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02270 Modelling of the hydro-generator local network operation and load disturbance rejection
11 Engines (power generation and propulsion, electrical vehicles) compared to the rates obtained experimentally, the temporal evolution of some combustion parameters have been analysed and the influence of NN combustion simulation in global transient modelling has been presented.
06•02264 Ecological coefficient of performance (ECOP) optimization for an irreversible Brayton heat engine with variable-temperature thermal reservoirs Ust, Y. et al. Journal ~?fthe Energy hzstitute, 2006, 79, (1), 47 52. An ecological performance analysis for an irreversible Brayton heat engine with variable-temperature thermal reservoirs based on the ecological criterion called ecological coefficient of performance is presented. The model considered includes irreversibilities due to finiterate heat transfer and internal dissipations. The effects of design parameters such as isentropic temperature ratio, heat exchanger effectiveness, thermal reservoir inlet temperature ratio and the ratio of hot-to-cold thermal capacity rates of thermal reservoirs, on the general and optimal ecological performances have been investigated in detail, Comparisons of the results with those of an alternative ecological objective function defined in the literature, the maximum power output conditions, and thermal efficiency are also provided.
06/02265 Effects of ethanol-unleaded gasoline blends on cyclic variability and emissions in an SI engine Ceviz, M. A. and Y/iksel, F. Applied Thermal Engineeril~g, 2005, 25, (5 6), 917 925. One important design goal for spark-ignited (SI) engines is to minimize cyclic variability. A small amount of cyclic variability (slow burns) can produce undesirable engine vibrations. On the other hand, a larger amount of cyclic variability (incomplete burns) leads to an increase in hydrocarbon consumption and emissions. This paper investigates the effects of using ethanol-unleaded gasoline blends on cyclic variability and emissions in an SI engine. Results of this study showed that using ethanol-unleaded gasoline blends as a fuel decreased the coefficient of variation in indicated mean effective pressure, and CO and HC emission concentrations, while increased carbon dioxide concentration up to 10 vol% ethanol in fuel blend. On the other hand, after this level of blend a reverse effect was observed on the parameters aforementioned. The 10 vol% ethanol in fuel blend gave the best results.
06/02266 Effects of friction and temperature-dependent specific-heat of the working fluid on the performance of a Diesel-engine Al-Sarkhi, A. et al. Applied Energy, 2006, 83, (2), 153-165. Using finite-time thermodynamics, the relations between the power output, thermal efficiency and compression ratio have been derived. The effect of the specific heat of the working fluid, being temperature dependent, on the irreversible cycle performance, is significant. The conclusions obtained in this investigation are in full agreement with those of published studies for other cycles and may be used when considering the designs of actual diesel-engines.
06/02267
Efficiency of a Miller engine
Al-Sarkhi, A. et al. Applied Energy, 2006, 83. (4), 343-351. Using finite-time thermodynamics, the relations between thermal efficiency, compression and expansion ratios for an ideal naturally aspirated (air-standard) Miller cycle have been derived. The effect of the temperature-dependent specific heat of the working fluid on the irreversible cycle performance is significant. The conclusions of this investigation are of importance when considering the designs of actual Miller-engines.
06/02268
Gasoline direct injection spray simulation
Rotondi, R. and Bella, G. International Journal of Thermal Sciences, 2006, 45, (2), 168 179. In this paper the problems related to mixture formation in a GDI engine are analysed. The atomization of a hollow cone fuel spray generated by a high pressure swirl injector is studied by means of a numerical technique. The model distinguishes between primary atomization and secondary breakup. The latter was modelled, as done in a previous work on Diesel atomization, using different mechanisms as the droplet Weber number changes. At first the spray atomization in a quiescent chamber, at ambient pressure and temperature, was considered. The validation of the model was made comparing the numerical penetration and spray morphology with experimental results. Combustion simulations were also performed comparing numerical results with experimental data of a GDI (Gasoline Direct Injection), four stroke, four cylinder, four valves per cylinder engine. Such simulations were made to analyse and understand the mixture formation mechanism in both stoichiometric and stratified operation mode. The results show how, the interaction between the air motion and the fuel spray, leading factor in spray atomization, is fundamental to realize an efficient mixture formation and combustion locally very lean, typical of stratified charge combustion.
346
Fuel and Energy Abstracts
September 2006
06102269 Influence of a catalytic stripper on the response of real time aerosol instruments to diesel exhaust aerosol Kittelson, D. B. et al. Journal o/'Aerosol Science, 2005, 36, (9), 10891107. The objective of this study was to evaluate the response of a suite of portable, real-time aerosol instruments to Diesel exhaust aerosol wan and without a catalytic stripper (CS) to determine the change in response as a function of particle size and volatility. The response of the photoemission aerosol sensor (PAS) was strongly influenced by the physical and chemical nature of Diesel aerosol. The presence of a large, predominantly volatile nuclei mode, and/or the presence of volatn~ material on the surface of the solid carbonaceous agglomerates in the accumulation mode suppressed the PAS response. Removal of the volatile material by passage of the aerosol through the CS enhanced the response, and improved correlations between the PAS, the diffusion charger (DC) and the scanning mobility particle sizer (SMPS). Data on aerosol size distributions, number, volume, and surface area concentrations with and without the CS in the sample stream are reported.
06/02270 Modelling of the hydro-generator local network operation and load disturbance rejection Puleva, T. T. and Petkanchin, L. T. International Journal (~/' Nuclear Governance, Economy and Ecology, 2006, 1, (1), 96 108. The paper describes models of the local network operation of the hydraulic turbine-generator unit. Two different models are proposed. They describe the dynamic behaviour of a system in which the unit is connected on an equivalent system. A non-linear model of the interconnection to an equivalent power system is considered. An optimal controller for load disturbance rejection in water turbine speed and power control is designed. The frequency and power deviations are examined in the case of a sudden load change.
06102271 Optimal configuration of a two-heat-reservoir heat-engine with heat-leak and finite thermal-capacity Chen, L. et al. Applied Energy, 2006, 83, (2), 71 81. Based on a model of a two-heat-reservoir heat-engine cycle with a finite high-temperature source and bypass heat-leak, in which the maximum work output can be obtained under a given cycle time is determined with the considerations of heat-leak, finite heat-capacity high-temperature source and infinite heat-capacity low-temperature heat-sink with another linear heat-transfer law Q c~ 2x(T 1 ). The beatengine cycles considered are: (1) infinite low-and high-temperature reservoirs without heat-leak; (2) infinite low- and high-temperature reservoirs with heat-leak; (3) finite high-temperature source and infinite low-temperature sink without heat-leak and (4) finite high-temperature source and infinite low-temperature sink with heat-leak. It is assumed that the heat-transfer between the working fluid and the reservoirs obeys another linear heat-transfer law, i.e. the linear phenomenological heat-transfer law, Q c~ A(ir-~). It is shown that the existence of heatleak does not affect the configuration of a cycle with an infinite hightemperature source. The finite heat-capacity of the high-temperature source without heat-leak makes the cycle a generalized Carnot heatengine cycle. There exists a great difference of the cycle configurations for the finite high-temperature source with heat-leak and the former three cases. Moreover, the relations between the optimal power-output and the efficiency of the former three configurations are derived, and they show that the heat-leak affects the power versus efficiency characteristics of the heat-engine cycles,
06/02272 Optimization criteria for the important parameters of an irreversible Otto heat-engine Chert, J. et al. Applied Energy, 2006, 83, (3), 228-238. An irreversible cycle model of an Otto heat-engine is established, in which the main irreversibilities result from the non-isentropic compression and expansion processes; finite-time processes and heat loss through the cylinder wall are taken into account. The power output and efficiency of the cycle are derived. The curves of the power output and efficiency varying with the compression ratio of two isochoric processes are presented. It is found from the curves that there are optimal values of the compression ratio at which the power output and efficiency attain their maxima. Moreover, the maximum power-output and efficiency and the corresponding relevant parameters are calculated, and consequently, the optimization criteria of some important parameters such as the power output, efficiency, compression ratio, and temperatures of the working substance are obtained.
06/02273 Parametric investigation of cylinder and jacket side convective heat transfer coefficients of gasoline engines Karamangil, M. I. et al. Energy Conversion and Management, 2006, 47, (6), 800-816.
06•02264 Ecological coefficient of performance (ECOP) optimization for an irreversible Brayton heat engine with variable-temperature thermal reservoirs Ust, Y. et al. Journal ~?fthe Energy hzstitute, 2006, 79, (1), 47 52. An ecological performance analysis for an irreversible Brayton heat engine with variable-temperature thermal reservoirs based on the ecological criterion called ecological coefficient of performance is presented. The model considered includes irreversibilities due to finiterate heat transfer and internal dissipations. The effects of design parameters such as isentropic temperature ratio, heat exchanger effectiveness, thermal reservoir inlet temperature ratio and the ratio of hot-to-cold thermal capacity rates of thermal reservoirs, on the general and optimal ecological performances have been investigated in detail, Comparisons of the results with those of an alternative ecological objective function defined in the literature, the maximum power output conditions, and thermal efficiency are also provided.
06/02265 Effects of ethanol-unleaded gasoline blends on cyclic variability and emissions in an SI engine Ceviz, M. A. and Y/iksel, F. Applied Thermal Engineeril~g, 2005, 25, (5 6), 917 925. One important design goal for spark-ignited (SI) engines is to minimize cyclic variability. A small amount of cyclic variability (slow burns) can produce undesirable engine vibrations. On the other hand, a larger amount of cyclic variability (incomplete burns) leads to an increase in hydrocarbon consumption and emissions. This paper investigates the effects of using ethanol-unleaded gasoline blends on cyclic variability and emissions in an SI engine. Results of this study showed that using ethanol-unleaded gasoline blends as a fuel decreased the coefficient of variation in indicated mean effective pressure, and CO and HC emission concentrations, while increased carbon dioxide concentration up to 10 vol% ethanol in fuel blend. On the other hand, after this level of blend a reverse effect was observed on the parameters aforementioned. The 10 vol% ethanol in fuel blend gave the best results.
06/02266 Effects of friction and temperature-dependent specific-heat of the working fluid on the performance of a Diesel-engine Al-Sarkhi, A. et al. Applied Energy, 2006, 83, (2), 153-165. Using finite-time thermodynamics, the relations between the power output, thermal efficiency and compression ratio have been derived. The effect of the specific heat of the working fluid, being temperature dependent, on the irreversible cycle performance, is significant. The conclusions obtained in this investigation are in full agreement with those of published studies for other cycles and may be used when considering the designs of actual diesel-engines.
06/02267
Efficiency of a Miller engine
Al-Sarkhi, A. et al. Applied Energy, 2006, 83. (4), 343-351. Using finite-time thermodynamics, the relations between thermal efficiency, compression and expansion ratios for an ideal naturally aspirated (air-standard) Miller cycle have been derived. The effect of the temperature-dependent specific heat of the working fluid on the irreversible cycle performance is significant. The conclusions of this investigation are of importance when considering the designs of actual Miller-engines.
06/02268
Gasoline direct injection spray simulation
Rotondi, R. and Bella, G. International Journal of Thermal Sciences, 2006, 45, (2), 168 179. In this paper the problems related to mixture formation in a GDI engine are analysed. The atomization of a hollow cone fuel spray generated by a high pressure swirl injector is studied by means of a numerical technique. The model distinguishes between primary atomization and secondary breakup. The latter was modelled, as done in a previous work on Diesel atomization, using different mechanisms as the droplet Weber number changes. At first the spray atomization in a quiescent chamber, at ambient pressure and temperature, was considered. The validation of the model was made comparing the numerical penetration and spray morphology with experimental results. Combustion simulations were also performed comparing numerical results with experimental data of a GDI (Gasoline Direct Injection), four stroke, four cylinder, four valves per cylinder engine. Such simulations were made to analyse and understand the mixture formation mechanism in both stoichiometric and stratified operation mode. The results show how, the interaction between the air motion and the fuel spray, leading factor in spray atomization, is fundamental to realize an efficient mixture formation and combustion locally very lean, typical of stratified charge combustion.
346
Fuel and Energy Abstracts
September 2006
06102269 Influence of a catalytic stripper on the response of real time aerosol instruments to diesel exhaust aerosol Kittelson, D. B. et al. Journal o/'Aerosol Science, 2005, 36, (9), 10891107. The objective of this study was to evaluate the response of a suite of portable, real-time aerosol instruments to Diesel exhaust aerosol wan and without a catalytic stripper (CS) to determine the change in response as a function of particle size and volatility. The response of the photoemission aerosol sensor (PAS) was strongly influenced by the physical and chemical nature of Diesel aerosol. The presence of a large, predominantly volatile nuclei mode, and/or the presence of volatn~ material on the surface of the solid carbonaceous agglomerates in the accumulation mode suppressed the PAS response. Removal of the volatile material by passage of the aerosol through the CS enhanced the response, and improved correlations between the PAS, the diffusion charger (DC) and the scanning mobility particle sizer (SMPS). Data on aerosol size distributions, number, volume, and surface area concentrations with and without the CS in the sample stream are reported.
06/02270 Modelling of the hydro-generator local network operation and load disturbance rejection Puleva, T. T. and Petkanchin, L. T. International Journal (~/' Nuclear Governance, Economy and Ecology, 2006, 1, (1), 96 108. The paper describes models of the local network operation of the hydraulic turbine-generator unit. Two different models are proposed. They describe the dynamic behaviour of a system in which the unit is connected on an equivalent system. A non-linear model of the interconnection to an equivalent power system is considered. An optimal controller for load disturbance rejection in water turbine speed and power control is designed. The frequency and power deviations are examined in the case of a sudden load change.
06102271 Optimal configuration of a two-heat-reservoir heat-engine with heat-leak and finite thermal-capacity Chen, L. et al. Applied Energy, 2006, 83, (2), 71 81. Based on a model of a two-heat-reservoir heat-engine cycle with a finite high-temperature source and bypass heat-leak, in which the maximum work output can be obtained under a given cycle time is determined with the considerations of heat-leak, finite heat-capacity high-temperature source and infinite heat-capacity low-temperature heat-sink with another linear heat-transfer law Q c~ 2x(T 1 ). The beatengine cycles considered are: (1) infinite low-and high-temperature reservoirs without heat-leak; (2) infinite low- and high-temperature reservoirs with heat-leak; (3) finite high-temperature source and infinite low-temperature sink without heat-leak and (4) finite high-temperature source and infinite low-temperature sink with heat-leak. It is assumed that the heat-transfer between the working fluid and the reservoirs obeys another linear heat-transfer law, i.e. the linear phenomenological heat-transfer law, Q c~ A(ir-~). It is shown that the existence of heatleak does not affect the configuration of a cycle with an infinite hightemperature source. The finite heat-capacity of the high-temperature source without heat-leak makes the cycle a generalized Carnot heatengine cycle. There exists a great difference of the cycle configurations for the finite high-temperature source with heat-leak and the former three cases. Moreover, the relations between the optimal power-output and the efficiency of the former three configurations are derived, and they show that the heat-leak affects the power versus efficiency characteristics of the heat-engine cycles,
06/02272 Optimization criteria for the important parameters of an irreversible Otto heat-engine Chert, J. et al. Applied Energy, 2006, 83, (3), 228-238. An irreversible cycle model of an Otto heat-engine is established, in which the main irreversibilities result from the non-isentropic compression and expansion processes; finite-time processes and heat loss through the cylinder wall are taken into account. The power output and efficiency of the cycle are derived. The curves of the power output and efficiency varying with the compression ratio of two isochoric processes are presented. It is found from the curves that there are optimal values of the compression ratio at which the power output and efficiency attain their maxima. Moreover, the maximum power-output and efficiency and the corresponding relevant parameters are calculated, and consequently, the optimization criteria of some important parameters such as the power output, efficiency, compression ratio, and temperatures of the working substance are obtained.
06/02273 Parametric investigation of cylinder and jacket side convective heat transfer coefficients of gasoline engines Karamangil, M. I. et al. Energy Conversion and Management, 2006, 47, (6), 800-816.