Heat release rate materials

The surface burning characteristics (flame spread index and smoke developed index) for wood and wood products as measured by American Society for Testing and Materials (44) can be reduced with fire retardant treatments, either chemical impregnation or coatings (48). Fire retardant treatments also reduce the heat release rate of a burning piece of wood (49,50). The heat release rates (51) of the burning materials are an important factor in fire growth. 

Freeder, B. G. et al., J. Loss Prev. Process Ind., 1988, 1, 164-168 Accidental contamination of a 90 kg cylinder of ethylene oxide with a little sodium hydroxide solution led to explosive failure of the cylinder over 8 hours later [1], Based on later studies of the kinetics and heat release of the poly condensation reaction, it was estimated that after 8 hours and 1 min, some 12.7% of the oxide had condensed with an increase in temperature from 20 to 100°C. At this point the heat release rate was calculated to be 2.1 MJ/min, and 100 s later the temperature and heat release rate would be 160° and 1.67 MJ/s respectively, with 28% condensation. Complete reaction would have been attained some 16 s later at a temperature of 700°C [2], Precautions designed to prevent explosive polymerisation of ethylene oxide are discussed, including rigid exclusion of acids covalent halides, such as aluminium chloride, iron(III) chloride, tin(IV) chloride basic materials like alkali hydroxides, ammonia, amines, metallic potassium and catalytically active solids such as aluminium oxide, iron oxide, or rust [1] A comparative study of the runaway exothermic polymerisation of ethylene oxide and of propylene oxide by 10 wt% of solutions of sodium hydroxide of various concentrations has been done using ARC. Results below show onset temperatures/corrected adiabatic exotherm/maximum pressure attained and heat of polymerisation for the least (0.125 M) and most (1 M) concentrated alkali solutions used as catalysts. 

The flammability of solids may be considered to be a function of the heat release rate and critical ignition energy of the material being studied. Flammability is an inverse function of the actual ignition energy of the material in question, and it is directly related to the rate of heat liberated after ignition of the sample. 

At the USDA Forest Service, Forest Products Laboratory (FPL), Brenden and Chamberlain (6) examined the feasibility of measuring heat release rate from an ASTM E-119 furnace. Three methods of measuring heat release were considered the substitution method, oxygen consumption method, and weight of material/heat of combustion method. The oxygen consumption method was shown to be the most advantageous way to measure heat release. However, data were limited to a few assemblies. Chamberlain... 

Because heat of combustion of the volatile product is not the same as that of whole wood, one cannot estimate heat release rate based on mass loss rate as can be done with ideal fuels such as gases, liquids, and some noncharring solid materials. Thus, measuring heat release rate rather than mass loss rate is appropriate for wood and charring materials. Several bench-scale calorimeters have been developed to measure heat release rate of materials (1,11,12,13). 

Calculations of heat release rate by the oxygen consumption method as described by Parker (16) for various applications will be used here. Basically, heat release by the wall is heat release rate as measured in the furnace stack using the oxygen consumption method minus the heat release rate from the fuel gas. The comprehensive equation for heat release rate of the materials (Qwan) as given in Parker s paper (16) is... 

Babrauskas, V., "Development of the Cone Calorimeter - A Bench-Scale Heat Release Rate Apparatus Based on Oxygen Consumption," 1984, Fire and Materials, 8, 81. 

Fig. 5. Developmental concept for a process for the conversion of trees to electricity (12). Dried trees are cut into sections that will fit the boiler chamber. Successive rams push the trees into a charge pit, and then into the furnace. Although larger than a gas-fired boiler, the whole-tree-energy boiler is otherwise similar. The greater height helps achieve a high heat-release rate and complete combustion. Cinders from the burning bed of trees fall through a grate into an area where any remaining carbon in the material bums away. Air is fed into the boiler both below and above the bed of trees to promote complete...

Heat release rate is another relevant measure of the combustibility of a material along with ease of ignition and flame spread. Smith (55) points out that the release rate data, obtained under different test exposures, will be useful in predicting the performance in actual fires under different fuel loading. Release rate data can thus be used—along with other... 

There are two intrinsic material characteristics that are related to heat release rate. These two properties are the effective heat of combustion, AHc (MJ/kg), and the heat of gasification, L (MJ/kg). The effective heat of combustion is the ratio of heat release rate to mass loss rate measured in a bench-scale calorimeter ... 

Babrauskas, V., Development of the cone calorimeter—A bench-scale heat release rate apparatus based on 02 consumption. Fire and Materials 1984, 8, 81-95. 

Smith, E., Heat release rate of building materials. In Ignition, Heat Release and Noncombustibility of Materials, ASTM STP 502, American Society of Testing and Materials, Philadelphia, PA October 6, 1971, Washington, DC, 1972, pp. 119-134. 

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