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01608 Errors and correction in complex heat capacity measurements by temperature modulated DSC
16 Fuel science and technology (fundamental science, analysis, instrumentation) 04/01603 Development of a numerical simulation system toward comprehensive assessments of urban warming countermeasures including their impacts upon the urban buildings' energy-demands Kikegawa, Y. et al. Applied Energy, 2004, 76, (4), 449 466. One of the detrimental effects caused by the urban warming phenomena is the increase of energy consumption due to the artificial air-conditioning of buildings in summer. In greater Tokyo, the temperature sensitivity of the peak electricity demand reaches up to 3%/°C in recent years, and about 1.5 GW of new demand is required as the daily maximum temperature increases by 1.0°C. This huge demand for summer electricity is considered to be one of the common characteristics of big cities in Asian countries. In order to simulate this increase in cooling energy demands and to evaluate urban warming countermeasures from the viewpoint of buildings' energy savings, a numerical simulation system was developed adopting a new onedimensional urban canopy meteorological model coupled with a simple sub-model for the building energy analysis. Then, the system was applied to the Ootemachi area, a central business district in Tokyo. Preliminary verification of the simulation system using observational data on the outdoor and indoor thermal conditions showed good results. Simulations also indicated that the cut-off of the anthropogenic heat from air-conditioning facilities could produce a cooling energy saving up to 6% with the outdoor air-temperature decrease by more than I°C in the summer urban canopy over Ootemachi area.
04/01604 Effect of experimental conditions on cogasification of coal, biomass and plastics wastes with air/ steam mixtures in a fiuidized bed system Pinto, F. et al. Fuel, 2003, 82, (15-17), 1967-1976. The effect of temperature and of gasification medium was studied, using only air, only steam and mixtures of both as gasification medium, with the aim of optimizing co-gasification of coal and wastes. The rise in gasification temperature promoted further hydrocarbon reactions, leading to a decrease in tar and hydrocarbon content and an increase in H2 release. Increasing temperature, from 750 to 890°C, during gasification of a mixture with 60% (w/w) of coal, 20% of pine and 20% of PE wastes, ted to a decrease in methane and other hydrocarbons concentration of about 30 and 63%, respectively, whilst hydrogen concentration increased around 70%. Hydrocarbons contents decrease was also achieved by increasing air flow rate, because partial combustion caused by oxygen decreased tars and gaseous hydrocarbons, with even a decrease in heating requirements. However, the presence of air is disadvantageous, because it decreases the higher heating value of the gasification gas, due to nitrogen diluting effect. The rise of steam flow rate has proven to be advantageous, because reforming reactions were favoured, thus hydrocarbons concentrations decreased and hydrogen release increased.
04•01605 Effects analysis fuzzy inference system'in nuclear problems using approximate reasoning Guimarfies, A. C. F. and Lapa, C. M. F. Annals of Nuclear Energy, 2004, 31, (1), 107-115. In this paper a fuzzy inference system modelling technique applied on failure mode and effects analysis (FMEA) is introduced in reactor nuclear problems. This method uses the concept of a pure fuzzy logic system to treat the traditional F M E A parameters: probabilities of occurrence, severity and detection. The auxiliary feed-water system of a typical two-loop pressurized water reactor (PWR) was used as practical example in this analysis. The kernel result is the conceptual confrontation among the traditional risk priority number (RPN) and the fuzzy risk priority number (FRPN) obtained from expert opinion. The set of results demonstrated the great potential of the inference system and advantage of the gray approach in this class of problems.
04/01606 Enthalpies of formation of steam coals from elements under standard conditions Samuilov, E. V. et al. Khimiya Tverdogo Topliva (Moscow, Russian Federation), 2003, 1, 42-57. (In Russian) A study on calculation of thermodynamic properties and composition of products of combustion, gasification, and pyrolysis of coals is presented. Suggestions as to calculation (from literature data) of initial composition of coals were made. A method for calculation of standard enthalpies of formation of coals from elements was proposed. The results of the calculations of formation enthalpies for basic steam coals were presented. As an example of use of formation enthalpies, adiabatic temperatures of coal gasification were calculated. At these temperatures concentrations of basic components of gasification products (e.g. CO, H2, H20, CO2) and S-containing gas components (e.g. SO2, HzS, COS) vs specific concentration of oxygen (for oxygen and air as gasification media) were given.
04/01607 Entropy generation due to laminar forced convection in the entrance region of a concentric annulus Haddad, O. M. et al. Energy, 2004, 29, (1), 35-55.
218
Fuel and Energy Abstracts
May 2004
This study is focused on the entropy production due to laminar forced convection in the entrance region of a concentric cylindrical annulus. The present hydrodynamic and temperature fields are obtained numerically. Local entropy generation distributions are obtained based on the resulting velocity and temperature fields by solving the entropy generation equation. The effect of different flow parameters on thermal, viscous, and total entropy generation is studied for different thermal boundary conditions. Moreover, the effect of radius ratio on the entropy generation is investigated. Entropy generation was found to be inversely proportional to both Reynolds number and the dimensionless entrance temperature. The results also show that increasing Eckert number and/or the radius ratio will increase the entropy generation. Finally, it is found that thermal entropy generation is relatively dominant over viscous entropy generation.
04/01608 Errors and correction in complex heat capacity measurements by temperature modulated DSC Kanari, K. and Ozawa, T. Thermochimica Aeta, 2003, 399, (1-2), 189201. For complex heat capacity measurements, various types of temperature modulated differential scanning calorimetry (tm-DSC) can be used. However, three factors have an influence on the steady state of tmDSC and, hence, cause errors in complex heat capacity measurements. These factors are heat capacities along heat paths in the instrument, temperature distribution within the sample, and thermal contact among the sample, the sample cell, and its holder plate. They are theoretically investigated by a set of comprehensive fundamental equations of heat balance based on a common model applicable to all existing types of tm-DSC. For heat paths in the instrument, heat loss to the environment and mutual heat exchange between the sample and the reference material are also taken into accounts, beside the main heat flows from the heat sources to the sample and the reference material. Rigorous and general solutions have been obtained, and useful relations for complex heat capacity measurements have been derived for each type of tm-DSC. Examining the solutions, new insight into tm-DSC is obtained, and errors and their correction are discussed. They are characteristic of tm-DSC types and compared with each other.
04•01609 Estimating geomechanical properties by using an integrated flow model Fanchi, J. R. SPE Reservoir Evaluation & Engineering, 2003, 6, (2), 108116, This study shows how to obtain inexpensive estimates of geomechanical parameters by explicitly coupling a petrophysical model with a traditional flow simulator. The usefulness of development geophysical information from the resulting integrated flow model is illustrated for improved recovery and coalbed methane production processes.
04/01610 Experimental and artificial neural network modeling study on soot formation in premixed hydrocarbon flames Inal, F. et al. Fuel, 2003, 82, (12), 1477 1490. The formation of soot in premixed flames of methane, ethane, propane, and butane was studied at three different equivalence ratios. Soot particle sizes, number densities, and volume fractions were determined using classical light scattering measurement techniques. The experimental data revealed that the soot properties were sensitive to the fuel type and combustion parameter equivalence ratio. Increase in equivalence ratio increased the amount of soot formed for each fuel. In addition, methane flames showed larger particle diameters at higher distances above the burner surface and propane, ethane, and butane flames came after the methane flames, respectively. Three-layer, feedfolward type artificial neural networks having seven input neurons, one output neuron, and five hidden neurons for soot particle diameter predictions and seven hidden neurons for volume fraction predictions were used to model the soot properties. The network could not be trained and tested with sufficient accuracy to predict the number density due to a large data range and greater uncertainty in determination of this parameter. The number of complete data set used in the model was 156. There was a good agreement between the experimental and predicted values, and neural networks performed better when predicting output parameters (i.e. soot particle diameters and volume fractions) within the limits of the training data.
04/01611 Experimental and numerical analysis of sawdust char combustion reactivity in a drop tube reactor Meesri, C. and Moghtaderi, B. Combustion Science and Technology, 2003, 175, (4), 793-823. This article discusses the results of a combined experimental and numerical investigation of the combustion reactivity of sawdust char in a drop tube furnace. The work presented here was motivated by the lack of reliable data in the open literature on the combustion reactivity of woody biomass char. This study involved the experimental detection of the global kinetic parameters of sawdust-char oxidation and the
04/01604 Effect of experimental conditions on cogasification of coal, biomass and plastics wastes with air/ steam mixtures in a fiuidized bed system Pinto, F. et al. Fuel, 2003, 82, (15-17), 1967-1976. The effect of temperature and of gasification medium was studied, using only air, only steam and mixtures of both as gasification medium, with the aim of optimizing co-gasification of coal and wastes. The rise in gasification temperature promoted further hydrocarbon reactions, leading to a decrease in tar and hydrocarbon content and an increase in H2 release. Increasing temperature, from 750 to 890°C, during gasification of a mixture with 60% (w/w) of coal, 20% of pine and 20% of PE wastes, ted to a decrease in methane and other hydrocarbons concentration of about 30 and 63%, respectively, whilst hydrogen concentration increased around 70%. Hydrocarbons contents decrease was also achieved by increasing air flow rate, because partial combustion caused by oxygen decreased tars and gaseous hydrocarbons, with even a decrease in heating requirements. However, the presence of air is disadvantageous, because it decreases the higher heating value of the gasification gas, due to nitrogen diluting effect. The rise of steam flow rate has proven to be advantageous, because reforming reactions were favoured, thus hydrocarbons concentrations decreased and hydrogen release increased.
04•01605 Effects analysis fuzzy inference system'in nuclear problems using approximate reasoning Guimarfies, A. C. F. and Lapa, C. M. F. Annals of Nuclear Energy, 2004, 31, (1), 107-115. In this paper a fuzzy inference system modelling technique applied on failure mode and effects analysis (FMEA) is introduced in reactor nuclear problems. This method uses the concept of a pure fuzzy logic system to treat the traditional F M E A parameters: probabilities of occurrence, severity and detection. The auxiliary feed-water system of a typical two-loop pressurized water reactor (PWR) was used as practical example in this analysis. The kernel result is the conceptual confrontation among the traditional risk priority number (RPN) and the fuzzy risk priority number (FRPN) obtained from expert opinion. The set of results demonstrated the great potential of the inference system and advantage of the gray approach in this class of problems.
04/01606 Enthalpies of formation of steam coals from elements under standard conditions Samuilov, E. V. et al. Khimiya Tverdogo Topliva (Moscow, Russian Federation), 2003, 1, 42-57. (In Russian) A study on calculation of thermodynamic properties and composition of products of combustion, gasification, and pyrolysis of coals is presented. Suggestions as to calculation (from literature data) of initial composition of coals were made. A method for calculation of standard enthalpies of formation of coals from elements was proposed. The results of the calculations of formation enthalpies for basic steam coals were presented. As an example of use of formation enthalpies, adiabatic temperatures of coal gasification were calculated. At these temperatures concentrations of basic components of gasification products (e.g. CO, H2, H20, CO2) and S-containing gas components (e.g. SO2, HzS, COS) vs specific concentration of oxygen (for oxygen and air as gasification media) were given.
04/01607 Entropy generation due to laminar forced convection in the entrance region of a concentric annulus Haddad, O. M. et al. Energy, 2004, 29, (1), 35-55.
218
Fuel and Energy Abstracts
May 2004
This study is focused on the entropy production due to laminar forced convection in the entrance region of a concentric cylindrical annulus. The present hydrodynamic and temperature fields are obtained numerically. Local entropy generation distributions are obtained based on the resulting velocity and temperature fields by solving the entropy generation equation. The effect of different flow parameters on thermal, viscous, and total entropy generation is studied for different thermal boundary conditions. Moreover, the effect of radius ratio on the entropy generation is investigated. Entropy generation was found to be inversely proportional to both Reynolds number and the dimensionless entrance temperature. The results also show that increasing Eckert number and/or the radius ratio will increase the entropy generation. Finally, it is found that thermal entropy generation is relatively dominant over viscous entropy generation.
04/01608 Errors and correction in complex heat capacity measurements by temperature modulated DSC Kanari, K. and Ozawa, T. Thermochimica Aeta, 2003, 399, (1-2), 189201. For complex heat capacity measurements, various types of temperature modulated differential scanning calorimetry (tm-DSC) can be used. However, three factors have an influence on the steady state of tmDSC and, hence, cause errors in complex heat capacity measurements. These factors are heat capacities along heat paths in the instrument, temperature distribution within the sample, and thermal contact among the sample, the sample cell, and its holder plate. They are theoretically investigated by a set of comprehensive fundamental equations of heat balance based on a common model applicable to all existing types of tm-DSC. For heat paths in the instrument, heat loss to the environment and mutual heat exchange between the sample and the reference material are also taken into accounts, beside the main heat flows from the heat sources to the sample and the reference material. Rigorous and general solutions have been obtained, and useful relations for complex heat capacity measurements have been derived for each type of tm-DSC. Examining the solutions, new insight into tm-DSC is obtained, and errors and their correction are discussed. They are characteristic of tm-DSC types and compared with each other.
04•01609 Estimating geomechanical properties by using an integrated flow model Fanchi, J. R. SPE Reservoir Evaluation & Engineering, 2003, 6, (2), 108116, This study shows how to obtain inexpensive estimates of geomechanical parameters by explicitly coupling a petrophysical model with a traditional flow simulator. The usefulness of development geophysical information from the resulting integrated flow model is illustrated for improved recovery and coalbed methane production processes.
04/01610 Experimental and artificial neural network modeling study on soot formation in premixed hydrocarbon flames Inal, F. et al. Fuel, 2003, 82, (12), 1477 1490. The formation of soot in premixed flames of methane, ethane, propane, and butane was studied at three different equivalence ratios. Soot particle sizes, number densities, and volume fractions were determined using classical light scattering measurement techniques. The experimental data revealed that the soot properties were sensitive to the fuel type and combustion parameter equivalence ratio. Increase in equivalence ratio increased the amount of soot formed for each fuel. In addition, methane flames showed larger particle diameters at higher distances above the burner surface and propane, ethane, and butane flames came after the methane flames, respectively. Three-layer, feedfolward type artificial neural networks having seven input neurons, one output neuron, and five hidden neurons for soot particle diameter predictions and seven hidden neurons for volume fraction predictions were used to model the soot properties. The network could not be trained and tested with sufficient accuracy to predict the number density due to a large data range and greater uncertainty in determination of this parameter. The number of complete data set used in the model was 156. There was a good agreement between the experimental and predicted values, and neural networks performed better when predicting output parameters (i.e. soot particle diameters and volume fractions) within the limits of the training data.
04/01611 Experimental and numerical analysis of sawdust char combustion reactivity in a drop tube reactor Meesri, C. and Moghtaderi, B. Combustion Science and Technology, 2003, 175, (4), 793-823. This article discusses the results of a combined experimental and numerical investigation of the combustion reactivity of sawdust char in a drop tube furnace. The work presented here was motivated by the lack of reliable data in the open literature on the combustion reactivity of woody biomass char. This study involved the experimental detection of the global kinetic parameters of sawdust-char oxidation and the