The 14th International Conference and Exhibition on Fire and Materials, 2015
A mathematical model, FiresCone, was developed to simulate pyrolysis and combustion
processes of... more A mathematical model, FiresCone, was developed to simulate pyrolysis and combustion
processes of combustible materials considering both gas and solid phases. FiresCone has been
validated by experimental results of four types of combustible materials in a cone calorimeter,
including wood, non-charring, charring and intumescent polymers. It was known that modeling results
of mass loss rate fitted reasonably well with experiments under various heat fluxes. Both experiments
and modeling results showed that peak mass loss rate of wood, non-charring and charring polymers
happened near the end of burning, but for intumescent polymers they showed at the beginning
because of expanded protective char layer. It was also known from modeling results that non-charring
polymer were different from other three types of materials because of the characteristics of in-depth
radiation and no burning residue. FiresCone intends to provide a practical tool for the investigation of
fire behaviors of different types of combustible materials. It can expand the application fields of
modeling as fire processes of different types of combustible materials under complicated
environmental conditions have been considered.
Procedia Engineering - Proceedings of 9th Asia-Oceania Symposium on Fire Science & Technology, 2013
Carbon monoxide (CO) is always a significant judgment criterion in fire risk evaluation. Therefor... more Carbon monoxide (CO) is always a significant judgment criterion in fire risk evaluation. Therefore, a model to predict CO of woods under external heat flux was developed in this study. To improve modeling accuracy, fire processes such as water evaporation, volume shrinkage, liquid and gas transport inside wood slab were considered in this model. Three reactions such as water evaporation, oxidation of virgin wood and char were included. For oxidation reactions of virgin wood and char, CO yields of each reaction were considered constant even under various external heat fluxes. This will expand the applications of this model as limited experimental data of CO yields under different external heat flux. Temperature and moisture dependent thermal properties were used for modeling input. Comparisons between experiment and modeling showed that CO production of woods under different external heat flux can be well predicted by this model. This model intends to provide a practical tool to predict toxic gases of combustible materials under fire conditions.
Procedia Engineering - Proceedings of 9th Asia-Oceania Symposium on Fire Science & Technology, 2013
A model to predict carbon monoxide (CO) of woods under external heat flux was developed. To impro... more A model to predict carbon monoxide (CO) of woods under external heat flux was developed. To improve the modeling accuracy, fire processes such as water evaporation, volume shrinkage, water and gas transport inside wood slab were considered. Three reactions such as water evaporation, oxidation reactions of virgin wood and char were included. Temperature and moisture dependent thermal properties were used for modeling input. In the second part of this study, this model was validated by experiments. Comparisons between modeling and experiments showed that mass loss rate and CO release rate can be well predicted for woods under different moisture contents and external heat flux. Volume shrinkage, transport processes of water and gas volatiles inside wood slab were also included.
This paper serves as validation and application of a mathematical model in Part I: Theory of a model to predict CO of woods under external heat flux. This model intends to provide a practical tool to predict toxic gases of combustible materials under fire conditions.
Besides piloted ignition, autoignition is also an important aspect to real fire development as co... more Besides piloted ignition, autoignition is also an important aspect to real fire development as combustible materials may be ignited without independent flame. Fire behaviors of non-charring and charring polymers were then investigated in a cone calorimeter under autoignition conditions. Fire risk of non-charring polymers are higher than those of charring polymers because of high heat release, and the increase of heat release rate is much obvious with a higher heat flux or thickness. Charring polymers seem to have a higher CO yield, while non-charring polymers have a higher CO2 yield. Ignition methods have influences to combustion efficiency of non-charring polymers as effective heat of combustion under autoignition are observed lower than those reference data under piloted ignition conditions. Its influences to charring polymers are not obvious. Both CO and CO2 yields under flaming combustion are higher than those under non-flaming combustion, but mass percent of carbon seem to has limited effect. Experimental data in this study can provide a guidance to fire risk evaluation of non-charring and charring polymers.
A review of fire processes modeling of combustible materials under external heat flux
One-dimensional model is fundamental to two- or three-dimensional modeling of combustible materia... more One-dimensional model is fundamental to two- or three-dimensional modeling of combustible materials, which can be classified into wood, non-charring polymer, charring polymer and intumescent polymer according to their characteristics. Four fire processes are involved in fire development, such as thermal process, physical process, chemical process and failure process. Consideration of all four fire processes for these combustible materials is significant to modeling accuracy and application fields. Therefore, the state of the art of one-dimensional modeling describing all four fire processes of woods, non-charring polymers, charring polymers and intumescent polymers under external heat flux was reviewed. A summary of typical considerations in previous one-dimensional models was provided, including heat conduction, pyrolysis, production of gas volatiles, volume change, water evaporation, internal gas pressure, properties of permeability and porosity, and mechanical behaviors. Empirical models and critical data of fire processes were also collected for modeling input. This paper can provide a guide to one-dimensional modeling and build basis for two- and three-dimensional modeling.
Fire design is the basis of quantitative evaluation in performance-based fire design,which includ... more Fire design is the basis of quantitative evaluation in performance-based fire design,which includes the determination of fire location and heat release rate(HRR).Take large-scale exhibition hall for example,utilizing fire radiation model and smoke radiation model and combining the simulate result of CFAST 6.0,analysis of fire grown situation is taken with different fire locations in large space.Research reveals: only considering fire radiation,when fire develops in a location of bilateral symmetry,fire grows faster with HRR peak values are larger and the time of attain HRR peak value earlier and duration time are shorter than others.Thereinto,fire grow fastest when fire develops in the location of center symmetry.Moreover,combining fire radiation and smoke radiation, HRR peak values consumedly increases and almost the same in each scenarios.But other rules,which contain fire growth and the correlative time,when considering fire radiation and smoke radiation,is the same as the situation of just considering fire radiation.
The situation in large hospital is complex,and different areas in hospital have different methods... more The situation in large hospital is complex,and different areas in hospital have different methods to gain the number of people,who have different kinds of speeds for different kinds of people.Using evacuation software SIMULEX to analysis the situation in large hospital will guide the application to the similar buildings.
Fire properties of cigarette and its packing materials are studied by using ISO 5660 cone calorim... more Fire properties of cigarette and its packing materials are studied by using ISO 5660 cone calorimeter.Various fire parameters such as ignition time,heat release rate,and mass loss rate were obtained.The result indicates that cigarette and its packing materials can be ignited under radiation.Higher radiation will induce shorter ignition time and increases the heat release rate accordingly.The fire risk of the package is generally high when the radiation flux exceeds 25 kW/m2.
Fire protection of historic buildings has been a subject of many investigations over the last 2 d... more Fire protection of historic buildings has been a subject of many investigations over the last 2 decades. In this article, the perspective of historic buildings, fire situations, and fire protective documents in recent years are introduced briefly; important literatures on fire performance of historic materials and assemblies, and fire propagation risk are reviewed; fire risk analysis approaches and fire protection measures are discussed. It is suggested that emphasis should be laid on (1) establishing specific fire databases for historic buildings, (2) improving related legislation and guidance, (3) exploring more suitable methods for fire risk assessment, and (4) formulating appropriate fire protective strategies.
Performance-based design (PBD) has been playing an important function in fire safety of buildings... more Performance-based design (PBD) has been playing an important function in fire safety of buildings, and how to accurately simulate occupants’ behavior gains attention from fire engineers. With booming development of evacuation software, developing an extensive database for evacuation models is imperative and urgent. According to the literature, the whole process of evacuation includes several stages, such as pre-movement, action period, walking period, etc. In order to develop an evacuation model, data in these stages concerning pre-movement time, walking speed, occupant characteristics, actions and exit choice decisions are compiled in this paper. These data can be used as input parameters for evacuation models in PBD or in validating the evacuation models’ accuracy.
Under different heating rates and atmospheres,TG-DTA technique is used to study the pyrolysis of ... more Under different heating rates and atmospheres,TG-DTA technique is used to study the pyrolysis of enclosure materials of computer monitors.By analysis of experiment data,the pyrolysis kinetic parameters from different stages are obtained,and the influences of heating rates and atmospheres are investigated.
The structure importance in Fault Tree Analysis (FTA) reflects how important Basic Events are to ... more The structure importance in Fault Tree Analysis (FTA) reflects how important Basic Events are to Top Event. Attribute at alternative level in Analytic Hierarchy Process (AHP) also reflect its importance to general goal. Based on the coherence of these two methods, an improved AHP is put forward. Using this improved method, how important the attribute is to the fire safety of public building can be analyzed more credibly because of the reduction of subjective judgment. Olympic venues are very important public buildings in China. The fire safety evaluation of them will be a big issue to engineers. Improved AHP is a useful tool to the safety evaluation to these Olympic venues, and it will guide the evaluation in other areas.
As an emerging indoor entertainment place,the carnie has the characteristics of large-scale and f... more As an emerging indoor entertainment place,the carnie has the characteristics of large-scale and function-diversity. In addition,the existing Code for Fire Prevention of Building Design has been no longer fully applicable to such buildings,which further highlight the fire safety problems. The evacuation of a large carnie was simulated and the time for evacuation was obtained in this paper using the simulation software STEPS based on the method of fire performance design. The evacuation study on large carnie not only has guidance meanings to such places, but also will guide the app lication to the similar buildi
Combustion properties and pyrolysis characteristics of materials commonly used to make personal c... more Combustion properties and pyrolysis characteristics of materials commonly used to make personal computer monitors were investigated using pyrolysis combustion flow calorimeter (PCFC) and simultaneous TG/DTA analyzer. Six typical brands of PC monitors were selected for the study. The study has shown that three specimens have similar combustion properties and pyrolysis characteristics with polycaprolactam (PA 6), and the other three specimens are closed to high impact polystyrene (HIPS), polyethylene (PE), polycarbonate (PC) respectively. This study serves as a precursor for Part II: Experiment study on fire characteristics of PC monitors under different ventilation conditions of this two-part study.
The increasing uses of electrical equipment in daily lives raise fire risk and bring many casualt... more The increasing uses of electrical equipment in daily lives raise fire risk and bring many casualties. Gas products from electrical fires will cause incapacitation and death if they present in sufficient quantities for a sufficient period. Those products also delay evacuation or contribute to post-exposure injury and death. In this article, eight full-scale fire experiments on two types of personal computer monitors (PC monitor) have been carried out under different ventilation conditions. To connect these two types of PC monitors, net heat release rate (HRRnet) is defined by peak heat release rate (HRRpeak) which is calculated under non-ventilation condition. The study shows that the ratio, maximum extinction coefficient (EXTmax), as well as maximum values of gas yield rate to HRRnet, rises exponentially with the increase of ventilation factor. In addition, relationship between gas yield rate and heat release rate (HRR) is analyzed in this article. Studies on fire characteristics under different ventilation conditions are meaningful to fire risk assessment and can be used as input data for analytical and computational fire model validation. This article is the further study of Part I: Combustion properties and pyrolysis characteristics of PC monitors of this two-part study.
International Journal on Architectural Science, 2011
Pyrolysis experiments were carried out on Kapur and Nyatoh hardwood species in ovens isothermally... more Pyrolysis experiments were carried out on Kapur and Nyatoh hardwood species in ovens isothermally at low temperatures 160°C, 175°C and 190°C for extended durations up to 153 days in aerobic condition. Oxygen chemisorption and functionality of chars were analysed using thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy.
Pyrolysis kinetic models for Nyatoh and Kapur wood under isothermal conditions in air were developed based on weight loss history. Thermal degradation of wood samples in the study followed a first-order reaction process after the initial period of fast degradation. The model can be used to estimate the heating period to reach different degrees of degradation under air condition as a function of temperature and to predict the duration to reach the final stage where self ignition is most likely at a particular low temperature.
The study has shown that chars created at low temperature for long duration in aerobic condition were susceptible to oxygen chemisorption. Results indicated that they were reactive and prone to self ignition.
This paper reviewed the state of the art in designing renewable energy systems specifically solar... more This paper reviewed the state of the art in designing renewable energy systems specifically solar-based energy system, ground source-based system and day-lighting system, to gain optimum performances in sustainable buildings. Efficiency of each of these systems in reducing resource consumption was evaluated. Geometric conditions have a determining effect on the performances of solar-based energy system and day-lighting system. In solar-based energy system, designing factors, such as system selection, building's orientation, installation location, area of installation, tilt angle and surface temperature, are needed to be considered. Factors of day-lighting system, such as fenestration option, material, area or size, shape, orientation, position, ceiling and shading devices, are needed to be designed carefully to optimize the quality of the luminous environment for occupants. For ground source-based energy system, season condition, operating condition, mode of system, selection of compressor, ground heat exchanger, pump, are important to improve system's performance and reduce cost.
Piloted ignition of woods has been commonly investigated, which is accelerated by a spark plug. A... more Piloted ignition of woods has been commonly investigated, which is accelerated by a spark plug. Autoignition is a complex phenomenon that combustible materials are ignited by internal heating, without the spark plug. Compared with piloted ignition, process of autoignition is closer to the development of real fire. Very few studies have focused on the prediction of ignition time and average mass loss rate by autoignition. Therefore, ignition time and mass loss rate on six species of commonly used wood samples, namely pine, beech, cherry, oak, maple, and ash, were studied under external heat flux by autoignition in a cone calorimeter. Three mass loss stages of woods under external heat flux was observed. Empirical models of ignition time and average mass loss rate for woods under external heat flux were developed. These empirical models can be used not only for fire risk evaluation, but also for modeling input and validation.
Toxic gases are significant in fire risk evaluation. Previous studies have focused on their chara... more Toxic gases are significant in fire risk evaluation. Previous studies have focused on their characteristics by piloted ignition. Spontaneous ignition is a complex phenomenon that combustible materials are ignited by internal heating, without the spark plug. Comparing with piloted ignition, process of spontaneous ignition is much closer to the development of real fire. Therefore, carbon monoxide (CO) of six species of wood samples under external heat flux by spontaneous ignition in a cone calorimeter was investigated. Results showed that influence of thickness to peak CO release rate can be ignored, but time to peak is postponed with a higher thickness. Peak CO release rate decreases with a higher external heat flux, but the decrease is not obvious when heat flux increases from 50 to 75 kW/m2. The flame also has influences to the CO release rate. A sharp decrease of CO release rate happens shortly after ignition and a second peak is near the end of the experiment. Moisture reduces CO release rate and postpones time to peak CO release rate. An empirical model of CO yield of wood samples under different external heat flux and moisture content by spontaneous ignition was developed. This empirical model can be used not only for fire risk evaluation, but also for modeling input and validation.
Six species of wood samples, namely, pine, beech, cherry, oak, maple, and ash, were investigated ... more Six species of wood samples, namely, pine, beech, cherry, oak, maple, and ash, were investigated by autoignition in a cone calorimeter to identify the influence of moisture on autoignition. It was observed that (1) for autoignition, as different from piloted ignition, there is no obvious trend in ignition temperature when moisture content increases from 0% to 11%; (2) ignition temperature decreases with a higher external heat flux, and the influence of specimen thickness to the ignition temperature can be ignored; (3) ignition time correlates linearly with Formula , and the coefficient rises with the increase of moisture content; and (4) the influence of moisture to the average mass loss rate and time at 50% mass loss can be ignored if the moisture content of wood sample is lower than 11%.
The 14th International Conference and Exhibition on Fire and Materials, 2015
A mathematical model, FiresCone, was developed to simulate pyrolysis and combustion
processes of... more A mathematical model, FiresCone, was developed to simulate pyrolysis and combustion
processes of combustible materials considering both gas and solid phases. FiresCone has been
validated by experimental results of four types of combustible materials in a cone calorimeter,
including wood, non-charring, charring and intumescent polymers. It was known that modeling results
of mass loss rate fitted reasonably well with experiments under various heat fluxes. Both experiments
and modeling results showed that peak mass loss rate of wood, non-charring and charring polymers
happened near the end of burning, but for intumescent polymers they showed at the beginning
because of expanded protective char layer. It was also known from modeling results that non-charring
polymer were different from other three types of materials because of the characteristics of in-depth
radiation and no burning residue. FiresCone intends to provide a practical tool for the investigation of
fire behaviors of different types of combustible materials. It can expand the application fields of
modeling as fire processes of different types of combustible materials under complicated
environmental conditions have been considered.
Procedia Engineering - Proceedings of 9th Asia-Oceania Symposium on Fire Science & Technology, 2013
Carbon monoxide (CO) is always a significant judgment criterion in fire risk evaluation. Therefor... more Carbon monoxide (CO) is always a significant judgment criterion in fire risk evaluation. Therefore, a model to predict CO of woods under external heat flux was developed in this study. To improve modeling accuracy, fire processes such as water evaporation, volume shrinkage, liquid and gas transport inside wood slab were considered in this model. Three reactions such as water evaporation, oxidation of virgin wood and char were included. For oxidation reactions of virgin wood and char, CO yields of each reaction were considered constant even under various external heat fluxes. This will expand the applications of this model as limited experimental data of CO yields under different external heat flux. Temperature and moisture dependent thermal properties were used for modeling input. Comparisons between experiment and modeling showed that CO production of woods under different external heat flux can be well predicted by this model. This model intends to provide a practical tool to predict toxic gases of combustible materials under fire conditions.
Procedia Engineering - Proceedings of 9th Asia-Oceania Symposium on Fire Science & Technology, 2013
A model to predict carbon monoxide (CO) of woods under external heat flux was developed. To impro... more A model to predict carbon monoxide (CO) of woods under external heat flux was developed. To improve the modeling accuracy, fire processes such as water evaporation, volume shrinkage, water and gas transport inside wood slab were considered. Three reactions such as water evaporation, oxidation reactions of virgin wood and char were included. Temperature and moisture dependent thermal properties were used for modeling input. In the second part of this study, this model was validated by experiments. Comparisons between modeling and experiments showed that mass loss rate and CO release rate can be well predicted for woods under different moisture contents and external heat flux. Volume shrinkage, transport processes of water and gas volatiles inside wood slab were also included.
This paper serves as validation and application of a mathematical model in Part I: Theory of a model to predict CO of woods under external heat flux. This model intends to provide a practical tool to predict toxic gases of combustible materials under fire conditions.
Besides piloted ignition, autoignition is also an important aspect to real fire development as co... more Besides piloted ignition, autoignition is also an important aspect to real fire development as combustible materials may be ignited without independent flame. Fire behaviors of non-charring and charring polymers were then investigated in a cone calorimeter under autoignition conditions. Fire risk of non-charring polymers are higher than those of charring polymers because of high heat release, and the increase of heat release rate is much obvious with a higher heat flux or thickness. Charring polymers seem to have a higher CO yield, while non-charring polymers have a higher CO2 yield. Ignition methods have influences to combustion efficiency of non-charring polymers as effective heat of combustion under autoignition are observed lower than those reference data under piloted ignition conditions. Its influences to charring polymers are not obvious. Both CO and CO2 yields under flaming combustion are higher than those under non-flaming combustion, but mass percent of carbon seem to has limited effect. Experimental data in this study can provide a guidance to fire risk evaluation of non-charring and charring polymers.
A review of fire processes modeling of combustible materials under external heat flux
One-dimensional model is fundamental to two- or three-dimensional modeling of combustible materia... more One-dimensional model is fundamental to two- or three-dimensional modeling of combustible materials, which can be classified into wood, non-charring polymer, charring polymer and intumescent polymer according to their characteristics. Four fire processes are involved in fire development, such as thermal process, physical process, chemical process and failure process. Consideration of all four fire processes for these combustible materials is significant to modeling accuracy and application fields. Therefore, the state of the art of one-dimensional modeling describing all four fire processes of woods, non-charring polymers, charring polymers and intumescent polymers under external heat flux was reviewed. A summary of typical considerations in previous one-dimensional models was provided, including heat conduction, pyrolysis, production of gas volatiles, volume change, water evaporation, internal gas pressure, properties of permeability and porosity, and mechanical behaviors. Empirical models and critical data of fire processes were also collected for modeling input. This paper can provide a guide to one-dimensional modeling and build basis for two- and three-dimensional modeling.
Fire design is the basis of quantitative evaluation in performance-based fire design,which includ... more Fire design is the basis of quantitative evaluation in performance-based fire design,which includes the determination of fire location and heat release rate(HRR).Take large-scale exhibition hall for example,utilizing fire radiation model and smoke radiation model and combining the simulate result of CFAST 6.0,analysis of fire grown situation is taken with different fire locations in large space.Research reveals: only considering fire radiation,when fire develops in a location of bilateral symmetry,fire grows faster with HRR peak values are larger and the time of attain HRR peak value earlier and duration time are shorter than others.Thereinto,fire grow fastest when fire develops in the location of center symmetry.Moreover,combining fire radiation and smoke radiation, HRR peak values consumedly increases and almost the same in each scenarios.But other rules,which contain fire growth and the correlative time,when considering fire radiation and smoke radiation,is the same as the situation of just considering fire radiation.
The situation in large hospital is complex,and different areas in hospital have different methods... more The situation in large hospital is complex,and different areas in hospital have different methods to gain the number of people,who have different kinds of speeds for different kinds of people.Using evacuation software SIMULEX to analysis the situation in large hospital will guide the application to the similar buildings.
Fire properties of cigarette and its packing materials are studied by using ISO 5660 cone calorim... more Fire properties of cigarette and its packing materials are studied by using ISO 5660 cone calorimeter.Various fire parameters such as ignition time,heat release rate,and mass loss rate were obtained.The result indicates that cigarette and its packing materials can be ignited under radiation.Higher radiation will induce shorter ignition time and increases the heat release rate accordingly.The fire risk of the package is generally high when the radiation flux exceeds 25 kW/m2.
Fire protection of historic buildings has been a subject of many investigations over the last 2 d... more Fire protection of historic buildings has been a subject of many investigations over the last 2 decades. In this article, the perspective of historic buildings, fire situations, and fire protective documents in recent years are introduced briefly; important literatures on fire performance of historic materials and assemblies, and fire propagation risk are reviewed; fire risk analysis approaches and fire protection measures are discussed. It is suggested that emphasis should be laid on (1) establishing specific fire databases for historic buildings, (2) improving related legislation and guidance, (3) exploring more suitable methods for fire risk assessment, and (4) formulating appropriate fire protective strategies.
Performance-based design (PBD) has been playing an important function in fire safety of buildings... more Performance-based design (PBD) has been playing an important function in fire safety of buildings, and how to accurately simulate occupants’ behavior gains attention from fire engineers. With booming development of evacuation software, developing an extensive database for evacuation models is imperative and urgent. According to the literature, the whole process of evacuation includes several stages, such as pre-movement, action period, walking period, etc. In order to develop an evacuation model, data in these stages concerning pre-movement time, walking speed, occupant characteristics, actions and exit choice decisions are compiled in this paper. These data can be used as input parameters for evacuation models in PBD or in validating the evacuation models’ accuracy.
Under different heating rates and atmospheres,TG-DTA technique is used to study the pyrolysis of ... more Under different heating rates and atmospheres,TG-DTA technique is used to study the pyrolysis of enclosure materials of computer monitors.By analysis of experiment data,the pyrolysis kinetic parameters from different stages are obtained,and the influences of heating rates and atmospheres are investigated.
The structure importance in Fault Tree Analysis (FTA) reflects how important Basic Events are to ... more The structure importance in Fault Tree Analysis (FTA) reflects how important Basic Events are to Top Event. Attribute at alternative level in Analytic Hierarchy Process (AHP) also reflect its importance to general goal. Based on the coherence of these two methods, an improved AHP is put forward. Using this improved method, how important the attribute is to the fire safety of public building can be analyzed more credibly because of the reduction of subjective judgment. Olympic venues are very important public buildings in China. The fire safety evaluation of them will be a big issue to engineers. Improved AHP is a useful tool to the safety evaluation to these Olympic venues, and it will guide the evaluation in other areas.
As an emerging indoor entertainment place,the carnie has the characteristics of large-scale and f... more As an emerging indoor entertainment place,the carnie has the characteristics of large-scale and function-diversity. In addition,the existing Code for Fire Prevention of Building Design has been no longer fully applicable to such buildings,which further highlight the fire safety problems. The evacuation of a large carnie was simulated and the time for evacuation was obtained in this paper using the simulation software STEPS based on the method of fire performance design. The evacuation study on large carnie not only has guidance meanings to such places, but also will guide the app lication to the similar buildi
Combustion properties and pyrolysis characteristics of materials commonly used to make personal c... more Combustion properties and pyrolysis characteristics of materials commonly used to make personal computer monitors were investigated using pyrolysis combustion flow calorimeter (PCFC) and simultaneous TG/DTA analyzer. Six typical brands of PC monitors were selected for the study. The study has shown that three specimens have similar combustion properties and pyrolysis characteristics with polycaprolactam (PA 6), and the other three specimens are closed to high impact polystyrene (HIPS), polyethylene (PE), polycarbonate (PC) respectively. This study serves as a precursor for Part II: Experiment study on fire characteristics of PC monitors under different ventilation conditions of this two-part study.
The increasing uses of electrical equipment in daily lives raise fire risk and bring many casualt... more The increasing uses of electrical equipment in daily lives raise fire risk and bring many casualties. Gas products from electrical fires will cause incapacitation and death if they present in sufficient quantities for a sufficient period. Those products also delay evacuation or contribute to post-exposure injury and death. In this article, eight full-scale fire experiments on two types of personal computer monitors (PC monitor) have been carried out under different ventilation conditions. To connect these two types of PC monitors, net heat release rate (HRRnet) is defined by peak heat release rate (HRRpeak) which is calculated under non-ventilation condition. The study shows that the ratio, maximum extinction coefficient (EXTmax), as well as maximum values of gas yield rate to HRRnet, rises exponentially with the increase of ventilation factor. In addition, relationship between gas yield rate and heat release rate (HRR) is analyzed in this article. Studies on fire characteristics under different ventilation conditions are meaningful to fire risk assessment and can be used as input data for analytical and computational fire model validation. This article is the further study of Part I: Combustion properties and pyrolysis characteristics of PC monitors of this two-part study.
International Journal on Architectural Science, 2011
Pyrolysis experiments were carried out on Kapur and Nyatoh hardwood species in ovens isothermally... more Pyrolysis experiments were carried out on Kapur and Nyatoh hardwood species in ovens isothermally at low temperatures 160°C, 175°C and 190°C for extended durations up to 153 days in aerobic condition. Oxygen chemisorption and functionality of chars were analysed using thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy.
Pyrolysis kinetic models for Nyatoh and Kapur wood under isothermal conditions in air were developed based on weight loss history. Thermal degradation of wood samples in the study followed a first-order reaction process after the initial period of fast degradation. The model can be used to estimate the heating period to reach different degrees of degradation under air condition as a function of temperature and to predict the duration to reach the final stage where self ignition is most likely at a particular low temperature.
The study has shown that chars created at low temperature for long duration in aerobic condition were susceptible to oxygen chemisorption. Results indicated that they were reactive and prone to self ignition.
This paper reviewed the state of the art in designing renewable energy systems specifically solar... more This paper reviewed the state of the art in designing renewable energy systems specifically solar-based energy system, ground source-based system and day-lighting system, to gain optimum performances in sustainable buildings. Efficiency of each of these systems in reducing resource consumption was evaluated. Geometric conditions have a determining effect on the performances of solar-based energy system and day-lighting system. In solar-based energy system, designing factors, such as system selection, building's orientation, installation location, area of installation, tilt angle and surface temperature, are needed to be considered. Factors of day-lighting system, such as fenestration option, material, area or size, shape, orientation, position, ceiling and shading devices, are needed to be designed carefully to optimize the quality of the luminous environment for occupants. For ground source-based energy system, season condition, operating condition, mode of system, selection of compressor, ground heat exchanger, pump, are important to improve system's performance and reduce cost.
Piloted ignition of woods has been commonly investigated, which is accelerated by a spark plug. A... more Piloted ignition of woods has been commonly investigated, which is accelerated by a spark plug. Autoignition is a complex phenomenon that combustible materials are ignited by internal heating, without the spark plug. Compared with piloted ignition, process of autoignition is closer to the development of real fire. Very few studies have focused on the prediction of ignition time and average mass loss rate by autoignition. Therefore, ignition time and mass loss rate on six species of commonly used wood samples, namely pine, beech, cherry, oak, maple, and ash, were studied under external heat flux by autoignition in a cone calorimeter. Three mass loss stages of woods under external heat flux was observed. Empirical models of ignition time and average mass loss rate for woods under external heat flux were developed. These empirical models can be used not only for fire risk evaluation, but also for modeling input and validation.
Toxic gases are significant in fire risk evaluation. Previous studies have focused on their chara... more Toxic gases are significant in fire risk evaluation. Previous studies have focused on their characteristics by piloted ignition. Spontaneous ignition is a complex phenomenon that combustible materials are ignited by internal heating, without the spark plug. Comparing with piloted ignition, process of spontaneous ignition is much closer to the development of real fire. Therefore, carbon monoxide (CO) of six species of wood samples under external heat flux by spontaneous ignition in a cone calorimeter was investigated. Results showed that influence of thickness to peak CO release rate can be ignored, but time to peak is postponed with a higher thickness. Peak CO release rate decreases with a higher external heat flux, but the decrease is not obvious when heat flux increases from 50 to 75 kW/m2. The flame also has influences to the CO release rate. A sharp decrease of CO release rate happens shortly after ignition and a second peak is near the end of the experiment. Moisture reduces CO release rate and postpones time to peak CO release rate. An empirical model of CO yield of wood samples under different external heat flux and moisture content by spontaneous ignition was developed. This empirical model can be used not only for fire risk evaluation, but also for modeling input and validation.
Six species of wood samples, namely, pine, beech, cherry, oak, maple, and ash, were investigated ... more Six species of wood samples, namely, pine, beech, cherry, oak, maple, and ash, were investigated by autoignition in a cone calorimeter to identify the influence of moisture on autoignition. It was observed that (1) for autoignition, as different from piloted ignition, there is no obvious trend in ignition temperature when moisture content increases from 0% to 11%; (2) ignition temperature decreases with a higher external heat flux, and the influence of specimen thickness to the ignition temperature can be ignored; (3) ignition time correlates linearly with Formula , and the coefficient rises with the increase of moisture content; and (4) the influence of moisture to the average mass loss rate and time at 50% mass loss can be ignored if the moisture content of wood sample is lower than 11%.
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Papers by Long SHI
processes of combustible materials considering both gas and solid phases. FiresCone has been
validated by experimental results of four types of combustible materials in a cone calorimeter,
including wood, non-charring, charring and intumescent polymers. It was known that modeling results
of mass loss rate fitted reasonably well with experiments under various heat fluxes. Both experiments
and modeling results showed that peak mass loss rate of wood, non-charring and charring polymers
happened near the end of burning, but for intumescent polymers they showed at the beginning
because of expanded protective char layer. It was also known from modeling results that non-charring
polymer were different from other three types of materials because of the characteristics of in-depth
radiation and no burning residue. FiresCone intends to provide a practical tool for the investigation of
fire behaviors of different types of combustible materials. It can expand the application fields of
modeling as fire processes of different types of combustible materials under complicated
environmental conditions have been considered.
This paper serves as validation and application of a mathematical model in Part I: Theory of a model to predict CO of woods under external heat flux. This model intends to provide a practical tool to predict toxic gases of combustible materials under fire conditions.
Pyrolysis kinetic models for Nyatoh and Kapur wood under isothermal conditions in air were developed based on weight loss history. Thermal degradation of wood samples in the study followed a first-order reaction process after the initial period of fast degradation. The model can be used to estimate the heating period to reach different degrees of degradation under air condition as a function of temperature and to predict the duration to reach the final stage where self ignition is most likely at a particular low temperature.
The study has shown that chars created at low temperature for long duration in aerobic condition were susceptible to oxygen chemisorption. Results indicated that they were reactive and prone to self ignition.
processes of combustible materials considering both gas and solid phases. FiresCone has been
validated by experimental results of four types of combustible materials in a cone calorimeter,
including wood, non-charring, charring and intumescent polymers. It was known that modeling results
of mass loss rate fitted reasonably well with experiments under various heat fluxes. Both experiments
and modeling results showed that peak mass loss rate of wood, non-charring and charring polymers
happened near the end of burning, but for intumescent polymers they showed at the beginning
because of expanded protective char layer. It was also known from modeling results that non-charring
polymer were different from other three types of materials because of the characteristics of in-depth
radiation and no burning residue. FiresCone intends to provide a practical tool for the investigation of
fire behaviors of different types of combustible materials. It can expand the application fields of
modeling as fire processes of different types of combustible materials under complicated
environmental conditions have been considered.
This paper serves as validation and application of a mathematical model in Part I: Theory of a model to predict CO of woods under external heat flux. This model intends to provide a practical tool to predict toxic gases of combustible materials under fire conditions.
Pyrolysis kinetic models for Nyatoh and Kapur wood under isothermal conditions in air were developed based on weight loss history. Thermal degradation of wood samples in the study followed a first-order reaction process after the initial period of fast degradation. The model can be used to estimate the heating period to reach different degrees of degradation under air condition as a function of temperature and to predict the duration to reach the final stage where self ignition is most likely at a particular low temperature.
The study has shown that chars created at low temperature for long duration in aerobic condition were susceptible to oxygen chemisorption. Results indicated that they were reactive and prone to self ignition.