scholarly journals Use of Air Infiltration in Swine Housing Ventilation System Design

2019 ◽  
Vol 35 (3) ◽  
pp. 325-338
Author(s):  
H T Jadhav ◽  
S J Hoff
Keyword(s):  
Ventilation System ◽  
Three Dimensional ◽  
Design Procedure ◽  
Field Testing ◽  
Air Distribution ◽  
Air Jets ◽  
Air Infiltration ◽  
Air Jet ◽  
Archimedes Number ◽  
Ventilation Systems

Abstract.The objective of this research was to develop and analyze the procedure for using recent air infiltration (AI) data collected from commercial swine finishing rooms (SFRs) in the design of negative pressure mechanical ventilation systems (VSs). Air infiltration is an integral part of any ventilation process. Infiltration reduces the pressure differential across planned inlets and at very low pressure differences, cold air jets may drop directly on the animals causing significant discomfort. In this article, a design procedure is proposed for swine housing ventilation systems with the influence of air infiltration included. The method was used on one SFR for which air infiltration data was collected by in-field testing. The air-jet throw, jet momentum number, a newly developed coverage factor, and Archimedes number were used to assess the influence of infiltration on predicted air-jet and fresh-air distribution and to help guide the design of planned inlets in SFR VSs with known infiltration. The analysis completed quantifies the severity of AI on air-jet and air distribution performance, and suggests that for the analysis room to ventilate properly requires a 50% reduction in AI levels beyond field measured curtain and fan infiltration. The analysis completed suggests a method for systematically planning three-dimensional ceiling inlet placement and operation and provides design guidance for new ceiling inlets suitable for SFR VSs. Keywords: Air distribution, Air-jets, Archimedes number, Infiltration, Jet Momentum Number.

scholarly journals Enhancing of energetic and economic efficiency of air distribution by swirled-compact air jets

2021 ◽  
Vol 27 (3) ◽  
pp. 171-175
Author(s):  
Vasyl Zhelykh ◽  
Orest Voznyak ◽  
Yuriy Yurkevych ◽  
Iryna Sukholova ◽  
Oleksandr Dovbush
Keyword(s):  
Indoor Air ◽  
Ventilation System ◽  
Air Distribution ◽  
Energy Audit ◽  
Indoor Climate ◽  
Air Jets ◽  
Air Jet ◽  
Urgent Task ◽  
Exhaust Heat ◽  
System Reconstruction

Abstract The article is devoted to solving the urgent task of increasing the efficiency of air distribution by swirled-compact air jets to ensure the normative parameters of indoor air. The dynamic parameters of the swirled-compact air jet during its leakage in the alternating mode and the formation of a dynamic indoor climate in the room are determined. For improvement of comfortable conditions in the room and design of energy saving circuits of air distribution it is suggested to use swirled-compact air jets, which flow from the inflow and exhaust heat recuperators with heat recovery of the exhaust air. An energy audit of the ventilation system reconstruction with a recuperator using was carried out. The method of taking into account the fact of application of several measures, which cannot be carried out simultaneously, and discount rate dynamics is proposed.

scholarly journals FEATURES OF VENTILATION SYSTEMS IN AUDITORIUM

2021 ◽  
Vol 9 (1) ◽  
pp. 11-15
Author(s):  
Dar'ya Abramkina ◽  
Gleb Petrov
Keyword(s):  
Indoor Air ◽  
Air Distribution ◽  
Thermal Mode ◽  
Air Velocity ◽  
Air Jets ◽  
Harmful Emissions ◽  
High Concentrations ◽  
Standard Calculation ◽  
Occupied Zone ◽  
Ventilation Systems

The choice of air distribution scheme is the most important task which determines indoor air quality, comfort thermal mode of the room and effectiveness of ventilation systems. The article presents comparative analysis of displacement and mixing ventilation systems for large premises. The methodology of the study is based on existing theoretical provisions and standard calculation approach of supply air jets. Multivariate calculations of mixing air distribution in cinema hall are presented. Horizontal jets along room surfaces can not provide required air velocity. In the case of vertical air distribution relative jet area beyond the recommended values. This factor had thus determined the possible formation of circulation contours with high concentrations of harmful emissions. The results of the calculation shows that the speed of the fan jet at the entrance of occupied zone lower than maximum permissible air mobility. The required temperature is achieved by using all air-distributing units considered.

scholarly journals Modelling of air flow supply in a room at variable regime by using both K - E and spalart – allmaras turbulent model

2017 ◽  
Vol 12 (2) ◽  
pp. 15-22
Author(s):  
Vadim Korbut ◽  
Orest Voznyak ◽  
Iryna Sukholova ◽  
Khrystyna Myroniuk
Keyword(s):  
Air Flow ◽  
Ventilation System ◽  
Air Distribution ◽  
Experimental Investigations ◽  
Human Organism ◽  
Ansys Fluent ◽  
Air Jets ◽  
Air Supply ◽  
Experimental Researches ◽  
Variable Regime

Abstract The abstract is to The article is devoted to the decision of actual task of air distribution efficiency increasing with the help of swirl and spread air jets to provide normative parameters of air in the production apartments. The mathematical model of air supply with swirl and spread air jets in that type of apartments is improved. It is shown that for reachin of air distribution maximal efficiency it is necessary to supply air by air jets, that intensively extinct before entering into a working area. Simulation of air flow performed with the help of CFD FLUENT (Ansys FLUENT). Сalculations of the equation by using one-parameter model of turbulence Spalart-Allmaras are presented. The graphical and the analytical dependences on the basis of the conducted experimental researches, which can be used in subsequent engineering calculations, are shown out. Dynamic parameters of air flow that is created due to swirl and spread air jets at their leakage at variable regime and creation of dynamic microclimate in a room has been determined. Results of experimental investigations of air supply into the room by air distribution device which creates swirl air jets for creation more intensive turbulization air flow in the room are presented. Obtained results of these investigations give possibility to realize engineer calculations of air distribution with swirl air jets. The results of theoretical researches of favourable influence of dynamic microclimate to the man are presented. When using dynamic microclimate, it’s possible to decrease conditioning and ventilation system expenses. Human organism reacts favourably on short lasting deviations from the rationed parameters of air environment.

Numerical Investigation of the Interaction between the Thermal and Dynamic Effects of Cross-Ventilation for a Generic Isolated Building

2021 ◽  
Vol 408 ◽  
pp. 141-153
Author(s):  
Abdelkrim Benlefki ◽  
Mohammed Hamel ◽  
Bendida Medjahed
Keyword(s):  
Numerical Investigation ◽  
Dynamic Behavior ◽  
Wall Temperature ◽  
Ventilation System ◽  
Three Dimensional ◽  
Its Region ◽  
Thermal Parameters ◽  
Heated Wall ◽  
Recirculation Flow ◽  
Air Jet

An efficient air ventilation requires knowledge of the complex interaction between the dynamic behavior and thermal parameters. For an isolated building the exact estimation of the interaction between the dynamics of cross-ventilation flow and a convective heat transfer, by overheating one of its internal walls, is an interest way to control the internal temperature’s distribution and the energy consumption of the ventilation system. The numerical simulation may provide an approximate solution to predict this kind of phenomenon. In this study, a numerical investigation of the thermal effect of a heated wall on a cross-ventilation for a generic isolated building with two parallel openings with a same dimension and at the same height is presented. The heat source is considered as solar radiation when it heats the exposed wall of the building. The wall temperature is assumed to be constant and homogeneous and it takes three values 25, 30 and 35°C. The highly three-dimensional flow is obtained by solving numerically the Reynolds averaged equations of mass, momentum and energy conservation for incompressible flow. The k-ω SST turbulent model is used to solve the turbulent quantities. The numerical results are validated by comparison of the horizontal component of velocity and the turbulent kinetic energy with the corresponding measurements. A detailed analysis of the interaction between the dynamic and thermal parameters is carried out and led to conclude that the distribution of the air temperature in the building is much influenced by the incoming fresh air jet. In its region the temperature difference between the air inside and outside the building is almost zero, however, below the jet region, characterized by air recirculation flow, the temperature takes its maximum value for the tree studies cases. Also, the thermal effects of air buoyancy may modify the dynamic behavior, especially at the building entrance, this modification is proportional to the wall temperature and it disappear after mid distance of the flow in the building.

Disorganization of a hole tone feedback loop by an axisymmetric obstacle on a downstream end plate

2014 ◽  
Vol 757 ◽  
pp. 908-942 ◽  
Author(s):  
K. Matsuura ◽  
M. Nakano
Keyword(s):  
Nozzle Exit ◽  
Passive Control ◽  
Control Method ◽  
Three Dimensional ◽  
Acoustic Power ◽  
Shear Layers ◽  
Mean Velocity ◽  
End Plate ◽  
Air Jet ◽  
Practical Engineering

AbstractThis study investigates the suppression of the sound produced when a jet, issued from a circular nozzle or hole in a plate, goes through a similar hole in a second plate. The sound, known as a hole tone, is encountered in many practical engineering situations. The mean velocity of the air jet $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}u_0$ was $6\text {--}12\ \mathrm{m}\ {\mathrm{s}}^{-1}$. The nozzle and the end plate hole both had a diameter of 51 mm, and the impingement length $L_{im}$ between the nozzle and the end plate was 50–90 mm. We propose a novel passive control method of suppressing the tone with an axisymmetric obstacle on the end plate. We find that the effect of the obstacle is well described by the combination ($W/L_{im}$, $h$) where $W$ is the distance from the edge of the end plate hole to the inner wall of the obstacle, and $h$ is the obstacle height. The tone is suppressed when backflows from the obstacle affect the jet shear layers near the nozzle exit. We do a direct sound computation for a typical case where the tone is successfully suppressed. Axisymmetric uniformity observed in the uncontrolled case is broken almost completely in the controlled case. The destruction is maintained by the process in which three-dimensional vortices in the jet shear layers convect downstream, interact with the obstacle and recursively disturb the jet flow from the nozzle exit. While regions near the edge of the end plate hole are responsible for producing the sound in the controlled case as well as in the uncontrolled case, acoustic power in the controlled case is much lower than in the uncontrolled case because of the disorganized state.

A Computational Analysis of Flow Field in Twin-Track Subway Tunnel to Improve Air Quality

2013 ◽  
Vol 319 ◽  
pp. 599-604
Author(s):  
Makhsuda Juraeva ◽  
Kyung Jin Ryu ◽  
Sang Hyun Jeong ◽  
Dong Joo Song
Keyword(s):  
Air Quality ◽  
Computational Model ◽  
Stokes Equations ◽  
Ventilation System ◽  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
Navier Stokes ◽  
Subway Tunnel ◽  
Air Supply ◽  
And Performance

A computational model of existing Seoul subway tunnelwas analyzed in this research. The computational model was comprised of one natural ventilationshaft, two mechanical ventilationshafts, one mechanical airsupply, a twin-track tunnel, and a train. Understanding the flow pattern of the train-induced airflow in the tunnel was necessary to improve ventilation performance. The research objective wasto improve the air quality in the tunnel by investigating train-induced airflow in the twin-track subway tunnel numerically. The numerical analysis characterized the aerodynamic behavior and performance of the ventilation system by solving three-dimensional turbulent Reynolds-averaged Navier-Stokes equations. ANSYS CFX software was used for the computations. The ventilation and aerodynamic characteristics in the tunnel were investigated by analyzing the mass flowrateat the exits of the ventilation mechanicalshafts. As the train passed the mechanical ventilation shafts, the amount of discharged-air in the ventilationshafts decreased rapidly. The air at the exits of the ventilation shafts was gradually recovered with time, after the train passed the ventilation shafts. The developed mechanical air-supply for discharging dusty air and supplying clean airwas investigated.The computational results showed that the developed mechanical air-supplycould improve the air quality in the tunnel.

Twin Pulsating Jets Impingement Heat Transfer for Fuel Preheating in Automotives

2014 ◽  
Vol 663 ◽  
pp. 322-328 ◽  
Author(s):  
Ali Ahmed Gitan ◽  
Rozli Zulkifli ◽  
Kamaruzaman Sopian ◽  
Shahrir Abdullah
Keyword(s):  
Heat Transfer ◽  
Ignition Process ◽  
Pulsation Frequency ◽  
Ir Camera ◽  
Copper Target ◽  
Air Jets ◽  
Air Jet ◽  
Impingement Heat Transfer ◽  
Pulsating Jet ◽  
Pulsating Jets

The problem of environmental pollution and depletion of fossil fuel can be reduced in automotives by using an alternative bio-fuel and improve the ignition process in engine. Both solutions need to use the fuel preheating technique. This work presents the idea of fuel preheating by using exhaust impingement on the fuel tank. Heat transfer between twin pulsating hot air jets and flat copper target was investigated as an application for preheating of automotive fuel to improve ignition process in the engine. The nozzle of 20 mm was used to produce air jet of Reynolds number, Re ≃ 5500 and a temperature of 54°C. The impinged target was imposed to still air surrounding at temperature of 24°C. Pulsating frequencies of 10-50 Hz were applied on air jets by using twin pulsating jet mechanism. The effect of pulsation frequency on heat transfer was measured using IR camera and heat flux-temperature micro foil sensor. The results obtained by both of these methods showed well agreement. Also, the results revealed significant influence of flow rate difference between steady and pulsating jet cases. In addition, the highest Nusselt number, Nu ≃ 7.2, was obtained at pulsation frequency of 20 Hz.

Multi-Objective Optimization of a Microturbine Compact Recuperator

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Diego Micheli ◽  
Valentino Pediroda ◽  
Stefano Pieri
Keyword(s):  
Heat Transfer ◽  
Three Dimensional ◽  
Numerical Procedure ◽  
Design Procedure ◽  
Domain Size ◽  
Multidisciplinary Optimization ◽  
Computational Domain ◽  
Surface Geometry ◽  
Multi Objective ◽  
Flux Boundary Conditions

An automatic approach for the multi-objective shape optimization of microgas turbine heat exchangers is presented. According to the concept of multidisciplinary optimization, the methodology integrates a CAD parametric model of the heat transfer surfaces, a three-dimensional meshing tool, and a CFD solver, all managed by a design optimization platform. The repetitive pattern of the surface geometry has been exploited to reduce the computational domain size, and the constant flux boundary conditions have been imposed to better suit the real operative conditions. A new approach that couples cold and warm fluids in a periodic unitary cell is introduced. The effectiveness of the numerical procedure was verified comparing the numerical results with available literature data. The optimization objectives are maximizing the heat transfer rate and minimizing both friction factor and heat transfer surface. The paper presents the results of the optimization of a 50kWMGT recuperator. The design procedure can be effectively extended and applied to any industrial heat exchanger application.

Fluid mechanical aspects of open- and closed-toe flue organ pipe voicing

2011 ◽  
Vol 2 (2) ◽  
pp. 284-295
Author(s):  
D. Steenbrugge
Keyword(s):  
Pressure Measurements ◽  
Jet Instability ◽  
Active Involvement ◽  
Air Jets ◽  
Air Jet ◽  
Hole Area ◽  
Power Regulation ◽  
Organ Pipes ◽  
Organ Pipe ◽  
Jet Characteristics

Open- and closed-toe voicing of flue organ pipes constitute two opposite extremes of possible ways todetermine the air-jet flow rate through the flue. The latter method offers more voicing control parametersand thus more flexibility, at the expense of a necessary pressure loss at the toe hole. Another differencebetween both cases arises from different air-jet characteristics, such as velocity profile, Re number, flowmomentum or aspect ratio, the latter influencing jet instability. Furthermore, for closed-toe voicing, the flowfield in the pipe foot is modified by an axisymmetric air jet created through the highly constricted toe hole.Velocity measurements on air jets, pressure measurements in the pipe foot are presented, compared anddiscussed for both voicing methods. The ratio of flue to toe hole area is shown to be the sole pipeparameter to entirely determine the jet velocity and can be useful to quantitatively characterize flue and toehole voicing. Open-toe voicing turns out to be the more delicate and low-pressure only method becauseany modification of the flue has consequences on all aspects of the pipe operation, whereas the closed-toemethod, in connection with higher pressures and with active involvement of cut-up adjustment, allows someseparation between sound timbre and power regulation.

scholarly journals Evaluation of litter material and ventilation systems in poultry production: III. litter reuse, darkling beetle populations and intestinal parasites

2011 ◽  
Vol 40 (6) ◽  
pp. 1372-1380
Author(s):  
Valéria Maria Nascimento Abreu ◽  
Doralice Pedroso de Paiva ◽  
Paulo Giovanni de Abreu ◽  
Arlei Coldebella
Keyword(s):  
Broiler Chickens ◽  
Intestinal Parasites ◽  
Organic Fertilizer ◽  
Ventilation System ◽  
Poultry Production ◽  
Rice Husks ◽  
Darkling Beetle ◽  
Eimeria Spp ◽  
Soybean Straw ◽  
Ventilation Systems

It was evaluated the quality of rice husks or soybean straw as litter substrate and the effect of litter reuse for four consecutive flocks of broiler chickens on populations of darkling beetle and intestinal parasite and as organic fertilizer. The experiment was carried out in four 12 m × 10 m poultry houses, internally divided in 4 boxes/poultry house with 200 birds/pen for four consecutive flocks, each flock with a duration of 42 days and with a 15-day downtime between flocks. The evaluated treatments were two ventilation systems (stationary or oscillating fans) and two litter materials (soybean straw or rice husks). Darkling beetle population was followed by collecting the insects in traps, three traps per box, and endoparasite litter contamination was determined by eggs/oocyst counts per gram of litter. Levels of dry matter, total nitrogen, total phosphorus, potassium, copper, zinc, manganese, iron, organic carbon and pH were evaluated by physical/chemical analyses of samples of the litters in each flock. Overall, litters of broilers used by three flocks meet the minimal legal requirements to be marketed as simple organic fertilizer, regardless to the material used as substrate. Soybean straw presented higher darkling beetle counts in stationary ventilation system as well as in oscillating ventilation system. The probability of rice husks litter present contamination by Eimeria spp oocysts is 18.78 times higher in rice husks than in soybean straw litter when both are submitted to oscillating ventilation, and 1.32 higher when stationary ventilation is used. Litter temperature does not influence significantly levels of contamination by oocysts.

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