Ventilation Fans Research Articles

Strategy of mine ventilation control in optimal mode using fuzzy logic controllers

The issues related to improving the efficiency of automatic ventilation control systems of mines that regulate the air supply to the mine in accordance with the need are considered. During the tests of such a system in the 3RU mine of OAO Belaruskali, the shortcomings of its existing, implementation, associated with the incorrect choice of the most difficult-to-ventilate direction, were revealed. The possibilities of implementing a control strategy, in which the system automatically determines the optimal configuration of the operating modes of fans and regulators, are demonstrated. As an alternative to the implemented algorithms, it is proposed to use a fuzzy control device to account for the nonlinearity of the dependence of the input and output parameters of ventilation equipment and to set the conditions for the optimal operating mode of the system in a declarative form. To assess the effectiveness of the proposed approach, the data of simulation modeling of the current ventilation mode and the transition from one ventilation mode to another are analyzed with comparison with the actual data of the system operation. The simulation results show that the use of an upgraded control scheme for the main ventilation fan based on fuzzy logic in the implementation of automatic ventilation control systems makes it possible to eliminate the possibility of a shortage of fresh air in the regulated directions of its movement, as well as excessive power consumption of the main ventilation fan.

Outdoor environmental comfort evaluation for retail planning in a tropical business district using Integrated Environmental Modeller.

This research proposes a simulation-based assessment of outdoor thermal and acoustic comfort for a planned business urban district in Singapore for retail planning using a customized OpenFOAM-centric multi-physics environmental simulation platform called the Integrated Environmental Modeller (IEM). IEM was employed to simulate the coupled impacts of solar radiation on wind and air temperature and wind and air temperature effects on traffic noise propagation in the district on the equinox and solstice day of the hottest period. Using IEM simulation results, we computed the thermal and acoustic comfort acceptability indicators derived from local field studies' results. The spatial distribution of environmental comfort acceptability indicators in the worst-case scenario can be used to distinguish the zones exposed to thermal or noise influence. The noise-affected zones are near the main roads and overlap a part of the thermal-affected area. The thermal-affected area is almost everywhere in the studied sites in the worst-case scenario. Having outdoor retail spaces with both poor thermal and acoustic comfort is not recommended if the thermal and acoustic comfort cannot be improved simultaneously. For the high-level retail planning, a simplified parametric analysis considering solar irradiance blockage and wind speed enhancements, is provided. Considering the worst-case scenario, ≥50% thermal acceptability can be achieved by blocking 54%-68% solar irradiance among the pedestrian thoroughfares and the retail spaces. Coupled together, blocking the solar irradiance and enhancing the wind speed can further improve thermal comfort locally. These results can guide the retail mix (e.g., al fresco restaurants, pop-up kiosks etc.) near high footfall areas and provide reference for future plans combining landscape and infrastructure, (e.g., trees with shelter walkaways, green walls with outdoor ventilation fans etc.) taking into account the environmental acceptability of people working in or visiting the tropical urban district.

Energy Cost Assessment and Optimization of Post-COVID-19 Building Ventilation Strategies

The advent of the COVID-19 pandemic puts stress on the requirements of indoor air quality. Significant improvements in the design of building ventilation systems have become necessary, as this allows for the supply of higher quantities of outdoor air in buildings. Additional capital investment is necessary for increases in the size of ventilation fans and ducts, as well as for the installation of efficient air-to-air recuperators, to recover the enthalpy of the rejected air. To address the increased operation costs, smart strategies are necessary to make rational use of the ventilation system. The required modifications are studied in the example of an 18-zone office building located in Volos, Greece. The building’s energy performance is studied by means of transient simulation. Operation of the ground-coupled heat pump, the upgraded ventilation system and the high-performance recuperators and filters’ interactions is presented in detail at various time scales. The results show the effect of increased ventilation requirements of new and renovated office and commercial buildings in the post-COVID era. The added capital equipment and operation costs must be met with a strong and sustained engineering effort. Especially in the case of nZEB buildings, the protection of public health must be attained, with reduction of the added electricity consumption penalties, in order to keep the nZEB character of the building.

Aerodynamic performance of the reversible axial fan for high air temperatures

The paper presents the aerodynamic performance of an axial reversible fan for high air temperatures, obtained by applying the similarity theory and numerical flow simulations. This analysis was performed for the possibility of installing the existing structure of an impeller of a reversible fan in a jet fan for the longitudinal ventilation of a tunnel. The direction of forced flow in tunnels changes, and it is always towards low atmospheric pressure, i.e. in the direction of natural air-flow. These fans often work with high air temperatures in the event of a fire. The paper shows the performance of fans for high operating air temperatures, up to 400?C. The results were obtained through numerical simulations of the flow in an original design fan, whose performance was experimentally determined for normal atmospheric operating conditions (? = 1.2 kg/m3). Performances are given for two fan speeds. Unnecessary corrections of the existing impeller design for use in jet fans for tunnel ventilation were also considered.

Long-term eff ects of carbon monoxide poisoning at Miike coal mine: A 33-year follow-up study

On November 9, 1963, during the afternoon shift change at the Miike coal mine, eight rail cars filled with coal broke free and fell 360 meters [1]. The impact ignited coal dust in the mine and set off two explosions, killing 20 people immediately and trapping nearly 1,400 other workers up to 450 meters below the surface and 8 kilometers from the mine entrance. The explosion damaged electrical and telephone lines, but the ventilation fan continued to operate and spread carbon monoxide throughout the mine [1].

ВЛИЯНИЕ РЕЦИРКУЛЯЦИОННОГО ПРОВЕТРИВАНИЯ НА СНИЖЕНИЕ ВЫБРОСОВ ПАРНИКОВЫХ ГАЗОВ КАЛИЙНОГО РУДНИКА

The paper considers air recirculation as an event to improve energy efficiency and reduce greenhouse gas emissions by reducing the power consumption of the main ventilation fan. The results are presented based on calculations of the required amount of air and modeling of air distribution in the ventilation network of the mine in the AeroSet software package. The methodology of determining the quantitative volume of greenhouse gas emissions, followed by comparison and analysis of the data obtained, has been studied.

Reduction of the risk of selecting the emergency ventilation mode through local control of ventilation flows

The implementation of measures regarding the organization of emergency ventilation of mine is connected with various types of risks, as in other cases of the operation of high-risk enterprises. In particular, this applies to the emergency risk that arises when there is a need for the emergency evacuation of people from the mine workings, gassed with fire products (that is, the risk of their poisoning or damage due to the thermal factor) and the emergency risk that is provoked by the wrong choice and implementation of the emergency ventilation mode. Both types of risks require to reduce the use of means of ventilation - main and local ventilation fans. Provision should also be made for the use of various passive control devices. The main result of the methodological approach used today is the selection of the emergency ventilation mode, which maximally limits the gassing zone of the mine ventilation network with gaseous combustion products. At the same time, the criterion for the effectiveness of the emergency evacuation of miners should be the maximum use of non-gasified workings, which achieves the goal of managing ventilation in the event of accidents. The proposed control function, which characterizes the degree of risk of distribution of fire gases in mine workings, is the root mean square deviation of the concentration of fire gases in the controlled branches of the network from the required level of stabilization. For two control devices and two controlled areas, it is part of a three-dimensional cone, and the control region is bounded by two hyperbolas. The problem formulation looks similar when the size of the base of the regulating devices is increased . A limitation on the task is formulated, and a conclusion is made regarding the possibility of applying analog methods of dynamic programming for its solution. As such, the multi-step optimization method, the one-step optimization method, and the extreme coordinate optimization method (the last one is the most effective) are considered. The greatest efficiency of their use will be achieved with the introduction of an automated ventilation control system, which provides feedback from the means of regulation and regulatory devices. Keywords: emergency risk, aerological risk, management functionality, regulatory devices, exogenous fire.

DEVELOPMENT AND PERFORMANCE OF A SOLAR DRYER HYBRID PHOTOVOLTAIC THERMAL SYSTEM

A solar dryer hybrid photovoltaic thermal (PV/T) system has been designed, built and its performance has been studied. This research aims to develop a stand-alone solar dyer system, portable and less maintenance. This system consists of three main parts; PV/T system with configuration-Z thermal absorber plate, multi-direction solar collector with cross absorber plate and drying chamber. Solar thermal collector which was designed in the system is called a multi-direction solar collector because the solar radiation does not get the heat through the upper part but also on the lower sides. This situation will then increase the amount of heat that will absorb by the absorber plate. The cross absorber plate will be used in a multi-direction solar collector because it can be assembled row by row. Six sets of cross absorber plates are used in this system. PV/T airflow uses configuration-Z absorber plate which is placed under the photovoltaic (PV) module. The amount of heat produced from the PV/T configuration-Z is used as the pre-heat before the hot air flows to the multi-direction solar collector. While electric energy from PV is used to operate the ventilation fan. The solar dryer hybrid PV/T system tested its effectiveness in the field under the daily solar radiation. The total efficiency generated from PV/T configuration-Z system is in the range of 35% to 52%. For the multi-direction solar collector system, the output range was generated between 32.0 °C to 46.6 °C, whereas the thermal efficiency is in the range of 50% to 70%.

Thermal Comfort Assessment of An Office Room Under High Air Conditioning Setting Temperatures with Fan-Assisted Ventilation

The usage of the air-conditioning system to provide comfortable indoor conditions is found necessary especially for hot-and warm countries. However, the excessive use of the air-conditioning system or without properly controlled will significantly affect the energy consumption of the building and also the environment badly. This study investigates the strategy to reduce energy for cooling in an office room by utilizing the high setting temperature of the air conditioning system with the addition of fan ventilation by field measurement. About 9 study cases have been investigated which includes the air-conditioning setting of 27°C to 28°C, with and without fan-assisted ventilation. The measured physical thermal comfort parameters are air temperature, relative humidity, wind speed, and black globe temperature. The operative temperature and Predicted Mean Vote value (PMV) have been calculated for each study case for analysis. The results revealed that the comfortable condition with neutral sensation can be achieved by air-conditioning setting of 28°C with an air speed of 1 m/s-1.2m/s. Moreover, the results showed that the room with 27°C-28°C setting temperature was in a comfortable condition before afternoon hours, while fan-assisted ventilation is required to enhance the comfortable hours through the rest working hour. By this practice, it is expected the energy consumption and cooling load of the building can be reduced.

Effects of Outdoor Air Pollutants on Indoor Environment Due to Natural Ventilation

This study measured ventilation volumes and particle concentrations in indoor environments with open windows and doors. In addition, the effect of the airflow mode of the air conditioner on the ventilation volume and indoor particle concentration variations was also measured. The ventilation fan could only provide approximately 43% of the ventilation volume during the design phase. The amount of ventilation differed depending on the opening area in windows and doors. The ventilation volume was increased by opening multiple windows or doors, even when the area of the opening was the same. No significant change in the ventilation rate was observed, although the air conditioner was expected to promote the ventilation rate in the room when set on blow mode. It was confirmed that both 0.3 and 1 μm particles could enter through the gaps around the windows and doors. Although most of the 5 μm particles were from the outdoor air, when the air conditioner was operated in airflow mode, the removal of 5 μm particles was performed by the air conditioner filter. The use of medium-performance or HEPA filters is expected to remove smaller particulates.

Study on pressure wave response and overpressure attenuation law of explosion-proof doors

In order to evaluate the pressure relief characteristics of the explosion-proof door, experiments were conducted in a self-built small size explosion-proof door experimental platform. The details of pressure changes in the pipeline were monitored in detail through four monitoring points set on the right end of the pipe, horizontal pipe, the main ventilation fan tunnel and below the explosion-proof door. The overpressure attenuation law at different positions and the effect of equivalent ratio on overpressure attenuation were studied when the explosion-proof door was normally opened for pressure relief and failed to open for pressure relief. The results showed that when the explosion-proof door cannot be opened for pressure relief, the overpressure of the main ventilation fan tunnel and the explosion-proof door will increase dramatically. Compared with the normal pressure relief by opening the explosion-proof door, it increased by 130.69 % and 100.36 % respectively. Through the explosion-proof door pressure relief, the overpressure attenuation at the main ventilation fan tunnel and the explosion-proof door exhibited a linear. However, the overpressure attenuation at the main ventilation fan tunnel was the most obvious when the ϕ = 0.94, and the overpressure attenuation at the position of the explosion-proof door was the most obvious when the ϕ = 1. With the increase of ϕ, the time interval between two overpressure peaks at each monitoring point showed a downward trend, and the decreasing trend was more obvious at the main ventilation fan tunnel compared to other monitoring points. It was also noted that the trend of the time interval between the two overpressure peaks at the four monitoring points will gradually stabilize with the increase of the equivalence ratio. Additionally, the peak overpressure decline rate at the explosion-proof door position was always greater than that in the main ventilation fan tunnel. This indicates that the overpressure attenuation effect at the explosion-proof door is stronger than that at the main ventilation fan tunnel.

Optimization of the primary nozzle for design a high entrainment ejector in spacesuit portable life support system

In looking forward to the future of human space exploration, it is increasingly stringent for the ventilation circuit subsystem in terms of reliability, simplicity and energy-efficient. Considering this requirement, the ejector, with the advantages of miniature size, no parasitic energy consumption and high reliability, is considered an appropriate alternative to the ventilation fan because it simultaneously implements the functions of mixing, entraining, and lifting pressure. This paper proposed a high entrainment ejector for application in spacesuit portable life support systems. The optimizations of the ejector nozzle geometrical parameters and nozzle exit position (NXP) were performed using a validated three-dimensional numerical model under various operating conditions. The results show that the NXP has a more significant effect on entrainment performance than other geometrical parameters in spacesuit portable life support systems, and the optimum NXP are not impacted by changes of the primary flow pressure and mixing chamber diameter, which similarly obtained the optimal entrainment ratio at the nozzle exit position of 2 mm. The maximum increments of entrainment ratio with the NXP varying from −4 mm to 8 mm are 0.2945 and 0.7664 under different primary flow pressures and mixing chamber diameters, respectively. Compared with the nozzle exit position, the most effects of nozzle converging angle and length on entrainment ratio are just 0.0864 and 0.0445. The optimum ejector extends the oxygen service duration by 12 min compared to the original one for the same volume of an oxygen tank, which is vital for the astronauts to conduct extravehicular activities in outer space.

A Comparative Study of the Performance of a Solar Radiation Shield for Ground Observations Based on the Stevenson Screen

The Stevenson screen has previously been used for ground temperature and humidity observations, but due to the computerization and miniaturization of observation equipment, a solar radiation shield has been more commonly employed in recent years. However, there is no detailed domestic standard for Stevenson screens or solar radiation shields in weather stations or weather observatories. Accordingly, this study was conducted to derive the required standard for solar radiation shields by comparing the temperature and humidity observations of a Stevenson screen and a solar radiation shield in Korea. Through these comparisons, the minimal standard requirements for solar radiation shields were determined. First, a solar radiation shield with natural ventilation should have a structure in which the inside (sensor) is not directly transmitted from the outside through a method such as a partition wall inside the plate. Second, in the case of forced ventilation, the structure fixing the ventilation fan must be firmly fixed. Moreover, there should be no interference between the installed sensor and the solar radiation shield. The natural ventilation method and the forced ventilation method showed similar results.

Evaluation of shields and ventilation as a countermeasure to protect bus drivers from infection

We evaluated the deposition of droplets and droplet nuclei—generated by simulated coughing and talking from three points in a bus—on the driver's face and on surfaces around the driver (e.g., the steering wheel), based on whether countermeasures were taken, and assuming that an infected passenger was talking to the driver. When a shield, such as acrylic boards or polyvinyl chloride (PVC) sheets, was used as the countermeasure, the deposition of artificial droplets (>4 μm), emitted from beside or behind the driver, on his eyes, mouth, and cheeks reduced by two to three orders of magnitude or more. Deposition on the surfaces around the driver was also reduced following the use of shields. For artificial droplet nuclei (1.3 μm of polystyrene latex (PSL)) emitted from atomizers beside the driver, the operation of the ventilation fan (VF) and air conditioner (AC), and defroster (DEF) greatly reduced the driver's exposure, while the use of the shield did not. The infection risk of the driver was estimated through exposure to the virus via transfer to the mucosa via hands or surface-to-finger, direct adhesion on the mucosa, and direct inhalation of droplets and droplet nuclei. This is under the assumption that the droplets and droplet nuclei measured in this study are 40% the diameter of those after immediately leaving the mouth of the infected person and are constant regardless of particle size. When using the shield, total infection risk via droplet, airborne, and contact transmission was decreased by 75.0–99.8%. When the shield was not installed, the infection risk decreased by 9.74–48.7% with the operation of the VF, AC, and/or DEF.

Legal Regulations of Restrictions of Air Pollution Made by Mobile Positive Pressure Fans—The Case Study for Europe: A Review

This paper presents a review of mobile positive pressure ventilation fans for use in rescue operations available on the European market in correlation with the approval regulations of the drive units. The authors determined the approval limits for harmful compound emissions by their power units, as applicable within the European Union. The purpose of this paper is to estimate the emissions of harmful compounds from the exhausts of rescue fan power units. It was demonstrated that electric fans are not in direct competition with internal combustion fans because they are provided in different power ranges, and 74% of the electric fan market falls between 1.1 kW and 2.2 kW, whereas fans powered by combustion engines are offered in a much higher power range from 0.7 kW to 92 kW, and the most popular power range offered by manufacturers is from 3.4 kW to 6.3 kW (57% of the market). On the basis of the limits derived from approval tests it can be demonstrated that 90% of engines on the European market which are used in fans (spark ignition (SI) engine up to 19 kW) are allowed carbon monoxide (CO) emissions of 610 g/kWh and hydrocarbon and nitrogen oxide emissions (HC + NOx) of 8 g/kWh.

An adaptive grain-bulk aeration system for squat silos in winter: Effects on intergranular air properties and grain quality

Grain can be stored for long periods under suitable storage conditions. The present study investigated the effects of cooling aeration on the intergranular air properties and grain quality of wheat stored in two squat silos during winter. In the first silo, 4759 tonnes of bulk wheat were downward-aerated in a suction-type way by four 11 kW centrifugal ventilation fans at an airflow rate of 10.1 m3/(h·t). The fans were firstly controlled by software based on a smart de-moisturization aeration model, and the grain bulk lost 0.8% moisture content (MC) and its average temperature was decreased by 5.8 °C. When the fans were then controlled using smart cooldown aeration model, the average bulk temperature decreased from 17.0 to 5.2 °C, and the average bulk MC was reduced by 0.6%. The cooling fronts moved predictably through the bulk layers during cooldown aeration, which consumed energy at a rate of 0.067 . In a second silo, 4,675 tonnes of wheat were also downward-aerated at 9.8 m3/(h·t) using smart cooldown aeration model and four 5.5 kW mixed-flow fans. There was a 0.7% MC loss and the average bulk temperature decreased by 6.7 °C. Except for the middle part (fourth and seventh) bulk layers, the other bulk layers in this silo had cooling fronts that moved at similar speeds. The energy consumed by cooldown aeration was 0.040kWh(t·∘C)−1 and 58% unit energy consumption was lowered when compared to a local grain squat silo with geosynclinal ventilation ducts under artificially controlled cooling-ventilation operations. The running conditions for the ventilation fans during cooldown aeration in the squat silos were verified. (i) The temperature difference between the grain bulk and ambient air was ≥ 4 °C. (ii) The humidity ratio of the grain bulk was higher than that of the ambient air. The equilibrium relative humidity of the intergranular air tended to decrease in both silos. After cooldown aeration, the wheat kernels had a higher water absorption rate and fatty acid value, retentive peak temperature of gelatinization, and a higher dough development time, protein network strength, and starch gelatinization rate. The proposed aeration control system has good application potential in squat silos used for grain storage.

단독형 CO 가스 경보기와 화재감지 신호를 연동하여 방재 장치와 보조 배터리 전원을 제어하는 캠핑카용 화재 수신기 시스템의 개발

A receiver capable of detecting and providing alerts about fire and CO gas during camper van accidents and operating a disaster prevention device was developed. The function of the proposed disaster prevention device was verified by designing and testing a receiver for fire detection. It includes a function for controlling windows and ventilation fans by interlocking a fire signal and a stand-alone CO gas alarm and cutting off the auxiliary-battery power. The proposed camper fire-detection receiver is considered a primary model in the development of additional disaster prevention facilities for campers considering that there are currently no commercialized products.

Experimental performance evaluation of a climate-responsive ventilated building façade

Enhancing building energy performance has become a focal point in reducing the environmental impacts of buildings to address climate change. Considering the high share of comfort-related energy use in buildings, and the importance of indoor environmental quality (IEQ), a balance between energy conservation and IEQ provision is required. Building façades are the primary boundary controlling mass and energy flow to and from buildings. Dynamic and climate-responsive façades are potential improvements to existing high-performance façades to enhance IEQ in buildings, as they change their functionality with time, in response to changing environmental loads. A multifunctional, integrated, climate-responsive, opaque, and ventilated building façade (MICRO-V) was designed to regulate the flow of heat, air, and moisture into buildings. The MICRO-V façade has a novel design to pre-condition the fresh air and regulate thermal loads in buildings on a daily and seasonal basis. The multiple components of this façade include phase change materials (PCMs), a bi-directional ventilation module and an adjustable insulation system. In this paper, the thermal performance of this façade was evaluated using long-term experimental tests. The real-scale prototype of the façade was constructed and installed in the full-scale BETOP test cell facility in Toronto, Canada. The results of different tests showed how the façade could pre-condition the fresh air acting as a decentralized ventilation module due to a high heat recovery efficiency of 81%. However, it was also shown that the significant impact of solar irradiance, which requires constant adjustment to the operation schedule of the ventilation fans in the façade.

Water-based air purifier with ventilation fan system: a novel approach for cleaning indoor/outdoor transitional air during the pandemic

This article presents the design and fabrication of an air purifier that uses a water-based technique to clean indoor/outdoor transitional air to provide a low-tech air purifier against the annual smog crisis and the ongoing COVID-19 pandemic. The air purifier was designed and built. All tests were conducted in a closed room as well as a semi-outdoor area. Particle sizes of PM0.3, 0.5, 1.0, 3.0, 5.0, and 10 μm (particle/m3) were measured at an air inlet, air outlet, 2 m from an air inlet, and 4 m from an air outlet after 0, 5, 10, 15, and 20 min of air treatment, respectively, as well as CO2 levels and relative humidity (RH). The average airflow rate was also measured. When compare to 0 min, all parameters, except semi-outdoor PM0.3 and CO2 levels, tend to decrease in both indoor and semi-outdoor conditions. When measure by total airflow specification of a dual ventilation fan, the average airflow rate at an air outlet is reduced by 20 times.Article HighlightsDesign and fabrication of a water-based air purifier.A low-tech air purifier helping to protect against the annual smog crisis and the ongoing COVID-19 pandemic.The novel water-based air purifier effectively traps air particles ranging in size from 0.5 to 10 µm.

Effect of ventilation and climatic conditions on COVID-19 transmission through respiratory droplet transport via both airborne and fomite mode inside an elevator

A numerical analysis using OpenFOAM has been performed in this work to investigate the infection risk due to droplet dispersal in an enclosed environment resembling an elevator, since infection risk in such confined places is very high. The effect of two scenarios on droplet dispersal, namely, the quiescent and the fan-driven ventilation, both subjected to various climatic conditions (of temperature and humidity) ranging from cold–humid (15 °C, 70% relative humidity) to hot–dry (30 °C, 30% relative humidity) have been studied. A risk factor derived from a dose–response model constructed upon the temporally averaged pathogen quantity existing around the commuter's mouth is used to quantify the risk of infection through airborne mode. It is found that the hot, dry quiescent scenario poses the greatest threat of infection (spatio-averaged risk factor 42%), whereas the cold–humid condition poses the least risk of infection (spatio-averaged risk factor 30%). The proper fan speed is determined for the epidemiologically safe operation of the elevator. The fan ventilation scenario with 1100 RPM (having a spatio-averaged risk factor of 10%) decreases the risk of infection by 67% in a hot, dry climatic condition as compared to a quiescent scenario and significantly in other climatic ambiences as well. The deposition potential of aerosolized droplets in various parts of the respiratory tract, namely, the extrathoracic and the alveolar and bronchial regions, has been analyzed thoroughly because of the concomitant repercussions of infection in various depths of the respiratory region. In addition, the airborne mode of infection and the fomite mode of infection (infection through touch) have also been investigated for both the ventilation scenarios.