scholarly journals Analysis of the Impact of Selected Parameters of the Hybrid Extinguishing System on the Fire Environment in a Closed Room

2019 ◽  
Vol 11 (23) ◽  
pp. 6867 ◽  
Author(s):  
Jerzy Gałaj ◽  
Tomasz Drzymała ◽  
Paweł Wolny
Keyword(s):  
Carbon Monoxide ◽  
Water Mist ◽  
Inert Gas ◽  
Fire Extinguishing ◽  
Fire Environment ◽  
Environment Temperature ◽  
Mist Flow ◽  
Characteristic Values ◽  
The Impact ◽  
Oxygen Concentrations

The main purpose of this study was to analyze the impact of some parameters (water mist flow rate and type of gas used) of the hybrid extinguishing system on the fire environment (temperature as well as carbon monoxide and oxygen concentrations) in a closed room. Hybrid fire-extinguishing systems in which water mist is driven by inert gas combine the advantages of typical fog systems and fixed gas extinguishing devices. They have been developed in the last years but are now being used more and more often and the preparation of standards for them is planned for 2020. For this purpose, many fire tests with this system should be conducted. Some of them are discussed in this paper. Two different flow rates of water mist (1.5 or 3 dm3/min) and inert gas (nitrogen or air) were used during hybrid system testing. Some parameters of the fire environment in the compartment such as temperature measured by thermocouples as well as carbon monoxide and oxygen concentrations measured by electrochemical gas sensors are presented here. The characteristic values of the extinguishing process are also included. The assumed times of ensuring safe conditions in the room have been confirmed.

scholarly journals Assessment of extinguishing efficiency of hybrid system using water mist and inert gas during class A fires

2018 ◽  
Vol 247 ◽  
pp. 00013
Author(s):  
Jerzy Gałaj ◽  
Tomasz Drzymała
Keyword(s):  
Water Flow ◽  
Hybrid System ◽  
New Technology ◽  
Water Mist ◽  
International Standards ◽  
Inert Gas ◽  
Pipe System ◽  
Class A ◽  
Fire Extinguishing ◽  
The Impact

Fixed hybrid fire extinguishing system, a new technology used in fire protection all over the world in the last years, was discussed. A four-head twin pipe system supplied with water mist and inert gas (air or nitrogen) was applied. A pile of 50 pine wood boards was used as a combustible material (class A fire). It was located in the corner of the compartment while the nozzles were mounted symmetrically in the centre (volume suppression). The extinguishing processes differing in the proportion of water mist to gas were analysed. The extinguishing time was taken as the most important parameter indicating the extinguishing efficiency. The impact of water flow on extinguishing process was discussed. The clear dependence of extinguishing time on the water/gas ratio was proven. The best performance of the hybrid system at water flow 3 dm3/min and nitrogen as inert gas was observed. The results obtained during experiments can be useful in developing new international standards e.g. NFPA.

Characterization of Twin-Fluid (Water Mist and Inert Gas) Fire Extinguishing Systems by Testing and Modeling

2014 ◽  
Vol 51 (4) ◽  
pp. 923-950 ◽  
Author(s):  
Hong-Zeng Yu ◽  
Robert Kasiski ◽  
Matthew Daelhousen
Keyword(s):  
Water Mist ◽  
Inert Gas ◽  
Fire Extinguishing

Modeling of Heat Transfer in a Mist/Steam Impinging Jet

2001 ◽  
Vol 123 (6) ◽  
pp. 1086-1092 ◽  
Author(s):  
X. Li ◽  
J. L. Gaddis ◽  
T. Wang
Keyword(s):  
Heat Transfer ◽  
Heat Flow ◽  
Impact Velocity ◽  
Turbine Blades ◽  
Water Mist ◽  
Spherical Cap ◽  
Gas Turbine Blades ◽  
Mist Flow ◽  
The Impact ◽  
Steam Heat

The addition of mist to a flow of steam or gas offers enhanced cooling for many applications, including cooling of gas turbine blades. The enhancement mechanisms include effects of mixing of mist with the gas phase and effects of evaporation of the droplets. An impinging mist flow is attractive for study because the impact velocity is relatively high and predictable. Water droplets, less than 15 μm diameter and at concentrations below 10 percent, are considered. The heat transfer is assumed to be the superposition of three components: heat flow to the steam, heat flow to the dispersed mist, and heat flow to the impinging droplets. The latter is modeled as heat flow to a spherical cap for a time dependent on the droplet size, surface tension, impact velocity and surface temperature. The model is used to interpret experimental results for steam invested with water mist in a confined slot jet. The model results follow the experimental data closely.

Comparison of a preferred versus non-preferred waterpipe tobacco flavour: subjective experience, smoking behaviour and toxicant exposure

2017 ◽  
Vol 27 (3) ◽  
pp. 319-324 ◽  
Author(s):  
Eleanor L Leavens ◽  
Leslie M Driskill ◽  
Neil Molina ◽  
Thomas Eissenberg ◽  
Alan Shihadeh ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Subjective Experience ◽  
Smoking Behaviour ◽  
Toxicant Exposure ◽  
P Values ◽  
Smoking Topography ◽  
Exhaled Carbon Monoxide ◽  
Continued Use ◽  
The Impact ◽  
Survey Questionnaires

IntroductionOne possible reason for the rapid proliferation of waterpipe (WP) smoking is the pervasive use of flavoured WP tobacco. To begin to understand the impact of WP tobacco flavours, the current study examined the impact of a preferred WP tobacco flavour compared with a non-preferred tobacco flavoured control on user’s smoking behaviour, toxicant exposure and subjective smoking experience.MethodThirty-six current WP smokers completed two, 45-minute ad libitum smoking sessions (preferred flavour vs non-preferred tobacco flavour control) in a randomised cross-over design. Participants completed survey questionnaires assessing subjective smoking experience, exhaled carbon monoxide (eCO) testing, and provided blood samples for monitoring plasma nicotine. WP smoking topography was measured continuously throughout the smoking session.ResultsWhile participants reported an enhanced subjective smoking experience including greater interest in continued use, greater pleasure derived from smoking, increased liking and enjoyment, and willingness to continue use after smoking their preferred WP tobacco flavour (p values <0.05), no significant differences were observed in nicotine and carbon monoxide boost between flavour preparations. Greater average puff volume (p=0.018) was observed during the non-preferred flavour session. While not significant, measures of flow rate, interpuff interval (IPI), and total number of puffs were trending towards significance (p values <0.10), with decreased IPI and greater total number of puffs during the preferred flavour session.DiscussionThe current study is the first to examine flavours in WP smoking by measuring preferred versus control preparations to understand the impact on subjective experience, smoking behaviour and toxicant exposure. The pattern of results suggests that even this relatively minor manipulation resulted in significant changes in subjective experience. These results indicate a possible need for regulations restricting flavours in WP tobacco as with combustible cigarettes.

scholarly journals Effects of Discharge Area and Atomizing Gas Type in Full Cone Twin-Fluid Atomizer on Extinguishing Performance of Heptane Pool Fire under Two Heat Release Rate Conditions in an Enclosed Chamber

2021 ◽  
Vol 11 (7) ◽  
pp. 3247
Author(s):  
Dong Hwan Kim ◽  
Chi Young Lee ◽  
Chang Bo Oh
Keyword(s):  
Heat Release ◽  
Flow Rate ◽  
Heat Release Rate ◽  
Release Rate ◽  
Water Mist ◽  
Pool Fire ◽  
Sauter Mean Diameter ◽  
Discharge Area ◽  
Fire Extinguishing ◽  
Enclosed Chamber

In this study, the effects of discharge area and atomizing gas type in a twin-fluid atomizer on heptane pool fire-extinguishing performance were investigated under the heat release rate conditions of 1.17 and 5.23 kW in an enclosed chamber. Large and small full cone twin-fluid atomizers were prepared. Nitrogen and air were used as atomizing gases. With respect to the droplet size of water mist, as the water and air flow rates decreased and increased, respectively, the Sauter mean diameter (SMD) of the water mist decreased. The SMD of large and small atomizers were in the range of approximately 12–60 and 12–49 μm, respectively. With respect to the discharge area effect, the small atomizer exhibited a shorter extinguishing time, lower peak surface temperature, and higher minimum oxygen concentration than the large atomizer. Furthermore, it was observed that the effect of the discharge area on fire-extinguishing performance is dominant under certain flow rate conditions. With respect to the atomizing gas type effect, nitrogen and air appeared to exhibit nearly similar extinguishing times, peak surface temperatures, and minimum oxygen concentrations under most flow rate conditions. Based on the present and previous studies, it was revealed that the effect of atomizing gas type on fire-extinguishing performance is dependent on the relative positions of the discharged flow and fire source.

scholarly journals Improving Sustainability of Smart Cities through Visualization Techniques for Big Data from IoT Devices

2020 ◽  
Vol 12 (14) ◽  
pp. 5595 ◽  
Author(s):  
Ana Lavalle ◽  
Miguel A. Teruel ◽  
Alejandro Maté ◽  
Juan Trujillo
Keyword(s):  
Big Data ◽  
Smart City ◽  
Smart Cities ◽  
Fire Department ◽  
Heterogeneous Data ◽  
Fire Extinguishing ◽  
Heterogeneous Data Sources ◽  
Iot Devices ◽  
Visualization Techniques ◽  
The Impact

Fostering sustainability is paramount for Smart Cities development. Lately, Smart Cities are benefiting from the rising of Big Data coming from IoT devices, leading to improvements on monitoring and prevention. However, monitoring and prevention processes require visualization techniques as a key component. Indeed, in order to prevent possible hazards (such as fires, leaks, etc.) and optimize their resources, Smart Cities require adequate visualizations that provide insights to decision makers. Nevertheless, visualization of Big Data has always been a challenging issue, especially when such data are originated in real-time. This problem becomes even bigger in Smart City environments since we have to deal with many different groups of users and multiple heterogeneous data sources. Without a proper visualization methodology, complex dashboards including data from different nature are difficult to understand. In order to tackle this issue, we propose a methodology based on visualization techniques for Big Data, aimed at improving the evidence-gathering process by assisting users in the decision making in the context of Smart Cities. Moreover, in order to assess the impact of our proposal, a case study based on service calls for a fire department is presented. In this sense, our findings will be applied to data coming from citizen calls. Thus, the results of this work will contribute to the optimization of resources, namely fire extinguishing battalions, helping to improve their effectiveness and, as a result, the sustainability of a Smart City, operating better with less resources. Finally, in order to evaluate the impact of our proposal, we have performed an experiment, with non-expert users in data visualization.

Numerical Simulation and Experimental Study on Water Mist Fire Suppression for Cooking Fog Discharge Pipe

2014 ◽  
Vol 915-916 ◽  
pp. 356-361
Author(s):  
Zheng Wen Xie
Keyword(s):  
Design Method ◽  
Fire Suppression ◽  
Orthogonal Design ◽  
Water Mist ◽  
Simulation Software ◽  
Droplet Radius ◽  
Test Analysis ◽  
Injection Angle ◽  
Fire Extinguishing ◽  
Flow Quantity

FDS simulation software was used to establish the full size lampblack physics model of single wind pipe, using the orthogonal design method design of analog calculation conditions, research in the nozzle pressure, the droplet radius, nozzle, flow quantity and injection angle parameters under different conditions of water mist fire extinguishing effect. Based on a full-scale combustion and water mist fire extinguishing experiment, the water mist fire suppression was observed and test analysis etc, to better understand the flue water mist fire extinguishing feasibility, provides the theory basis for the design of efficient, reliable flue fire extinguishing system.

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