Pub Date : 2019-10-01DOI: 10.1109/ICFSFPE48751.2019.9055840
Xiankun Wang, Yanqiu Chen
U-shaped facade structure exists in a lot of high-rise buildings. A numerical simulation study on vertical fire spread in u-shaped structure was carried out. Influence of area and the width-depth ratio of the u-shaped structure on the fire spread was analyzed through fire spreading speed, stack effect and heat release rate. It was found that the fire spreading speed and stack effect in the u-shaped structure decreased as $A^{ast}$ increased. When $A^{ast}$ is larger than 0.0069, the influence of $A^{ast}$ on the fire spreading speed and stack effect become very small. The maximum HRR was positively related with $A^{ast}$ except for the case when $A^{ast}$ is very small. As $K$ increased, the fire spreading speed and the maximum HRR first sharply decreased and then slowly decreased except for the case when K = 1. The relationship between stack effect and $K$ was very similar with the relationship between stack effect and $A^{ast}$, but in an opposite direction. When $K$ is larger than 2.25, the fire spreading speed, the stack effect and the maximum HRR did not change obviously with K.
{"title":"Fire Spread in U-shaped Facade Structures in High-rise Buildings","authors":"Xiankun Wang, Yanqiu Chen","doi":"10.1109/ICFSFPE48751.2019.9055840","DOIUrl":"https://doi.org/10.1109/ICFSFPE48751.2019.9055840","url":null,"abstract":"U-shaped facade structure exists in a lot of high-rise buildings. A numerical simulation study on vertical fire spread in u-shaped structure was carried out. Influence of area and the width-depth ratio of the u-shaped structure on the fire spread was analyzed through fire spreading speed, stack effect and heat release rate. It was found that the fire spreading speed and stack effect in the u-shaped structure decreased as $A^{ast}$ increased. When $A^{ast}$ is larger than 0.0069, the influence of $A^{ast}$ on the fire spreading speed and stack effect become very small. The maximum HRR was positively related with $A^{ast}$ except for the case when $A^{ast}$ is very small. As $K$ increased, the fire spreading speed and the maximum HRR first sharply decreased and then slowly decreased except for the case when K = 1. The relationship between stack effect and $K$ was very similar with the relationship between stack effect and $A^{ast}$, but in an opposite direction. When $K$ is larger than 2.25, the fire spreading speed, the stack effect and the maximum HRR did not change obviously with K.","PeriodicalId":6687,"journal":{"name":"2019 9th International Conference on Fire Science and Fire Protection Engineering (ICFSFPE)","volume":"1 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83567930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-01DOI: 10.1109/ICFSFPE48751.2019.9055839
Haoran Xing, Song Lu, N. Tao, Rulin Liu
New clean agent fire suppressant, Perfluoro-2-methyl-3-pentanone, also known as FK5112 or Novec 1230 has excellent environmental behavior and high efficiency, and has been considered as one of the most promising halon replacement extinguishing agents. However, its high boiling point and poor dispersibility has largely restricted further application. To address the issue, our present work proposes the novel method by introducing inert gas mixed with FK5112 to improve the agent dispersibility. The evaporation mechanism of FK5112 during the mixing has been demonstrated in detail, and the droplets evaporation time of FK5112 affected by the diameter, the partial pressure of vapor, and the diffusion coefficient of different inert gas is estimated. Our results show that the droplets size of FK5112 have significant effect on evaporation, as it takes only 0.076s for a 5µm droplet to completely evaporate in N2 even if the partial pressure is high(a=80%). After FK5112 has evaporated in the inert gas, dispersion properties of the binary agent have been calculated and discussed thoroughly. The precise equation to estimate the vapor pressure of FK5112 is selected and the relation with the boiling point, mixing ratio, and pressure of the binary agent is revealed. For the 20% mixing ratio of FK5112, the boiling point of the mixture can reach 8.49°C and for the 10% mixing ratio, the boiling temperature is -5.85°C, which shows mixing with inert gas could notably improve its dispersibility. Additionally, mixing ratio and droplets size of FK5112 have shown a great impact.
{"title":"Study on Dispersion Characteristics of FK5112 Mixed with Inert Gas","authors":"Haoran Xing, Song Lu, N. Tao, Rulin Liu","doi":"10.1109/ICFSFPE48751.2019.9055839","DOIUrl":"https://doi.org/10.1109/ICFSFPE48751.2019.9055839","url":null,"abstract":"New clean agent fire suppressant, Perfluoro-2-methyl-3-pentanone, also known as FK5112 or Novec 1230 has excellent environmental behavior and high efficiency, and has been considered as one of the most promising halon replacement extinguishing agents. However, its high boiling point and poor dispersibility has largely restricted further application. To address the issue, our present work proposes the novel method by introducing inert gas mixed with FK5112 to improve the agent dispersibility. The evaporation mechanism of FK5112 during the mixing has been demonstrated in detail, and the droplets evaporation time of FK5112 affected by the diameter, the partial pressure of vapor, and the diffusion coefficient of different inert gas is estimated. Our results show that the droplets size of FK5112 have significant effect on evaporation, as it takes only 0.076s for a 5µm droplet to completely evaporate in N2 even if the partial pressure is high(a=80%). After FK5112 has evaporated in the inert gas, dispersion properties of the binary agent have been calculated and discussed thoroughly. The precise equation to estimate the vapor pressure of FK5112 is selected and the relation with the boiling point, mixing ratio, and pressure of the binary agent is revealed. For the 20% mixing ratio of FK5112, the boiling point of the mixture can reach 8.49°C and for the 10% mixing ratio, the boiling temperature is -5.85°C, which shows mixing with inert gas could notably improve its dispersibility. Additionally, mixing ratio and droplets size of FK5112 have shown a great impact.","PeriodicalId":6687,"journal":{"name":"2019 9th International Conference on Fire Science and Fire Protection Engineering (ICFSFPE)","volume":"30 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90830029","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, a series of full-scale experiments were carried out to study the vertical fire spread characteristics of EPS, PIR and PF insulation systems. The fire development process and the vertical temperature distribution of the main wall are analyzed. Results show that PIR and PF do not shrink and melt like EPS under fire conditions, but carbonization appears on the surface and form carbonized cracks. In the PIR carbonization crack, a strip-shaped combustion flame appears. But the PF does not show a burning flame at the carbonization crack, and the flame height is only half of the height of the main wall, and no combustion occurs in the auxiliary wall. Overall, the PF insulation system is superior to the PIR insulation system in overall fire resistance, and the EPS insulation system has the worst fire performance.
{"title":"Full-scale Experimental Study on Vertical Fire Spread Characteristics of Different Organic Insulation Systems","authors":"Shoujiang Wang, Wei Cong, Yongzheng Yao, Yong Zhou, Xudong Cheng","doi":"10.1109/ICFSFPE48751.2019.9055823","DOIUrl":"https://doi.org/10.1109/ICFSFPE48751.2019.9055823","url":null,"abstract":"In this study, a series of full-scale experiments were carried out to study the vertical fire spread characteristics of EPS, PIR and PF insulation systems. The fire development process and the vertical temperature distribution of the main wall are analyzed. Results show that PIR and PF do not shrink and melt like EPS under fire conditions, but carbonization appears on the surface and form carbonized cracks. In the PIR carbonization crack, a strip-shaped combustion flame appears. But the PF does not show a burning flame at the carbonization crack, and the flame height is only half of the height of the main wall, and no combustion occurs in the auxiliary wall. Overall, the PF insulation system is superior to the PIR insulation system in overall fire resistance, and the EPS insulation system has the worst fire performance.","PeriodicalId":6687,"journal":{"name":"2019 9th International Conference on Fire Science and Fire Protection Engineering (ICFSFPE)","volume":"114 1","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77783622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-01DOI: 10.1109/ICFSFPE48751.2019.9055792
Ye Chen, Pengfei Wang, Xuanya Liu
The fire suppression effectiveness of water mist for different development stages of fire is obviously different. In order to study the suppression effectiveness of water mist on the post-flashover compartment fire, the interaction process of water mist and post-flashover fire was simulated by using FDS, the effect of water mist characteristics on fire suppression was analyzed, and the suppression mechanism of water mist for the post-flashover fire was proposed. The results show that the post-flashover compartment fire can be effectively suppressed when the minimum spray intensity of high pressure water mist system specified in GB 50898 standard increases to 2.22 L/min.m2; The suppression effectiveness of medium pressure water mist on post-flashover compartment fire is inferior to that of high pressure water mist; cooling effect on the flame and oxygen displacement are the primary suppression mechanisms of water mist for post-flashover compartment fire.
{"title":"Numerical Study on Suppression of Post-flashover Compartment Fire by Using Water Mist","authors":"Ye Chen, Pengfei Wang, Xuanya Liu","doi":"10.1109/ICFSFPE48751.2019.9055792","DOIUrl":"https://doi.org/10.1109/ICFSFPE48751.2019.9055792","url":null,"abstract":"The fire suppression effectiveness of water mist for different development stages of fire is obviously different. In order to study the suppression effectiveness of water mist on the post-flashover compartment fire, the interaction process of water mist and post-flashover fire was simulated by using FDS, the effect of water mist characteristics on fire suppression was analyzed, and the suppression mechanism of water mist for the post-flashover fire was proposed. The results show that the post-flashover compartment fire can be effectively suppressed when the minimum spray intensity of high pressure water mist system specified in GB 50898 standard increases to 2.22 L/min.m2; The suppression effectiveness of medium pressure water mist on post-flashover compartment fire is inferior to that of high pressure water mist; cooling effect on the flame and oxygen displacement are the primary suppression mechanisms of water mist for post-flashover compartment fire.","PeriodicalId":6687,"journal":{"name":"2019 9th International Conference on Fire Science and Fire Protection Engineering (ICFSFPE)","volume":"97 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88525249","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-01DOI: 10.1109/ICFSFPE48751.2019.9055773
Jixiang Xu, Fei You, Wenhao Huangfu, Kai Shui, Songtao Zhou, Zonglin Fu
In order to investigate influence of high-temperature and intense flames derived from real wildfires on air gap breakdown properties around high voltage transmission lines, a rod-rod electrode breakdown-discharge test system under clean flame conditions was developed. After igniting ethanol, the gap between two copper rod electrodes was adjusted from 3.0 to 8.0 cm above and into the bulk flame, and dynamic charge load (from 0 to 50 kV) was applied externally to electrodes at each gap distance until there occurred breakdown across air gap. Evolution waveform and data of leaked current and instantaneous breakdown were recorded during the breakdown and discharge processes. Results show that under condition of high-temperature flame (750.0 °C~850.0 °C), breakdown voltages decrease by 55.7 %~68.3 % and 78.6 %~82.9 % when the flame is not bridged and bridged between two electrodes compared with those in pure air atmosphere. Under the action of a certain portion of flame plasma, insulating strength of rod-rod gap decreases significantly compared with that of pure air, which indicates that the high-temperature flame has a great influence on the formation and development of streamer, and is easier to form discharge channels.
{"title":"Characteristics and Mechanisms of Rod-Rod Electrode Gap Breakdown Induced by High-temperature and Clean Flame","authors":"Jixiang Xu, Fei You, Wenhao Huangfu, Kai Shui, Songtao Zhou, Zonglin Fu","doi":"10.1109/ICFSFPE48751.2019.9055773","DOIUrl":"https://doi.org/10.1109/ICFSFPE48751.2019.9055773","url":null,"abstract":"In order to investigate influence of high-temperature and intense flames derived from real wildfires on air gap breakdown properties around high voltage transmission lines, a rod-rod electrode breakdown-discharge test system under clean flame conditions was developed. After igniting ethanol, the gap between two copper rod electrodes was adjusted from 3.0 to 8.0 cm above and into the bulk flame, and dynamic charge load (from 0 to 50 kV) was applied externally to electrodes at each gap distance until there occurred breakdown across air gap. Evolution waveform and data of leaked current and instantaneous breakdown were recorded during the breakdown and discharge processes. Results show that under condition of high-temperature flame (750.0 °C~850.0 °C), breakdown voltages decrease by 55.7 %~68.3 % and 78.6 %~82.9 % when the flame is not bridged and bridged between two electrodes compared with those in pure air atmosphere. Under the action of a certain portion of flame plasma, insulating strength of rod-rod gap decreases significantly compared with that of pure air, which indicates that the high-temperature flame has a great influence on the formation and development of streamer, and is easier to form discharge channels.","PeriodicalId":6687,"journal":{"name":"2019 9th International Conference on Fire Science and Fire Protection Engineering (ICFSFPE)","volume":"32 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77280768","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Due to the advantages of no pollution, rapid fire suppression, less water consumption, lower cost, and little damage to the object, water mist fire extinguishing system has been widely used in road tunnels. In order to improve the fire extinguishing performance of water mist fire extinguishing system, a water based extinguishing agent was used as additive and injected into the water mist fire extinguishing system at the proportion of 3%. The tunnel fire suppression tests were carried out, and the fire extinguishing performance of water mist fire extinguishing system under different longitudinal ventilation velocity and with and without additive were compared and analyzed. The results show that high pressure water mist system has good cooling and heat radiation blocking effect, and has good fire control and extinguishing effect for tunnel oil fire;the suitable additive can effectively improve the fire control and extinguishing effect of water mist extinguishing system used in road tunnel.
{"title":"Tunnel Fire Suppression Tests with Water Mist Fire Extinguishing System Containing an Additive","authors":"Mingqiang Yan, Zejiang Zhang, Wei Liu, Yaqiang Jiang, Pingli Li, Meng Yang","doi":"10.1109/ICFSFPE48751.2019.9055853","DOIUrl":"https://doi.org/10.1109/ICFSFPE48751.2019.9055853","url":null,"abstract":"Due to the advantages of no pollution, rapid fire suppression, less water consumption, lower cost, and little damage to the object, water mist fire extinguishing system has been widely used in road tunnels. In order to improve the fire extinguishing performance of water mist fire extinguishing system, a water based extinguishing agent was used as additive and injected into the water mist fire extinguishing system at the proportion of 3%. The tunnel fire suppression tests were carried out, and the fire extinguishing performance of water mist fire extinguishing system under different longitudinal ventilation velocity and with and without additive were compared and analyzed. The results show that high pressure water mist system has good cooling and heat radiation blocking effect, and has good fire control and extinguishing effect for tunnel oil fire;the suitable additive can effectively improve the fire control and extinguishing effect of water mist extinguishing system used in road tunnel.","PeriodicalId":6687,"journal":{"name":"2019 9th International Conference on Fire Science and Fire Protection Engineering (ICFSFPE)","volume":"7 3","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91463609","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-01DOI: 10.1109/ICFSFPE48751.2019.9055838
Mingxuan Li, Xiujuan Mei, Bo Zhong, Chang-zheng Zhao, J. Xiong
Seven small scale experiments were carried out to research the critical threshold value for backdraft to occur. Backdraft experiment platform with 0.9 m length, 1.2 m width and 0.6 m height was built, based on the platform, wood cribs which was 0.3 m length, 0.3 m width and 0.3 m height, was used as fuel. Data of temperature, oxygen concentration, combustible gases concentration within the compartment were collected, IR camera was used to record the size and temperature of fireballs. Results show that the minimum concentration of combustible gases for backdraft to occur is about 11.6 percent vol in the seven tests, and carbon monoxide and hydrogen play very important parts, Sizes of fireballs are proportional to the concentration of combustible gases, more powerful fireballs can be observed when the concentration of combustible gases is greater, temperature of fireballs is more than 180 Celsius degree. The critical threshold value of backdraft are crucial indicators for backdraft, lives of fire fighters can be saved with better understanding of backdraft and equipment.
{"title":"Small Scale Experimental Study on Backdraft","authors":"Mingxuan Li, Xiujuan Mei, Bo Zhong, Chang-zheng Zhao, J. Xiong","doi":"10.1109/ICFSFPE48751.2019.9055838","DOIUrl":"https://doi.org/10.1109/ICFSFPE48751.2019.9055838","url":null,"abstract":"Seven small scale experiments were carried out to research the critical threshold value for backdraft to occur. Backdraft experiment platform with 0.9 m length, 1.2 m width and 0.6 m height was built, based on the platform, wood cribs which was 0.3 m length, 0.3 m width and 0.3 m height, was used as fuel. Data of temperature, oxygen concentration, combustible gases concentration within the compartment were collected, IR camera was used to record the size and temperature of fireballs. Results show that the minimum concentration of combustible gases for backdraft to occur is about 11.6 percent vol in the seven tests, and carbon monoxide and hydrogen play very important parts, Sizes of fireballs are proportional to the concentration of combustible gases, more powerful fireballs can be observed when the concentration of combustible gases is greater, temperature of fireballs is more than 180 Celsius degree. The critical threshold value of backdraft are crucial indicators for backdraft, lives of fire fighters can be saved with better understanding of backdraft and equipment.","PeriodicalId":6687,"journal":{"name":"2019 9th International Conference on Fire Science and Fire Protection Engineering (ICFSFPE)","volume":"47 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81804757","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-01DOI: 10.1109/ICFSFPE48751.2019.9055886
Lu-qing Rong, Xudong Cheng, Yangyang Fu
The burning behaviors of 18650 type lithium ion batteries under various states of charge (SOCs) were investigated using a cone calorimeter under an incident heat flux of 50 kW/m2. Several parameters were measured, including heat release rate (HRR), time to ignition and concentration of toxic gases. The experimental results show that the peak HRR, concentration of CO2 and CO increase with the increasing SOCs, whereas the time to ignition, time to explosion and the released energy during the burning decrease. The 100 % SOC is the highest fire risk due to the most serious toxicity (CO concentration: 1500 ppm), the maximum HRR (2.78 kW) and the shortest time to ignition (43 s). Besides, the burning process of the lithium ion batteries with various SOCs could be divided into four phases and the SOCs show important influence on the combustion intensity. The HRR of the fully charged LIBs is fourth power of time, which is much higher than the time-squared fire model mentioned in NFPA for most combustibles. A correlation is developed to predict the peak HRR. This study could serve as a technical guide for safe storage, application, and transportation in lithium ion batteries.
{"title":"Effect of States of Charge on the Burning Behaviors of Lithium ion Batteries","authors":"Lu-qing Rong, Xudong Cheng, Yangyang Fu","doi":"10.1109/ICFSFPE48751.2019.9055886","DOIUrl":"https://doi.org/10.1109/ICFSFPE48751.2019.9055886","url":null,"abstract":"The burning behaviors of 18650 type lithium ion batteries under various states of charge (SOCs) were investigated using a cone calorimeter under an incident heat flux of 50 kW/m2. Several parameters were measured, including heat release rate (HRR), time to ignition and concentration of toxic gases. The experimental results show that the peak HRR, concentration of CO2 and CO increase with the increasing SOCs, whereas the time to ignition, time to explosion and the released energy during the burning decrease. The 100 % SOC is the highest fire risk due to the most serious toxicity (CO concentration: 1500 ppm), the maximum HRR (2.78 kW) and the shortest time to ignition (43 s). Besides, the burning process of the lithium ion batteries with various SOCs could be divided into four phases and the SOCs show important influence on the combustion intensity. The HRR of the fully charged LIBs is fourth power of time, which is much higher than the time-squared fire model mentioned in NFPA for most combustibles. A correlation is developed to predict the peak HRR. This study could serve as a technical guide for safe storage, application, and transportation in lithium ion batteries.","PeriodicalId":6687,"journal":{"name":"2019 9th International Conference on Fire Science and Fire Protection Engineering (ICFSFPE)","volume":"18 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81479397","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-01DOI: 10.1109/ICFSFPE48751.2019.9055826
Yixiang Zhang, Jianlu Zhu, Cunyong Song, Yuxing Li, Hui Han
In order to study the effect of wall insulation conditions and different airflows on burning rate of pool fires, a small-scale ethanol pool fire was conducted experimentally under three pool diameters and a certain lip height in a wind tunnel. The results showed that the non-monotonic mass loss rate decreases first and then increases with the increase of crosswinds at a certain lip height. The burning rate increases with the increased pool diameter of the non-insulated pool fires, while an opposite trend of burning rate was found in insulated pool fires at the same sizes. The dimensionless characteristics of Richard number presents the variation relationship between the buoyancy force and momentum during different airflows. The insulated liquid pool showed a higher burning rate than that in a non-insulated pool with the characteristic parameter of reciprocal of Richard number less than 2. With the value of Richard number continue increased, the burning rate in the insulated pool fires decreased due to the difference between the increased crosswind and heat transfer. The mass loss rate of pool fires without insulation increased with the increase of pool diameter, while an opposite trend was found in insulated pool fires at the same size. The experimental data supported to establish a ratio coefficient of burning rate with or without insulation under different crosswinds.
{"title":"Experimental Research on Burning Rate of Methane Pool Fires by Insulation and Crosswinds","authors":"Yixiang Zhang, Jianlu Zhu, Cunyong Song, Yuxing Li, Hui Han","doi":"10.1109/ICFSFPE48751.2019.9055826","DOIUrl":"https://doi.org/10.1109/ICFSFPE48751.2019.9055826","url":null,"abstract":"In order to study the effect of wall insulation conditions and different airflows on burning rate of pool fires, a small-scale ethanol pool fire was conducted experimentally under three pool diameters and a certain lip height in a wind tunnel. The results showed that the non-monotonic mass loss rate decreases first and then increases with the increase of crosswinds at a certain lip height. The burning rate increases with the increased pool diameter of the non-insulated pool fires, while an opposite trend of burning rate was found in insulated pool fires at the same sizes. The dimensionless characteristics of Richard number presents the variation relationship between the buoyancy force and momentum during different airflows. The insulated liquid pool showed a higher burning rate than that in a non-insulated pool with the characteristic parameter of reciprocal of Richard number less than 2. With the value of Richard number continue increased, the burning rate in the insulated pool fires decreased due to the difference between the increased crosswind and heat transfer. The mass loss rate of pool fires without insulation increased with the increase of pool diameter, while an opposite trend was found in insulated pool fires at the same size. The experimental data supported to establish a ratio coefficient of burning rate with or without insulation under different crosswinds.","PeriodicalId":6687,"journal":{"name":"2019 9th International Conference on Fire Science and Fire Protection Engineering (ICFSFPE)","volume":"86 5 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86498613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-01DOI: 10.1109/ICFSFPE48751.2019.9055870
Mingrui Zhang, Chunjie Zhai, Junhui Gong
Spontaneous ignition characteristics of thermally thin and thermally intermediate PMMA (polymethyl methacrylate) under linearly increasing heat flux (HF) are experimentally studied in this work utilizing a heating apparatus capable of flexibly controlling the radiation intensity. Ignition time, critical temperature, surface and in-depth temperatures of 1.5 and 6 mm PMMA at six sets of HFs were recorded in the tests. The corresponding measured values are estimated by numerical simulations considering the thermal decomposition of solid and insulation layer, and critical temperature is used as the ignition criterion. The results shown that the influences of insulation layer and solid pyrolysis on surface temperature are limited and significant, respectively. Thinner sample and larger HF growth rate lead to higher ignition temperature and shorter ignition time. Two stages are identified according to pyrolysis temperature prior to ignition. The measured critical temperature is 695.53 ± 16 K. Nonetheless, a more reasonable uncertainty range ± 30 K is suggested to interpret the variation of measured ignition time based on the simulation results.
{"title":"Spontaneous Ignition of Thermally Thin and Intermediate PMMA Exposed to Linearly Increasing Thermal Radiation","authors":"Mingrui Zhang, Chunjie Zhai, Junhui Gong","doi":"10.1109/ICFSFPE48751.2019.9055870","DOIUrl":"https://doi.org/10.1109/ICFSFPE48751.2019.9055870","url":null,"abstract":"Spontaneous ignition characteristics of thermally thin and thermally intermediate PMMA (polymethyl methacrylate) under linearly increasing heat flux (HF) are experimentally studied in this work utilizing a heating apparatus capable of flexibly controlling the radiation intensity. Ignition time, critical temperature, surface and in-depth temperatures of 1.5 and 6 mm PMMA at six sets of HFs were recorded in the tests. The corresponding measured values are estimated by numerical simulations considering the thermal decomposition of solid and insulation layer, and critical temperature is used as the ignition criterion. The results shown that the influences of insulation layer and solid pyrolysis on surface temperature are limited and significant, respectively. Thinner sample and larger HF growth rate lead to higher ignition temperature and shorter ignition time. Two stages are identified according to pyrolysis temperature prior to ignition. The measured critical temperature is 695.53 ± 16 K. Nonetheless, a more reasonable uncertainty range ± 30 K is suggested to interpret the variation of measured ignition time based on the simulation results.","PeriodicalId":6687,"journal":{"name":"2019 9th International Conference on Fire Science and Fire Protection Engineering (ICFSFPE)","volume":"86 1","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2019-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85874910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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