- Email: [email protected]
Power optimization of an endoreversible regenerative Brayton cycle
16 Fuel science and technology (fundamental science, analysis, instrumentation)
96/03402 Measurement of electrical properties of a carbon black Liu, C. C. et al., Carbon, 1995, 33, (12), 1699-1708. The direct measurement of electrical properties of a high-surface-area turbostratic carbon black by microwave techniques is reported. This approach obviates many difficulties associatedwith powder samples and allows absolute values of conductivity and mobility to be obtained from which charge carrier concentrations can be calculated and compared to those obtained by ESR methods. Preliminary results indicate that holes are the primary charge carriers in these carbon materials, which have small crystallite size and a small extent of graphitization.Oxygen chemisorbedon the pre-cleanedcarbon black surface increases the concentration of both localized spin centres and holes and creates a higher electrical conductivity. 96/03403 Method for measuring gas pressure Inside coal layer In coke oven Sato, E. and Kinoshita, M. (Assigned to) Shinnippon Seitetsu KK, JAP. Pat. JP.07,207,271, Aug. 1995. The method measures the swelling pressure of coal by inserting a pressure probe inserted in a metallic pipe. 96/03404 Modifier addition In mlcrocolumn supercritical fluid chromatography Robson, M. M. et al., J. Microcolumn Sep., 1995, 7, (4), 355-381. Recent advances in techniques for the packing of microcolumns of down to 50 urn inner diameter using supercritical CO2 have led to rapid growth in the use of high efficiency packed capillary columns in SFC. The application of the system to the analysis of PAHs in coal derivates is shown. The problems encountered in the use of formic acid as a modifier in SFC are discussed. 96/03405 Monitoring hydrofluorocarbon refrigerant leakage from air-conditioning systems in buildings Cheong, K. W. and Riffat, S. B. Applied Energy, Apr. 1996, 53, (4), 341-347. Hydrofluorocarbons (HFCs) are now widely used in refrigeration and airconditioning systems. These systems lose refrigerants through leaks and during servicing. The paper discusses the possibility of determining the emission rate of HFCs in buildings by applying tracer-gas techniques. The measurementof the emission rate of an HFC refrigerant (R134a) using the concentration-decay technique was carried out in a single-zone chamber. The results were compared with measurements made using an SF6 tracer and the Pitot-tube traverse method.
96/03406 Natural convectIon from a burled elliptIc heat source Facas, G. N. Int. J. Heat & Fluid Flow, Dec. 1995, 16, (6), 519-526. Numerical solutions are presented for the natural convection heat transfer from an elliptic heat source buried beneath a semi-infinite, saturated, porous medium. The surface of the medium is assumed to be permeable. The governing equations for Darcy flow are solved using finite differences. The complicated geometry is handled through the use of a body-fitted curvilinear coordinate system. Results are presented for Ra values ranging from 10 to 200 and ellipse aspect ratio values from 1.0 (circular cylinder) to 0.167. 96/03407 On the numerical near-wall correctIons of single hot-wire measurements Chew, Y. T. et aI., Int. J. Heat & Fluid Flow, Dec. 1995, 16, (6), 471-476. The paper numerically investigates the near-wall correction of velocity readings when using hot wires to measure the flows very close to walls. It was found that the near-wall correction is necessary not only for the conducting wall but also for the adiabatic wall. 96/03408 Postulational and statistical thermodynamics Rao, Y. V. Allied Publishers, New Delhi, India, US$24.00, 1996, 277 pp. 96/03409 Power optimization of an endoreverslble regenerative Brayton cycle Cheng, C. Y. and Chen, C. K. Energy, Apr. 1996,21, (4), 241-247. Finite-timethermodynamics has been applied to optimize the power output of endoreversible Brayton cycles with regeneration for infinite thermal capacitance rates of the heat reservoirs. The effect of regeneration on the thermal efficiency and power of endoreversible Brayton cycles is determined. The regenerative heat-transfer rate is positive for lower temperature ratios and negative for high temperature ratios. The maximum power and the correspondingthermal efficiency are decreased by the use of regenerators. The second-law efficiency at maximum power decreases as the number of transfer units of regenerative heat transfer is increased.
96/03410 Prediction of coal properties by derivative DRIFT spectroscopy Alciaturi, C. E. et al., Fuel, Mar. 1996, 75, (4), 491-499. Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy was evaluated as a method for the determination of volatile matter fixed carbon, ash, heating value, carbon, hydrogen, nitrogen, total sUlph~r and maximum vitrinite reflectance. 55 samples (mainly bituminous coals) were analysed by ASTM methods and the results correlated with multiple linear regression (MLR) and principal-components regression with the secondderivative DRIFT spectra. Good correlations (R>0.9) were obtained for volatile matter, fixed carbon, ash, carbon, hydrogen and vitrinite reflectance. 96/03411 Prediction of flow distributions and pressure changes In multi-layered annular packed beds Heggs, P. J. et aI., Gas Sep. Purif., 1995, 9, (4), 243-252. Annular packed bed configurationsare used in many different systems and the radial packing region is not always composed of a single layer of material. This work is based on a commercial air filter which was found to have several d~fferent layers ",:ithin the radially packed region, comprising a particulate filter and an activated carbon layer as the main flow resistances. To enable modelling of such a filter, an existing model has been extended to predict flow distributions and pressure profiles for annular packed bed systems. 96/03412 A reconciliation of mass ranges from matrixassisted laser desorption/ionization mass spectrometry and size exclusion chromatography for coal-derived materials Herod, A. A. et aI., Rapid Commun. Mass Spectrom., 1995, 9, (14), 1446-1451. Describes the use of THF in size-exclusion chromatography (SEC) which leads to partial loss of sample on column packings and results in some separationby an adsorption mechanism rather than by pure size exclusion. The results were compared with SEC data in which 1-methyl-2-pyrrolidone was used as the mobile phase, indicating that the largest molecules appear at the exclusion limit, with a continuum of material down to the total permeation limit of the column. 96/03413 Relationship between microstructure and high temperature corrosion behaviour ofaX20CrMoV 12-1 stainless steel Otero, E. et al., Materials at High Temperatures, 1995, 13, (2), 93-98. A study of the corrosion kinetics of X20CrMoV 12-1 heat resistant stainless steel, at temperatures between 973 and 1273 K, has been carried out. The kinetic laws that rule the process and the correspondingconstants for each temperature have been determined. The relation k=f(T) has also been established for the kinetic laws obtained. The results are justified by the microstructural changes observed during heat treatment. 96/03414 Residual and thermoelastoplastlc stress dIstributions In a heat treated solid cylinder Jahanian, S. Materials at High Temperatures, 1995, 13, (2), 103-110. An important consideration in design is the determination of residual stresses developed during heat treatment of steel. By selecting an appropriate heat treatment technique, one can control the level of residual stresses in the components. Obviously beneficial residual stresses in the material increase the life of components. On the other hand, the unexpected failure of components that is later attributed to detrimental residual stresses is not uncommon. In this paper, residual stress distribution in a quenched long solid cylinder with temperature dependent properties is evaluated. 96/03415 A review of METC's continuous process monitorIng devices for application to high temperature and pressure fossil fuel process streams Chisholm, W. P. Process Control Qual., 1995,7, (2), 113-116. The paper discusses the research and development of continuous process monitors for application in high-temperature and high-pressure fossil fuel processing. The continuous online process stream monitors include an inductively coupled plasma spectrometer, an alkali monitor, a particle counter and a sizer, and a water vapour monitor. 96/03416 RSYST: From nuclear reactor calculations towards a highly sophisticated scientific software Integration environment Noack, M. et aI., Kerntechnik, Feb. 1996, 61, (1), 10-15. The software environment RSYST was originally used to solve problems of reactor physics. The consideration of advanced scientific simulation requirements and the strict application of modern software design principles led to a system which is perfectly suitable to solve problems in various complex scientific problem domains. Starting with a review of the early days of RSYST, the authors describe the straight evolution driven by the need of software environment which combines the advantages of a highperformance database system with the capability to integrate sophisticated scientific technical applications. The RSYST architecture is presented and the data modelling capabilities are described. 96/03417 Sample preparation for kerogen analysIs Jones, R. A. and Ellin, S. J. (Assigned to) University of Sheffield, Brit. UK. GB.2,286,671, A«8. 1995.
Fuel and Energy Abstracts May 1996 233
96/03402 Measurement of electrical properties of a carbon black Liu, C. C. et al., Carbon, 1995, 33, (12), 1699-1708. The direct measurement of electrical properties of a high-surface-area turbostratic carbon black by microwave techniques is reported. This approach obviates many difficulties associatedwith powder samples and allows absolute values of conductivity and mobility to be obtained from which charge carrier concentrations can be calculated and compared to those obtained by ESR methods. Preliminary results indicate that holes are the primary charge carriers in these carbon materials, which have small crystallite size and a small extent of graphitization.Oxygen chemisorbedon the pre-cleanedcarbon black surface increases the concentration of both localized spin centres and holes and creates a higher electrical conductivity. 96/03403 Method for measuring gas pressure Inside coal layer In coke oven Sato, E. and Kinoshita, M. (Assigned to) Shinnippon Seitetsu KK, JAP. Pat. JP.07,207,271, Aug. 1995. The method measures the swelling pressure of coal by inserting a pressure probe inserted in a metallic pipe. 96/03404 Modifier addition In mlcrocolumn supercritical fluid chromatography Robson, M. M. et al., J. Microcolumn Sep., 1995, 7, (4), 355-381. Recent advances in techniques for the packing of microcolumns of down to 50 urn inner diameter using supercritical CO2 have led to rapid growth in the use of high efficiency packed capillary columns in SFC. The application of the system to the analysis of PAHs in coal derivates is shown. The problems encountered in the use of formic acid as a modifier in SFC are discussed. 96/03405 Monitoring hydrofluorocarbon refrigerant leakage from air-conditioning systems in buildings Cheong, K. W. and Riffat, S. B. Applied Energy, Apr. 1996, 53, (4), 341-347. Hydrofluorocarbons (HFCs) are now widely used in refrigeration and airconditioning systems. These systems lose refrigerants through leaks and during servicing. The paper discusses the possibility of determining the emission rate of HFCs in buildings by applying tracer-gas techniques. The measurementof the emission rate of an HFC refrigerant (R134a) using the concentration-decay technique was carried out in a single-zone chamber. The results were compared with measurements made using an SF6 tracer and the Pitot-tube traverse method.
96/03406 Natural convectIon from a burled elliptIc heat source Facas, G. N. Int. J. Heat & Fluid Flow, Dec. 1995, 16, (6), 519-526. Numerical solutions are presented for the natural convection heat transfer from an elliptic heat source buried beneath a semi-infinite, saturated, porous medium. The surface of the medium is assumed to be permeable. The governing equations for Darcy flow are solved using finite differences. The complicated geometry is handled through the use of a body-fitted curvilinear coordinate system. Results are presented for Ra values ranging from 10 to 200 and ellipse aspect ratio values from 1.0 (circular cylinder) to 0.167. 96/03407 On the numerical near-wall correctIons of single hot-wire measurements Chew, Y. T. et aI., Int. J. Heat & Fluid Flow, Dec. 1995, 16, (6), 471-476. The paper numerically investigates the near-wall correction of velocity readings when using hot wires to measure the flows very close to walls. It was found that the near-wall correction is necessary not only for the conducting wall but also for the adiabatic wall. 96/03408 Postulational and statistical thermodynamics Rao, Y. V. Allied Publishers, New Delhi, India, US$24.00, 1996, 277 pp. 96/03409 Power optimization of an endoreverslble regenerative Brayton cycle Cheng, C. Y. and Chen, C. K. Energy, Apr. 1996,21, (4), 241-247. Finite-timethermodynamics has been applied to optimize the power output of endoreversible Brayton cycles with regeneration for infinite thermal capacitance rates of the heat reservoirs. The effect of regeneration on the thermal efficiency and power of endoreversible Brayton cycles is determined. The regenerative heat-transfer rate is positive for lower temperature ratios and negative for high temperature ratios. The maximum power and the correspondingthermal efficiency are decreased by the use of regenerators. The second-law efficiency at maximum power decreases as the number of transfer units of regenerative heat transfer is increased.
96/03410 Prediction of coal properties by derivative DRIFT spectroscopy Alciaturi, C. E. et al., Fuel, Mar. 1996, 75, (4), 491-499. Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy was evaluated as a method for the determination of volatile matter fixed carbon, ash, heating value, carbon, hydrogen, nitrogen, total sUlph~r and maximum vitrinite reflectance. 55 samples (mainly bituminous coals) were analysed by ASTM methods and the results correlated with multiple linear regression (MLR) and principal-components regression with the secondderivative DRIFT spectra. Good correlations (R>0.9) were obtained for volatile matter, fixed carbon, ash, carbon, hydrogen and vitrinite reflectance. 96/03411 Prediction of flow distributions and pressure changes In multi-layered annular packed beds Heggs, P. J. et aI., Gas Sep. Purif., 1995, 9, (4), 243-252. Annular packed bed configurationsare used in many different systems and the radial packing region is not always composed of a single layer of material. This work is based on a commercial air filter which was found to have several d~fferent layers ",:ithin the radially packed region, comprising a particulate filter and an activated carbon layer as the main flow resistances. To enable modelling of such a filter, an existing model has been extended to predict flow distributions and pressure profiles for annular packed bed systems. 96/03412 A reconciliation of mass ranges from matrixassisted laser desorption/ionization mass spectrometry and size exclusion chromatography for coal-derived materials Herod, A. A. et aI., Rapid Commun. Mass Spectrom., 1995, 9, (14), 1446-1451. Describes the use of THF in size-exclusion chromatography (SEC) which leads to partial loss of sample on column packings and results in some separationby an adsorption mechanism rather than by pure size exclusion. The results were compared with SEC data in which 1-methyl-2-pyrrolidone was used as the mobile phase, indicating that the largest molecules appear at the exclusion limit, with a continuum of material down to the total permeation limit of the column. 96/03413 Relationship between microstructure and high temperature corrosion behaviour ofaX20CrMoV 12-1 stainless steel Otero, E. et al., Materials at High Temperatures, 1995, 13, (2), 93-98. A study of the corrosion kinetics of X20CrMoV 12-1 heat resistant stainless steel, at temperatures between 973 and 1273 K, has been carried out. The kinetic laws that rule the process and the correspondingconstants for each temperature have been determined. The relation k=f(T) has also been established for the kinetic laws obtained. The results are justified by the microstructural changes observed during heat treatment. 96/03414 Residual and thermoelastoplastlc stress dIstributions In a heat treated solid cylinder Jahanian, S. Materials at High Temperatures, 1995, 13, (2), 103-110. An important consideration in design is the determination of residual stresses developed during heat treatment of steel. By selecting an appropriate heat treatment technique, one can control the level of residual stresses in the components. Obviously beneficial residual stresses in the material increase the life of components. On the other hand, the unexpected failure of components that is later attributed to detrimental residual stresses is not uncommon. In this paper, residual stress distribution in a quenched long solid cylinder with temperature dependent properties is evaluated. 96/03415 A review of METC's continuous process monitorIng devices for application to high temperature and pressure fossil fuel process streams Chisholm, W. P. Process Control Qual., 1995,7, (2), 113-116. The paper discusses the research and development of continuous process monitors for application in high-temperature and high-pressure fossil fuel processing. The continuous online process stream monitors include an inductively coupled plasma spectrometer, an alkali monitor, a particle counter and a sizer, and a water vapour monitor. 96/03416 RSYST: From nuclear reactor calculations towards a highly sophisticated scientific software Integration environment Noack, M. et aI., Kerntechnik, Feb. 1996, 61, (1), 10-15. The software environment RSYST was originally used to solve problems of reactor physics. The consideration of advanced scientific simulation requirements and the strict application of modern software design principles led to a system which is perfectly suitable to solve problems in various complex scientific problem domains. Starting with a review of the early days of RSYST, the authors describe the straight evolution driven by the need of software environment which combines the advantages of a highperformance database system with the capability to integrate sophisticated scientific technical applications. The RSYST architecture is presented and the data modelling capabilities are described. 96/03417 Sample preparation for kerogen analysIs Jones, R. A. and Ellin, S. J. (Assigned to) University of Sheffield, Brit. UK. GB.2,286,671, A«8. 1995.
Fuel and Energy Abstracts May 1996 233