Ventilation Pipe Research Articles

Attempts to reduce cavitation phenomena at the Ciawi Dam inlet conduit using CFD Modeling

The conduit bottom outlet is prone to cavitation damage on its channel surface, and one preventive measure is the installation of air ventilation. This research aims to grasp flow characteristics comprehensively, predict cavitation likelihood at the intake, and assess the impact of a ventilation pipe’s installation. Utilizing Computational Fluid Dynamics (CFD), the study modeled flow dynamics, focusing on velocity and pressure variables. The Ciawi bottom outlet intake was meticulously modeled at a 1:1 scale under normal water level conditions, and model accuracy was validated through physical testing by BHGK. The research includes two series: Series 0 (intake without ventilation pipe) and Series 1 (intake with ventilation pipe), with gate opening heights varied at 25%, 50%, 75%, and 100% for both series. Simulation results show that in Series 0, potential cavitation damage is indicated at a 75% gate opening in sections 3 and 4 with a cavitation index of 0.11. Series 1, featuring ventilation pipe installation, demonstrated positive outcomes, eliminating potential cavitation damage in the inlet bottom outlet, with all cavitation indices surpassing 0.2. This study provides crucial insights for preventing cavitation damage in conduit bottom outlets through the strategic deployment of ventilation systems.

Enhancing Dehumidification in the Cable Room of a Ring Main Unit through CFD-EMAG Coupling Simulation and Experimental Verification

The cable room, located at the base of the ring main unit, is prone to water vapor due to its proximity to damp cable holes and its relatively enclosed structure. This may penetrate internally and ultimately affect operational safety. Therefore, a dehumidifier was introduced to utilize dry air for internal circulation. To enhance the dehumidification in the cable room, the cable room device was designed for experimental research. Meanwhile, computational fluid dynamics (CFD)-electromagnetic (EMAG) coupling simulation is used to calculate the power loss of heat sources and their influence on multiple physical fields in numerical simulations. The feasibility of this study was confirmed by comparing the relative humidity, temperature, and velocity values between the experimental and numerical approaches. Furthermore, the layout of the ventilation pipes was modified to a vertical distribution, with upward supply and downward suction, to improve the airflow. The results indicate that the maximum relative errors in temperature, relative humidity, and velocity are only 3.61%, 7.14%, and 7.14%, respectively, which fall within an acceptable range. On this basis, additional simulation analysis was conducted on the humidity, dew point temperature, and airflow within the cable room, using an optimized model with a more comprehensive internal structure and cables. After implementing an optimized ventilation pipe layout, the relative humidity at the corresponding measuring points can decrease by up to 10.6%. The dew point temperature has decreased by 2.61 °C and the airflow has become more stable.

Ventilation characteristics of double-forced air pipe ventilation in comprehensive mechanized excavation face and determination of its optimal parameters

ABSTRACT This study proposes a ventilation and dust control approach using double-forced air pipes at the tunnel excavation face, aiming to optimize the dust control and reduction measures for underground coal mining environment. We designed a physical model in proportion to the 11,139 excavation face in the Zhangji Coal Mine of China Huaihe Energy Holding Group Coal Company. To begin with, CFD numerical simulation was employed to unveil the basic laws of the double-forced air pipe ventilation approach, including airflow characteristics and dust concentrations. The orthogonal experimental method was then adopted to analyze the influence mechanism of installation location and airflow ratio of the double pipes on the dust density around the driver’s operating space. Results suggest that the double-forced air pipe ventilation can efficiently improve the airflow velocity at the excavation face, reaching 5.54 m/s. With the minimum dust density around the driver’s operating space as the optimal parameter standard and combined with the R value, the three factors in the orthogonal experiment can be sorted as: the distance between the forced ventilation pipe at the driver’s side and the excavation face (R = 206.91) > the distance between the forced ventilation pipe at the return air side and the excavation face (R = 171.72) > the airflow ratio of the two pipes (R = 77.52). The optimal combination is that the distance between the ventilation pipe at the driver’s side and the excavation face is 5 m, the distance between the ventilation pipe at the return air side and the excavation face is 5 m, and the airflow ratio of the two pipes is 6:4. In such a case, the dust density around the driver’s operating space is 48.21 mg/m3, achieving an ideal dust control effect.

Особенности газодинамики испытательного бокса для наземных испытаний микроразмерных турбореактивных двигателей

The features of testing microscale turbojet engines on the test bench of the D.F. Ustinov BGTU “VOENMEH” in different weather conditions and with different engine locations relative to the exhaust ventilation pipe are discussed. The problems that arise during testing of micro scale turbojet engines are identified, and the influence of climate conditions on engine operation and test stand operation is revealed.

Analysis of the Effect of Equipment Readiness on the Tank Cleaning Process (Case Study of MT. Akra 102)

Tank cleaning is defined as the activity of cleaning tanks from residues of previous cargo, including cleaning and checking pumping equipment, heater equipment, filling pipes, ventilation pipes and auxiliary engines. During the tank cleaning process there were many obstacles such as the tool not working normally, the crew's lack of knowledge, and the tank not being clean and dry which resulted in an attack on the loading process. This study set out to ascertain how equipment preparedness affected tank cleaning. This study employed a descriptive method with a quantitative approach as its research methodology. The IBM SPSS 26 program is used to process some sample data. Respondents are given questionnaires as part of data gathering processes.The results showed that equipment readiness had a significant effect on the tank cleaning process.

Experimental study on air extraction performance of novel rooftop natural ventilators

The air extraction performance of novel rooftop natural ventilators was experimentally investigated and compared to the conventional turbine ventilator. The newly developed ventilator integrates a vertical-axis wind turbine with a static ventilator, where the wind turbine, equipped with 8C-type rotors and six rotor guide vanes, serves to drive the rotation of the static ventilator. The static ventilator is an exhaust cowl with curved guide vanes inside. The wind turbine, including 8C-rotors and 6 flat guide vanes, is 10 cm in height with a diameter of 21 cm. The dimensions of static ventilation are 7 cm in height, and 26 cm and 21 cm in bottom and top diameters, respectively, with curved guide vanes inside. Various heights of guide vanes (0.5 and 3 cm) and numbers of guide vanes (0, 6 and 12) were investigated. An open wind tunnel system was used to simulate the condition where the wind blows over the rooftop ventilator. The ventilator air extraction rates were determined using the mean air velocities, measured using a hot-wire anemometer at an open slot in a ventilation pipe connected to the ventilator. The results indicated that the rotating and non-rotating novel ventilators exhibited superior air extraction rates at most tested wind speeds compared to the rotating conventional turbine ventilator. The curved guide vanes inside the static ventilator played the most important role in the air extraction rate. This study suggests that a static ventilator with an adequate guide-vane design may be more suitable for rooftop ventilation than a conventional turbine ventilator.

Parameter Study of a Loss Reducing Passive Flow Control Method in a Square-to-square Sudden Expansion

The energy consumption of mechanical ventilation in buildings needs to be reduced. An efficient way to achieve this goal is to reduce the hydraulic resistance of the ventilation duct system elements, for example, that of sudden expansions. Ventilation ducts and pipe fittings are frequently of rectangular cross-section. The present paper investigates a passive flow control method in order to reduce the loss coefficient of a square-to-square sudden expansion, where the loss-reducing appendages are short guide vanes, termed as miniflaps, placed at the step edge of the sudden expansion. The turbulent flow is examined numerically using the generalized k-ω model of the Ansys Fluent software for different area ratios of the sudden expansion, miniflap lengths, and miniflap angle setups. The Reynolds number is kept constant at 1.08·105. Based on the results of the numerical simulations, the loss coefficient of the sudden expansion can be reduced by ~20–25% for an optimum miniflap angle between 9° and 12°. Increasing the length of the miniflaps leads to a greater reduction of the loss coefficient up to a miniflap length of 0.3 dh1, where dh1 is the upstream hydraulic diameter of the duct.

Experimental study on precise control air quantity on demand by the cooperation of multiple main fans in mine

Due to the global energy crisis worsening, numerous businesses have prioritized energy conservation and consumption reduction. However, in mines with multiple main fans, the main fans' operation efficiency is low to meet the ventilation on-demand, and the ventilation system's energy consumption is very high. This paper proposes an energy-saving control strategy for ventilation on demand with multiple fans network, which can save much energy in mines. We use the circuit method to calculate the operating condition parameters required for the joint control of multiple main fans by analyzing the influence features of multiple fans' mutual disturbance. We study the advantages and shortcomings of the traditional fan control method and create control strategy expressions for multiple fans. The two-step fan control strategy uses the adjusting wheel blades' angle method to determine the high-efficiency operating angle and the modulating fan speed method for accurate air quantity control. Furthermore, the effectiveness of the control strategy in ventilation on demand and fan energy-saving are verified on the three-dimensional complex ventilation pipe network experimental platform. The research results show that, compared to the two typical fan control strategies, our control strategy can save energy by 27.74% and 26.92%, respectively. If this strategy is applied to a mine with two main fans rated power of 500 kW, it can save energy 2,429,806 kW per year, saving USD 442.69 per day or USD 161,582.1 per year. The payback period for this strategy is approximately 14.1 months. Therefore, this research can provide a promising step towards intelligent control of air quantity on-demand while indicating enormous potential for energy savings in mine ventilation systems.

Estimation of methane emission from Piyungan landfill using IPCC method

One of the greenhouse gases that causes climate change is the emission of methane (CH4) produced by landfills. The methane comes from the anaerobic decomposition of organic matter in the waste at the landfill. The purpose of this study is to estimate methane emissions at the Piyungan landfill, Bantul, Yogyakarta, from 2021 to 2025 using IPCC method. No similar work has been conducted so far, especially in the Piyungan landfill. The result shows that methane emissions produced at the Piyungan landfill in 2021 is 544.05 tons with a total waste generation of 549.49 tons/year and is dominated by 88% organic waste. Meanwhile from 20,786 tons of waste generated in 2025, the methane emissions are estimated to be 573.85 tons. To minimize the methane emission from Piyungan landfill, it is recommended mitigation and adaptation efforts, i.e., the 3R method (reduce, reuse, recycle), the composting of organic waste, the addition of gas ventilation pipes. The methane gas from the Piyungan landfill should be explored as alternative energy fuel in future work.

LCC (LIFE CYCLE COST) Analysis On Septic Tank Alternative Types (Case Study Of Housing Pt Baruga Asrinusa Balithai Land Area Phase II, Makassar, Indonesia)

In the planning concept for the housing project, PT Baruga Asri, the Blaithai area, still uses a modular septic tank and is still conventional. Meanwhile, there are alternative choices for the type of Septic tank as a fecal treatment facility which are widely available in the market. The research method uses primary data, with sources of RAB, and Makassar City Work Unit Price Analysis. As well as secondary research methods with sources, from relevant books, and important data about the project such as price lists and wages. It can be concluded that among all Balithai Land housing developments by following the RAB reference for Bukit Baruga Asrinusa housing in the Balithai Land area and AHSP (Work Unit Price Analysis) Makassar city, sanitation work items are one of the work items that can be broken down in terms of the costs involved. also eat up a large budget, even though there are actual work items that cost more. And there was a difference in sanitation work items between the main design and alternative designs of Rp. 148,718.00 and there was 1 alternative design that was raised to replace the existing design currently used, namely by replacing the use of Septic Tank buis concrete Ø80 (4 stacks 2.0 m high) + Cover + Infiltration + 2.5" ventilation pipe with a septic tank with bio capacity of 3-5 0 people. Thus saving the cost of the Bukit Baruga Asrinusa housing development project in the Balithai Land area phase 2. From Rp. 7,025,788.31 to Rp. 6,877,070 ,15.

The strong influence of small construction errors on sound insulation of buildings with heavyweight concrete structure: A Portuguese case study

In order to attain an expected sound insulation in buildings, it is necessary to employ appropriated constructive solutions, but it is also fundamental to guarantee compatibility with other involved design professional fields, proper detailing of solutions and correct on site mounting. A solution with a predicted high acoustic performance may result in failure if there is no proper interconnection between other design professional areas or if execution mistakes occur, even if of very small dimension. The main objective of this technical paper is to analyse the influence of defects that typically occur in buildings, located in Portugal, resulting in very poor airborne or impact sound insulation performance. The chosen situations refer to buildings with heavyweight concrete structure, where small construction defects occurred and/or wrong decisions were taken, ending up with a large reduction on the final acoustic performance. Some of these errors, given their small size or because they occurred in hidden zones, easily passed unnoticed, on site. The defects here addressed in what refers to airborne sound insulation are related with execution of double masonry hollow brick walls, sound bridges in acoustic suspended ceilings, passage of ventilation or sewage pipes, inappropriate installation of acoustic doors, shutter boxes or windows. As for impact sound insulation, the presence of rigid connections is the main focus of the characterisation here performed.

Evaluating the performance of a novel ventilated embankment structure in warm permafrost regions by numerical simulation

Conventional ventilated embankments are commonly used on the Qinghai-Tibet Railway to reduce embankment settlement. However, the shortcoming of these systems may make them unsuitable for the Qinghai-Tibet Expressway (QTE). The heat absorption area of expressways in cold regions is significantly larger than that of railways, which results in a rapid temperature rise of the embankment above the permafrost, which significantly reduces the stability of the embankments. To facilitate the cooling of the expressway, the authors designed a novel ventilated embankment (NVE) structure and studied its cooling capacity. The results indicate that the NVE has a remarkable cooling effect. At the same location, the ground temperature under the NVE is clearly lower than that under the normal embankment. Moreover, the intelligent control ventilation mode of the NVE, which compares the soil and air temperatures to determine when to open and close ventilation pipes, provides better cooling performance than conventional ventilated embankments. To optimize the cooling effect of the ventilated pipe and construction of the subgrade, the following ideal pipe layout method is proposed: the pipe diameter is 0.4 m, the pipe spacing is 2.4 m, and the burial depth of the pipe is 0.0 m. With a decrease in site temperature and an increase in embankment height, the maximum pumping distance of the NVE increases. These results establish a theoretical basis for the future application of NVEs in engineering.

РАСПРОСТРАНЕНИЕ УГЛЕРОДА-14 В ОКРУЖАЮЩЕЙ СРЕДЕ ПРИ НОРМАЛЬНЫХ УСЛОВИЯХ ЭКСПЛУАТАЦИИ КУРСКОЙ АЭС

Introduction: 14C is one of the fifteen radionuclides that account for at least 99 % of the radiation dose to the critical group of the population from NPP emission sources. The continuous growth of the total capacity of operating NPPs leads to a significant increase in the amount of 14С emitted into the environment during NPP operation. Efficient capture and disposal of 14C, which has a half-life of 5760 years, is a very laborious undertaking. At the same time, due to the high mobility of this radionuclide, local foci of contamination with 14C can appear both near the NPP at a distance of 1–2 km from its ventilation pipe, and in soil and plants located at a distance of 20–30 km from the NPP due to the transfer of air masses. Therefore, the control of the formation of 14C during the operation of nuclear power plants, its content in emissions and discharges of nuclear power plants, as well as distribution in the environment is an urgent problem today. Purpose: Analysis of the environmental pollution due to emissions and discharges of radiocarbon from the Kurskaya nuclear power plant. Material and methods: During the research, a method being developed by specialists of the Laboratory for Radiation Safety of Personnel was used to determine the specific activity of 14C in soil and vegetation. To explore the 14C content in the air, the method of bubbling air through a TASC-HT-HTO-C-14 flow meter-sampler (Overhoff technology, USA) and the method of air conditioning through a Ballu BDH-15L air dryer (Ballu, Russia) were used. To prepare counting samples from selected soil and food samples, a method based on the combustion of selected samples in a Pyrolyser-6 Trio catalytic decomposition system was used. All prepared counting samples, including samples from surface water and biosubstrate of the personnel of the Kursk NPP and the population, were measured by liquid scintillation spectrometry on a Tri-Carb 3180 TR/SL alpha, beta spectrometer. Results: On the basis of an integrated approach to assessing the content of 14C in air, water, soil and food, an analysis of the formation of environmental pollution due to emissions and discharges 14C from the Kurskaya NPP was carried out. Conclusions: An increased content of the 14C radionuclide in soil samples, food products and vegetation in the area of the Kursk NPP with RBMK-1000 nuclear reactors is shown, both in comparison with the content of natural 14C and NPPs operating BN-600,800 and VVER-1000 nuclear reactors. The necessity of taking into account radiocarbon emissions from NPPs into the environment in the problem of optimizing the radiation protection of the population under the conditions of normal operation of NPPs is confirmed.

Study on the Effect of Non-Linear Ventilation Pipe Composite Measures on the Slope Permafrost Subgrade

In the alpine mountain area, the stability of the steep-slope permafrost subgrade is mainly affected by the temperature variation in the frozen soil layer at the base of the road. Under the conditions of climate warming and engineering-related disturbance, the cooling of the subgrade is an urgent problem to be solved in the field of construction. In this paper, the numerical calculation method, combined with data monitored in situ, is used to study the cooling effects of several subgrade cooling measures, in which the non-linear ventilation pipe and rubble layer are combined. The results show the following: (1) the temperature field of the steep-slope subgrade is clearly different in lateral terms—after 20 years of operation, the maximum difference in the melting depth between the left shoulder and the subgrade center is 3 m; (2) the maximum melting depth of the gravel subgrade center is 3.85 m, while the maximum difference in the melting depth between the left shoulder and the subgrade center is 2.3 m; (3) the cooling effect of the composite measures is noteworthy, and a −2.2 °C freezing area appears under the subgrade.

Numerical study of a novel ventilation system added to the structure of a catamaran for different slamming conditions using OpenFOAM

Large-size catamarans' structural behavior is sensitive and critical during the slamming phenomenon. “Ventilation pipes” within the center bow structure are proposed to discharge these cumulative pressure and related loads. The validation case is comprising two different simulation schemes, static and dynamic wedge. First, the appropriate method is chosen based on the accuracy and needed computational running time criteria. The numerical solution approach solves the RANS equation using the Open Field Operation and Manipulation (OpenFOAM) library called “InterFoam and OverInterDyMFoam for static and dynamic mesh respectively. Totally three different impact conditions with four different impact velocities (12 case studies) were considered for the case with added ventilation pipes (amended hull) and the standard model (parent-hull). Apart from the limitation of the proposed plan which is discussed, the results indicate that the recorded pressure and total force decreases by about (15%–50%), and (5%–25%) respectively.

The Influence of the Radiation Background of City-Forming Settlements with NPPs on Public Health and the Environment

The radioactive decay of elements as a result of a nuclear reaction is a powerful source of energy used in the production of electricity and heat in cities close to NPPs. The problem of using this kind of energy is the danger of radiation exposure. The production of nuclear energy has many advantages, including the profitability of the final product and its low cost; on the other hand, the half-life products of radionuclides in the composition of gas-aerosol emissions from ventilation pipes settle in the environment on the territory of city-forming nuclear power plants. The duality of the problems of the impact of radiation background on the urban areas near NPPs has become the purpose of this study. It is necessary to investigate the negative effect of radioactive waste emissions during the normal operation of nuclear power plants. For this purpose, the method of a project experiment was used, during which, using laboratory monitoring of external radiation safety and an automated radiation monitoring system, indicators of exposure dose capacities were collected from points in the 30-kilometre zone around the NPP. As a result of the monitoring of radiation samples from soil, atmospheric air and precipitation, and reservoirs, it was revealed that the natural radiation background is insignificant; the probability of harm from radiation exposure is small and insufficient for the development of radiation sickness. However, potentially unsafe sources of radiation exposure have been identified, such as natural radiation – the consumption of contaminated food, solar and cosmic radiation from radioactive elements present in the bowels of the earth; radionuclides, whose emissions uncontrollably occur into the atmosphere; radioactive waste, the disposal and storage technology of which is economically costly. Therefore, it is justified to conduct regular design experiments to check the operability of automated radiation monitoring systems. The materials of the study are of practical value for chemists, environmentalists, and ecotechnologists working at NPPs that monitor safety for human health and environmental protection in the field of atomic energy use

The importance of rest phase and pollutant removal mechanism of tidal flow constructed wetlands (TFCW) in rural grey water treatment

This paper explored the effects of the rest phase of tidal flow constructed wetlands (TFCW) on pollutant removal and microbial communities, and further analyzed the mechanism of TFCW removal of pollutants from grey water. The results showed that the removal rate of organic matter was 69.91 ± 2.44% in the control group (NR-TFCW) without the rest phase, 94.95 ± 1.17% in the experimental group (TFCW), and 96.95 ± 2.43% in the control group (P-TFCW) with the ventilation pipe enhanced rest phase. Limiting and enhancing the oxygen supply in the emptying stage of TFCW will enhance the overlap rate of microorganisms in the upper, middle and lower layers of the reactor. Enhancing the rest phase of TFCW leaded to better aerobic removal of organic matter in the microbial community, while limiting the rest phase of TFCW results in the opposite. In addition, the species overlap rate of the top, middle and bottom layers of NR-TFCW (69.98%) and P-TFCW (54.29%) was higher than that of TFCW (11.34%). The removal of organic matter by TFCW mainly relied on the adsorption of biochar in the flood phase, and the microorganisms aerobic degraded the organic matter adsorbed on the biochar in the rest phase. And thus form a continuous cycle of adsorption and biological regeneration. The microbial community in TFCW did not have the ability to nitrify, but had the ability to remove phosphorus. Ammonia nitrogen in the influent was adsorbed by biochar or converted into cytoplasm. While the phosphorus in the influent was adsorbed by the biochar, it was also being biologically removed.

Air Quality and Thermal Environment of Primary School Classrooms with Sustainable Structures in Northern Shaanxi, China: A Numerical Study

In northern Shaanxi, China, the air quality and thermal insulation properties of primary school classrooms should be given more attention due to the relatively low temperatures in the winter, which are significant to the learning processes of students in classrooms. Some sustainable building measures have been designed and constructed to improve the air quality and thermal comfort of classrooms in this region; however, is still unclear how these measures influence air quality and temperature. This study investigated the indoor air quality and thermal environment of a typical primary school classroom in Yulin city, Shaanxi Province, China. The classroom was characterized by sustainable structures, including double-sided corridors and an underground ventilation pipe, for better thermal insulation. By conducting on-site monitoring in the classroom and performing various numerical simulations based on finite element software, the variations in the indoor air quality (carbon dioxide, water vapor concentration) and temperature over time, and under different conditions, were investigated. Moreover, influences (i.e., of corridors, ventilation pipes, window areas, classroom areas, and the number of students) on the air quality and temperature were analyzed. It was proven that double-sided corridors, underground ventilation pipes, and windows with heights/widths equaling 1 could provide energy-efficient and livable building structures for primary school classrooms in the northern Shaanxi region of China.

Explosion Characteristics of Hydrogen Gas in Varying Ship Ventilation Tunnel Geometries: An Experimental Study

Hydrogen is widely regarded as a key element of prospective energy solutions for alleviating environmental emission problems. However, hydrogen is classified as a high-risk gas because of its wide explosive range, high overpressure, low ignition energy, and fast flame propagation speed compared with those of hydrocarbon-based gases. In addition, deflagration can develop into detonation in ventilation or explosion guide tunnels if explosion overpressure occurs, leading to the explosion of all combustible gases. However, quantitative evidence of an increase in the explosion overpressure of ventilation tunnels is unavailable because the explosive characteristics of hydrogen gas are insufficiently understood. Therefore, this study investigated an explosion chamber with the shape of a ventilation pipe in a ship compartment. The effect of tunnel length on explosion overpressure was examined experimentally. For quantitative verification, the size of the hydrogen gas explosion overpressure was analyzed and compared with experimental values of hydrocarbon-based combustible gases (butane and LPG (propane 98%)). The experimental database can be used for explosion risk analyses of ships when designing ventilation holes and piping systems and developing new safety guidelines for hydrogen carriers and hydrogen-fueled ships.

Numerical simulation study on optimization of ventilation airflow organization of a raw coal bunker

For the problem of gas accumulation in the product bunker of a company’s coal processing plant, three different ventilation schemes are proposed. The first one opens rectangular air inlet louvers on the wall of the product bunker and adds fans on the top for exhaust; the second one sets six ventilation windows evenly on the top of the product bunker for natural ventilation; the third one sends air to the interior of the bunker through small holes evenly distributed on the ventilation pipes and opens six exhaust ports on the wall. Finally, the effect of gas accumulation management of the ventilation scheme is simulated and analyzed through numerical simulation. The ventilation scheme is applicable to the gas accumulation management of raw coal bunkers with different coal storage heights, and provides a technical reference for the gas accumulation management of product bunkers in coal processing plants.