The Experts below are selected from a list of 79677 Experts worldwide ranked by ideXlab platform
Kazuaki Tokuhashi - One of the best experts on this subject based on the ideXlab platform.
-
flammability assessment of ch2cfcf3 comparison with fluoroalkenes and fluoroalkanes
Journal of Hazardous Materials, 2009Co-Authors: Kenji Takizawa, Kazuaki Tokuhashi, Shigeo KondoAbstract:Abstract The burning velocity, flammability limits, and Heat of Combustion of CH2 CFCF3 (1234yf) have been studied to elucidate the fundamental flammability properties of this new alternative refrigerant with low global-warming potential. The burning velocity of 1234yf was measured independently by schlieren photography and the spherical vessel method. In the spherical vessel method, the burning velocities of 1234yf and its analogues CH2 CFCHF2 (1243yf) and CH2 CHCF3 (1243zf) as well as those of typical fluoroalkanes CH2F2 (HFC-32) and CH3CHF2 (HFC-152a) were measured in mixtures of air at various O2/(N2 + O2) ratios. The maximum burning velocity of 1234yf was found to be 1.2 ± 0.3 cm s−1, which was approximately one-fifth that of HFC-32 (6.7 cm s−1) and one order of magnitude less than those of 1243yf (19.8 cm s−1) and 1243zf (14.1 cm s−1). The flame propagation of 1234yf was highly sensitive to flame temperature compared to that of the other compounds. The measured flammability limits and calculated Heat of Combustion of 1234yf were also determined.
-
theoretical calculation of Heat of formation and Heat of Combustion for several flammable gases
Journal of Hazardous Materials, 2002Co-Authors: Shigeo Kondo, Akifumi Takahashi, Kazuaki TokuhashiAbstract:Heats of formation have been calculated by the Gaussian-2 (G2) and/or G2MP2 method for a number of flammable gases. As a result, it has been found that the calculated Heat of formation for compounds containing, such atoms as fluorine and chlorine tends to deviate from the observed values more than calculations for other molecules do. A simple atom additivity correction (AAC) has been found effective to improve the quality of the Heat of formation calculation from the G2 and G2MP2 theories for these molecules. The values of Heat of formation thus obtained have been used to calculate the Heat of Combustion and related constants for evaluating the Combustion hazard of flammable gases.
-
rf number as a new index for assessing Combustion hazard of flammable gases
Journal of Hazardous Materials, 2002Co-Authors: Shigeo Kondo, Akifumi Takahashi, Kazuaki Tokuhashi, Akira SekiyaAbstract:A new index called RF number has been proposed for assessing the Combustion hazard of all sorts of flammable gases and their mixtures. RF number represents the total expectancy of Combustion hazard in terms of flammability limits and Heat of Combustion for each known and unknown compounds. The advantage of RF number over others such as R-index and F-number for classification of Combustion hazard has been highlighted.
Shigeo Kondo - One of the best experts on this subject based on the ideXlab platform.
-
flammability assessment of ch2cfcf3 comparison with fluoroalkenes and fluoroalkanes
Journal of Hazardous Materials, 2009Co-Authors: Kenji Takizawa, Kazuaki Tokuhashi, Shigeo KondoAbstract:Abstract The burning velocity, flammability limits, and Heat of Combustion of CH2 CFCF3 (1234yf) have been studied to elucidate the fundamental flammability properties of this new alternative refrigerant with low global-warming potential. The burning velocity of 1234yf was measured independently by schlieren photography and the spherical vessel method. In the spherical vessel method, the burning velocities of 1234yf and its analogues CH2 CFCHF2 (1243yf) and CH2 CHCF3 (1243zf) as well as those of typical fluoroalkanes CH2F2 (HFC-32) and CH3CHF2 (HFC-152a) were measured in mixtures of air at various O2/(N2 + O2) ratios. The maximum burning velocity of 1234yf was found to be 1.2 ± 0.3 cm s−1, which was approximately one-fifth that of HFC-32 (6.7 cm s−1) and one order of magnitude less than those of 1243yf (19.8 cm s−1) and 1243zf (14.1 cm s−1). The flame propagation of 1234yf was highly sensitive to flame temperature compared to that of the other compounds. The measured flammability limits and calculated Heat of Combustion of 1234yf were also determined.
-
theoretical calculation of Heat of formation and Heat of Combustion for several flammable gases
Journal of Hazardous Materials, 2002Co-Authors: Shigeo Kondo, Akifumi Takahashi, Kazuaki TokuhashiAbstract:Heats of formation have been calculated by the Gaussian-2 (G2) and/or G2MP2 method for a number of flammable gases. As a result, it has been found that the calculated Heat of formation for compounds containing, such atoms as fluorine and chlorine tends to deviate from the observed values more than calculations for other molecules do. A simple atom additivity correction (AAC) has been found effective to improve the quality of the Heat of formation calculation from the G2 and G2MP2 theories for these molecules. The values of Heat of formation thus obtained have been used to calculate the Heat of Combustion and related constants for evaluating the Combustion hazard of flammable gases.
-
rf number as a new index for assessing Combustion hazard of flammable gases
Journal of Hazardous Materials, 2002Co-Authors: Shigeo Kondo, Akifumi Takahashi, Kazuaki Tokuhashi, Akira SekiyaAbstract:A new index called RF number has been proposed for assessing the Combustion hazard of all sorts of flammable gases and their mixtures. RF number represents the total expectancy of Combustion hazard in terms of flammability limits and Heat of Combustion for each known and unknown compounds. The advantage of RF number over others such as R-index and F-number for classification of Combustion hazard has been highlighted.
A Scaltsoyiannes - One of the best experts on this subject based on the ideXlab platform.
-
use of natural resin to reduce water content in diesel fuel
Chemistry and Technology of Fuels and Oils, 2014Co-Authors: C G Tsanaktsidis, A Scaltsoyiannes, E X Katsidi, S G Christidis, G T TzilantonisAbstract:We propose using a wood resin to remove water from diesel fuel. We have studied the effect of thequantity of resin used and its contact time with the fuel on the water content in the fuel. We have alsodetermined the changes in density, kinematic viscosity, electrical conductivity, flash point, and Heat ofCombustion for diesel fuel after contact with the resin. Under optimal conditions, the Heat of Combustionof the fuel increases by 633 J/g, and the water content is reduced by 69%.Key words: diesel fuel, wood resin, water content, electrical conductivity, Heat of Combustion, Aleppopine.
-
natural resins and their application in antifouling fuel technology part i improving the physicochemical properties of diesel fuel using natural resin polymer as a removable additive
Fuel Processing Technology, 2013Co-Authors: C G Tsanaktsidis, A Scaltsoyiannes, E X Katsidi, S G Christidis, Evangelos P FavvasAbstract:Abstract A simple method is proposed for the improvement of diesel fuel properties without the addition of surfactants, chemicals or other pollutants components. Natural resin, a natural product from Pinus halepensis trees was used in order to remove water residues from diesel fuels. A simple but highly effective method was used in order to improve the physicochemical properties of commercial diesel fuels. The main idea is based on the property of the resin to adsorb water, especially when the water amount is dissolved into hydrocarbon fluids. This phenomenon was investigated as a resin concentration effecting into diesel fuel samples as well as a process of the mixing time. To this end different mass of resin was mixed with diesel fuel and after several times of blending process the main physicochemical properties were measured and compared with those of the raw diesel fuel. Specifically, the density, the kinematic viscosity, the conductivity, the humidity, the flash point and the Heat of Combustion were measured according to the ASTM standard protocols. This water removal improved the physicochemical properties of diesel fuel, up to 633 J/g for the Heat of Combustion, 69% for humidity and up to 74% for conductivity. In addition the humidity adsorption phenomenon was confirmable by water adsorption isotherm at 293 K as well as by using independent techniques such as FTIR, DSC and TGA. Overall, the proposed method can be used in a simple fuel cleaning process.
Charles Boardman - One of the best experts on this subject based on the ideXlab platform.
-
Treated and untreated foam core particleboards with intumescent veneer
Journal of Thermal Analysis and Calorimetry, 2013Co-Authors: Mark A. Dietenberger, Ali Shalbafan, Johannes Welling, Charles BoardmanAbstract:The effectiveness of treatments for the surface layer of novel foam core particleboards was evaluated by means of Cone calorimeter tests. Foam core particleboards with variations of surface layer treatment, adhesives, and surface layer thicknesses under similar processing conditions were used to produce the test specimen for the Cone calorimeter tests. Ignitability, Heat release rate profile, peak of Heat release rate, total Heat released, effective Heat of Combustion, mass loss rate, gaseous emissions, and specific extinction area were measured using the cone irradiance of 50 kW m^−2. Additional analysis of this data provided fuel composition information that could reveal the pyrolysis events of the composite boards. Thermocouples at various depths were used to provide further verification of pyrolysis events. The unprotected foam core panels generally had much higher Heat release rates, somewhat higher Heat of Combustion and much higher smoke production due to the polymeric foam component of tested panels, whereas time to ignition and total Heat release were not pronounced from the veneer treated boards. Adding the commercial fire retardant veneer to the face particleboard provided a dramatic improvement to the measured flammability properties. It worked sufficiently well with a 3 mm thick surface layer to improve the predicted flame spread rating of the foam core particleboards.
Richard E. Lyon - One of the best experts on this subject based on the ideXlab platform.
-
an exercise in obtaining flame radiation fraction from the cone calorimeter
Fire and Materials, 2016Co-Authors: James G Quintiere, Richard E. Lyon, Sean CrowleyAbstract:Summary The radiant fraction of the Heat of Combustion emitted by flames of burning fuels is an important quantity needed to predict the thermal radiation from pool fires to remote targets and as a local flame parameter in CFD models. Although there are data for radiant fraction of gas flames, there are little data for this parameter for burning solid materials. The sole source of these data is Archie Tewarson, who used the FMGlobal Fire Propagation Apparatus to compute the radiant fraction of the Heat of Combustion from energy losses associated with enthalpy flow and duct Heat losses. This paper describes a similar approach to obtain the radiant fraction of the Heat from flames of burning solids using the cone calorimeter. In the present work, the cone calorimeter is calibrated using a Meeker burner with a premixed methane/air flame that is small and blue and has minimum flame radiation. A Heat loss correction factor due to thermal conductance from the duct to the ambient air is determined from the calibration by measuring the temperature of the Combustion stream in the duct at the gas sampling location. That factor was found to be 13 ± 2 W/K by calibration compared with a theoretical estimate of 9.3 W/K. The effect of the Heat capacity of the duct walls is accounted for by de-convoluting the duct temperature history. The necessary measurements to compute the radiant fraction then become the Heat release rate by oxygen consumption, the mass flow rate in the duct, and the gas temperature in the duct at the sampling location. Results were obtained for 15 polymers, eight of which could be compared with data for nominally similar materials obtained by Tewarson. In addition, results are found to be in good agreement with a correlation by Tewarson in terms of Combustion efficiency. Copyright © 2016 John Wiley & Sons, Ltd.
-
influence of physical properties on polymer flammability in the cone calorimeter
Polymers for Advanced Technologies, 2011Co-Authors: Parina Patel, Richard T Hull, Andrew A. Stec, Richard E. LyonAbstract:The relationship between physical properties and fire performance as measured in the cone calorimeter is not well understood. A number of studies have identified relationships between the physical and chemical properties of polymeric materials and their gasification behavior which can be determined through numerical pyrolysis models. ThermaKin, a one-dimensional pyrolysis model, has recently been employed to predict the burning behavior in fire calorimetry experiments. The range of thermal, chemical, and optical properties of various polymers have been utilized to simulate the processes occurring within a polymer exposed to a uniform Heat flux, such as in a cone calorimeter. ThermaKin uses these material properties to predict the mass flux history in a cone calorimeter. Multiplying the mass flux history by the Heat of Combustion of the fuel gases gives the HRR history and these have been calculated for cone calorimeter experiments at 50 kW m−2 incident Heat flux for the lowest, average, and highest values of physical parameters exhibited by common polymers. In contrast with actual experiments in fire retardancy, where several parameters change on incorporation of an additive, this study allows for the effect of each parameter to be seen in isolation. The parameters used in this study are grouped into physical properties (density, Heat capacity, and thermal conductivity), optical properties (absorption and reflectivity), and chemical properties (Heat of decomposition, kinetic parameter, and Heat of Combustion). The study shows how the thermal decomposition kinetic parameters effect the surface burning (pyrolysis) temperature and resulting Heat release rate history, as well as the relative importance of other properties directly related to the chemical composition. It also illustrates the effect of thermal inertia (the product of density, Heat capacity, and thermal conductivity) and of the samples' ability to absorb radiant Heat. Copyright © 2011 John Wiley & Sons, Ltd.
-
a molecular basis for polymer flammability
Polymer, 2009Co-Authors: Richard E. Lyon, Michael T Takemori, Natallia Safronava, Stanislav I Stoliarov, Richard N. WaltersAbstract:Empirical molar group contributions to the thermal Combustion properties measured by microscale Combustion calorimetry were determined by multiple linear regression of data for engineering polymers of known chemical composition. Char yield, Heat of Combustion and Heat release capacity of polymers calculated from their chemical structure using optimized additive molar group contributions were in reasonable agreement with measured values for these properties. The relationship between the thermal Combustion properties and the results of standardized flame and fire tests (i.e., flammability) was examined statistically for an expanded data set.
-
solid state thermochemistry of flaming Combustion
1999Co-Authors: Richard E. LyonAbstract:Abstract : The thermal and chemical processes which occur in the solid state during flaming Combustion are examined. A phenomenological model of fuel generation provides the relationships between macroscopic flammability parameters and polymer chemical structure and shows how the coupling of thermal diffusion and chemical kinetics occurs naturally in the pyrolysis zone. Fire behavior and flammability of solid polymers are predicted using the ignition temperature, Heat of Combustion, Heat of gasification, and char yield calculated from the chemical structure; and the results are compared to experimental values. The objective of this work is to develop a consistent, solid-state physical chemistry of flaming Combustion which bridges the gap between fire and material sciences to help guide the discovery of new, more fire-resistant polymers.
