Ventilation Door Research Articles

Numerical analysis of the effect of ventilation door on the propagation characteristics of gas explosion shock waves

Ventilation door are commonly found in tunnels and other underground engineering ventilation structures, disaster periods using its explosion isolation, explosion relief, wind regulation characteristics for disaster prevention and mitigation is of great significance. This paper numerically simulates the propagation characteristics of the gas explosion shock wave in the nearby tunnel when the ventilation door are opened at different degrees, and analyzes the influence mechanism of the opening degree on the change law of the shock wave overpressure distribution in the nearby tunnel. The results show that the shock wave forms a strong turbulence area (high pressure area) on both sides in front of the ventilation door, and the area range and the overpressure value decrease with the increase of the opening degree; the ventilation door reduce the intensity of the shock wave, so that the overpressure behind the ventilation door decreases, and the smaller the opening degree, the lower the overpressure behind the ventilation door. The secondary explosion formed shock wave and the ventilation door reflected shock wave meet to form a stronger shock wave, which leads to different opening degrees of ventilation door, its before, after the roadway and after the bifurcation of the main roadway in the measured points of the overpressure change curve is different, the main difference is that the peak overpressure for the first wave or the second wave peak. The peak overpressure in the tunnel before and after the ventilation door decreases and increases respectively with the increase of the opening length, and the overall decay of the peak overpressure at 5 m and 10 m before the ventilation door is 49.56% and 4.04% respectively and only has an effect on the peak overpressure in main tunnel within 20 m from the bifurcation.

Research on General Structure of Double Returns Vertical Wind Tunnel

Vertical wind tunnels play very important role in parachute training, helicopter rotor test, flight experience and other aspects, among which the double returns vertical wind tunnel has spread widely due to its low lose and low running cost. By using innovative structure design and finite element method, the general layout, research on design of supports and important sections are completed. The design part mainly describes glass flight section, integrated fan section, wind speed adjust device, ventilation door and the whole raft foundation structure. The dynamic debugging results show that the double return vertical wind tunnel has rational design, little vibration and high efficiency.

CONSTRUCTION METHOD OF ABILA PRECAST CONCRETE FOR HOUSING

The purpose of this research is to arrange the stages of implementation of the ABILA precast concrete construction method to be applied to housing construction so that it can be used as a reference for future development. While the purpose of this research is to arrange the stages of housing construction with ABILA precast panels starting from the precast concrete production stage, transportation or mobilization of materials to the installation process and final completion. Precast concrete can speed up processing time, save costs, and minimize waste for formwork and scaffolding. In the world of construction, any waste of construction material must be reduced or even eliminated. The application of Precast Concrete is very easy, considering its plug and play nature. Besides being easy, precast concrete has quite a lot of applications, especially the Abila Panel which has a function as a building structure, it can also be used as fences, floors and drainage channels. The level of the implementation method for the development of precast concrete technology is divided into several levels between prefabrication, preassembly, and module. The implementation method of building a house with ABILA precast concrete takes 14 days in the field, starting from panel installation to finishing. The construction method includes prefabrication in the workshop, mobilization of panels to the job site, assembly of structural elements, installation of brick walls, installation of roof structures and roof coverings, electrical and mechanical floor work, installation of ventilation doors and windows and paint finishing.

CONSTRUCTION METHOD OF ABILA PRECAST CONCRETE FOR HOUSING

The purpose of this research is to arrange the stages of implementation of the ABILA precast concrete construction method to be applied to housing construction so that it can be used as a reference for future development. While the purpose of this research is to arrange the stages of housing construction with ABILA precast panels starting from the precast concrete production stage, transportation or mobilization of materials to the installation process and final completion. Precast concrete can speed up processing time, save costs, and minimize waste for formwork and scaffolding. In the world of construction, any waste of construction material must be reduced or even eliminated. The application of Precast Concrete is very easy, considering its plug and play nature. Besides being easy, precast concrete has quite a lot of applications, especially the Abila Panel which has a function as a building structure, it can also be used as fences, floors and drainage channels. The level of the implementation method for the development of precast concrete technology is divided into several levels between prefabrication, preassembly, and module. The implementation method of building a house with ABILA precast concrete takes 14 days in the field, starting from panel installation to finishing. The construction method includes prefabrication in the workshop, mobilization of panels to the job site, assembly of structural elements, installation of brick walls, installation of roof structures and roof coverings, electrical and mechanical floor work, installation of ventilation doors and windows and paint finishing.

Automated ventilation control in mines. Challenges, state of the art, areas for improvement

The article is divided into three main parts. The first part provides an overview of the existing literature on theoretical methods for calculating the optimal air distribution in mines according to the criteria of energy efficiency and providing all sections of mines with the required amount of air. It is shown that by the current moment there are many different formulations of the problem of searching the optimal air distribution, many different approaches and methods for optimizing air distribution have been developed. The case of a single (main) fan is most fully investigated, while for many fans a number of issues still remain unresolved.
 The second part is devoted to the review of existing methods and examples of the automated mine ventilation control systems implementation in Russia and abroad. Two of the most well-known concepts for the development of such systems are automated ventilation control systems (AVCS) in Russia and the CIS countries and Ventilation on demand (VOD) abroad. The main strategies of ventilation management in the framework of the AVCS and VOD concepts are described and also the key differences between them are shown. One of the key differences between AVCS and VOD today is the automatic determination of the operation parameters of fan units and ventilation doors using the optimal control algorithm, which is an integral part of the AVCS.
 The third part of the article describes the optimal control algorithm developed by the team of the Mining Institute of the Ural Branch of the Russian Academy of Sciences with the participation of the authors of the article. In this algorithm, the search for optimal air distribution is carried out by the system in a fully automated mode in real time using algorithms programmed into the microcontrollers of fans and ventilation doors. Minimization of energy consumption is achieved due to the most efficient selection of the fan speed and the rate of ventilation doors opening and also due to the air distribution shift control and the partial air recirculation systems introduction.
 It is noted that currently the available literature poorly covers the issue related to emergency operation modes ventilation systems of mines and also with the adaptation of automated control systems to different mining methods. According to the authors, further development of automated ventilation control systems should be carried out, in particular, in these two areas.

Numerical Simulation on Destruction Process of Ventilation Door by Gas Explosion

Abstract After gas explosion in an underground space such as a coal mine and tunnel, the shock wave and flame wave will destroy the ventilation structures, the destruction of ventilation door may lead to failure of ventilation function of the underground ventilation system. Therefore, this study used ANSYS (LS-DYNA) software to establish the mathematical and physical model of the ventilation door impacted by gas explosion, the destruction was numerically simulated from the displacement (displacement nephogram and displacement-time-history curve), equivalent stress (equivalent stress nephogram and stress-time-history curve of the ventilation door) and equivalent strain of the ventilation doors with five kinds of different thicknesses. The results showed that the displacement of the unit body on the ventilation door increases with the action time, and the displacement curve is exponential. The displacement nephogram increases gradually from the edge to the center, and develops symmetrically; the displacement nephogram in central region decreases gradually. Finally, nephograms with some regular shape appear. The stress of the whole ventilation door increases with the action time. The larger stress region extends to the central region, the stress near the edge is the largest; the strain increases with time. The stress on the unit body first increases and then decreases, finally, the stress on the unit body basically approaches a steady value. When the impact pressure is constant and thickness of the ventilation door is little, the ventilation door can be instantaneously destroyed, but the deformation is smaller. However, as the thickness of the ventilation door increases, the impact pressure does not destroy the ventilation door, but the deformation of the unit body is large. The stress of the unit body of the ventilation door decreases first, then increases, finally, stress decreases. The research results can guide the material selection and structure improvement of the ventilation door.

The Study Natural Ventilation by Using Buildings Windows: Case Study in a Hot Dry Climate, Ghardaïa, Algeria

Natural ventilation in buildings can create a comfortable and healthy indoor environment, and save energy used in the mechanical ventilation systems, have an important role on the balance between heating and cooling needs, It is also necessary to study the possible combinations with natural resources.With natural ventilation the internal building structure is cooled through open windows and/or air vents, in order to provide a wind induced flow or stack effect. It is dependent on natural forces to move air through a building: so the disadvantage is that there is no direct control of the ventilation, but on the other hand it delivers low running costs and low energy usage by reducing the electrical energy used for air-conditioning.The building design must implement simple principles based on common sense and have proven their effectiveness in traditional constructions. It must be adapted to seasonal needs (warm in winter, cool in summer) and promote maximum passive solar gain and minimize lossesIn the first part of this article, the building geometry, its operation and the thermo-aerodynamics numerical model are developed under the TRNSYS-CONTAM environment are presented. In the second part, the simulation is performed for both cases; with ventilation natural night and without natural ventilation. The study will ensure the night ventilation door and window of the cell which are open from 20 pm until 8 am.

METHOD FOR IMPROVING THE MANAGEMENT OF MINE VENTILATION NETWORKS AFTER AN EXPLOSION

During the development of an underground explosion phenomenon, due to the energy of dynamic wave, important mechanical effects are registered both in the affected mine workings and in ventilation constructions (stoppings and seals, ventilation doors, regulators and air crossings). An explosion directly affects the ventilation network by modifying specific operational parameters of the main fans. This creates a different natural post event repartition of the air flows, at the branch level. In order to ensure safety conditions after the event, it is necessary to restore the ventilation network. This complex process is based on critical pathways, for whose identification were first established ventilation constructions in relation with their emergency level. This paper presents the process for restoring a mining ventilation network affected by an explosion, following the determination of critical pathways, through successive steps for restoring the ventilation in circuits affected by the wave front. For presenting these steps and for highlighting obtained results, a case study was conducted, based on a hypothetical, medium intensity explosion scenario, produced in the underground of Uricani coal mine, a mining unit in the Jiu Valley carboniferous basin, Romania, using 3D CANVENT specialized software for modeling, simulating and solving ventilation networks.

通風ドアに用いるアレイ状の枝管消音器に関する研究（直線的に拡大する形状の枝管による減音特性の改善）

通風ドアに用いるアレイ状の枝管消音器に関する研究（直線的に拡大する形状の枝管による減音特性の改善）

Analysis of the effect of different absorber materials and loading on the shielding effectiveness of a metallic enclosure

Abstract. Metallic rooms as part of a complex system, like a ship, are necessarily connected electromagnetically via apertures and cables to the outside. Therefore, their electromagnetic shielding effectiveness (SE) is limited by ventilation openings, cable feed-throughs and door gaps. Thus, electronic equipment inside these rooms is susceptible to outer electromagnetic threats like IEM (Intentional Electromagnetic Interference). Dielectric or magnetic absorber inside such a screened room can be used in order to prevent the SE from collapsing at the resonant frequencies. In this contribution, the effect of different available absorber materials is compared, as well as other properties like weight and workability. Furthermore, parameter variations of the absorber as well as the effect of loading in form of metallic and dielectric structures on the SE are analyzed.

Data Acquisition and Remote Control Systems in Coal Mines: A Serbian Experience

The paper presents the development and application of measurement and control devices and control information systems in coal mines with underground exploitation. The locations of units for measuring the concentration of methane, carbon monoxide and oxygen; the control of short circuits on ventilation doors; the control of main fan depression and the airflow speed are proposed. As a result of the research, the structure of control information system in Senje mine and ergonomic analysis of measurement and control devices in this mine are presented. Further modes of development of control information systems in underground mines in Serbia and solutions for their reconstruction are proposed.

Study of arrayed side branch silencer for ventilation door (Theoretical analysis and measurement of transmission loss)

This study focuses on acoustic silencers on indoor-use doors positioned in an array. In this paper, we discuss our studies of side branch silencers which are built in the ventilation door. By designing and fabricating a special attachment, we were able to attach silencers to the measurement tube that had larger cross sections than the impedance measurement tube. Using this attachment, we measured acoustic transmission losses for each of six different prototype silencers. By adding orifice silencer effects, we obtained transmission losses across a wide frequency range. However, attenuation decreased in frequency ranges below the attenuation peak of the side branch tubes. A wedge-shaped longitudinal cross section for the side branch tubes can double the length of the silencer and develop lower-frequency attenuation effects, while maintaining the same volume. This wedge-shaped side branch tube is suitable for a long silencer placed side by side in an array formation. We performed theoretical analyses of acoustic transmission losses of silencers using the transfer matrix method based on a one-dimensional wave equation. We performed element decomposition on the transfer matrix for silencers with side branch tubes with a wedge-shaped longitudinal cross section. We obtained calculated results that were sufficiently valid compared to our experimental measurements.

Simulation of Char Dust Combustion Inside a Pyroscrubber Downstream of a Petroleum Coke Calcining Kiln

A pyroscrubber is a furnace used in the petroleum coke calcining industry to recover energy from the carbonaceous contents, including char dust and hydrocarbon volatiles of the exhaust gas from the calcination kiln. The combusted hot gases are used to generate steam and produce electricity, so it is important to optimize the pyroscrubber performance to produce high-grade combusted gases to generate steam but with minimal emissions. A previous study employed the locally-homogeneous flow (LHF) model to study the means to improve combustion efficiency and reduce emissions. In the LHF model, the interphase exchange rates of mass, momentum and energy are assumed to be infinitely fast, so the dispersed phase (char dust) can be simplified as the gas phase, and the complex two-phase flow is then treated as a single-phase flow. In this study, LHF model is replaced with a solid particle combustion model by incorporating both finite-rate heterogeneous and homogeneous combustion processes. Results reveal that the particle combustion model generates much higher local flame temperature (2200 K) than in LHF model (1800 K). All char particles are burned before or in the high-bay area. Total energy output of the case with particle combustion model is 92% of the LHF model. Furthermore, motivated by the potential energy saving from removing the air blower power supply, this study further investigates the possible benefit of running the pyroscrubber with the ventilation doors open. Three cases with different combinations of air injections and door opening have been studied. Results show that the gas flow is stably stratified with a large amount of the entrained cold air moving at the bottom of the chamber and the hot combusted gas moving through the top. With the bottom doors completely open, sufficient air can be drawn into the pyroscrubber without the need of blowing air in, but the combustion gases will be overcooled making this practice unfavorable from the energy saving point of view.

Analysis of mine’s air leakage based on pressure gradient matrix between nodes

Air leakage may significantly affect the effectiveness of mine ventilation by increasing the cost of ventilation and arousing problems for ventilation management. Furthermore, air leakage may accelerate the process of coal spontaneous combustion and cause gas explosion, thus greatly threatens the safety of coal production. The estimation of air leakage, therefore, have great practical significance. For any ventilation system of coal mines, there is a defined pattern of pressure gradient which drived the mine air to flow in the network, drives possible air leakage to go shortcut as well. Air leakage may occur through ventilation structures such as ventilation doors and fractures of the surroundig coal and rock of airways. A concept and the relevent calculation method of the pressure gradient matrix was put forward to assist the analysis of potential air leakage routes. A simplified example was used to introduce the application principle of pressure gradient matrix in identifying all the potential air leaking routes, which offers a deeper understanding over the ventilation system and the prevention of coal spontaneous combustion.

Controlled recirculation in Canadian underground potash mines

Increasing energy costs and the need to conserve energy compounded with low mineral prices have prompted some Canadian mines to examine their energy-consuming operations and identify potential energy saving methods. Reusing or recirculating a fraction of ventilating airflow may make it possible for these mines to reduce heating costs. Such a study was conducted at Rocanville Division of Potash Corporation of Saskatchewan to determine the feasibility of controlled recirculation for reducing winter heating costs by reducing the intake airflows. This study was divided into two parts: the first involved taking measurements of mine contaminants in the return and intake airways, the second was monitoring air quality during a recirculation trial. Recirculation of air was created by opening an existing ventilation door located between the return and intake airways. Two shifts were continuously monitored in the return airways and the local recirculation experiment was carried out for five hours while a continuous miner was cutting. With the recirculation system in operation, a slight increase in temperature (1.00°C) was recorded between the intake and mixed intake. The overall quality of the exhaust air was found to be unchanged within the measurement limits despite the high percentage recirculation. A 5% increase in dustiness in the mixed intake was recorded. The results obtained from these studies indicate that controlled recirculation of return air is feasible. Some of the results from this work are illustrated and discussed.

Infiltration of Roof Exhaust Gases into Aluminum Potrooms

Atmospheric tracer techniques were used in 21 tests to determine infiltration rates of roof exhaust gases in downwind potrooms at an aluminum reduction plant during two summer months. During each tracer test SF6 and, in some cases, CBrF3 were released to simulate the exhaust gases, and tracer concentrations were measured along the ventilation doors of downwind rooms. Maximum infiltration rates were less than 5 % of the tracer release rate. The location of the maximum infiltration occurred along the upwind side of the first downwind room in two thirds of the cases and along the downwind edge of the same room where tracer was released in one third of the tests. For rooms further downwind the infiltration rate was less than 1%.