Smoke Generation Research Articles

Оценка выполнения условия безопасной эвакуации из детских игровых помещений при пожаре

PURPOSE. Soft children's toys located in children's playrooms are ones of the most dangerous combustible materials. However, their fire hazardous properties, data on which are necessary to calculate the time of blocking escape routes from the above mentioned rooms in case of fire, have not been studied. The study is aimed at assessing the compliance with the conditions for safe evacuation from children's play rooms, taking into account experimental data on the formation of dangerous fire factors when soft toys burn. To achieve the goal, experimental studies on the specific smoke generation coefficient of soft toy samples have been carried out. METHODS. The work uses an experimental standard method for measuring smoke production capacity. Numerical experiments have been carried out to calculate the time of blocking evacuation routes by dangerous fire factors. FINDINGS. The results of measuring the smoke-generating ability of soft toy samples made in China are presented. It has been shown that the smoke generation coefficient of soft toys significantly exceeds the corresponding values for rooms with similar functional purposes. Based on the obtained experimental data and a review of literature sources, a new fire load “soft children's toys” is proposed. The authors present the results of calculating the time of blocking evacuation routes using the analytical solution of the integral model for children's playrooms of various sizes and heights in cases of the proposed fire load, which is most dangerous for rooms of similar functional purposes given in the regulatory documents. It has been found that the condition for safe evacuation during free development of fire is not met. At the same time, loss of visibility is the first dangerous factor of a fire, blocking escape routes, and the highly toxic gas – phosgene – has the shortest blocking time among toxic gases. RESEARCH APPLICATION FIELD. The data obtained can be used to calculate fire risks in children's play rooms of preschool institutions and multifunctional shopping and entertainment centers. CONCLUSIONS. When calculating fire risks in children's play areas, which contain a lot of soft toys, it is necessary to use the proposed fire load “soft children's toys”.

Effects of Optical Properties of Smoke Particles on Fire Detection Characteristics predicted by a Fire Dynamic Simulator Model

This study examined the smoke detection time prediction performance of the Fire Dynamics Simulator (FDS) in relation to the optical properties of smoke particles. Specifically, this work explored how smoke detection times are affected by the mass-specific light extinction coefficient, an input value needed to predict FDS smoke detection times. Therefore, a smoke generator and a smoke detection sensor that employs the light extinction principle were installed in a fire compartment, with the mass-specific light extinction coefficients of the smoke particles generated by the smoke generator measured through Gravimetric Sampling and Light Extinction (GSLE) experiments. FDS fire simulations were performed under the same conditions as the smoke detection experiments to compare the Optical Per Meter (OPM) of the detector. The results confirmed that the F DS fire simulation was consistent with the smoke detection experiments when the measured mass-specific light extinction coefficient of the smoke particles was entered as input. In addition, it was found that fluctuations in the mass-specific light extinction coefficient, an optical property of smoke particles, may significantly affect smoke detection times by directly affecting the OPM.

Exhaust Smoke Validity of Vertical Shaft in Restrooms using the Stack Effect

This study is performed to validate a quantitative relationship between the exhaust rate through vertical shaft, which are used for restroom ventilation, and smoke generation based on NFSC 501. The exhaust rate is calculated using heat balance equations and is based on the input and exhaust air temperatures. The neutral plan in the vertical shaft was formed at approximately 46% of the total height. Because the smoke that is exhausted through the vertical shaft is more than 20% of the minimum smoke generation suggested by NFSC 501, the smoke exhaust through the vertical shaft is considered to be possible.

Fire Protection of Wood and Structures with Mineral Paints

The paper presents the results of fire tests of mineral paint for wood and structures based on it. Mineral paint tests were carried out in accordance with the EN 13823: 2010 + A1: 2014 (SBI method) procedure, namely: the rate of heat release, smoke generation, total heat release, total smoke generation, indices of ignition rate and smoke content were determined. It has been established that mineral paint is characterized by non-combustibility, absence of flaming particles and droplets, burning droplets; lateral flame spread to the edge of the substrate. Mineral paint, during the fire test, has low heat generation, smoke generation and combustion rate. The indicated indicators are achieved due to the compositional composition of the mineral paint and primer, as well as the mechanism of their action.

Preparation of a Reactive Phosphorus/nitrogen-Based Intumescent Flame Retardant Coating for Cotton Fabrics

ABSTRACT This study focuses on the synthesis of a reactive phosphorus-/nitrogen-based intumescent flame retardant (IFR) agent using diethyl phosphite, urea, and glutaraldehyde through Kabachnik-Fields reaction. We further studied the potential applications in IFR modification of cotton fabrics through surface coating approach. The chemical structure of IFR agent and its potential grafting action with cotton fibers were characterized. The thermal stability, smoke and heat release performance, flame retardancy, and durability of the IFR-coated cotton fabrics were explored. Char residue analyses were also performed to confirm the FR mechanism of IFR coating. The results revealed that IFR coating significantly inhibited the heat and smoke generation of cotton. The IFR coating showed high functional efficiency due to phosphorus/nitrogen synergism. The IFR-coated fabrics passed vertical burning B1 level and obtained an limiting oxygen index (LOI) value of higher than 32.0%. The introduction of IFR coating to cotton by covalent bonds imparted excellent washing resistance to cotton as indicated by the self-extinguishing action of the IFR-coated cotton fabrics after 10 launderings. In general, the present study offers a novel strategy to prepare reactive and efficient IFR coating for cellulose-based textiles.

Combustion characteristics and fire hazard of polystyrene exterior wall thermal insulation materials

AbstractTo study the combustion characteristics and fire hazard of polystyrene building exterior wall thermal insulation materials, the combustion, fire, and pyrolysis characteristics of thermosetting polystyrene (TPS) insulation, graphite polystyrene (GEPS), and expanded polystyrene (EPS) are compared and analyzed using a cone calorimeter and a thermo‐gravimetric analyzer. From the structure and flame retardant components of thermal insulation board, their flame retardant mechanisms are described. Results show that in a nitrogen atmosphere, the pyrolysis range is 30–600°C. Only one weight loss stage in EPS and GEPS and two weight loss stages in TPS are observed. Comparison of the combustion characteristics of the three demonstrates that TPS has short ignition time, low fire performance index. This result indicates that TPS has the characteristics of good flammability and easy to explode. The smoke generation rate, total smoke production, time heat release index and total heat release of TPS are lower than those of EPS and GEPS. This result indicates that the fire thermal hazard and fire smoke risk of TPS are relatively small. Comparison of various indexes presents that the flammability and fire risk of TPS are evidently better than those of EPS and GEPS.

Особенности оценки пожарной опасности и выбора теплоизоляционных материалов для трубопроводов и оборудования в зданиях и сооружениях

Thermal insulation of pipelines, in addition to energy-saving functions, must ensure the operational reliability and safety of the functioning of heating systems, water supply, heating networks, technological systems and air conditioning in industrial, public, and residential buildings and structures. Use of fire-hazardous thermal insulation of the pipelines and equipment during an ignition creates conditions for the development of a fire, the manifestation of its hazardous factors, which can lead to material damage and death of people. Analysis of the normative documents regulating the installation and operation of thermal insulation for pipes and equipment showed that the fire safety requirements are established only with respect to the combustibility group of thermal insulation materials. At the same time, their ability to spread flame over the surface, smoke formation and the release of gaseous toxic combustion products are not considered. The article presents the results of experimental studies of the complex of fire hazard characteristics of pipe insulation materials, and the study of methodological features of assessing their combustibility group according to GOST 30244 (method 2). The expediency is identified concerning the formulation of the principles of fire-fighting rationing of the pipelines and equipment for industrial, production, residential and public buildings (premises) and structures. These criteria set limits on combustibility, flammability, flame spread, smoke generation and the release of toxic combustion products. It is determined that the selection and justification of fire hazard indicators can be performed for thermal insulation of pipes and equipment with various functional purposes, applications, and technological features.

Comprehensive Satellite Observations and a Numerical Study of a Wintertime Shallow Sea Smoke Event in the Yellow Sea

Abstract A winter storm triggered a significant sea smoke with the northwesterly wind to the Yellow Sea, China, on 7 January 2021. The ocean responses to this event lasted about 3 days. Satellite observations show that the sea surface temperature dropped from 5.7° to 4.7°C on the following day and then recovered to the previous level; the chlorophyll-a, a bio-growth indicator, increased from 3.6 to 3.9 mg m−3 due to cooling-induced coastal upwelling between 7 and 9 January. Two buoys measurements showed that the air temperature dropped to −13.3°C and high relative humidity with a maximum value of 89.0% above the sea surface, creating favorable conditions for sea smoke generation. A Regional Ocean Modeling System (ROMS) and Weather Research and Forecasting (WRF) Model coupled model with the Goddard Chemistry Aerosol Radiation and Transport (GOCART) chemical module was implemented to reproduce this sea smoke phenomenon and analyze the air–sea interaction. The 20°C temperature difference between extreme cold air (−13.3°C) and the relatively warm stable sea surface (4.7°–5.7°C) enhanced the seawater evaporation. In addition, we suppose the concentration of sea salt, a kind of condensation nucleus, with a particle diameter of 0.5–1.5 μm above the sea surface increased quickly on 7 January. The boiling-water-like sea surface was imaged on a synthetic aperture image. We developed an image analysis method to describe the cell-shaped texture characteristics imaged by Synthetic Aperture Radar (SAR). We also found that the sea surface imprints of sea smoke are governed by the thermal, not the dynamical instability. Significance Statement On 7 January 2021, a significant sea smoke event happened in the Yellow Sea. The ocean response to the event lasted 3 days. First, on a synoptic scale, this study presents the comprehensive satellite observations of the sea surface temperature drop and chlorophyll-a increase associated with the sea smoke. Second, a coupled air–sea interaction model with the Goddard Chemistry Aerosol Radiation and Transport (GOCART) chemical module was implemented to reproduce this sea smoke phenomenon and identify which condensation nucleus induced such heavy sea smoke. Third, we developed an image analysis method to analyze high-resolution synthetic aperture radar images and found that the sea surface imprints of sea smoke are governed by the thermal, not the dynamical instability.

Local Heat Transfer Measurements for an Impinging Synthetic Jet

Abstract Research results demonstrate the heat transfer effectiveness of an impinging synthetic jet toward cooling a plane normal to it. The utility of the synthetic jet lies in that the supply of coolant comes from the device itself as an alternating jetting flow that emerges from a plenum followed by a sink flow that returns to that same plenum. Experiments reported herein were conducted with the synthetic jet driven by an oscillating diaphragm powered by a rotating cam to expel fluid from the plenum out of a single hole, then return it through the same hole. The frequency of diaphragm oscillation and the distance from the synthetic jet's orifice to the surface being cooled are varied in the test program to determine their effects on cooling performance. A numerical study agrees with the results given by the experiment and flow visualization utilizing a smoke generator supports the data and numerical results. The local, time-average Nusselt numbers were measured in the experiment using the thermochromic liquid crystal technique and air as coolant. The color display of each test case was recorded with a fisheye camera. In the case of the highest frequency and shortest distance from orifice to cooled plate, a Nusselt number of nearly 40 was achieved within the central region of the cooled plate when the Reynolds number based upon jet maximum velocity and orifice diameter was 7500 and the distance from the orifice to cooled plate was 3.2 orifice diameters.

Direct adsorption sampling and ambient mass spectrometry analysis of tobacco smoke with porous paper strips.

Chemical analysis of atmospheric aerosols by conventional analytical methods is usually required to perform complicated and time-consuming sample preparation processes. In recent decades, ambient ionization mass spectrometry (AI-MS) methods have been proven to be simple, rapid, and effective analytical tools for direct analysis of various complex samples. In this work, we applied porous paper filters for direct adsorptive sampling of tobacco smoke, and then the sampled paper filters were performed the emitters of the paper spray ionization (PSI) device. An auto-sampling device was made to control the generation and collection of tobacco smoke. Nicotine, the typical compound of tobacco smoke, was used to optimize the key conditions of auto-sampling. Moreover, different types of tobacco smoke were also compared with multivariate variable analysis, and the makers of tobacco smoke from different sources of tobacco smoke were investigated. By using this method, direct sampling and analysis of a single tobacco sample can be completed within minutes. Overall, our results show that PSI-MS is a powerful tool that integrates collection, extraction, ionization, and identification analytes in smoke.

Improving the Reaction-to-Fire Properties of Thermoplastic Polyurethane by New Phosphazene-Triazinyl-Based Covalent Organic Framework.

In this study, an approach to simultaneously improve fire resistance and mechanical performance of thermoplastic polyurethane (TPU) was introduced through the penetration of a conjugated network containing nitrogen and phosphorus elements. For this purpose, a Bg-HCCP COF was synthesized through a solvothermal method from benzoguanamine (Bg) and hexachlorophosphazene (HCCP) monomers. Then, it was combined with TPU using the wet mixing method. The TPU/Bg-HCCP composites showed better mechanical strength than the untreated sample. The fire safety of TPU/Bg-HCCP composites was greatly improved by increasing the Bg-HCCP contents. The reduction of the peak heat release rate and the total heat release for the TPU/Bg-HCCP composite with 3 wt % Bg-HCCP were about 44.8 and 60.4%, respectively. Besides, the results showed that adding Bg-HCCP to TPU significantly improved the suppression of smoke generation so that 3% by weight of the fire retardant reduced the total smoke released by 53.1%. It also decreased the peak of the carbon monoxide production rate by 26.5%. Generally, our research provides a promising strategy for constructing flame-retardant composites with high performance.

Experimental Study of a Hybrid Turbine for Hydrokinetic Applications on Small Rivers in Malaysia

Energy consumption has become a primary commodity due to technological revolutions in developing countries, such as the expansion of the hydrokinetic turbine as a renewable energy source to mitigate environmental issues. However, conventional vertical axis turbines in hydrokinetic applications particularly for small rivers with low speeds, have limited capabilities such as great power but poor self-start or vice versa. Therefore, the current study aims to address this issue by investigating a hybrid turbine through quantitative and qualitative wind tunnel experiments to improve the performance and self-start capability by integrating Savonius and Darrieus turbines. The findings discovered that the maximum torque coefficient of the hybrid turbine is 37% higher than that of a single conventional Savonius turbine. The integration of the hybrid turbine has resulted in a higher torque coefficient which has enhanced the self-start performance. The hybrid turbine achieved a maximum power output improvement of 30% at a low Reynolds number of 89500, typically representing the small river flow conditions. The presence of a substantial wake captured by the smoke generator at the rear part of the hybrid turbine signifies large drag resulting in power loss and a subsequent decrement in power output. The hybrid turbine has demonstrated its potential to be implemented in hydrokinetic applications in developing countries such as Malaysia for sustainable energy generation.

Bioinspired multilayer multiscale architectures into PDMS for simultaneously enhancing the thermal conductivity and flame retardancy

Combing high thermal conductivity and excellent flame retardancy is crucial for the development of thermal management composites. Herein, we report a bioinspired multilayer multiscale architecture comprising nanoscale MXene as the protective layer 1, atomic Cu2+ coordination molecular scale dendritic PEI as the protective layer 2 and encapsulated flammable PDMS as a matrix. Upon exposure to flame, the two layers can hinder polymer combustion, wherein MXene nanosheets and PEI-Cu serve as a barrier and thermally conductive layers, as well as catalytic and adsorption layers, respectively. As a result, the as-prepared PDMS composites exhibit a high out-of-plane thermal conductivity of ∼0.60 W m−1k−1, a reduced heat release rate and extremely low smoke (CO and CO2) generation at low filler loadings, suggesting excellent smoke suppression and toxicity reduction. This study provides a new strategy for the development of polymer composites with high thermal management capabilities and excellent flame retardancy.

In-situ fabrication of a sustainable, synergistic and durable flame-retardant coating for phytic acid modified silk fabric

BackgroundThe novel strategies for fabricating durable flame retardant (FR) silk fabric with biomass phytic acid (PA) is of interest. MethodIn this study, a highly sticky coating was in-situ developed on the surface of silk fabric by adsorption of PA, 1,4-Phthalaldehyde and followed by adsorption of 3-aminopropyltriethoxysilane (KH550). The Schiff base reaction would occur between 1,4-Phthalaldehyde and silk fiber/KH550, and thus the sticky coating could be firmly grafted on silk surface. The thermal degradation, smoke and heat emission properties, flame retardancy, and washing durability of coated silk were explored. Significant findingsThe FR coating displayed high functional efficiency and thermal stability by taking advantage of synergistic effect with phosphate groups and silica networks. The modified silk fabrics also possessed lower fire hazards as suggested by significantly reduced smoke and heat generation. The coated silk fabrics self-extinguished and obtained a char length of 13.5 cm after 20 washing cycles. The improved washing resistance should be ascribed to the covalently grafted sticky coating on silk surface. In general, this work reports a novel and feasible strategy to develop durable silk textile using bioderived PA.

Smoke Emission and Distribution Characteristics of Overloaded Wire Insulations under Microgravity

With the development of manned space technology, spacecraft safety and fire prevention have attracted more and more attention. Due to the disappearance of buoyancy in microgravity, the fire early monitoring, detection and alarm technologies designed based on the ground experimental results are not suitable for spacecraft. It is necessary to develop fire early monitoring technology in microgravity. Smoke is an important early monitoring signal for fire prevention both in normal gravity and microgravity. Under microgravity, fire is mostly caused by overload or aging of wire insulations. In order to study the smoke emission characteristics of wire insulations under microgravity, we carried out the overload experiments of wire insulations on board the SJ-10 Chinese recoverable satellite. The smoke generation characteristics captured by laser extinction methods, and a large number of experimental data in the real microgravity environment were obtained for the first time. In this paper, the smoke volume fraction in the early and axisymmetric stages of smoke emission from the wire insulating layer are obtained by using the method of Abel transform and convolution, and the MATLAB algorithm program is compiled. In the later stage of smoke emission, it does not show axisymmetric distribution, but the laser extinction results can be used for obtaining the smoke emission trajectory. According to the results, edge jet smoke emission modes in the early stage of ignition of wire insulation in microgravity are quantitatively analyzed. The effects of insulation thickness, overload current and insulation material on smoke emission are discussed.

Numerical visualization of wind turbine wakes using passive scalar advection–diffusion equation and its application for wake management

To visualize and characterize the unsteady properties of the wake trailing behind a wind turbine, we propose a novel numerical methodology in this study. Through a wind-tunnel experiment using a smoke generator, we succeeded in visualizing a compact-type small-scale wind turbine wake using continuous scalar plumes from a single point source. Next, to simulate the above wind-tunnel experiment, we proposed a method using the passive scalar advection–diffusion equation based on a high-fidelity large-eddy simulation (LES). The actuator-line method (ALM) was adopted for the wind turbine model. We succeeded in qualitatively reproducing the wake visualization experiment in the wind tunnel described above and verified the effectiveness of the proposed numerical visualization method. To evaluate the characteristics of wakes generated by wind turbines in more detail, we conducted a quantitative comparison using a disk-shaped volume source with the same size as the swept area, set behind the wind turbine model. The results indicated that the non-dimensional time-averaged passive scalar profile in the near- and far-wake regions qualitatively matched the shape of the stream-wise velocity profile, despite having opposite signs. In other words, it was shown that if a disk-shaped volume source with the same size as the swept area is placed just behind the wind turbine, it is possible to accurately predict the behavior of the wind turbine wake. Finally, to validate the proposed method for wind farm wake management, we performed a visualization of wake flows in a virtual offshore wind farm consisting of 12 wind turbines with short separation distances. Through detailed comparison of two types of numerical results with different wind directions, we showed that the proposed method can effectively demonstrate the range of spatial influence of the wakes formed by the wind turbine with special attention.

Particle tracer analysis for PIV experiments in a closed loop transonic wind tunnel

A performance study of several tracer particles for PIV has been conducted. The study included particle response time analysis of an oblique shock wave generated by a conical nose of a store model in a closed loop transonic wind tunnel, and in-situ measurements of the particle size distribution in a low-speed wind tunnel facility. From the oblique shock wave analysis, the estimated particle response time for different smoke materials and generator settings was of the order of 1.4 - 2.2 μs and the effective particle size was 0.58 - 0.85 μm, which was much larger than the measured geometric mean particle size. This larger size was mainly attributed to the correlation bias towards larger particles in PIV measurements. The effective particle size from the particle response time analysis accounts for the holistic performance of the PIV system. Additionally, particle response analysis was performed on ambient water droplets resident in the tunnel. The estimated particle response time for the water droplets was in the order of 3.4 μs and the effective particle size was 0.97 μm, revealing inferior performance compared to the smoke particles.

Management of the Common Vole in the Czech Lands: Historical and Current Perspectives

The integrated management of a serious agricultural pest, the common vole (Microtus arvalis), should be based on modern and empirically proven approaches. The aim of this paper was to map the historical development of the monitoring and control practices of the common vole in the Czech Republic (CR) territory. Published records of vole population outbreaks and heavy crop damage have been documented in the Czech literature since the turn of the 20th century, and even in crops planted in highly fragmented and diversified agricultural landscapes. In the CR, systematic state monitoring was introduced in 1955. In the 1930’s, there were more than 100 various rodent preparations against the common vole, which were formulated as smoke generators, gases, baits, dusts, toxic mushy mass, and insecticide sprays. Currently, there are only six preparations with three active ingredients registered in the CR. Zinc phosphide is the only active ingredient that has been used from the 1940s to the present, whereas anticoagulants were banned for vole control in 2011 owing to the high environmental risks. The poisoning of nontarget animals by rodenticides is not a new phenomenon tied to synthetic pesticides; poisoning by botanical extracts (strychnine) was documented more than 100 years ago. This review may provide both historical lessons for current practice and new incentives for future research.

자체 제작된 리튬이온 배터리팩의 과충전에 따른 화재위험성 연구

Lithium-ion battery packs are used in various electronic devices such as camping batteries, electric kickboard, and supplementary battery due to their high volumetric energy storage density. Recently, however, as more and more people make and use outdoor lithium-ion battery packs such as hiking, fishing, and camping, there is a battery fire while charging their own battery packs. This paper investigated the operating principle of these battery packs and conducted a study on the fire risk caused by overcharging in the presence or absence of lithium-ion batteries with the same capacity, lithium-ion batteries with different capacity, and PCM(Protection Circuit Module). As a result of the overcharging experiment, the battery pack was completely destroyed combustible gas and smoke generation near the lithium-ion battery anode of the battery pack without a protection circuit, followed by explosive combustion accompanied by flame. Vent and safety devices(PTC, CID) could be observed to have been lost due to overcharging explosion pressure.

Selective laser sintering of PEG treated inorganic fullerene-like tungsten disulfide nanoparticles/polyamide 12 nanocomposites and fire safety behavior

Research has focused on developing advanced polyamide 12(PA12) engineering plastics with low flammability and low levels of smoke evolution during combustion. To satisfy green and safe industrial criteria, it is essential to minimize the emission of smoke and harmful gases generated during the burning of PA12. As a result, utilizing inorganic fullerene-liked tungsten sulfide (IF-WS2) nanoparticles as the precursor and polyethylene glycol (PEG) as the interfacial functional agent, a flame retardant grafted with the –OH functional group on the surface of IF-WS2 nanoparticles was designed and synthesized. Selective laser sintering (SLS) was used to fabricate the PA12/F-IF-WS2 nanocomposites. The multiple –OH groups provided by PEG could enhance the hydrogen bonding active sites of F-IF-WS2 nanoparticles and PA12 molecular chain groups, which could further boost the flame-retardant efficiency of PA12. The apparent decline in the peak heat release (26.55%), peak smoke generation (23%), and total CO production (40.4%) values proved the increased fire safety of the PA12 composite. Depending on the characterization results, a possible flame-retardant mechanism was proposed. Furthermore, the addition of F-IF-WS2 had a decisive effect on mechanical properties, including tensile properties, and dynamic mechanical properties. The PA12/F-IF-WS2 nanocomposites prepared using SLS molding provide a new direction for preparation and flame-retardant applications.