scholarly journals Experimental Studies on High Efficiency Flow Straightener for Fire Extinguishing Equipment

2011 ◽  
Vol 31 (2) ◽  
pp. 9-14
Author(s):  
Hiroshi IBARAKI ◽  
Katsumi AOKI ◽  
Hiromu HASHIMOTO
Keyword(s):  
High Efficiency ◽  
Experimental Studies ◽  
Fire Extinguishing

scholarly journals Experimental Investigation and Comparison of the Thermal Performance of Additively and Conventionally Manufactured Heat Exchangers

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 574
Author(s):  
Ana Vafadar ◽  
Ferdinando Guzzomi ◽  
Kevin Hayward
Keyword(s):  
Surface Roughness ◽  
Thermal Performance ◽  
Heat Exchangers ◽  
High Efficiency ◽  
Cooling System ◽  
Fluid Dynamic ◽  
Dynamic Performance ◽  
Experimental Studies ◽  
Manufacturing Method ◽  
Industrial Sectors

Air heat exchangers (HXs) are applicable in many industrial sectors because they offer a simple, reliable, and cost-effective cooling system. Additive manufacturing (AM) systems have significant potential in the construction of high-efficiency, lightweight HXs; however, HXs still mainly rely on conventional manufacturing (CM) systems such as milling, and brazing. This is due to the fact that little is known regarding the effects of AM on the performance of AM fabricated HXs. In this research, three air HXs comprising of a single fin fabricated from stainless steel 316 L using AM and CM methods—i.e., the HXs were fabricated by both direct metal printing and milling. To evaluate the fabricated HXs, microstructure images of the HXs were investigated, and the surface roughness of the samples was measured. Furthermore, an experimental test rig was designed and manufactured to conduct the experimental studies, and the thermal performance was investigated using four characteristics: heat transfer coefficient, Nusselt number, thermal fluid dynamic performance, and friction factor. The results showed that the manufacturing method has a considerable effect on the HX thermal performance. Furthermore, the surface roughness and distribution, and quantity of internal voids, which might be created during and after the printing process, affect the performance of HXs.

scholarly journals Experimental Evaluation of Airlift Performance for Vertical Pumping of Water in Underground Mines

2021 ◽  
Author(s):  
Parviz Enany ◽  
Oleksandr Shevchenko ◽  
Carsten Drebenstedt
Keyword(s):  
Water Flow ◽  
High Efficiency ◽  
Experimental Studies ◽  
Theoretical Models ◽  
Injection System ◽  
Experimental Investigations ◽  
Flow Mode ◽  
New Device ◽  
Riser Pipe ◽  
Airlift Pump

AbstractThis paper presents experimental studies on the optimization of air–water flow in an airlift pump. Airlift pumps use compressed gas to verticall transport liquids and slurries. Due to the lack of theoretical equations for designing and predicting flow regimes, experimental investigations must be carried out to find the best condition to operate an airlift pump at high efficiency. We used a new air injection system and different submergence ratios to evaluate the output of a simple pump for vertical displacement of water in an underground mine. The tests were carried out in a new device with 5.64 m height and 10.2 cm circular riser pipe. Three air-jacket pipes, at different gas flows in the range of 0.002–0.09 m3/s were investigated with eight submergence ratios. It was found that with the same air flow rate, the most efficient flow of water was achieved when an air jacket with 3 mm diameter holes was used with a submergence ratio between 0.6 and 0.75. In addition, a comparison of practical results with two theoretical models proposed by other investigators showed that neither was able to accurately predict airlift performance in air–water flow mode.

The Study of Fire-extinguishing Process of Modelled Fire Seats

2021 ◽  
pp. 57-62
Author(s):  
V.N. Bordakov ◽  
Keyword(s):  
Flow Rate ◽  
Experimental Studies ◽  
Physical Modelling ◽  
Specific Flow Rate ◽  
Specific Flow ◽  
Acceptable Error ◽  
Fire Extinguishing ◽  
Fire Zone ◽  
Analysis Of Results ◽  
Fire Extinguishers

Test-fires to determine fire-extinguishers’ efficiency for extinguishing B class fires are conducted by operators equipped with working clothes, which does not comply with the requirements of physical modelling. This is why the ranks of extinguished modelled seats are significantly overestimated. The quantitative results of fire seats’ extinguishing can be comparatively evaluated in accordance with the value of specific flow rate of a fire-extinguishing agent. As it was detected, the specific flow rate of a fire-extinguishing agent does not actually depend on the rank of modelled fire seat when extinguished by an operator wearing thermal-protective clothes. At the same time, it is increasing along with the expansion of the fire zone scale in case the fire is extinguished without special protective clothes. Consequently, to increase the fire-extinguisher’s efficiency data reliability, the certifying tests should be conducted in conditions close to the real application conditions when the first person to firefight is not equipped with such special protective clothes. The experimental studies to determine the specific flow rate of a fire-extinguishing agent used modelled fire seats of various ranks. The analysis of results showed that the fire-extinguishers ensuring generation of drops of prevailing size more than 0,5 mm are required to extinguish the modelled sire seats. The degree of increasing flow rate for the fire-extinguishing agent to eliminate a fire and observation of a safe distance from the flame for an operator are conditioned by the scale of fire zone and affect the specific flow rate of agent required to ensure stable fire-extinguishing. Based on the results of extinguishing the fire seats «34В» or «55В», it is demonstrated that via using a correction factor it is possible, assuming an acceptable error, to evaluate the flow rate of fire-extinguishing agent to extinguish a modelled fire seat of any rank.

scholarly journals COHERENT PROPAGATION OF LASER BEAMS IN MCF FIBERS

2019 ◽  
Vol 47 (1) ◽  
pp. 21-23
Author(s):  
A.A. Balakin ◽  
S.A. Skobelev ◽  
A.V. Andrianov ◽  
E.A. Anashkina ◽  
A.G. Litvak
Keyword(s):  
Solid State ◽  
Optical Fibers ◽  
High Efficiency ◽  
Radiation Power ◽  
Experimental Studies ◽  
Pump Energy ◽  
Total Power ◽  
Beam Power ◽  
Self Focusing ◽  
Weakly Coupled

The successful development of fiber-optic technologies in recent decades has stimulated research on the replacement of components of solid-state laser systems with fiber components, which can drastically change the attractiveness of the corresponding applied developments. Yielding on the energy characteristics of solid-state systems, fiber lasers and nonlinear optical devices have high efficiency of conversion of pump energy to radiation energy associated with waveguide geometry, high quality of the spatial profile of the laser beam, as well as low cost, compactness, lack of alignment in work process. Note that the maximum achievable radiation power in a single fiber is limited primarily by the process of self-focusing, which leads to fiber damage. The use of a multi-core fiber (MCF), consisting of identical equidistant weakly coupled optical fibers, makes it possible to realize initially coherent propagation of laser radiation with a total power noticeably higher than it can be transmitted in a single optical fiber. However, as theoretical and experimental studies have shown, such systems have its own critical power (Balakin et al., 2016) whereby the self-focusing of the quasihomogeneous distribution of the wave field and its separation into a set of incoherent structures occurs. Therefore, we have considered a small-sized optical system of 2N identical weakly coupled optical fibers arranged in a ring (Balakin et. al., 2018). In such systems, it is possible to find stable distributions of intense wave beams, which allow coherent radiation transport over long distances. The total radiation power in the found distributions can significantly (up to 2N times) exceed the critical self-focusing power in continuous media. This manifests itself most clearly for the distribution of un ~ (-1)n with antiphase fields in neighboring waveguides, which is stable at an arbitrary wave beam power. Direct numerical simulation of a nonlinear wave equation confirms the stability of the field distributions found. The research was supported by the RAS Presidium Program «Nonlinear dynamics: fundamental problems and applications».

scholarly journals Load characteristics of three-plunger pumps for spray seawater fire-fighting

2020 ◽  
pp. 142-146
Author(s):  
В.А. Наумов ◽  
Н.Л. Великанов ◽  
А.В. Тришина
Keyword(s):  
Satisfactory Agreement ◽  
Test Data ◽  
High Efficiency ◽  
Measurement Data ◽  
Fire Fighting ◽  
Test Results ◽  
Hydraulic Characteristics ◽  
Fire Extinguishing ◽  
Load Characteristics ◽  
Low Pressures

Цель статьи – получить эмпирические зависимости для характеристик трехплунжерных противопожарных насосов (ТПН), необходимые для автоматизации расчетов систем тушения пожаров на судах с применением распыленной морской воды. Задачи исследования: проверка непротиворечивости данных испытаний; определение расчетных зависимостей производительности ТПН, к.п.д., затраченной мощности от давления. Проведенный анализ результатов испытаний ТПН подтвердил возможность использования предложенных зависимостей в инженерных расчетах. Данные измерений удовлетворительно согласуются с результатами расчетов, за исключением к.п.д. Отклонение экспериментальных точек от эмпирических зависимостей, скорее всего, связано с занижением значений затраченной мощности на испытаниях при небольших давлениях. Предложено для оценки к.п.д. использовать ранее полученную типовую зависимость. Построены графики для характеристик насоса NP25/41-170S. Пример расчета рабочей точки насосной установки с использованием приближенной гидравлической характеристики водяной пожарной системы судна показал высокую эффективность предложенных методик. The purpose of the article is to obtain empirical dependences for the characteristics of three-plunger fire-fighting pumps (TFP), which are necessary for automating calculations of fire extinguishing systems on ships using sprayed seawater. Research objectives: checking the consistency of test data; determining the calculated dependences of the TFP performance, efficiency, power expended on pressure. The analysis of the TFP test results confirmed the possibility of using the proposed dependencies in engineering calculations. The measurement data are in satisfactory agreement with the results of calculations, with the exception of efficiency. The deviation of experimental points from the empirical dependences is most likely due to an underestimation of the power consumed during tests at low pressures. It is proposed to use the previously obtained typical dependence to estimate the efficiency. Graphs are plotted for the characteristics of the NP25/41-170S pump. An example of calculating the working point of a pumping unit using the approximate hydraulic characteristics of the ship's water fire system showed the high efficiency of the proposed methods.

scholarly journals A Novel Piezoceramic-Based Sensing Technology Combined With Visual Domain Networks for Timber Damage Quantification

2021 ◽  
Vol 8 ◽  
Author(s):  
Haibei Xiong ◽  
Lin Chen ◽  
Cheng Yuan ◽  
Qingzhao Kong
Keyword(s):  
Time Domain ◽  
Damage Assessment ◽  
Structural Damage ◽  
High Efficiency ◽  
Experimental Studies ◽  
Stress Wave Propagation ◽  
Timber Structures ◽  
Sensing Technology ◽  
The Time Domain ◽  
Visual Domain

Early detection of timber damage is essential for the safety of timber structures. In recent decades, wave-based approaches have shown great potential for structural damage assessment. Current damage assessment accuracy based on sensing signals in the time domain is highly affected by the varied boundary conditions and environmental factors in practical applications. In this research, a novel piezoceramic-based sensing technology combined with a visual domain network was developed to quantitatively evaluate timber damage conditions. Numerical and experimental studies reveal the stress wave propagation properties in different cases of timber crack depths. Through the spectrogram visualization process, all sensing signals in the time domain were transferred to images which contain both time and frequency features of signals collected from different crack conditions. A deep neural network (DNN) was adopted for image training, testing, and classification. The classification results show high efficiency and accuracy for identifying crack conditions for timber structures. The proposed technology can be further integrated with a fielding sensing system to provide real-time monitoring of timber damage in field applications.

Structure and properties of powders obtained by electrodispersion of corrosion-resistant metal waste in kerosine

2021 ◽  
pp. 276-281
Author(s):  
E.V. Ageeva ◽  
E.V. Ageev ◽  
A.A. Sysoev
Keyword(s):  
High Efficiency ◽  
Experimental Studies ◽  
Low Energy ◽  
Powder Materials ◽  
Energy Costs ◽  
Structure And Properties ◽  
Corrosion Resistant ◽  
High Chromium ◽  
Metal Waste ◽  
Industrial Use

The results of experimental studies of the structure and properties of electroerosive high-chromium powders obtained in kerosene are presented. The high efficiency of using the electrodispersing technology is shown, which provides for obtaining new corrosion-resistant powder materials suitable for industrial use at low energy costs.

scholarly journals Analysis of roof greening technology impact on rain and meltwater retention

2020 ◽  
Vol 175 ◽  
pp. 11023
Author(s):  
Elena Sysoeva ◽  
Margarita Gelmanova
Keyword(s):  
High Efficiency ◽  
Green Roof ◽  
Experimental Studies ◽  
Green Roofs ◽  
Climatic Conditions ◽  
Water Runoff ◽  
Substrate Thickness ◽  
Runoff Reduction ◽  
The Usa ◽  
Analytical Review

Over the past 20 years, a large number of studies have been published on reducing storm runoff by various types of green roofs. This article analyzes the results of experimental studies presented in 39 publications on green roof runoff reduction in a climate similar to the climate of Russia: in Canada, the USA, Finland, Norway, France. An analytical review found that the ability of green roofs to retain rainfall varies from 20 to 99.5% depending on climatic conditions (duration and intensity of rains, duration of dry periods, solar radiation, temperature and humidity, wind conditions), the properties of green roof layers (moisture capacity of the substrate and a drainage layer, the substrate thickness), the type of vegetation, the geometry of a green roof (slope and orientation). Green roofs can be a useful tool for reducing urban storm water runoff. However, in order to ensure high efficiency, it is necessary to use green roof technology with other measures to reduce runoff.

Sign in / Sign up

Export Citation Format

Share Document