CFD modeling of air flow, humidity, CO2 and NH3 distributions in a caged laying hen house with tunnel ventilation system

2022 ◽  
Vol 193 ◽  
pp. 106677
Author(s):  
Keyvan Ahmadi Babadi ◽  
Hossein Khorasanizadeh ◽  
Alireza Aghaei
Keyword(s):  
Air Flow ◽  
Ventilation System ◽  
Laying Hen ◽  
Cfd Modeling ◽  
Tunnel Ventilation

scholarly journals Active Disturbance Rejection Control of a Longitudinal Tunnel Ventilation System

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1871
Author(s):  
Liyun Si ◽  
Wenping Cao ◽  
Xiangping Chen
Keyword(s):  
Flow Rate ◽  
Disturbance Rejection ◽  
Air Flow ◽  
Ventilation System ◽  
Active Disturbance Rejection Control ◽  
Air Flow Rate ◽  
Long Distance ◽  
Tunnel Ventilation ◽  
Active Disturbance Rejection ◽  
Disturbance Rejection Control

This paper proposes an innovative approach for controlling pollutant release in a long-distance tunnel via longitudinal ventilation. Enhanced by an active disturbance rejection control (ADRC) method, a ventilation controller is developed to regulate the forced air ventilation in a road tunnel. As a result, the pollutants (particulate matter and carbon monoxide) are reduced by actively regulating the air flow rate through the tunnel. The key contribution of this study lies in the development of an extended state observer that can track the system disturbance and provide the system with compensation via a nonlinear state feedback controller equipped by the ADRC. The proposed method enhances the disturbance attenuation capability in the ventilation system and keeps the pollutant concentration within the legitimate limit in the tunnel. In addition to providing a safe and clean environment for passengers, the improved tunnel ventilation can also achieve better energy saving as the air flow rate is optimized.

A New Advance in Tunnel Ventilation Design Planning

2017 ◽  
Author(s):  
Mark P. Colino ◽  
Elena B. Rosenstein
Keyword(s):  
Ventilation System ◽  
National Fire Protection Association ◽  
Capital Cost ◽  
Smooth Transition ◽  
Mechanical Equipment ◽  
Tunnel Ventilation ◽  
Tunnel Fire ◽  
Ventilation Shaft ◽  
Emergency Ventilation ◽  
Ventilation Fan

The new train signaling, traction power and tunnel ventilation system coordination guidelines enacted in National Fire Protection Association (NFPA) Standard 130 have brought the necessity and cost of tunnel ventilation fan shafts into greater focus. The guidelines were aimed at coordinating the three aforementioned rail systems to control the number of trains that could be between successive ventilation shafts during an emergency — in recognition of the fact that the best protection to both incident and non-incident train passengers and crew is to allow no more than one train in each ventilation zone. Though based in safety, these new NFPA guidelines can substantially expand the capital cost and environmental impact of new rail tunnel projects by adding more ventilation shafts and tunnel fan equipment to the scope of work. In addition, the resulting increase in the required number of ventilation shafts and tunnel fan equipment can hinder existing railroad properties as they seek to either increase their train throughput rates, or reduce their tunnel electrical infrastructure. Fortunately, a new kind of emergency ventilation shaft has been developed to facilitate compliance with the NFPA 130 Standard without the excessive capital cost and far-reaching environmental impacts of a traditional emergency ventilation shaft. This new kind of emergency ventilation shaft is called the Crossflue. The Crossflue is a horizontal passage between parallel rail tunnels with a single ventilation fan-motor unit installation. The Crossflue fan is designed to transfer air/smoke flows from one (occupied, incident) tunnel to another (unoccupied, non-incident) tunnel — thereby protecting the incident tunnel at the expense of the non-incident tunnel. The Crossflue passage has angled construction to allow a smooth transition of airflows both into and out of the adjoining tunnels. In addition to the fan, the Crossflue contains a ventilation damper, sound attenuators, ductwork transitions and flexible connectors within the fan equipment line-up; the functionality of all this mechanical equipment is described in the paper. To preserve underground space and minimize the rock excavation, the Crossflue fan is both remotely-powered and remotely-controlled; the fan is only operated as part of a pre-programmed response to tunnel fire events. The methodology utilized to design the Crossflue was taken from the Subway Environmental Design Handbook (SEDH); the SEDH [1] was specifically developed for rail tunnel ventilation design and is the preeminent reference volume in the industry. In summary, the Crossflue provides a dual benefit of achieving NFPA 130 compliance, while at the same time minimizing the construction, equipment, environmental, and energy costs of a traditional tunnel ventilation shaft.

Rack Level Modeling of Air Flow Through Perforated Tile in a Data Center

2012 ◽  
Author(s):  
Vaibhav K. Arghode ◽  
Pramod Kumar ◽  
Yogendra Joshi ◽  
Thomas S. Weiss ◽  
Gary Meyer
Keyword(s):  
Data Center ◽  
Body Force ◽  
Air Flow ◽  
The Body ◽  
Physical Models ◽  
Cfd Modeling ◽  
Computational Time ◽  
Force Model ◽  
Flow Through ◽  
Tile Surface

Effective air flow distribution through perforated tiles is required to efficiently cool servers in a raised floor data center. We present detailed computational fluid dynamics (CFD) modeling of air flow through a perforated tile and its entrance to the adjacent server rack. The realistic geometrical details of the perforated tile, as well as of the rack are included in the model. Generally models for air flow through perforated tiles specify a step pressure loss across the tile surface, or porous jump model based on the tile porosity. An improvement to this includes a momentum source specification above the tile to simulate the acceleration of the air flow through the pores, or body force model. In both of these models geometrical details of tile such as pore locations and shapes are not included. More details increase the grid size as well as the computational time. However, the grid refinement can be controlled to achieve balance between the accuracy and computational time. We compared the results from CFD using geometrical resolution with the porous jump and body force model solution as well as with the measured flow field using Particle Image Velocimetry (PIV) experiments. We observe that including tile geometrical details gives better results as compared to elimination of tile geometrical details and specifying physical models across and above the tile surface. A modification to the body force model is also suggested and improved results were achieved.

scholarly journals Three-Dimensional Simulation of Wind-Driven Ventilation Through a Windcatcher With Different Inlet Designs

2019 ◽  
Vol 12 (4) ◽  
Author(s):  
Peter Abdo ◽  
Rahil Taghipour ◽  
B. Phuoc Huynh
Keyword(s):  
Wind Speed ◽  
Average Velocity ◽  
Natural Ventilation ◽  
Ventilation System ◽  
Three Dimensional ◽  
Cfd Modeling ◽  
Ansys Fluent ◽  
Wind Velocities ◽  
Dimensional Simulation ◽  
Convergent Inlet

Abstract Windcatcher is an effective natural ventilation system, and its performance depends on several factors including wind speed and wind direction. It provides a comfortable and healthy indoor environment since the introduced fresh air decreases the moisture content and reduces the pollutant concentration. Since the wind speed and its direction are generally unpredictable, it is important to use special inlet forms and exits to increase the efficiency of a windcatcher. In this study, computational fluid dynamics (CFD) modeling is implemented using ansys fluent to investigate the airflow entering a three-dimensional room through a windcatcher with different inlet designs. Three designs are studied which are a uniform inlet, a divergent inlet, and a bulging-convergent inlet. The airflow pattern with all inlets provided adequate ventilation through the room. With all the applied wind velocities (1, 2, 3, and 6 m/s) at the domain's inlet, the divergent inlet shape has captured the highest airflow through the room and provided higher average velocity at 1.2 m high enhancing the thermal comfort where most of the human occupancy occurs. With 6 m/s wind velocity, the divergent inlet has captured 2.55% more flow rate compared to the uniform inlet and 4.70% compared to the bulging-convergent inlet, and it has also provided an average velocity at 1.2 m high in the room of 7.16% higher than the uniform inlet and 8.44% higher than the bulging-convergent inlet.

Air Flow Straighteners’ Application to Reduce the Power Consumption of Exhaust Ventilation Schemes

2018 ◽  
Vol 875 ◽  
pp. 137-140 ◽  
Author(s):  
Valery N. Azarov ◽  
Natalia M. Sergina ◽  
I.V. Stefanenko
Keyword(s):  
Power Consumption ◽  
Air Flow ◽  
Ventilation System ◽  
Aerodynamic Resistance ◽  
Experimental Studies ◽  
Swirling Flows ◽  
Dust Collector ◽  
Exhaust Ventilation ◽  
Outlet Pipe ◽  
Ventilation Systems

It was proposed to use air flow screw straightened units in outlet pipe of the dust collectors to reduce the aerodynamic resistance of exhaust ventilation systems. It is allowed to decrease power consumption for their maintenance operation consequently. The article describes the results of experimental studies to evaluate its effectiveness by applying the tangential screw straightened unit within ventilation system. The obtained results showed that the use of this device allows reducing the aerodynamic resistance of the cyclone by 14.6%, and for counter-swirling flows’ dust collector (CSFC) by 17.2-23.6%. It was found that meanings of the aerodynamic resistance depend on value the share proportion of the flow entering into lower CSFC apparatus’ input.

Analysis of a new strategy for emergency ventilation and escape scenario in long railway tunnels in the fire mode

2018 ◽  
Vol 233 (3) ◽  
pp. 239-250 ◽  
Author(s):  
Behtash Hakimzadeh ◽  
Mohammad Reza Talaee
Keyword(s):  
Ventilation System ◽  
Control Panel ◽  
Fire Dynamics ◽  
Railway Tunnel ◽  
Rescue Operation ◽  
Tunnel Ventilation ◽  
Precise Control ◽  
Ventilation Shaft ◽  
Emergency Ventilation ◽  
Safe Path

The creation of a safe path for evacuating passengers from a tunnel during fire accidents is an important function of a mechanical ventilation system in tunnels. In this work, the operation of emergency ventilation in the fire mode in a long railway tunnel with push–pull ventilation shafts is analyzed using a fire dynamics simulator. As the passenger trains are lengthy – and so is a tunnel – when trains pass through a tunnel, the position of fire on the train becomes an important parameter for rescuing the passengers through a safe path. The novelty of this study is in the design of emergency ventilation scenarios that consider the position of fire on the train in addition to the tunnel ventilation shafts. For this case study, a lengthy (8 km) urban railway tunnel in Tehran with four rail tracks and eight ventilation shafts is considered for designing emergency ventilation scenarios and control of fire products. The fire source is a passenger train wagon with a 25-MW heat release rate. It is shown that, during the rescue operation of the passengers, the location of fire on the train may lead to reverse the ventilation scenario compared with the traditional ones that use only the tunnel shafts. Also, it is observed that there is a region with 50 m radius around each ventilation shaft, i.e. the absolute exhaust zone, where the ventilation system must be set at the exhaust mode due to the presence of fire, to minimize the spreading of fire products downstream. All the logical scenarios of the tunnel ventilation system are designed and demonstrated to create a critical ventilation velocity in the tunnel, which would help in developing a more precise control panel of the tunnel in the fire mode.

Three Dimensional Simulation of Ventilation Flow Through a Solar Windcatcher

2019 ◽  
Author(s):  
Peter Abdo ◽  
Rahil Taghipour ◽  
B. P. Huynh
Keyword(s):  
Natural Ventilation ◽  
Air Flow ◽  
Ventilation System ◽  
Three Dimensional ◽  
Windward Side ◽  
Efficient Design ◽  
Indoor Space ◽  
Wind Speeds ◽  
Air Stream ◽  
Stack Ventilation

Abstract Natural ventilation is the process of supplying and removing air through an indoor space by natural means. There are two types of natural ventilation occurring in buildings: winddriven ventilation and buoyancy driven or stack ventilation. The most efficient design for natural ventilation in buildings should implement both types of natural ventilation. Stack ventilation which is temperature induced is driven by buoyancy making it less dependent on wind and its direction. Heat emitted causes a temperature difference between two adjoining volumes of air, the warmer air will have lower density and be more buoyant thus will rise above the cold air creating an upward air stream. Combining the wind driven and the buoyancy driven ventilation will be investigated in this study through the use of a windcatcher natural ventilation system. Stack driven air rises as it leaves the windcatcher and it is replaced with fresh air from outside as it enters through the positively pressured windward side. To achieve this, CFD (computational fluid dynamics) tool is used to simulate the air flow in a three dimensional room fitted with a windcatcher based on the winddriven ventilation alone, buoyancy driven ventilation alone, and combined buoyancy and winddriven ventilation. Different wind speeds between 0 up to 2.5 m/s are applied and the total air flow rate through the windcatcher is investigated with and without temperature of 350 K applied at the windcatcher’s outlet wall. As the wind speed increased the efficiency of the solar windcatcher decreased.

Application of Fuzzy Mathematics in Selection Air Flow Regulating Program

2013 ◽  
Vol 423-426 ◽  
pp. 2291-2296
Author(s):  
Wei Wei Ye ◽  
Xian Ping Xie ◽  
Meng Wei Han ◽  
Shi Yun Luo ◽  
Zhen Li ◽  
...  
Keyword(s):  
Air Flow ◽  
Ventilation System ◽  
Mine Ventilation ◽  
Practical Significance ◽  
Ventilation Network ◽  
The North ◽  
Regulation Scheme ◽  
Controlling System ◽  
North Part ◽  
Optimal Tree

Selecting the optimal air regulation scheme of mine ventilation network, the essence is to choose the network a most optimal tree and obtain the corresponding optimal cosine tree combination program.Due to a synthetic consideration of the influence of production.Management economy and other aspects on the tree selection,the air flow regulating and controlling system made by the authors is optimum It is satisfactory to use the model for the north part ventilation system of Laochang tin mine of Yunnan tin Industrial crop. It is of practical significance to combine organically air flow regulating and controlling system with mine ventilation system.

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