics were selected to generate calculation grids to compromise with calculation CPU time and result accuracy and the grids of different parts were generated with ICEM-CFD. The flow characteristic of different parts was analyzed and flow flux of different section was obtained. The research indicated that the flow from leakage gap between poles and stators formed "air wall", which generated a recirculation zone and made the bar cooling bad. The local pressure loss of stator entrance is dominant. There are leeward and windward areas for the air flowing with circumferential velocity component. Rational design of stator ducts entrance with some diversion effect, can reduce the pressure loss of the stator ventilation and improve the cooling of leeward area in stator ducts.
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Peszyński, Kazimierz. "Building a bridge between industry and theory on the example of a new ventilation system." EPJ Web of Conferences 213 (2019): 01001. http://dx.doi.org/10.1051/epjconf/201921301001.
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The paper presents the possibilities of simplified determination of the air volumetric flow rate in ventilation ducts. This problem occurred during the tests of local losses in the elements of a new ventilation system based on ducts with a rounded rectangular cross-section. The presented method requires mathematical modelling of the flow velocity distribution in the ducts. The paper presents four models of the velocity distribution. The necessity of using so many models resulted from the wide coverage of the tested sections: Amax/Amin= 46.88.
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Peszynski, Kazimierz, Jan Novosád, Emil Smyk, Lukasz Olszewski, and Petra Dančová. "Modelling of air flow rate in significantly flattened rounded rectangular ventilation ducts." EPJ Web of Conferences 180 (2018): 02082. http://dx.doi.org/10.1051/epjconf/201818002082.
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Paper presents new mathematical model for air flow velocity distribution in rounded rectangular ducts and its experimental verification. In papers [1, 2] an mathematical model based on modified Prandtl equation for power power-law velocity profile was determined. It works very well for smaller cross sections. During the study of larger cross sections new phenomena in flowing air have been observed, it forced the search for a new model. The new model is based on a rounded rectangular division into two parts: slot and rounded square.
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Абдразаков, Ф., Fyarid Abdrazakov, А. Поваров, and Andrey Povarov. "RESEARCH EFFICIENCY OF NATURAL VENTILATION SYSTEM OF APARTMENT BUILDING." Bulletin of Belgorod State Technological University named after. V. G. Shukhov 4, no. 7 (July 21, 2019): 49–56. http://dx.doi.org/10.34031/article_5d35d0b78284d1.97759530.
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The analysis of existing research in the field of ventilation systems is performed and the current shortcomings of the ventilation systems of secondary apartment houses of series 114–85 are identified. The instability of the natural ventilation system of an apartment building characterized by variable air exchange and overturning ventilation in the ventilation ducts is demonstrated. Field studies of the natural ventilation system efficiency of an apartment house series 114–85 located in Saratov are carried out. According to the research results, the absence of traction and the presence of reverse traction in the exhaust ducts of the ventilation system are revealed. The initial reason for the lack of normal traction in the ventilation system associated with its calculation in the project of building a house series 114-85 for open mode operation is stablished. The increased tightness of windows and doors of apartments is determined, resulting in a reversed traction and the impossibility of uniform distribution of air vertically of the house, therefore installing only the exhaust system of the natural ventilation of an apartment building is inefficient. It is established that the ventilation channel in the kitchen is constantly working to extract air from the premises of the apartments, since the bathroom door is tightly closed that does not correspond to the normative indicators. The analysis of ventilation system on the example of three-bedroom apartments shows the need for additional supply devices for controlled flow of outside air into the premises of apartments. The use of supply wall valves of KIV-125 brand and window ventilation valves of Air Box Comfort brand is provided. A methodology of selection the modern, highly efficient energy saving models of turbo ventilators is presented, increasing traction in exhaust ventilation ducts at 40 % and independent of direction and wind gusts.
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Peszynski, Kazimierz, Jan Novosád, Emil Smyk, Lukasz Olszewski, and Petra Dančová. "Modelling of air flow rate in significantly flattened rounded rectangular ventilation ducts." EPJ Web of Conferences 180 (2018): 02082. http://dx.doi.org/10.1051/epjconf/201817002082.
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Oldham, D. J., Jian Kang, and M. W. Brocklesby. "Modelling the Acoustical and Airflow Performance of Simple Lined Ventilation Apertures." Building Acoustics 12, no. 4 (December 2005): 277–92. http://dx.doi.org/10.1260/135101005775219139.
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The pressure differences that can be used to drive a natural ventilation system are very small and thus large apertures are required to allow sufficient air to enter and leave a building to ensure good air quality or thermal comfort. Large apertures are potential acoustic weak points on a façade and may require some form of acoustic treatment such as absorbent linings, in which case the ventilator is similar to a short section of lined duct. In ducts, the performance of absorbent linings increases with the length of lining and the ratio of the length of lined perimeter to the cross sectional area of the duct. Thus, for a duct of a given cross sectional area, a lining is more effective for a duct with a high aspect ratio than for a duct with a square cross section. However, the high aspect ratio cross section will result in greater flow resistance and impede the airflow performance. In this paper numerical methods are employed to investigate the effect of different configurations of a lined aperture on the acoustical and ventilation performance of the aperture in order to establish the optimum configurations.
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Ju, Fa-Li, Liying Liu, and Xiaoping Yu. "An analytical study to evaluate the impact of distributed zone fans on the air flow rate in a mechanical ventilation system." Building Services Engineering Research and Technology 41, no. 4 (September 5, 2019): 507–16. http://dx.doi.org/10.1177/0143624419873761.
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Based on air flow rate testing of each branch fan in a distributed fan ventilation system under different branch air duct inlet static pressures, the conclusion can be drawn that there is a branch fan air flow rate deviation phenomenon. The air flow rate of the branch fan increases with the branch air duct inlet static pressure at the same branch fan speed, and the branch fan hinders the air flow rate in some cases. In this study, a theoretical expression of the deviation of the branch air duct design air flow rate was established, and the influencing factors of the deviation were determined to include the branch air duct resistance characteristics, branch fan performance, and branch air duct inlet pressure ratio. A graphic analytical method for determining the deviation of the branch fan design air flow rate was also proposed. Both methods can provide a theoretical basis for calculating and analysing the deviation of the branch fan design air flow rate in a distributed fan ventilation system. Practical application: This paper provides new data on the performance of a distributed fan ventilation system. Our results could be used to evaluate the impact of distributed zone fans on the air flow rate in a mechanical ventilation system. Crucially, we not only propose two types of methods that can be applied to predict deviations of the air flow rate in a distributed fan ventilation system caused by the branch air duct inlet static pressures but also obtain the factors that are important for understanding the true impact of the deviation of the branch fan air flow rate. This study lays an important foundation for the design and operation of building mechanical ventilation systems.
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Xing, Xia Qiong, Xin Fei Zhao, Zhang Qin, and Xiao Hong Zhou. "Numerical Simulation the Airflow Field in the Flame Retardant Cloth Ducts." Advanced Materials Research 796 (September 2013): 643–48. http://dx.doi.org/10.4028/www.scientific.net/amr.796.643.
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Fiber air dispersion system (FADS) is a new flexible ventilation terminal in ventilated areas. It can be used in both air transmission and air diffusion. The cloth duct made of flame retardant polyester is critical. The conditioned air can be dispersed to environment by not only micro pores in the fabric but also slot and orifice on the fabric. The micro-pores in the fabric exist in the yarns and fibers. The laser can be used to cut the slot and orifice on the fabric. They can be designed based on the application. In this paper, air dispersion models and basic characteristics of fiber air dispersion system were introduced. Based on computational fluid mechanics theory, the flame retardant cloth ducts (FRCD) is regard as an isotropic porous media. The air dispersion physical model for micro porous that sends the air to the environment was established. And the Carman-kozeny equation was used in this model, which was described the airflow field in the FRCD. Finally the airflow field in the FRCD was numerically simulated with the FLUENT software based on the finite element method. The air flow resistance of the fabrics was calculated by the Darcy model.
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Li, Xiao Feng, and Qing Li. "Study on the Flow Numerical Simulation of Jet Ventilation in Multi Tunnel Excavation." Advanced Materials Research 524-527 (May 2012): 731–34. http://dx.doi.org/10.4028/www.scientific.net/amr.524-527.731.
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Pressed ventilation in heading face is actually turbulent jet ventilation. In the blind drift, the air ducts are usually laid on one side of the drifting tunnel forming the wall-attached jet along the side of the tunnel and in order to dilute and pour out harmful gas and dust, and create an backflow at the same time, the airflow of the ventilation jet must reach at the head of the tunnel. Therefore, the forced ventilation in heading face is actually restrained wall attached jet ventilation in confined space.
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Gol'tsov, A. B., K. I. Logachev, O. A. Averkova, V. A. Tkachenko, and I. V. Khodakov. "The investigation of the air flow distribution swirling by the rotating suction cylinder." NOVYE OGNEUPORY (NEW REFRACTORIES), no. 6 (July 26, 2018): 56–60. http://dx.doi.org/10.17073/1683-4518-2018-6-56-60.
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The improvement of the local exhaust ventilation consists in the emission and pollution agents' concentration at the electrical power minimum expenses. The using of the rotating exhaust cylinder in the aspiration hoods can result in the reduction of both the dust loss into the aspiration system and the dust aerosol transportation costs in the air transfer ducts. We investigated the air flow velocity distribution near the rotating exhaust cylinder depending on the rotation frequency and vented air consumption. The obtained results can be applied when the local closed exhaust hoods designing, that is the designing of the aspiration hoods with the dust-collecting chambers.
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Oz, S., S. Fogel, V. Dubovsky, G. Ziskind, and R. Letan. "Solar-Assisted Induced Ventilation of Small Field Structures." Journal of Solar Energy Engineering 126, no. 2 (May 1, 2004): 781–88. http://dx.doi.org/10.1115/1.1669029.
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Induced passive ventilation was studied in a small field structure, about 60cm×30cm×85cm in size, heated by solar irradiation. The structure has three stories, connected by a vertical duct, which in turn is connected to a horizontal duct above the upper level of the structure. The outer walls of these two ducts are metal sheets painted on the outside with black matte paint and covered by glass sheets. The other outer walls and inner partitions of the structure are made of cardboard attached to a metal frame. Additional elements included in some experiments were a water tank, used for heat storage, and a chimney for enhancing air flow. The structure orientation was with its vertical metal sheet facing south-west. Experimental study, based on temperature and velocity measurement, and computer simulations, using the FLUENT software, were performed. During a typical experiment, the structure has been exposed to the sun for a full day in July through November. The ports of the system were either opened in the morning, or kept closed until about 13:45-14:00 and then opened. The results of the study indicate that effective ventilation has been achieved: the calculated rates of air change inside the stories were rather high, and the mean air temperatures were only about 1-2°C above the ambient in its lower stories and 2-3°C above the ambient in the upper story. Detailed comparison of the experimental and numerical results is presented and discussed.
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Osipov, S. N., S. L. Danilevskiy, and A. V. Zacharenko. "THE USE OF AIR LAYERS IN BUILDING ENVELOPES FOR ENERGY SAVING DURING AIR CONDITIONING." ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations 60, no. 5 (September 28, 2017): 470–83. http://dx.doi.org/10.21122/1029-7448-2017-60-5-470-483.
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Since there are no large natural energy resources in Belarus, energy savings ought to be a point of the special attention. With this regard it is important to develop modern ways of savings during the process of air conditioning inside new buildings with an air layer in the enclosure, especially in translucent ones. The system of ventilation of air layers in the enclosure of a building has been introduced in which air movement is caused by the gravitational and aerodynamic forces. It makes it possible to arrange further ventilation – a natural, forced or a hybrid one. With the purpose of increasing and streamlining natural draught the partitions are used separating the different parts of air layers. For natural ventilation with the use of gravitational forces the holes in the upper and lower parts of the partitions between adjacent air layers are applied. Natural ventilation in the holes of the partitions is regulated by movable shutters, blinds or other adjusting devices. For combined or forced air exchange between adjacent zones of air layers fans are used pumping air from the air layer zones with a higher temperature to zones of air layers with lower temperature and vice versa. When air exchange is forced, in order to intensify the infiltration of air into zones of air layers jets are laid on a hard surface. In order to cool a multi-layered enclosure of a building, where the movement of air between the air layers (that have been formed by internal partitions) is being fulfilled by a natural, forced or combined mode, a part of the air or the total air processed inside the building (i.e. conditioned or non-conditioned air cooler as compared with the outside one) is being sent to these strata. Combined or forced flow of the air processed inside the building into the air layers is done through the ducts associated with the output channels of the air conditioners. The internal partitions are equipped with the air valve hole.
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Korbut, V., V. Mileikovskyi, V. Dziubenko, and I. Sachenko. "The use of the interaction of convex wall jets for ventilation with variable air flow." Ventilation, Illumination and Heat Gas Supply 37 (April 1, 2021): 7–12. http://dx.doi.org/10.32347/2409-2606.2021.37.7-12.
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The most energy efficient ventilation and air-conditioning is variable air flow (VAV) depending on the needs of a room. To avoid broken air circulation by gravitational forces, the most of air diffusers should change geometrical shape and sizes using additionall automation of them. In contrast, high stability of a scheme of air exchange organization with air supply over a working zone by convex wall jets that interact with each other under conditions of variable air flow, is confirmed. This scheme is useful in cases where it is impossible to supply air directly to the working zone. Simulation of the air exchange organization in an exhibition hall of International Exhibition Centre in Kyiv with ventilation at a variable air volume (VAV) in the entire possible range of performance control has been performed. The floor area is 5258 m2, the height is 19 m. The outdoor air-flow at design conditions (100 % load) is 21.667 m3/s (78000 m3/h). The minimum load corresponds to the absence of solar radiation and only some people in the room. The minimum air-flow is 25 % of the design one. The proposal air scheme is single-zonal using 24 diffusers PES-D-8-10/15-0,9 4 m above the floor and air removal from the upper zone. The air distributor have a diameter of a cylindrical surface and an inlet branch pipe of 8 dm (800 mm). There are 10 rows of nozzles at an angle π/12 (15 °) to the horizon on each distributor. The total area of the air outlet on them is equal to 0.9 of the cross-sectional area of the inlet pipes. Due to forces of the vacuum holding of jets on the wall surfaces, the influence of gravitational forces is significantly reduced. This avoids the automation of air distribution devices to stabilize the scheme of air circulation in the room by gravitational forces. It is enough to install valves with actuators on branches of a network of air ducts. Thus, the economic benefit of the system is confirmed both at the stage of installing and during operation.
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Przydrozny, Edward, and Aleksandra Przydrozna. "Temperature and airflow setting in dual-duct ventilation systems." E3S Web of Conferences 116 (2019): 00063. http://dx.doi.org/10.1051/e3sconf/201911600063.
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Past experiences of excess energy consumption and malfunctioning controls introduced prejudice when considering dual-duct ventilation systems during design stages. Modern technologies, however, can be used to improve performance and control of dual-duct systems, thus making these a sensible and safe design option. In the paper, we discuss challenges associated with setting the warm and cold supply air temperatures and how these set-points affect the airflows. We present limitations in temperature settings, due to instantaneous room thermal conditions and the individual design temperature requirements. Portions of warm and cold air (the ratio of these in the ventilating airflow) affect the transport costs of ventilating airflow. In many cases, rational control of warm and cold air temperature set-points, in a yearly cycle, enables distribution of similar portions of warm and cold air within the system. Even airflows in warm and cold air installations minimise the overall flow resistance, so that the air transport costs are minimal. Simultaneously, apart from minimising the energy for air transport, the primary energy demand for air treatment should be controlled and minimised.
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Waddington, D. C., and D. J. Oldham. "Noise Generation in Ventilation Systems by the Interaction of Airflow with Duct Discontinuities: Part 1 Bends." Building Acoustics 14, no. 3 (September 2007): 179–202. http://dx.doi.org/10.1260/135101007781998956.
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Discontinuities in air duct systems give rise to turbulence and some of this turbulence results in airflow generated noise. One potential source of flow generated noise in ducts is the presence of a bend. Various strategies are employed to reduce turbulence by smoothing the flow around a bend, such as the use of turning vanes, large radius of curvature and the associated use of splitters, and these will also affect the noise generated. Recent work on the prediction of airflow generated noise in ducts based upon pressure loss characteristics is applied to a range of bends including mitred bends, with and without turning vanes, and radiussed bends, with and without splitters. The effect of bends with different aspect ratios is also examined. An excellent collapse of measured data onto a single characteristic curve is reported for each configuration based upon standard values of pressure loss coefficients. It is suggested that these characteristic curves might form the basis for a practical prediction method.
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Szelka, Michał, Mariusz Woszczyński, Jerzy Jagoda, and Paweł Kamiński. "Wireless Leak Detection System as a Way to Reduce Electricity Consumption in Ventilation Ducts." Energies 14, no. 13 (June 23, 2021): 3774. http://dx.doi.org/10.3390/en14133774.
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This article presents a proposal for a wireless diagnostic system for checking the air tightness of the ventilation network. The solution is designed to increase crew safety in underground mining plants and increase the energy efficiency of the ventube ventilation system. The system is based on sensors measuring the pressure inside the ventilation duct in relation to the barometric pressure in the immediate vicinity of the duct. The flow of diagnostic data is based on a cascade transfer. The data from the first sensor are transferred successively to the last one. Based on the prior calibration of alarm thresholds in each device, the leakage or factor influencing the increase of air flow resistance is located. The article presents the genesis of the creation and discusses the principle and purpose of the system. In the following chapters, the progress of work related to testing the system in laboratory, industrial, and underground conditions at the Velenje Premogovnik mine (Slovenia) is presented. The authors analyze the test results and indicate the directions of possible further work on improving the system. The proposed leak detection system is based on a network of pressure sensors that communicate with each other to clearly pinpoint the leak location. The system has been designed for operation in underground mining plants with limited space.
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Ala-Kotila, Paula, Terttu Vainio, and Jarmo Laamanen. "The Influence of Building Renovations on Indoor Comfort—A Field Test in an Apartment Building." Energies 13, no. 18 (September 22, 2020): 4958. http://dx.doi.org/10.3390/en13184958.
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This article presents a field test of how deep renovation affects indoor climate quality. The studied apartment building was built in 1968 and is located in Finland, within the Nordic climate zone. The deep renovation included façade repair with extra insulation, new windows with trickle vents, new balcony glass and doors, and the installation of an exhaust air heat pump into the existing mechanical exhaust air ventilation. The indoor climate conditions and building envelope tightness were measured before and after the renovation. As a result of these energy renovation measures, the building envelope tightness improved by nearly 40% and the uncontrolled supply of air (draughts) decreased by approximately 24%. The overall energy consumption of the building decreased by 45%. Above all, the long testing period gives credibility to the study. The field test brought up the challenge of supplying an adequate amount of fresh air. This article highlights the fact that windows are part of a mechanical ventilation system if fresh air is not controlled by being led through inlet ducts. The supply air flow and volume must be ensured by correctly dimensioned valves, and therefore we stress the importance of the technical cooperation of technical designers.
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Park, Jongmyung, Youngdo Jo, and Gyesoon Park. "Flow characteristics of fresh air discharged from a ventilation duct for mine ventilation." Journal of Mechanical Science and Technology 32, no. 3 (March 2018): 1187–94. http://dx.doi.org/10.1007/s12206-018-0222-9.
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Ju, Fa-Li, Qinrong Sun, Changlei Hou, Xue Huang, Xiaoping Yu, and Liying Liu. "Test and analysis of air flow rate adaptive performance in a distributed fan ventilation system." Building Services Engineering Research and Technology 42, no. 2 (January 6, 2021): 223–36. http://dx.doi.org/10.1177/0143624420986000.
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In this study, adaptive branch fan performance in a distributed fan ventilation system was tested. The results demonstrate that the adaptive branch fan stabilises the branch air flow rate within a certain air pressure range corresponding to the branch duct inlet, and this range becomes increasingly narrow as the fan control signal is adjusted to reduce the speed of the fan. The adaptive branch fan is less affected by the main fan and other branch fans in the distributed fan ventilation system because it has a good self-adaptive ability of ventilation duct resistance characteristics and anti-interference ability of the air flow rate. Furthermore, the hydraulic characteristics of the branch fans in the distributed fan ventilation system were analysed. The new performance characterisation parameters and method for modifying the engineering design for the adaptive branch fan were presented. Practical application: This study investigates the adaptive performance of the branch fan in a distributed fan ventilation system. Our results demonstrate that the new branch fan can stabilise the air flow rate in a mechanical ventilation system. More importantly, we not only propose performance characterisation parameters of the adaptive branch fan that are important for understanding the operation of a mechanical ventilation system, but also present a method of engineering design application. This study can guide the design and operation of mechanical ventilation systems.
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Nan, Chun Zi, Ji Ming Ma, and Luo Zhao. "Numerical Simulation of Impacts of Different Types of Air Duct Outlets on Ventilation Efficiency." Applied Mechanics and Materials 438-439 (October 2013): 1098–103. http://dx.doi.org/10.4028/www.scientific.net/amm.438-439.1098.
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To enhance the exhaust efficiency during ventilation, three types of air duct outlets were imported. According to the characteristics of velocity distribution simulated by numerical method, the flow field is divided into the mixing zone and the exhaust zone. The gradual contracted air duct outlet can enhance the mixing effect between fresh air and smoke. In the exhaust zone, however, the flow velocity on the upper section of the tunnel is weakened, which is unfavorable for smoke exhaust. Gradual expanded air duct outlet, on the contrary, may weaken the concentration effect of the airflow. The flow velocity on the upper section of the tunnel is increased in the exhaust zone, thus the flow field is more homogenized, which is in favor of smoke exhaust.
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Yi, Huiuk, Jongmyung Park, and Min Sik Kim. "Characteristics of mine ventilation air flow using both blowing and exhaust ducts at the mining face." Journal of Mechanical Science and Technology 34, no. 3 (March 2020): 1167–74. http://dx.doi.org/10.1007/s12206-020-0218-0.
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Millar, Dean, Michelle Levesque, and Stephen Hardcastle. "Leakage and air flow resistance in mine auxiliary ventilation ducts: effects on system performance and cost." Mining Technology 126, no. 1 (July 2016): 10–21. http://dx.doi.org/10.1080/14749009.2016.1199182.
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Semin, M. A., and L. Yu Levin. "Theoretical research of heat exchange between air flow and shaft lining subject to convective heat transfer." Mining informational and analytical bulletin, no. 6 (May 20, 2020): 151–67. http://dx.doi.org/10.25018/0236-1493-2020-6-0-151-167.
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The heat and mass transfer in a mine shaft under construction is researched theoretically under temperature conditions in the shaft lining lower than the temperature of air flow fed in the shaft via a ventilation duct. The research was aimed to ensure stable airing of mine shafts in the period of construction before cutting a shaft-to-shaft connection with artificial freezing of surrounding rock mass. The multi-parametric numerical modeling of nonstationary aeroand thermo-dynamic parameters in a mine shafts was performed using 3D convective heat transfer model in ANSYS. It is found that convective heat can exert considerable influence on the heat and mass exchange in the air space of the shaft when the shaft lining temperature is lower than the temperature of air flow from the ventilation duct at the shaft bottom. Inside the shaft, the back convective flows appear and air circulates in convective cells, which increases air flow rate in the shaft. As a consequence, the heat transfer factor at the shaft lining-air interface is much higher than the calculated factor without regard to the convective heat. The influence of the temperature difference at the air and shaft lining interface and the shaft lining roughness on the average values of the heat transfer factor and heat flow at the shaft lining and air interface is investigated. The empirical formulas are proposed for calculating the heat transfer factor and specific heat flow at the shaft lining and air interface depending on the temperature difference, shaft diameter and roughness of walls of underground openings.
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Wu, Kuan, Shiliang Shi, Yijie Shi, and Yong Chen. "CFD-Based Determination of the Optimal Blowing and Suction Air Volume Ratio of Dual-Radial Swirl Shielding Ventilation in a Fully Mechanized Excavation Face." Geofluids 2021 (September 14, 2021): 1–12. http://dx.doi.org/10.1155/2021/5473256.
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Dust is one of the main pollutants in coal mines, which seriously affects the physical and mental health of workers, as well as the safe production in underground mines. Dual-radial swirl shielding ventilation is a new ventilation method for a fully mechanized excavation face and can effectively reduce the dust concentration in the underground. The dust control effect of dual-radial swirl shielding ventilation is mainly affected by the thickness and integrity of the shielding air curtain, as well as the disturbance of the flow field near the air curtain. By changing the blowing and suction air volume ratio of the air duct, the strength of the radial air curtain can be improved, and the dust control effect of the dual-radial swirl shielding ventilation system can be effectively improved. In order to determine the optimal operating parameters of the dual-radial swirl shielding ventilation system, a numerical simulation method was used to conduct an in-depth study on the blowing and suction air volume ratio of the system. The results showed that when the blowing and suction air volume ratio of the air duct was 1.5, the radial air curtain had the highest strength. Under this condition, the dust concentration at the driver’s position of the roadheader was the lowest, and the dual-radial swirl shielding ventilation system can achieve an ideal dust control effect.
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Yaropud, Vitalii, and Yelchin Aliyev. "RESULTS OF INSPECTION OF THE STATE OF PROVIDING THE MICROCLIMATE IN THE PIG FARM WITH A NEGATIVE PRESSURE VENTILATION SYSTEM." ENGINEERING, ENERGY, TRANSPORT AIC, no. 2(113) (June 29, 2021): 168–77. http://dx.doi.org/10.37128/2520-6168-2021-2-17.
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The most popular microclimate system today is based on a negative pressure ventilation system. Because it is easier to use and consumes less energy than any other forced ventilation system. The purpose of the research is to inspect the room for keeping piglets on rearing with a negative pressure ventilation system to identify shortcomings and deviations of the microclimate parameters necessary for further improvement. According to the results of the inspection of the rearing room for piglets, it was found that according to the existing system of negative pressure in the rearing room for piglets, most indicators (air velocity, ammonia, carbon dioxide, hydrogen sulfide, oxygen) are within normal limits. According to the results of the inspection of the room for keeping piglets for rearing with a negative pressure microclimate system, it was found that the air temperature in the room does not meet the recommended limits and reaches 30 °C, while the maximum recommended temperature for piglets for fattening is 20 °C. The air temperature is uneven along the length of the room, which is caused by uneven air supply from the vents. According to the results of the inspection of the room for piglets with a negative pressure microclimate system, it was found that the relative humidity at the height of the animals is higher than the recommended norms and reaches 95%, while the recommended humidity for piglets for fattening is not more than 80%. According to the results of the inspection of the room for keeping piglets for rearing with a negative pressure microclimate system, it can be stated that it is necessary to improve the air cooling system and replan the ventilation ducts of the ventilation system to ensure even air flow.
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Krauter, Paula, and Arthur Biermann. "Reaerosolization of Fluidized Spores in Ventilation Systems." Applied and Environmental Microbiology 73, no. 7 (February 9, 2007): 2165–72. http://dx.doi.org/10.1128/aem.02289-06.
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ABSTRACT This project examined dry, fluidized spore reaerosolization in a heating, ventilating, and air conditioning duct system. Experiments using spores of Bacillus atrophaeus, a nonpathogenic surrogate for Bacillus anthracis, were conducted to delineate the extent of spore reaerosolization behavior under normal indoor airflow conditions. Short-term (five air-volume exchanges), long-term (up to 21,000 air-volume exchanges), and cycled (on-off) reaerosolization tests were conducted using two common duct materials. Spores were released into the test apparatus in turbulent airflow (Reynolds number, 26,000). After the initial pulse of spores (approximately 1010 to 1011 viable spores) was released, high-efficiency particulate air filters were added to the air intake. Airflow was again used to perturb the spores that had previously deposited onto the duct. Resuspension rates on both steel and plastic duct materials were between 10−3 and 10−5 per second, which decreased to 10 times less than initial rates within 30 min. Pulsed flow caused an initial spike in spore resuspension concentration that rapidly decreased. The resuspension rates were greater than those predicted by resuspension models for contamination in the environment, a result attributed to surface roughness differences. There was no difference between spore reaerosolization from metal and that from plastic duct surfaces over 5 hours of constant airflow. The spores that deposited onto the duct remained a persistent source of contamination over a period of several hours.
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Kumar, Dileep, Abdul Ghafoor Memon, Rizwan Ahmed Memon, Intizar Ali, and Natasa Nord. "Parametric study of condensation at heating, ventilation, and air-conditioning duct's external surface." Building Services Engineering Research and Technology 39, no. 3 (December 9, 2017): 328–42. http://dx.doi.org/10.1177/0143624417743119.
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The compression of insulation causes around a heating, ventilation, and air-conditioning duct usually resulted in dew formation around the outer surfaces because of low temperature, which causes significant energy and financial losses. The parameters such as supply air flow rate, supply air temperature, ambient air speed, and the convective heat transfer coefficient (ho) plays significant role in dew formation. In this paper, the parametric study is performed to investigate the effects of these parameters on the external surface temperature of the duct to avoid condensation. A mathematical model is developed to quantify these effects using preliminary data obtained from the heating, ventilation, and air-conditioning system of a pharmaceutical company. The results reveal that external surface temperature increases with an increase in insulation thickness and supply air temperature, whereas it decreases with higher supply air flow rate. It is estimated that the minimum insulation thickness at joint and bend should be maintained between 15–55 and 15–35 mm, respectively, with a variation in ho between 6 and 22 W/m2K to avoid condensation. Additionally, it is estimated that air flow rate should be greater than 1.4 m3/s at 10 W/m2 K and 2.2 m3/s at 22 W/m2 K. Similarly, the ambient air speed should be greater than 2.8 m/s at 6 W/m2 K, respectively. Practical application: Building services engineers have a paucity of information on the effects of the compression of heating, ventilation, and air-conditioning duct thermal insulation. It can cause condensation that will adversely affect the insulation material, thereby increasing the maintenance cost as well increasing the heat loss from the duct so affecting the conditions of supply air. Proper insulation thickness and operating parameters are important for building owners and operators to control ongoing expenses of buildings. This paper seeks to quantify the effect of insulation compression to improve understanding so that this important area may be properly considered by the building services engineer.
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Rymarov, A., and V. Agafonova. "Персонализированная приточная система вентиляции в помещении офисного здания." Vodosnabzhenie i sanitarnaia tehnika, no. 11 (November 15, 2019): 60–64. http://dx.doi.org/10.35776/mnp.2019.11.08.
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Улучшение качества воздуха в рабочей зоне офисных помещений является актуальной задачей. Конструктивная особенность таких помещений заключается в небольшой высоте (порядка 3 м), что затрудняет подачу необходимого объема приточного воздуха, не создавая сквозняков в рабочей зоне. Отмечено, что решение данного вопроса связано с использованием на практике новых материалов и технологий. К их числу относятся текстильные воздуховоды из 100процентного полиэстера с вплетением карбонового волокна. Данный материал обладает прочностью, износостойкостью, минимальным уносом частиц с поверхности. В отличие от стальных оцинкованных воздуховодов в текстильном воздуховоде можно вырезать лазером точные отверстия с оплавленными краями необходимого шага и диаметра. Представлена схема организации персонализированной приточной вентиляции в офисном помещении на основе разработанного воздухораспределительного устройства с микроперфорированным текстильным вкладышем. Данное устройство позволяет регулировать расход воздуха в зависимости от индивидуальной потребности человека вплоть до отключения системы при отсутствии работника. Снижение расхода приточного воздуха способствует повышению энергоэффективности системы вентиляции.Improving the air quality in the working area of the office space is an urgent task. The design feature of such rooms is a small height (about 3 m) that complicates supplying the required volume of induced air without creating drafts in the working area. It is noted that the solution to this issue is associated with the use of new materials and technologies in practice. These include textile ducts made of 100 polyester with carbonic fiber weave. This material possesses strength, wearresistance, minimal ablation of particles from the surface. Unlike steel zinccoated airducts, it is possible to cut with laser precision holes with fused edges of the required pitch and diameter in the textile ducts. A layout of arranging personalized forced ventilation in an office building based on a designed air terminal device with a microperforated textile insert is presented. This device provides for adjusting the air flow depending on the individual needs of the person up to shutting down the system in the absence of an employee. Reducing induced air flow contributes to the energy efficiency of the ventilation system.
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Chen, Fu-Jiang, Qin-Yu Wu, Dan-Dan Huang, Yun Zhang, Wang Lu, and Meng-Meng Chen. "Validation of the free area method for modelling fabric air dispersion system without orifices in computational fluid dynamics simulation." Indoor and Built Environment 27, no. 7 (March 7, 2017): 969–82. http://dx.doi.org/10.1177/1420326x17698532.
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The fabric air dispersion system (FADS) is a ventilation terminal made of special polymer fabric. The porous structure of the fabric causes complex flow motion. Due to its advantages over the conventional ventilation system, i.e. ducts and diffusers, the FADS has been widely favoured by architects and researchers. In computational fluid dynamics (CFD) simulation the FADS is usually simplified into a free opening with an area equal to all pores and perforations, called the free area (FA) method in this present work. However, the effectiveness of this simplified method has not been validated. The present work took a half cylindrical FADS without orifices as an example and employed the FA method to simulate the airflow properties inside a chamber under isothermal and non-isothermal conditions. The simulated distributions of air velocity and temperature were compared with those by the direct description (DD) method. Meanwhile, the uniformity of air velocity distribution close to the FADS was validated against test data and the flow visualization using the dry ice as a smoking material. Results demonstrate that the FA method is effective and easy to implement, and performs as well as the DD method in predicting the distribution of airflow generated by the FADS without orifices.
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Jeon, Shinyoung, Changmin Son, Jangsik Yang, Sunghoon Ha, and Kyeha Hwang. "Full Surface Heat Transfer Characteristics of Stator Ventilation Duct of a Turbine Generator." Energies 13, no. 16 (August 10, 2020): 4137. http://dx.doi.org/10.3390/en13164137.
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Turbine generators operate with complex cooling systems due to the challenge in controlling the peak temperature of the stator bar caused by Ohm loss, which is unavoidable. Therefore, it is important to characterize and quantify the thermal performance of the cooling system. The focus of the present research is to investigate the heat transfer and pressure loss characteristics of a typical cooling system, the so-called stator ventilation duct. A real scale model was built at its operating conditions for the present study. The direction of cooling air was varied to consider its operation condition, so that there are: (1) outward flow; and (2) inward flow cases. In addition, the effect of (3) cross flow (inward with cross flow case) was also studied. The transient heat transfer method using thermochromic liquid crystals is implemented to measure full surface heat transfer distribution. A series of computational fluid dynamics (CFD) analyses were also conducted to support the observation from the experiment. For the outward flow case, the results suggest that the average Nusselt numbers of the 2nd and 3rd ducts are at maximum 100% and 30% higher, respectively, than the inward flow case. The trend was similar with the effect of cross flow. The CFD results were in good agreement with the experimental data.
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Wang, Weiliang, Junfu Lyu, Hai Zhang, Qing Liu, Guangxi Yue, and Weidou Ni. "Utilization of the lateral accelerated cross-wind to improve the cooling performance of a natural draft dry cooling tower." Thermal Science 23, Suppl. 4 (2019): 1013–24. http://dx.doi.org/10.2298/tsci19s4013w.
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Cross-wind degrades the performance of a natural draft dry cooling tower (NDDCT). Based on the basic affecting mechanism, this paper introduces a wind collecting approach. By using a wind collecting duct, the lateral flow acceleration of cross-wind is broken up, and the lateral flow kinetic energy is utilized to increase the lateral and rearward static pressure outside the radiator inlet. By adoption of a CFD model, the effect of the wind collecting approach is investigated comprehensively. It is found that the wind collecting ducts could improve the pressure distribution around the radiator bundle, reinforce the lateral air intake, and reduce the intensity of mainstream vortices, so as to enhance the ventilation rate of a NDDCT. For an outstanding performance, the two-duct wind collecting scheme is suggested, which may assure a NDDCT working in an approximately wind free manner in all investigated cross-wind range, and increase the ventilation rate by ~63% under the high cross-wind condition, which may reduce the overall coal consumption by 23500~33500 tons annually for a 660 MW coal-fired unit. The numerical results are confirmed by a hot state modelling experiment conducted in a wind tunnel.
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Yao, Xingbo, Shuo Han, and Bart Julien Dewancker. "Study on the Combined Effect of Multiple Passive Energy-Saving Methods for Rural Houses with Cold Alleys." Applied Sciences 11, no. 12 (June 18, 2021): 5636. http://dx.doi.org/10.3390/app11125636.
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China’s rural houses are mostly courtyard-style independent houses. Such houses have certain characteristics, e.g., small mutual influences between houses, strong transformation flexibility, and an easier approach to using the natural environment to develop passive energy-saving characteristics. Therefore, rural houses have large energy-saving potential. In this study, for the first time, the cold alleys between buildings were used as an energy source for passive cooling and ventilation. Traditional houses in Shuhe, China, were used as a case study. The cold alleys in the settlements were used to compensate for the natural conditions in summer, and the cold air in the cold alley was introduced into each room using hot-press ventilation and by employing an accumulation effect from a corresponding patio. The room was ventilated and cooled, and air ducts were used to connect the rooms on both sides of the patio to improve the cooling efficiency. The research variables included the existence or non-existence of wall heat radiation (WHR), and the importance and influence of the WHR on the indoor conditions were verified. The cold air trapped in the new system formed an air partition wall, effectively blocking the direct influence of solar radiation on the room, reducing the heat transfer rate of the residential wall, and consuming part of the heat. In winter, based on using air ducts as supporting members, a glass roof was added to the patio, which improved the heat storage capacity of the patio and turned it into a constant-temperature heater for heating the building interior. Based on calculations, in the new system without WHR, the annual cooling load reduction was 55,417.33 kWh. With WHR, the annual cooling load reduction was 28,537.57 kWh. The annual cooling load of the air insulation wall of the new system was reduced to 1133.7 kWh. In winter, using the glass roof to increase the heat storage capacity of the patio reduced the heating load to 54,537.78 kWh.
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Shi, Ling, Hong Mei Chen, Xin Ming Yu, Wei Zhong Yang, and Jin Can Deng. "Experimental Study of the Tunnel Thermal Environment Adjustment." Advanced Materials Research 485 (February 2012): 169–72. http://dx.doi.org/10.4028/www.scientific.net/amr.485.169.
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Abstract. The purpose of the paper is study the tunnel air environment adjustment. We built a set-up according to the similarity law. Temperature, air flow velocity, and the humidity in the model tunnel were measured using a measurement system. Experimental data were obtained under the ventilation duct at the top of the tunnel. The results show that adjusting velocity and humidity of the supply air flow can satisfy the Safety Regulation for Metal and No-metal Mines.
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Czetany, Laszlo, and Peter Lang. "Impact of Inlet Boundary Conditions on the Fluid Distribution of Supply Duct." Applied Mechanics and Materials 861 (December 2016): 384–91. http://dx.doi.org/10.4028/www.scientific.net/amm.861.384.
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Ventilation is important to maintain the indoor air quality and other comfort parameters in the occupied zone. The design of ventilation systems is based on one dimensional approach. When the air distribution is modelled in the ventilated space usually CFD simulation is performed and simplified boundary conditions are defined at the locations where the supply air enters the room. However, in some cases it is difficult to predict the duct flow by 1D methods. The flow in the duct system determines the outflow at the air terminal devices. The interaction between the multiple system elements is important, since many different combinations are possible, for instance multiple bends can create a special flow field which also influences the distribution performance of the duct. It is very important to determine this impact, because the room airflow depends on it. In this study the impact of the inlet boundary conditions on the fluid distribution performance of a special supply duct –which is designed to provide uniform distribution– is investigated with CFD. Three different inlet boundary conditions are defined: constant inlet velocity and turbulence parameters estimated from intensity and hydraulic diameter, diffuser after fully developed turbulent pipe flow, diffuser with one bend and a Venturi-tube upstream. In each case, the simulations are performed with the realizable k-epsilon model. The reliability of the results is estimated with the grid convergence index.
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Lackowski, Marcin, Andrzej Krupa, and Anatol Jaworek. "Nanofabric nonwoven mat for filtration smoke and nanoparticles." Polish Journal of Chemical Technology 15, no. 2 (July 1, 2013): 48–52. http://dx.doi.org/10.2478/pjct-2013-0023.
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The process of production of filtration mats of various thickness from PVC and PVDF polymers by the electrospinning method is presented in the paper. Filtration of nanoparticles and submicron particles is an important problem in industry and health protection systems, in particular in air-conditioning and ventilation appliances. This problem can be effectively solved by application of non-woven fibrous filtration mats. The experimental investigations of mechanical properties of nanofibrous filtration mats produced by electrospinning and the measurements of removal efficiency of submicron particles from flowing gas have indicated potential usefulness of these nanomats for gas cleaning of air-conditioning systems and/or ventilation ducts. The experimental results obtained for cigarette smoke of a mass median diameter of about 1 μm, used as test particles, have shown that nonwoven nanofibrous filtration mats produced by electrospinning have a good filtration efficiency for nano- and submicron particles, owing to a pressure drop similar to HEPA filters. Particles of this size are particularly difficult to be removed from the flow by a conventional method, for example, by a cyclone or electrostatic precipitator.
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Filkin, N. M., and A. M. Tatarkin. "NUMERICAL RESEARCH OF THE MOISTURE CONDENSATION ELIMINATION IN THE CABIN OF THE UNIFIED TECHNOLOGICAL ELECTRIC TRANSPORT VEHICLE." Vestnik SibADI 15, no. 4 (September 12, 2018): 538–46. http://dx.doi.org/10.26518/2071-7296-2018-4-538-546.
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Introduction. This article deals with the problem of moisture condensation inside the cabin of the technological electric transport vehicle. The hypothesis of using the forced air ventilation in the cabin is substantiated, by which such problem could be solved.Materials and methods. The article describes the application of the ANSYS Fluent Software Package to assess the effect of the location and shape of the ducts on the ventilation process inside the cabin. Accordingly, the key stages of air flow modeling in this program are considered.Results. The main content of the research is to analyze the modeling airflow process in the cabins with a different configuration of inlet and outlet nozzles. Therefore, basing on the analysis of the obtained airflow velocity contours, the conclusion is made about the rational arrangement of the inlet and outlet channels.Discussion and conclusions. The conclusion is made about the necessity of the further research that would refer to creating a three-dimensional model of the cabin. The results of the research as well as resolutions are taken into account.
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Aureliano, Filipe dos Santos, Alessandro Ferreira Alves, Rodrigo Franklin Frogeri, Wanderson Gomes de Souza, Simone de Paula Teodoro Moreira, and Laísa Cristina Carvalho. "Eulerian Video Magnification for Cleaning and Inspection of Air Conditioning Ducts With Rover Robot." International Journal for Innovation Education and Research 8, no. 3 (March 1, 2020): 38–47. http://dx.doi.org/10.31686/ijier.vol8.iss3.2176.
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This paper presents a diversied artifice of a Rover robot prototype in order to inspect abnormalities in air conditioning ducts and ventilation through an integrated rotating high-resolution camera system Eulerian Video Magnification is a method capable of revealing temporal variations of a body in videos that are impossible to see with the naked eye. Using this method, it is possible to visualize the flow of microorganisms present in the ducts, in which the images are R.W. transmitted in real time to the operator, allowing the cleaning with rotating brushes that adapt themselves according to the pipeline geometry, linked to the rover making the removal of impurities which are found on the walls, as well as the application of fungicides and bactericides, and finally the mechanism structure allows the manipulation of small objects held by a claw, which ensures greater operating flexibility compared to existing systems on the market. Due to weather problems being the main responsible for the considerable rise in temperature around the world, this has led man to seek ways by which people have comfort in both residential and industrial context. The most widely used alternative to soften or even solve this problem indoors has been the use of air conditioning systems. Despite the many advantages that these systems provide, there is great concern with the quality of air being supplied to the user according to the procedures and requirements of NBR 15848: 2010.
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Chezganova, Evgenia, Olga Efimova, Vera Sakharova, Anna Efimova, Sergey Sozinov, Anton Kutikhin, Zinfer Ismagilov, and Elena Brusina. "Ventilation-Associated Particulate Matter Is a Potential Reservoir of Multidrug-Resistant Organisms in Health Facilities." Life 11, no. 7 (June 30, 2021): 639. http://dx.doi.org/10.3390/life11070639.
Full textAbstract:
Most healthcare-associated infections (HCAIs) develop due to the colonisation of patients and healthcare workers by multidrug-resistant organisms (MDRO). Here, we investigated whether the particulate matter from the ventilation systems (Vent-PM) of health facilities can harbour MDRO and other microbes, thereby acting as a potential reservoir of HCAIs. Dust samples collected in the ventilation grilles and adjacent air ducts underwent a detailed analysis of physicochemical properties and biodiversity. All Vent-PM samples included ultrafine PM capable of reaching the alveoli. Strikingly, >70% of Vent-PM samples were contaminated, mostly by viruses (>15%) or multidrug-resistant and biofilm-producing bacterial strains (60% and 48% of all bacteria-contaminated specimens, respectively). Total viable count at 1 m from the ventilation grilles was significantly increased after opening doors and windows, indicating an association between air flow and bacterial contamination. Both chemical and microbial compositions of Vent-PM considerably differed across surgical vs. non-surgical and intensive vs. elective care units and between health facilities located in coal and chemical districts. Reduced diversity among MDRO and increased prevalence ratio in multidrug-resistant to the total Enterococcus spp. in Vent-PM testified to the evolving antibiotic resistance. In conclusion, we suggest Vent-PM as a previously underestimated reservoir of HCAI-causing pathogens in the hospital environment.
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Hastings, R. H., and F. L. Powell. "High-frequency ventilation of ducks and geese." Journal of Applied Physiology 63, no. 1 (July 1, 1987): 413–17. http://dx.doi.org/10.1152/jappl.1987.63.1.413.
Full textAbstract:
We studied gas exchange in anesthetized ducks and geese artificially ventilated at normal tidal volumes (VT) and respiratory frequencies (fR) with a Harvard respirator (control ventilation, CV) or at low VT-high fR using an oscillating pump across a bias flow with mean airway opening pressure regulated at 0 cmH2O (high-frequency ventilation, HFV). VT was normalized to anatomic plus instrument dead space (VT/VD) for analysis. Arterial PCO2 was maintained at or below CV levels by HFV with VT/VD less than 0.5 and fR = 9 and 12 s-1 but not at fR = 6 s-1. For 0.4 less than or equal to VT/VD less than or equal to 0.85 and 3 s-1. less than or equal to fR less than or equal to 12 s-1, increased VT/VD was twice as effective as increased fR at decreasing arterial PCO2, consistent with oscillatory dispersion in a branching network being an important gas transport mechanism in birds on HFV. Ventilation of proximal exchange units with fresh gas due to laminar flow is not the necessary mechanism supporting gas exchange in HFV, since exchange could be maintained with VT/VD less than 0.5. Interclavicular and posterior thoracic air sac ventilation measured by helium washout did not change as much as expired minute ventilation during HFV. PCO2 was equal in both air sacs during HFV. These results could be explained by alterations in aerodynamic valving and flow patterns with HFV. Ventilation-perfusion distributions measured by the multiple inert gas elimination technique show increased inhomogeneity with HFV. Elimination of soluble gases was also enhanced in HFV as reported for mammals.(ABSTRACT TRUNCATED AT 250 WORDS)