Underground fires are characterized by smouldering combustion with a slow rate of spread rate and without flames.Although smouldering combustion releases large amounts of gaseous pollutants,it is difficult to discover...Underground fires are characterized by smouldering combustion with a slow rate of spread rate and without flames.Although smouldering combustion releases large amounts of gaseous pollutants,it is difficult to discover by today's forest fire monitoring technologies.Carbon monoxide(CO),nitrogen oxides(NO_(x))and sulfur dioxide(SO_(2))were identified as high concentration marker gases of smouldering combustion-easily-be monitored.According to a two-way ANOVA,combustion time had a significant impact on CO and NO_(x) emissions;smoldering-depth also had a significant impact on NO_(x) emissions but not on CO emissions.Gas emission equations were established by multiple linear regression,C_(co)=156.989-16.626 t and C_(NOx)=3.637-0.252 t-0.039 h.展开更多
Underground fires are a smoldering combustion with a slow spread rate, low temperatures and no flame. They can last from days to several months, and can even become overwintering fires. They are difficult to find, lea...Underground fires are a smoldering combustion with a slow spread rate, low temperatures and no flame. They can last from days to several months, and can even become overwintering fires. They are difficult to find, leading to considerable damage to the forests. The moisture content of combustible fuels is an important factor in the occurrence and persistence of underground forest fires. The Daxing’an Mountains are a hot spot for underground fires in China. This paper looks at the influence of different moisture contents on underground fire characteristics using simulation combustion experiments in the laboratory. The study showed that peak temperature and spread rate fluctuation of humus at different moisture levels increased with humus depth. Peak temperature and spread rate fluctuation of humus at different depths decreased with increased moisture;moisture content and depth of humus had a significant effect on peak temperature and spread rate fluctuation;peak temperature at different depths decreased with increased moisture;the spread rate in upper layers increased with moisture content, while the spread rate in the lower layers decreased with increased moisture content.展开更多
Underground fires are slow spreading,long-lasting and low temperature smoldering combustion without flames,mainly occurring in peatlands and wetlands with rich organic matter.The spread of the smoldering is maintained...Underground fires are slow spreading,long-lasting and low temperature smoldering combustion without flames,mainly occurring in peatlands and wetlands with rich organic matter.The spread of the smoldering is maintained by heat released during combustion and monitoring this is an important approach to detect underground fires.The Daxing'an Mountains region is a hotspot for underground fires in northeast China.This study examined a L arix gmelinii plantation in the Tatou wetlands of the Daxing'an Mountains and determined the maximum temperature variation of humus of varying particle sizes,and the temperature rising process based on non-linear mixed effects models by an indoor combustion experiment.Maximum combustion temperatures up to 897.5°C,increased with humus depth;among the three models tested,Richard's equations were best for characterizing temperature variations;a non-linear equation with three parameters had the highest accuracy in fitting the combustion temperature variations with varying humus particle sizes.These results are informative for predicting temperature variations and provide technical support for underground fire monitoring.展开更多
基金supported financially by the National Key Research and Development Plan(2018YFD0600205)the National Natural Science Foundation of China(31971669)。
文摘Underground fires are characterized by smouldering combustion with a slow rate of spread rate and without flames.Although smouldering combustion releases large amounts of gaseous pollutants,it is difficult to discover by today's forest fire monitoring technologies.Carbon monoxide(CO),nitrogen oxides(NO_(x))and sulfur dioxide(SO_(2))were identified as high concentration marker gases of smouldering combustion-easily-be monitored.According to a two-way ANOVA,combustion time had a significant impact on CO and NO_(x) emissions;smoldering-depth also had a significant impact on NO_(x) emissions but not on CO emissions.Gas emission equations were established by multiple linear regression,C_(co)=156.989-16.626 t and C_(NOx)=3.637-0.252 t-0.039 h.
基金financially supported by the National Natural Science Foundation of China (31971669)the Postgraduate Innovation Project of Beihua University (2021-013)
文摘Underground fires are a smoldering combustion with a slow spread rate, low temperatures and no flame. They can last from days to several months, and can even become overwintering fires. They are difficult to find, leading to considerable damage to the forests. The moisture content of combustible fuels is an important factor in the occurrence and persistence of underground forest fires. The Daxing’an Mountains are a hot spot for underground fires in China. This paper looks at the influence of different moisture contents on underground fire characteristics using simulation combustion experiments in the laboratory. The study showed that peak temperature and spread rate fluctuation of humus at different moisture levels increased with humus depth. Peak temperature and spread rate fluctuation of humus at different depths decreased with increased moisture;moisture content and depth of humus had a significant effect on peak temperature and spread rate fluctuation;peak temperature at different depths decreased with increased moisture;the spread rate in upper layers increased with moisture content, while the spread rate in the lower layers decreased with increased moisture content.
基金funded by the National Natural Science Foundation of China(Grant No.31971669)。
文摘Underground fires are slow spreading,long-lasting and low temperature smoldering combustion without flames,mainly occurring in peatlands and wetlands with rich organic matter.The spread of the smoldering is maintained by heat released during combustion and monitoring this is an important approach to detect underground fires.The Daxing'an Mountains region is a hotspot for underground fires in northeast China.This study examined a L arix gmelinii plantation in the Tatou wetlands of the Daxing'an Mountains and determined the maximum temperature variation of humus of varying particle sizes,and the temperature rising process based on non-linear mixed effects models by an indoor combustion experiment.Maximum combustion temperatures up to 897.5°C,increased with humus depth;among the three models tested,Richard's equations were best for characterizing temperature variations;a non-linear equation with three parameters had the highest accuracy in fitting the combustion temperature variations with varying humus particle sizes.These results are informative for predicting temperature variations and provide technical support for underground fire monitoring.
