Study on inhibitory efficacy of dry ice as a novel fire extinguishing agent for lithium-ion batteries

Wood stack fire tests to evaluate the influence of extinguishing medium and driving pressure on fire extinguishing efficacy of forest trees

Currently, the creation of fundamentally new technical means of fire extinguishing and the development of new methods for delivering fire extinguishing substances to a remote distance when extinguishing complex fires is the actual scientific and technical problem. The fire fighting equipment currently used in the territorial divisions of the SES of Ukraine does not allow delivering of fire extinguishing substances at a distance of 100 m and more. Existing fire fighting equipment is designed to deliver water, aqueous solutions and foams at a distance of up to 100 meters, as well as dry chemicals at a distance of up to 70 meters. Today various researchers are developing technical means and methods for remote delivery of such fire extinguishing agents as aerosol-forming compounds, dry chemical powders, fire extinguishing freons, solid carbon dioxide and organometallic compounds. At the same time, the use of the considered fire extinguishing agents did not become widespread in the fire and rescue units due to insufficient development of technical means and methods of delivery. To solve the problem of delivering fire extinguishing substances to a remote distance while extinguishing complex fires, it was proposed to use a barrelled fire extinguishing system, which ensures high-precision delivery by throwing the containers filled with extinguishing agent directly into the combustion zone along the ballistic trajectory. The analysis of various fire extinguishing substances and compositions for use in containers showed that to achieve the highest efficiency of fire extinguishing, it is advisable to use dry chemical powders. As a result of the study of the use of dry chemical powders as container fillers, the mechanics of the fire extinguishing action of dry chemical compositions after releasing from the container by excessive pressure, created by detonation products of explosives, was investigated. A method for determining the total mass of dry chemical powder and the required number of containers filled with dry chemical powder for extinguishing class A and B fires has been developed. Keywords

Introduction. Fires in high-rise buildings and structures constitute a grave danger both to the people inside, valuables, and the building structure. More often than not, fires develop on the external surface of construction facilities that are in operation or inside those facilities that are under construction, and they give rise to the problem of using standard fire extinguishing solutions and require the employment of mobile machinery by fast response units of the fire-fighting service who apply fire extinguishing agents from the outside of a building. The purpose of this article is to substantiate the in expediency of, or, on the contrary, the need to make the proposed amendments to Federal Law No. 123-FZ of July 22, 2008 “Technical Regulation of Fire Safety Requirements”.The scope of the problem. The analysis of the effectiveness of various methods of application of fire extinguishing agents used to extinguish outdoor fires in high-rise buildings has shown the insufficiently high efficiency of ground-mounted machinery, which preconditions the need to make an enquiry into the possibility of using aircraft to extinguish high-rise buildings and structures. Given the need to ensure effective fire extinguishing, meet safety and economic feasibility requirements, an autonomous unmanned aerial vehicle (AURA) was selected as the delivery vehicle. Systems using various fire extinguishing agents and methods of their application were used for fire extinguishing purposes, including a pulsed water application system, capsules containing the fire extinguishing composition, high-pressure water mist and compressed air foam. Their applicability at the height of 300 meters has determined their choice.Research results. The testing task was to confirm the possibility of application of fire extinguishing agents to the fire seat in the course of the flight of an unmanned aerial vehicle, to identify the effectiveness of fire extinguishing agents and to assess the stability of extinguishing agents applied to the fire seat. To ensure safety, testing was carried out at the height not exceeding 10 m, and the results confirmed the possibility of using the above substances to extinguish fires.Conclusions. The research has confirmed the possibility of using unmanned aerial vehicles and various methods of fire extinguishing by means of the horizontal application of extinguishing agents inside high-rise buildings and structures, if extinguishing agents are applied from outside of a construction facility.

At present, with the rapid development of the national economy, China’s demand for energy is becoming stronger. It is particularly important to develop an efficient and environmentally friendly fire extinguishing agent to ensure energy security. As a new type of environmentally friendly fire extinguishing agent, dry water has the advantages of both water mist and dry powder fire extinguishing agent. The core-shell structure of dry water fire extinguishing agent makes it have fluidity and dispersibility similar to powder fire extinguishing agent, while maintaining extremely high-water content, making it of great application value in the field of fire extinguishing agents. In this paper, the preparation, physical and chemical properties of dry water extinguishing agents and the fire extinguishing performance of Class B fires are studied, based on the existing fire extinguishing theories and experimental results, the fire extinguishing mechanism of dry water extinguishing agents is discussed.

Synergistic effects of typical clean gaseous fire-extinguishing agents

Purpose. The article analyzes assessment methods of existing fire extinguishing agent (FEA) jet ballistics. FEA discharge velocity from the nozzle effect on FEA drops in the air motion and trajectory has been investigated. Applying a new method for calculating FEA jets ballistics has been grounded. With the help of mathematical modeling, calculations have been carried out for FEA flow rate indicators depending on the pressure and flow rate for a universal nozzle, which forms different jet discharge angles from solid to spray. A model has been developed that describes FEA jet ballistics for both universal and conical or conoid fire nozzles. Methods. A logical method based on forces influence on a water drop in a medium has been used, as well as an empirical method, i.e. experiment. Findings. To confirm the developed jet ballistics theory, a series of field tests has been carried out. A fire monitor with a universal nozzle has been used as a test unit under the following conditions: equivalent diameter 29 mm; pressure in front of the nozzle 0.6 MPa; flow rate at the outlet 35 m/s (calculated by numerical simulation); nozzle inclination angle in relation to horizon 30°; nozzle cutting height from the horizon 1 m. The discrepancy in the indices of calculated and experimental jet range did not exceed 3 %. An insignificant effect of medium density change on jet range capability has been revealed, that is, under the same initial conditions, but at different ambient temperatures, fire extinguishing agent jet range capability will differ. This should be taken into account when using fire extinguishing installations based on monitors in different climatic regions. Research application field. The research results will simplify nozzle fire equipment development and design process, algorithm construction for robotic fire extinguishing installations operation based on fire monitors. Conclusions. The developed method for calculating jet ballistics is fully correlated with in-situ indicators. Jet ballistics is highly effected by fire extinguishing agents nozzle discharge velocity and medium density in which the fire extinguishing agent is flowing. In the future, it is required to conduct a number of scientific studies to determine extinguishing agent discharge velocity from various nozzles dependences on pressure and consumption.

This research paper delves into the studies of the fire extinguishers with the combined supply of the foam-water extinguishing agents in an aerosol state used for the extinguishing simulated fires of "A" and "B" classes. The research was done using a mobile module with a 150-liter water tank and a pumping station equipped with a gasoline engine, and a finely atomized foam-water solution (water + foam concentrate) was used as a fire extinguishing agent, while the concentration of foam concentrate in the fire extinguishing agent was 3%, and that of water 97%. Experimental studies were conducted in three series, and each series of studies included three experiments. Thus, during the studies of the 1st series, the simulated fires of an "A" class were extinguished, and the 2nd and 3rd series of studies dealt with the extinguishing of simulated fires of a "B" class. The research data provided the values of the duration of supply of the fire extinguishing agents and their consumption. Using the method of least squares, the root means square values of the duration of supply of the fire extinguishing agent and the consumption of it when supplied by technical fire extinguishing means were obtained according to the research series and the number of the experiment. It has been established that the duration of supply of the fire extinguishing agents by technical fire extinguishing means depends on such factors as the type of fire extinguishing agent, the percentage and type of impurities in its composition, the tactical and technical characteristics of the fire extinguishing agent, the professional skills of the operator and methodical support.

This study defines fire hazard parameters for the Panasonic NCR18650B (LiNi0.8Co0.15Al0.05O2) lithium-ion battery (LIB). The task to obtain high-quality fire extinguishing substances and materials to prevent the spread of combustion implies determining the appropriate data experimentally. In particular, establishing the thermophysical characteristics and time dependence of the change in temperature indicators for the Panasonic NCR18650B (LiNi0.8Co0.15Al0.05O2) LIB depending on different fire extinguishing substances is a relevant issue that is resolved in this work. Based on the results of experimental studies, it was determined that the time of occurrence of the critical temperature inside LIB (~ 170°C) exposed to an external energy source (~ 300°C) is ~ 400 s. The effectiveness of the use of water and carbon dioxide (CO2) on the effectiveness of reducing (cooling) the temperature of the internal filling was experimentally established. Accordingly, the time for reducing the battery temperature to 20°C with water is 400 s; when using CO2, it is 280 s. The mathematical model reasonably describes the cooling process of the LIB internal filling and accordingly verifies the experimental results of the study. The proposed mathematical model makes it possible to predict the complete cooling of the LIB depending on the type of extinguishing agent and the initial temperature of the substance. Additionally, the LIB heat transfer coefficients α (W/m2·°C) exposed to the action of water and CO2 were established, which are 20 and 50, respectively. The results make it possible to devise effective fire extinguishing agents and an algorithm for their application, in particular, to set the parameters of the extinguishing time and the required volume of the extinguishing agent in accordance with the power and type of battery. Additionally, the mathematical model built can be used for other types of LIBs with already known thermophysical characteristics

Ability of fire extinguishing agents to absorb half of the heat flow escaped while burning, that can lead to flame extinction, raises doubts in calculation of the thermal balance of a powder and, further, of sprayed water. It turned out that the balance of heat has a big advantage towards heat escaped during flame combustion. Amount of powder or sprayed water become insufficient to absorb half of the heat flow of flame. This work contains data and results of complex experimental and theoretical researches of the process of extinguishing of the flame of hydrocarbons by various types of fire extinguishing agents, including sprayed water, fire extinguishing powder, reactive freon and low expansion foam. On the basis of experimental researches of the process of extinguishing by means of streams of dispersed extinguishing agent and low expansion foam it is offered and substantiated the "local" mechanism of suppression of a flame of liquids by extinguishing agents. Existence of the minimum on curves of dependence of specific consumption on flow rate in the area of optimal flow rate of extinguishing agent is experimentally shown and theoretically substantiated. It is also offered two-stage mechanism of suppression. The first stage consists in interaction of the stream of extinguishing agent with part of a flame jet which is in contact with front of extinguishing agent. The flow of extinguishing agent interacts only with a small (local) area of the flame. Fire extinguishing agent allows not only to absorb half of the heat from flame jet in a local part, but also to cool it practically up to the temperature close to water boiling point. It leads to termination of burn directly on the front of movement of a fire extinguishing stream. Such "local" mechanism of interaction of sprayed water stream leads to evaporation of larger or smaller part of sprayed stream depending on its dispersion degree. The second stage of suppression process provides spreading of water vapor, as a layer of certain thickness, over the burning surface. The higher dispersion degree of sprayed water, the larger volume of water vapor and higher it's covering rate of burning surface. Such extinguishing mechanism is also implemented in case of application of sprayed freon, sprayed powder, solid aerosol and low expansion foam. Standard equations for calculation of time and specific consumption of different types of extinguishing agents during suppression of flammable liquids are proposed. Satisfactory congruence of experimental results with data obtained by calculation using formulas which correspond to the "local" mechanism of suppression of a flame by fire extinguishing substances is shown.

Since January 28, 2017, domestic fire extinguishers have been manufactured nationwide, and a domestic fire extinguisher can be used for 10 years. Hence, the treatment of the extinguishing agent existing in waste extinguishers is a critical issue economically and environmentally. Accordingly, the manufacturer reuses and recycles the fire extinguishing agent, and this recycling method has been approved for fire extinguishers. In some cases, the quality of reused extinguishing agents and fire extinguishers are uncertain. Therefore, in this study, the physical and chemical properties of recycled extinguishing agents were evaluated through accelerated aging tests to verify the quality of the recycled extinguishing agents. The accelerated aging test results were obtained according to the approval criteria type for the physical and chemical properties of the recycled extinguishing agent. As a substitute effect, it was found that the import substitution effect and resource effect could be regarded as a circulating resource for fire-extinguishing agents that are imported in full quantity, and the price competitiveness of fire extinguishers can be achieved.

This article provides a method for intelligent fire detection and extinguishing agent selection based on machine olfactory technology. The machine olfactory system is used for non-destructive detection of odor information in the event of a fire, obtain multi-dimensional feature data, and analyze and explore electronic The feasibility of using the nose to detect and classify fire odors, and establish the best detection and pattern recognition methods, and use the flavor database obtained by sorting to classify the molecular element categories to determine the type of fire extinguishing agent used. It solves the problem of not being able to choose which extinguishing agent and the wrong extinguishing agent in time when a fire occurs.

A review of fire-extinguishing agent on suppressing lithium-ion batteries fire

In this work, four new dry water fire extinguishing agents (FEAs) were prepared by hydrophobic SiO2 and aqueous solution under certain conditions. The dry water FEAs were developed and we conducted two types of fire extinguishing experiments (i.e., class A solid fire and class B liquid fire test). Thermocouples and a color video camera were used to measure burning temperature and record the fire extinguishing process. Results indicate that the new dry water FEAs have the ability to extinguish A, B and C fires, and have a better cooling effect than dry powder FEA. It is noted, compared with traditional FEAs, that dry water FEAs have the advantages of high efficiency and high speed, and have a potential application prospect.

Containment and suppression of compartment fires using specialized liquid compositions

One of the tasks to be solved when deploying fire extinguishing systems is to determine the range of the fire extinguishing agent supply to the combustion center. This problem is solved using data on the trajectory of the fire-extinguishing agent in the combustion center. The presence of wind impact on the process of supplying a fire extinguishing agent will lead to a change in its trajectory. To take into account wind impact, it becomes necessary to assess the result of such impact. Using the basic equation of dynamics for specific forces, a system of differential equations is obtained that describes the delivery of a fire extinguishing agent to the combustion center. The system of differential equations takes into account the presence of wind impact on the movement of the extinguishing agent. The presence of wind action is taken into account by the initial conditions. To solve such a system, the integral Laplace transform was used in combination with the method of undefined coefficients. The solution is presented in parametric form, the parameter of which is time. For a particular case, an expression is obtained that describes the trajectory of the supply of the extinguishing agent into the combustion center. Nomograms are constructed, with the help of which the operative determination of the estimate of the maximum range of the fire-extinguishing agent supply is provided. Estimates are obtained for the time of delivery of a fire-extinguishing agent to the combustion center, and it is shown that for the characteristic parameters of its delivery, this value does not exceed 0.5 s. The influence of wind action on the range of supply of a fire extinguishing agent is presented in the form of an additive component, which includes the value of the wind speed and the square of the time of its delivery. To assess the effect of wind impact on the movement of the fire extinguishing agent, an analytical expression for the relative error was obtained and it was shown that the most severe conditions for supplying the fire extinguishing agent to the combustion center, the value of this error does not exceed 5.5%. Taking into account the wind effect when assessing the range of supply of a fire-extinguishing agent makes it possible to increase the efficiency of fire-extinguishing systems due to its more accurate delivery to the combustion center