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01843 Analysis of factors affecting power systemnormal form results
16 Fuel science and technology (fundamental science, analysis, instrumentation)
16
FUEL SCIENCE A N D TECHNOLOGY
the characteristic parameter, gave average absolute percent deviation of 2.01% for the same pure compounds and 1.57% for the 58 multicomponent systems. The accuracy of the simplified model has been compared with other correlations and equations of states.
05/01840 A simplified method to estimate energy savings of artificial lighting use from daylighting
Myers, T. G. and Charpin, J. P. F. International Journal of Heat and Mass Transfer, 2004, 47, (25), 5483-5500. A mathematical model is developed to describe ice accretion and water flow on a cold substrate of arbitrary shape. It is shown how the model may be applied to practical substrate shapes, such as flat surface, cylinder and aerofoil. A numerical scheme to solve the governing equations is then described. Results are presented for an aerofoil under conditions appropriate to in-flight icing and for a cylinder in conditions for atmospheric icing.
Krarti, M. et al. Building and Environment, 2005, 40, (6), 747 754. This paper provides a simplified analysis method to evaluate the potential of daylighting to save energy associated with electric lighting use. Specifically, impacts on daylighting performance are investigated for several combinations of building geometry, window opening size, and glazing type for four geographical locations in the United States. Four building geometries with various window-to-floor areas, along with different glazing types have been analysed. It was determined that for most commercial buildings with glass transmittance values above 0.5, increasing window area to floor area ratio above 0.5, daylighting does not provide significant additional lighting energy savings. A direct correlation has been established between window transmittance and window area on annual lighting reductions. A model is proposed to estimate lighting energy savings given perimeter area, window area, and window type. Verification and validation of the model's predictions are demonstrated using results from building energy simulation as well as experimental data.
05/01837 A numerical method for natural convection and heat conduction around and in a horizontal circular pipe
05•01841 An experimental and modeling analysis of vapor transport deposition of cadmium telluride
Fundamental science, analysis, instrumentation 05•01836 A mathematical model for atmospheric ice accretion and water flow on a cold surface
Yamamoto, S. et al. International Journal of Heat and Mass Transfer, 2004, 47, (26), 5781 5792. Natural convection around a horizontal circular pipe coupled with heat conduction in the solid structure is numerically investigated using a preconditioning method for solving incompressible and compressible Navier-Stokes equations. In this method, fundamental equations are completely reduced to an equation of heat conduction when the flow field is static (zero velocity). Therefore, not only compressibie flows but also very slow flows such as natural convection in a flow field and heat conduction in a static field can be simultaneously calculated using the same computational algorithm. This study first calculated the compressible flow around a NACA0012 airfoil with conduction in the airfoil and then simulated natural convections around a horizontal circular pipe with a different heat conductivity. Finally, the effect of heat conductivity of the pipe on natural convection was numerically investigated.
05•01838 A numerical study of the aspiration efficiency of a thin-walled sampler facing the wind for high velocity ratios Dunnett, S. J. Journal of Aerosol Science, 2005, 36, (l), 111-122. In this work the fluid flow and particle trajectories for a thin-walled sampling probe facing the wind are considered. The flow around the sampler and into the sampler has been determined numerically and the paths of the particles in the flow are then traced and the efficiency of the sampler investigated. A variety of operating conditions have been considered, in particular large values of the velocity ratio, R, which is equal to the ratio of the undisturbed free stream air velocity to the average sampling velocity. The situation of large R values is becoming increasingly important as samplers are developed with low flow rates. Previous experimental results have shown that the empirical model developed for sampling in moving air does not accurately predict the efficiency of samplers operating at these high vaiues of R. The numerical results show that the aspiration efficiency for high R is not significantly affected by gravitational effects for the majority of cases of interest but it is dependent upon the magnitude of the reversal of the flow within the sampling tube.
05•01839 A simplified method for calculating saturated liquid densities Mchaweh, A. et al. Fluid Phase Equilibria, 2004, 224, (2), 157-167. A simplification for the Nasrifar-Moshfeghian (NM) Iiquid density correlation has been developed. A replacement for the Mathias and Copeman temperature-dependent term with the original Soave-Redlich-Kwong equation of state (SRK EOS) temperature-dependent term has been done. This replacement has overcome the limitations in use for the original model due to the Mathias and Copeman vapour pressure-dependent parameters. The new correlation uses one characteristic parameter for each compound and suggests a value of z e r o / o r generalization purpose. The revised model has been tested for pure compounds liquid density prediction of different types including paraffins, cyclo-paraffins, olefins, diolefins, cyclic olefins, aromatics, ethers, liquefied inorganic gases and alcohols. The average absolute percent deviation for 76 compounds consisting of 2379 experimental data points was found to be 0.58%. The simplified method was then used to predict the saturated liquid density of multi-component systems. The average absolute percent deviation for 58 multicomponent systems consisting of 978 experimental points was found to be 0.67%. Generalizing the correlation, by setting a value of zero for
Kestner, J. M. et al. Solar Energy Materials and Solar Cells, 2004, 83, (1), 55-65. Vapour transport deposition (VTD) was employed for high-rate deposition of CdTe thin film solar absorbers. A detailed model was developed for CdTe deposition that included the role of source conditions, convective mass transport, and deposition chemistry. A Langmuir formulation that was consistent with experimental observations of resublimation was used to describe the surface reaction probability. Comparisons of experiment and model showed very good agreement over a range of operating conditions. The model predicts an optimum operating pressure for VTD, arising from a competition between surface kinetics and dilution of the precursor species. For VTD deposition of CdTe the optimum pressure is in the range of 2-5 Tort. These modelling concepts may be easily extended to VTD of other materials as well.
05•01842 An experimental study of stability of oil-water emulsion Chen, G. and Tao, D. Fuel Processing Technology, 2005, 86, (5), 499508. There has been much interest in alternative fuels made from coal which is much more abundant than oil. The coal-oil-water slurry is a new type of oil-based synfael composed of finely pulverized coal, oil and water. It has lower viscosity, lower ignition point and higher heating value than coal-water slurry. The preparation of stable water-in-oil (W/ O) emulsion is critical for the success of production of stable coal-oilwater slurry. The present study was undertaken to experimentally investigate the effects of different process variables on emulsion stability. The emulsion was prepared using 100 ml colloid mill with sorbitan monooleate (SM) as emulsifier. The variables studied include emulsifier dosage, ratio of oil to water, stirring intensity, emulsifying temperature and mixing time. The results showed that the optimum process conditions are: emulsifier dosage, 0.5%; oil to water ratio, 1:1; stirring intensity, 2500 rpm; and mixing temperature, 30°C.
05•01843 Analysis of factors affecting power system normal form results Barocio, E. et al. Eleetric Power Systems Research, 2004, 70, (3), 223236. This paper discusses the experience in the use of normal form (NF) theory to study non-linear modal behaviour in stressed power systems. Making use of NF theory, the use of several analytical indices was examined to quantify system non-linear modal interaction and discuss major factors affecting NF results and interpretation. Specifically, the influence of the initial conditions and the effect of strong modal resonance on the normal form analysis is studied. Based on this understanding, heuristic criteria for guessing initial conditions area devised for assessing model adequacy. New insights into the nature of system oscillations are offered and criteria for characterizing nonlinear effects are discussed. The analysis of factors affecting NF results is illustrated on a four-machine two-area test power network. Numerical calculations are presented and discussed to check the accuracy of the method analysis.
05•01844 Application embedded chaos search immune genetic algorithm for short-term unit commitment Liao, G.-C. and Tsao, T. P. Electric Power Systems Research, 2004, 71, (2), 135-144.
Fuel and Energy Abstracts
July 2005
269
16
FUEL SCIENCE A N D TECHNOLOGY
the characteristic parameter, gave average absolute percent deviation of 2.01% for the same pure compounds and 1.57% for the 58 multicomponent systems. The accuracy of the simplified model has been compared with other correlations and equations of states.
05/01840 A simplified method to estimate energy savings of artificial lighting use from daylighting
Myers, T. G. and Charpin, J. P. F. International Journal of Heat and Mass Transfer, 2004, 47, (25), 5483-5500. A mathematical model is developed to describe ice accretion and water flow on a cold substrate of arbitrary shape. It is shown how the model may be applied to practical substrate shapes, such as flat surface, cylinder and aerofoil. A numerical scheme to solve the governing equations is then described. Results are presented for an aerofoil under conditions appropriate to in-flight icing and for a cylinder in conditions for atmospheric icing.
Krarti, M. et al. Building and Environment, 2005, 40, (6), 747 754. This paper provides a simplified analysis method to evaluate the potential of daylighting to save energy associated with electric lighting use. Specifically, impacts on daylighting performance are investigated for several combinations of building geometry, window opening size, and glazing type for four geographical locations in the United States. Four building geometries with various window-to-floor areas, along with different glazing types have been analysed. It was determined that for most commercial buildings with glass transmittance values above 0.5, increasing window area to floor area ratio above 0.5, daylighting does not provide significant additional lighting energy savings. A direct correlation has been established between window transmittance and window area on annual lighting reductions. A model is proposed to estimate lighting energy savings given perimeter area, window area, and window type. Verification and validation of the model's predictions are demonstrated using results from building energy simulation as well as experimental data.
05/01837 A numerical method for natural convection and heat conduction around and in a horizontal circular pipe
05•01841 An experimental and modeling analysis of vapor transport deposition of cadmium telluride
Fundamental science, analysis, instrumentation 05•01836 A mathematical model for atmospheric ice accretion and water flow on a cold surface
Yamamoto, S. et al. International Journal of Heat and Mass Transfer, 2004, 47, (26), 5781 5792. Natural convection around a horizontal circular pipe coupled with heat conduction in the solid structure is numerically investigated using a preconditioning method for solving incompressible and compressible Navier-Stokes equations. In this method, fundamental equations are completely reduced to an equation of heat conduction when the flow field is static (zero velocity). Therefore, not only compressibie flows but also very slow flows such as natural convection in a flow field and heat conduction in a static field can be simultaneously calculated using the same computational algorithm. This study first calculated the compressible flow around a NACA0012 airfoil with conduction in the airfoil and then simulated natural convections around a horizontal circular pipe with a different heat conductivity. Finally, the effect of heat conductivity of the pipe on natural convection was numerically investigated.
05•01838 A numerical study of the aspiration efficiency of a thin-walled sampler facing the wind for high velocity ratios Dunnett, S. J. Journal of Aerosol Science, 2005, 36, (l), 111-122. In this work the fluid flow and particle trajectories for a thin-walled sampling probe facing the wind are considered. The flow around the sampler and into the sampler has been determined numerically and the paths of the particles in the flow are then traced and the efficiency of the sampler investigated. A variety of operating conditions have been considered, in particular large values of the velocity ratio, R, which is equal to the ratio of the undisturbed free stream air velocity to the average sampling velocity. The situation of large R values is becoming increasingly important as samplers are developed with low flow rates. Previous experimental results have shown that the empirical model developed for sampling in moving air does not accurately predict the efficiency of samplers operating at these high vaiues of R. The numerical results show that the aspiration efficiency for high R is not significantly affected by gravitational effects for the majority of cases of interest but it is dependent upon the magnitude of the reversal of the flow within the sampling tube.
05•01839 A simplified method for calculating saturated liquid densities Mchaweh, A. et al. Fluid Phase Equilibria, 2004, 224, (2), 157-167. A simplification for the Nasrifar-Moshfeghian (NM) Iiquid density correlation has been developed. A replacement for the Mathias and Copeman temperature-dependent term with the original Soave-Redlich-Kwong equation of state (SRK EOS) temperature-dependent term has been done. This replacement has overcome the limitations in use for the original model due to the Mathias and Copeman vapour pressure-dependent parameters. The new correlation uses one characteristic parameter for each compound and suggests a value of z e r o / o r generalization purpose. The revised model has been tested for pure compounds liquid density prediction of different types including paraffins, cyclo-paraffins, olefins, diolefins, cyclic olefins, aromatics, ethers, liquefied inorganic gases and alcohols. The average absolute percent deviation for 76 compounds consisting of 2379 experimental data points was found to be 0.58%. The simplified method was then used to predict the saturated liquid density of multi-component systems. The average absolute percent deviation for 58 multicomponent systems consisting of 978 experimental points was found to be 0.67%. Generalizing the correlation, by setting a value of zero for
Kestner, J. M. et al. Solar Energy Materials and Solar Cells, 2004, 83, (1), 55-65. Vapour transport deposition (VTD) was employed for high-rate deposition of CdTe thin film solar absorbers. A detailed model was developed for CdTe deposition that included the role of source conditions, convective mass transport, and deposition chemistry. A Langmuir formulation that was consistent with experimental observations of resublimation was used to describe the surface reaction probability. Comparisons of experiment and model showed very good agreement over a range of operating conditions. The model predicts an optimum operating pressure for VTD, arising from a competition between surface kinetics and dilution of the precursor species. For VTD deposition of CdTe the optimum pressure is in the range of 2-5 Tort. These modelling concepts may be easily extended to VTD of other materials as well.
05•01842 An experimental study of stability of oil-water emulsion Chen, G. and Tao, D. Fuel Processing Technology, 2005, 86, (5), 499508. There has been much interest in alternative fuels made from coal which is much more abundant than oil. The coal-oil-water slurry is a new type of oil-based synfael composed of finely pulverized coal, oil and water. It has lower viscosity, lower ignition point and higher heating value than coal-water slurry. The preparation of stable water-in-oil (W/ O) emulsion is critical for the success of production of stable coal-oilwater slurry. The present study was undertaken to experimentally investigate the effects of different process variables on emulsion stability. The emulsion was prepared using 100 ml colloid mill with sorbitan monooleate (SM) as emulsifier. The variables studied include emulsifier dosage, ratio of oil to water, stirring intensity, emulsifying temperature and mixing time. The results showed that the optimum process conditions are: emulsifier dosage, 0.5%; oil to water ratio, 1:1; stirring intensity, 2500 rpm; and mixing temperature, 30°C.
05•01843 Analysis of factors affecting power system normal form results Barocio, E. et al. Eleetric Power Systems Research, 2004, 70, (3), 223236. This paper discusses the experience in the use of normal form (NF) theory to study non-linear modal behaviour in stressed power systems. Making use of NF theory, the use of several analytical indices was examined to quantify system non-linear modal interaction and discuss major factors affecting NF results and interpretation. Specifically, the influence of the initial conditions and the effect of strong modal resonance on the normal form analysis is studied. Based on this understanding, heuristic criteria for guessing initial conditions area devised for assessing model adequacy. New insights into the nature of system oscillations are offered and criteria for characterizing nonlinear effects are discussed. The analysis of factors affecting NF results is illustrated on a four-machine two-area test power network. Numerical calculations are presented and discussed to check the accuracy of the method analysis.
05•01844 Application embedded chaos search immune genetic algorithm for short-term unit commitment Liao, G.-C. and Tsao, T. P. Electric Power Systems Research, 2004, 71, (2), 135-144.
Fuel and Energy Abstracts
July 2005
269