Cup Burner Research Articles

Energy, Exergy and Economic Analysis of Boiler Systems

This paper presents a framework for energy, exergy utilization, and economic analysis of industrial steam boiler system in Nigerian Bottling Company (NBC), Enugu, Nigeria. The study was carried out by an investigative approach in which all other parameters were kept constant, and a particular one was varied, and the desired quantity measured. The results of the effects of burner rotary cup speed and fuel nozzle sizes on emissions show that for boiler having liquid fuel nozzle sizes 3mm, 4mm and 6mm and with constant fuel inlet temperature of 82oC were analysed. Nozzle size of 4mm diameter with burner rotary cup operating at speed of 2920rev/min to 3200rev/min generated minimum emission while burning fuel oil of 82oC with excess air of 12.36%. Similarly, nozzle size of 6mm with rotary cup burner operating between 3950rev/min to 4400rev/min at 12.36 % excess air generated no emission of CO and NOx. It was concluded that the combustor yielded the highest energy efficiency of 99.8% while the heat exchanger gave the lowest energy efficiency of 94% when run on both fuel oil and natural gas. This improved efficiency translates to a savings of approximately 89 million naira annually for a boiler operating at 46% availability yearly.

Enhancement and suppression of counterflow diffusion flame by HFC-125

Efficient fire extinguishing is a safety prerequisite for protecting the environment from fire damage. Understanding the effect of fire extinguishing agent on flame in complex environment is basic work for efficient fire extinguishing. We investigate the impact of HFC-125 on the extinguishment of propane-air highly stretched diffusion flames. Flame thickness is measured using the proportional method. Parameters such as dimensionless flame stand-off distance and flame stretch rate are calculated. Low concentrations of HFC-125 initially increase the flame thickness, but as the concentration increases further, the flame thickness decreases and the flame suppression effect of HFC-125 intensifies. HFC-125 reduces the amount of carbon soot generated and accelerates the transition from yellow to blue flame. Within a specific concentration range, N2 has a minimal effect on flame structural parameters compared to HFC-125. High concentration of N2 forms a high bright blue flame, while HFC-125 reacts with the flame to form a blue-violet flame. Compared to HFC-125, HFC-227ea can significantly reduce flame thickness and increase dimensionless flame stand-off distance, exhibiting a notable suppression effect. Furthermore, high concentrations of HFC-125 substantially reduce the critical flame stretch rate and provide a lower extinguishing concentration in counterflow diffusion flames than in the cup burner.

Inhibitory effects of water mist containing alkali metal salts on hydrogen–natural gas diffusion flames

Fire extinguishing technologies of fine water mist containing additives have good application prospects. Additives that are efficient, nontoxic, nonpolluting, widely used, economical and reliable provide a reference for the application and promotion of fine water mist fire extinguishing systems containing alkali metal salts. In this paper, six potential alkali metal salt additives were selected: potassium carbonate (K2CO3), sodium carbonate (Na2CO3), potassium oxalate (K2C2O4·H2O), potassium acetate (CH3COOK), potassium chloride (KCl), and potassium bicarbonate (KHCO3); these additives were delivered into the fires as mists of their solutions at certain concentrations, the extinguishing time was recorded, and the minimum fire extinguishing concentration (MEC) of fine water mist containing alkali metal salt was tested by using a cup burner experimental apparatus. In addition, different types of alkali metal salts were compared to determine the anions and cations with better fire suppression performance levels. The suppression efficiencies of different ratios of additive packages for hydrogen-doped natural gas diffusion flames were studied to determine a specific ratio of additive packages. Based on the results of the experiment, in contrast to the pure water mist, the suppression efficiency of alkali metal salt greatly improved. The cation extinguishing ability was K+>Na+, and CO32- and CH3COO− were better than other anions in alkali metal salts. An efficient compound additive was identified as 1.5% K2CO3 + 0.5% CH3COOK. With increasing hydrogen addition, the MEC of fine water mist with additives increased.

An improved method to determine the minimum extinguishing concentrations of ultrafine dry powder agents: Taking NaHCO3 and KHCO3 as examples

Ultrafine dry powder agents (UDPAs) are the most potential Halon substitutes due to the high extinguishing effectiveness and excellent environmental friendliness. Nevertheless, the method for obtaining minimum extinguishing concentration (MEC) is flawed and inaccurate. An improved method is proposed by developing the special laser measurement system without powder contamination, the concentration calibration test bench and the cup burner with uniform aerosol generating. The results show that the optimum calibration position is 0.35–0.65 m from the inlet in the y-axis coordinate. More accurate mathematical relationships between the transmittance of the laser measurement system and the NaHCO3 and KHCO3 powders are established, with the errors less than 12%. Upon reaching MECs in the modified cup burner, the flames pulsate, then fade and eventually die. Based on the phenomenon of the sudden change in the transmittance of the laser measurement system at the moment of flame extinguishment, i.e. the “step shape” curve, a more accurate critical criterion point for the MEC is proposed. The measured MECs for methane flames by NaHCO3 (32.2 g/m3) are approximately 4 times that of KHCO3 (8.2 g/m3), consistent with previous studies. The obtained MECs of NaHCO3 and KHCO3 for kerosene flame are verified by 1 m3 total flooding fire extinguishing experiments. The improved method may guide the design of industry fire protection systems based on UDPAs to achieve process safety.

Study on the Minimum Fire-Extinguishing Concentration of Several Commonly Used Extinguishing Agents to Suppress Pyrolysis Gas of Red Pine Wood.

The suppression of forest wood burning has been one of the important research directions in the field of solid combustible fire safety. The process of forest wood flame propagation is a coupled process of solid-phase pyrolysis and gas-phase combustion chemical reactions; therefore, as long as the solid-phase pyrolysis or gas-phase combustion can be suppressed, the forest wood flame propagation can be suppressed and an important contribution can be made to the subsequent suppression of forest wood fires. Previous studies have focused on the inhibition of solid-phase pyrolysis of forest wood, so this paper examines the effectiveness of several common fire suppressants for suppressing forest wood gas-phase flames, starting with the inhibition of forest wood gas-phase combustion. In this paper, for the convenience of the study, we narrowed the scope of the research object to the previous research ideas for gas fires, established a simplified small-scale flame model for forest wood fire suppression, took red pine wood as the research object, analyzed the pyrolysis gas components after high-temperature pyrolysis, and constructed a Cup burner suitable for N2, CO2, fine water mist, and NH4H2PO4 powder to extinguish the pyrolysis gas flame of red pine wood, respectively. The experimental system, together with the 9306 fogging system and the improved powder delivery control system, shows the process of extinguishing fuel flames such as red pine pyrolysis gas at 350, 450, and 550 °C with various types of fire-extinguishing agents on this device. It was found that the flame morphology was related to the composition of the gas and the type of extinguishing agent. At the same time, NH4H2PO4 powder appeared to burn above the cup mouth when pyrolysis gas interacted with it at 450 °C, but this phenomenon did not occur when other extinguishing agents interacted with it and only appeared when pyrolysis gas interacted with it at 450 °C, so it was judged that this phenomenon was related to the CO2 content of the gas component and the type of extinguishing agent. The study found that the four extinguishing agents extinguish red pine pyrolysis gas flame MEC value. There's a big difference. The worst performance is N2. Compared with N2 suppression of red pine pyrolysis gas flame, CO2 suppression effectiveness is 60% higher, but compared to the suppression effectiveness of fine water mist and far away, the suppression effectiveness of fine water mist is much higher than the suppression effectiveness of CO2. However, the difference in effectiveness between fine water mist and NH4H2PO4 powder is almost double. In summary, in the suppression of red pine gas-phase flame, four kinds of fire-extinguishing agents are ranked as follows: N2 < CO2 < fine water mist < NH4H2PO4 powder. Finally, the suppression mechanism of each type of extinguishing agent was analyzed. The study of this paper can provide some data to support the extinguishing of open fires in forest fires or suppressing the rate of forest fire spread.

Fire suppression using trifluoroiodomethane (CF3I)-carbon dioxide (CO2) mixtures

With the regulatory prohibition for using Halon 1301 (CF3Br) in fire suppression systems onboard newly certified aircraft, significant research efforts have been undertaken to develop suitable halon replacements with comparable suppression performance that are also eco-friendly with low Ozone Depletion Potential (ODP) and Global Warming Potential (GWP). This paper determined the fire suppression effectiveness for mixtures of trifluoroiodomethane (CF3I) with carbon dioxide (CO2) under development as a drop-in halon replacement for onboard aircraft fire suppression systems. Through both experimental measurements and flame simulations using detailed chemical kinetics, we demonstrated that the extinguishment performance of CF3I-CO2 blends can be superior to that of the individual components alone. The extinction concentrations were determined for different CF3I-to-CO2 ratios introduced into ambient air using a heptane cup burner. The extinction concentrations for pure CF3I in air (3.36 ± 0.13% vol.) and CO2 in air (20.74 ± 0.64% vol.) are in close agreement with previously reported values, and first-time extinction concentration data for CF3I-CO2 blends are reported. To elucidate important reaction pathways, detailed chemical mechanisms have been compiled for modeling methane-, propane- and heptane-air flame inhibition at ambient conditions. These mechanisms were constructed from published sub-mechanisms for C7 and C1-C3 hydrocarbons and hydrofluorocarbons with additional oxidation chemistry developed for trifluoroiodomethane. The latter sub-mechanism contains 14 species and 91 reactions. Using the CANTERA software package, critical concentration values of CF3I-CO2 mixtures in air for extinguishing methane, propane, and n-heptane counterflow flames were determined and compared against experimental non-premixed flame extinction data.

A reduced kinetic scheme for methyl methacrylate gas-phase combustion

Gas-phase combustion of methylmethacrylate (MMA) monomer is an essential stage of solid polymethylmethacrylate (PMMA) combustion, which is of interest in many applications. A skeletal kinetic scheme for MMA combustion in air is proposed including 44 irreversible elementary reactions for 29 species. The mechanism is derived from the reduced kinetic scheme for MMA oxidation comprised of 263 reactions for 66 components. In this work, the mechanism predictive capabilities are demonstrated by solving the self-ignition problem, as well as the premixed flame propagation problem for MMA-air mixtures. It is shown that the skeletal mechanism overpredicts the ignition delay times due to significant simplification of the MMA decomposition stage reaction pathways. The flame propagation speed is predicted reasonably for lean and nearly-stoichiometric mixtures, but overpredicted for fuel-rich mixtures. Also, a diffusion flame representing the cup burner of liquid MMA is simulated in two-dimensional statement of the problem, the results are shown to agree well with the measurements and numerical simulations performed earlier on the basis of a detailed kinetic scheme. The skeletal mechanism can be used in the numerical simulations of gas-phase combustion of MMA, including the problems of flame propagation over the solid PMMA polymer.

Fire and explosion characteristics of vent gas from lithium-ion batteries after thermal runaway: A comparative study

The combustion and explosion of the vent gas from battery failure cause catastrophe for electrochemical energy storage systems. Fire extinguishing and explosion proof countermeasures therefore require rational dispose of the flammable and explosive vent gas emitted from battery thermal runaway. However, the fire and explosion nature of the multiphase vent gas remains unclear. This paper comparatively investigates the fire and explosion hazards of the vent gas emitted by different kinds of lithium-ion batteries after thermal runaway. Hazard data are collected for batteries with cathode LiNixCoyMnzO2 (x from 0.33 to 0.8) and LiFePO4, which are prevailingly used or to be used in energy storage scenarios. The composition and content of the vent gas were analyzed using a pressurized container and gas chromatography. A 1-liter explosion sphere was used to determine the explosion limits, explosion pressure, and maximum rise rate of explosion pressure for five cell chemistries at 298 K and 101 kPa absolute pressure. The laminar burning velocities of the five vent gases were measured by Bunsen burner. The minimum concentration of fire extinguishing agent was tested using a cup burner. The results show that the fire and explosion hazards posed by the vent gas from LiFePO4 battery are greater than those from Li(NixCoyMn1-x-y)O2 battery, which counters common sense and sets reminders for designing electric energy storage stations. We may need reconsider the choice of cell chemistries for electrical energy storage systems, and care more about the safety design against the fire and explosion disaster that may occur at system level. The explosion characteristics of the vent gases from five cell chemistries and the minimum fire extinguishing concentration can enlighten future risk assessments of electrochemical energy storage systems.

Study on the fire extinguishing efficiency and mechanism of composite superfine dry powder containing ferrocene

This paper reported that ferrocene was utilized as the additive for extinguishants to suppress combustion reaction, which was known as composite superfine dry power containing Ferrocene (CSFP-Fc). Gaussian was applied to simulate the chemical inhibition mechanism of CSFP-Fc. It verified that the addition of ferrocene can promote the fire extinguishing performance of superfine ABC dry powder (SDP) to some extent. By studying the fire extinguishing effect on liquid hydrocarbon flames in the cup burner, it was determined that the optimal mass fraction of ferrocene added was 4 wt%. Then the physical and chemical properties of CSFP-Fc were characterized by laser particle size analysis, scanning electron microscope (SEM), thermal gravity analyzer (TGA) and differential scanning calorimetry (DSC). The results indicated that CSFP-Fc had better fire extinguishing efficiency than ordinary ABC dry powder (ODP). Furthermore, the article confirmed that a more practical extinguishant was proposed and it can provide guidance for the application and development of extinguishants.

An Investigation of Rotary Cup Burner Assembly with Three Vehicle-Mounted Cooking Stoves by Numerical Evaluation Method

The adaptability of vehicle-mounted heating systems that include burner and stove remarkably influences the system efficiency, heat flux uniformity, and pollutants emission. In this work, the performance of a rotary cup burner assembly with three different cooking stoves was investigated using ANSYS Fluent software based on five factors of thermal efficiency, heat transfer intensity, heating uniformity, CO emissions, and flue gas outlet temperature. The Eulerian-Lagrangian method was used to perform the diesel spray, and the shear stress transfer k-ω turbulence model and the probability density function model were employed to simulate the turbulent combustion. Based on the simulation results, the performance pentagon of the above five factors was constructed to evaluate the comprehensive performance of the new rotary cup burner system. The rotary cup burner had a good performance when it is used in two staple food stoves and a subsidiary food stove. In staple food stove A, its higher furnace increased the heat exchange area of the vessel, while the higher fireboard of staple food stove B caused a higher heat transfer intensity at the bottom of the vessel. However, the higher fireboard also led to higher CO emissions. In consideration of these two factors, the thermal efficiency of stove A was about 7% higher than that of stove B. Different from the staple food stove, the furnace of subsidiary food stove C had better wrapping to the bottom of the boiler so that it had the highest heat transfer intensity. The obtained performance pentagon shows that the comprehensive adaptability performance of stove A was the best and that of stove B was the worst, which is mainly caused by the height of the fireboard and the shape of the vessel. This research guides the optimization of the heating system and promotes the application of the rotary cup burner.

Experimental and numerical simulation research on fire suppression efficiency of dry powder mediums containing molybdenum flame retardant additive

In order to cope with the frequent fire accidents in modern society, it is crucial to develop efficient fire extinguishing agents to stamp out fires in its early stage. In this work, a new composite ultrafine dry powder extinguishing agent containing ammonium molybdate ((NH4)2MoO4) is prepared, and its fire extinguishing efficiency is studied. The cup burner experimental results show that with the increase of the mass fraction of (NH4)2MoO4, the flame temperature drop and flame height variation rate show a trend of increasing and then decreasing, while the MEC and extinguishing time present a trend of a decrease and then an increase. It is indicated that the composite dry powder has the best fire extinguishing efficiency when the mass fraction of (NH4)2MoO4 is 7%. Besides, in terms of the pyrolysis results of TGA and DSC, it is found that the degree of thermal decomposition is significantly promoted under the condition of 7% addition. Based on the gas-solid two-phase flow theory and multiphase flow model, a simplified simulation model of the cup burner is established by the ANSYS-FLUENT software to analyze the variation of temperature and particle motion trajectory. The simulation results demonstrate that the ultra-fine dry powder mediums have a good dispersibility after entering the cup burner. This can achieve a full submerged state at a faster speed, and the flame temperature of the entire fire suppression stage is consistent with the experimental results. This article mainly develops the application of fire extinguishing media in the field of fire protection from the perspective of process safety.

Evaluating the suppression effectiveness of hybrid nitrogen and water mist with a cup burner coflowing flame

SummaryThe suppression effectiveness of an intrinsically clean hybrid fire suppressant consisting of nitrogen and water mist was experimentally studied by a cup burner method with methane/air coflowing flame. A series of hybrid agents with different weight ratios of nitrogen and water mist (Sauter mean diameter: 12.6 μm) were tested and compared with nitrogen and water mist used alone. The minimum mass‐based extinction concentration (MEC) of neat nitrogen and water mist was measured as 32.1% and 15.2%, respectively. When combined, MEC of the hybrid agents fell between the limiting values of nitrogen and water mist used alone. An approximately linear relationship was shown for the suppression behavior of nitrogen and water mist in combination. The flow field of suppressants during the flame suppression process was studied by particle imaging velocimetry (PIV) technique. A small portion of water droplets near the flame front evaporated, which contributed to flame extinction by heat absorption and oxygen dilution. The remaining bulk mist was entrained vertically with the air flow, showing little effect on the flame base.

Performance evaluation of nitrogen for fire safety application in aircraft

Fire suppression is an important safety certification requirement for aircraft as it is for all safety critical systems. Risk analyses are required at the design and certification stages to determine the probabilities and means of mitigating such risks. Apostolakis et al. (1995) shows an approach for spacecraft, Spyrou and Koromila (2020) for passenger ships and Arshi et al. (2010) for reactors. An important analysis tool for aircraft is the Zonal Analysis process (Chen and Fielding, 2018) Such analyses include investigation of means of fire suppression for which the use of Halon 1301 was a popular choice. The production of Halon and several halocarbons were banned under the Montreal Protocol in 1994, which necessitates an investigation for use of environmental-friendly agents for this application. The primary objective of this paper is to determine the ‘design concentration’11Design concentration is the volumetric concentration of the agent to achieve successful fire suppression in an enclosure. of nitrogen required for fire suppression. Computational Fluid Dynamics (CFD), in combination with experimental verification is described in this paper. The air flow rate in the cup-burner model was varied between 10 L/min and 40 L/min for a low-speed numerical model and was validated against the BS ISO 14520 cup burner test (BS ISO 14520 Annex, 2006) to determine the extinguishing concentration of nitrogen. The study revealed that the design concentration of nitrogen was 34% (14% oxygen concentration). Further investigation suggested that at low air flow rates (10 L/min and 20 L/min case), distortions produced in the flow led to erroneous measurement of oxygen concentration in experiments. The fire suppression model was extended to an n-heptane pool fire in a large enclosure. The recorded design concentration was approximately 39% additional nitrogen corresponding to 13% oxygen concentration by volume. It was observed that the weight of nitrogen required increased by 7.5 times compared to Halon 1301 use for this model. Future work can be explored in aircraft cargo and engine bay fire safety systems through Minimum Performance Standard (MPS) testing and simulations with nitrogen as the agent. Such work will feed directly into system safety assessments during the early design stages, where analyses must precede testing.

Suppression of propane cup-burner flame with HFO-1336mzz(Z) and its thermal stability study

Cis-1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz(Z)) conforms the most of necessary requirements as an environment-friendly extinguishant. However, its fire suppression performance has not been investigated. In this study, the fire suppression effectiveness of HFO-1336 was evaluated by a cup burner apparatus. The extinguishing concentration indicates nonpositive correlation with the fuel flow. On the other hand, to characterize the heat release of the reaction kernel, the temperature of the flame base was measured. The results showed that the temperature increased with HFO-1336 loading in the range of 2–5 %, while decreased as the concentration exceeded 5 %. In addition, the thermal decomposition properties of HFO-1336 were investigated over a temperature range of 100–800 ℃ and the products were analyzed by GC–MS. According to the detected products, the possible decomposition pathways were proposed and the extinguishing mechanism were discussed.

Extinguishment of hydrocarbon pool fires by ultrafine water mist with ammonium/amidogen compound in an improved cup burner

SummaryUltrafine water mist (UFWM) (&lt;10 μm), as a total flooding agent, has been proven to overcome obstructions in extinguishing fire. To examine the efficacy of UFWM extinguishing pool fires and reveal the primary fire extinguishing mechanisms of heat adsorption, a predictive model of minimum extinguishing concentration (MEC) is developed based on heat extraction, and the experimental data of MECs were obtained with an improved cup burner. The contribution of heat adsorption is about 25% to 50%, and turbulence effect also plays an important role in extinguishing fire. To improve fire inhibition effectiveness of UFWM by turbulence effect, CO (NH2)2, NH4HCO3, and (NH4)2HPO4 were selected as additives; KCl and KH2PO4 were also chosen for comparison purpose. It is discovered that CO (NH2)2 and (NH4)2HPO4 in the low concentrations can improve the fire extinction effectiveness except NH4HCO3. CO (NH2)2 has the most contribution to fire extinction at the optimum concentration (about 0.01 mol L−1 for n‐heptane fire and 0.03 mol L−1 for ethanol fire). Moreover, CO (NH2)2 (at 0.03 mol L−1) was dramatically better than KH2PO4 in extinguishing ethanol fire, and its effect is very close to that of KCl (at 0.067 mol L−1) for ethanol fire.

Application of thermal mechanism to evaluate the effectiveness of the extinguishment of CH4/air cup-burner flame by water mist with additives

A cup burner was used to measure the minimum fire extinguishing concentrations for methane extinguishment by fine water mist with additives/air co-flow diffusion flames based on ultrasonic atomization. The comparison of the minimum fire extinguishing concentrations of pure and fine water mist revealed that the existence of additives could change the fire extinguishing efficiency of pure water, with their improvement effect ranked as KCl > KH2PO4 > NH4H2PO4. A flame thermal balance equation was established, and a model for predicting the minimum fire extinguishing concentrations of different fire extinguishing agents was developed. A differential scanning calorimeter was used to measure solution heat capacity, and the physicochemical properties of different liquid extinguishers were predicted. When the mass fractions of the additives equated to 2%, the chemical fire extinguishing effect was superior. The influence of additives on fire extinguishing efficiency mainly involves an increase in chemical actions and a reduction in the competition between the evaporative capacities of pure water.

Extinguishment of hydrogen laminar diffusion flames by water vapor in a cup burner apparatus

Transient computations with full hydrogen chemistry were performed to reveal the flame structure and extinguishment process of co-flow, hydrogen diffusion flame suppressed by water vapor. As the concentration of water vapor was increased, the flame detached away from the burner brim and formed an edge flame at the flame base. Water vapor showed larger chemical inhibition effect than nitrogen when extinguishing hydrogen flame, which was attributed to its enhanced third body effect in the reaction H + O2 + M = HO2 + M. The minimum extinguishing concentration (MEC) of water vapor and nitrogen was predicted by Senecal formula and perfectly stirred reactor (PSR) model respectively. The MECs predicted by PSR model agree with the MECs calculated by Fluent, which shows that 1) the flame extinction is controlled by the flame base, and 2) radiation absorption is negligible. The measured MECs are in a reasonable agreement with the values calculated by Fluent, which demonstrates the accuracy of the CFD model. A simple model was used to investigate the relative importance of extinguishing mechanisms of water vapor. The results show that in a co-flow configuration the thermal cooling and chemical inhibition effect are the main extinguishing mechanisms in suppressing hydrogen diffusion cup burner flame.

Extinguishment of hydrogen diffusion flames by ultrafine water mist in a cup burner apparatus – A numerical study

Transient simulations with full hydrogen chemistry were performed to reveal the flame structure and extinguishment process of co-flow hydrogen diffusion flame suppressed by ultrafine water mist (UFM). As UFM was added incrementally to the oxidizer stream, the flame experienced a series of destabilization process, i.e., detachment, drifting and blowoff. The simulations predicted that the critical mass flow rate of 10-μm UFM was 6 g/min, which is in agreement with the value calculated by a perfectly stirred reactor model and the value measured by the experiments. The critical mass flow rate exhibited a plateau region as the diameter increased from 5 μm to 20 μm. The optimal diameter for UFM was ≈ 10 μm. A scrutiny on the extinguishing mechanisms reveals that both the chemical kinetic effect and latent heat play important roles in determining the optimal diameter in this configuration. For the chemical kinetic effect, water molecule inhibits the flame through 1) enhancing the chain-terminating reaction H + O2 (+M) = HO2 (+M) and 2) subsequently scavenging free radicals in the flame. An energy equation was used to investigate the relative importance of extinguishing mechanisms for UFM. It shows that the thermal cooling outweighs the chemical kinetic effect in terms of contributions to flame inhibition although the chemical kinetic effect is obviously enhanced compared with N2.

Experimental studies on the extinction of methane/air cup-burner flames with gas–solid composite particles

Fire suppression effectiveness of gas–solid composite particles consisting of 2-bromo-3,3,3-trifluoropropene (BTP) and zeolite 13X was evaluated on a cup-burner apparatus with coflowing methane/air flame. A series of composite samples with the weight concentration of BTP (ω) varying from 1.0 to 12.0% were tested. For comparison, extinction measurements were also conducted using neat BTP and zeolite 13X, respectively. Results indicated that the composite particles on a mass basis were much more effective than that of BTP and zeolite 13X used alone. A synergistic effect was exhibited by the BTP/zeolite 13X composites, which was affected by the ω values. Furthermore, significantly reduced HF concentrations (<70 ppm) were detected in the suppression tests with the composite particles, in comparison to that of neat BTP (1436ppm). The composite particles extinguished the flame through a blowoff process, in which the flame base oscillated, detached from the cup-burner rim and extinguished eventually. Mechanism of the composite particles in suppressing the cup burner flame was studied.

컵버너시험에서 소화기준에 따른 불활성기체의 소화농도에 대한 정량적 차이

The concentrations of inert gases (N , Ar, CO and He) required to induce the flame instabilities such as swing, rotation, lifted and blow-out were measured in a cup burner nonpremixed flames for CH and C H fuels. Quantitative differences in the extinguishing concentration with fire suppression criteria (i.e. blow-out or onset of flame instability) were also examined. It was found that the difference in extinguishing concentration was increased with the appearance of lifted flame and the low extinguishing performance of inert gaseous. The maximum difference in extinguishing concentration with the suppression criteria was approximately 35% at the highest fuel velocity condition (1.3 cm/s) for the C H -air nonpremixed flame. It can be also expected that the extinguishing concentration by the criteria based on the onset of flame instability will provide the useful information from the viewpoint of the accurate and economical design concentration.