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01181 Effect of turbocharging system on the performance of a natural gas engine
10 Engines (power generation and propulsion, electrical vehicles) throttle positions of 50, 75 and 100%. Engine torque, power, brake mean effective pressure, specific fuel consumption, fuel flow, and exhaust emissions such as SO2, CO2, NOx and smoke level (%N) have been investigated. The back-propagation learning algorithm with three different variants, single and two hidden layers, and a logistic sigmoid transfer-function have been used in the network. In order to train the network, the results of these measurements have been used. Injection pressure, engine speed, and throttle position have been used as the input layer; performance values and exhaust emissions characteristics have also been used as the output layer. It is shown that the R 2 values are about 0.9999 for the training data, and 0.999 for the test data; RMS values are smaller than 0.01; and mean % errors are smaller than 8.5 for the test data.
05/01179 Data reconciliation and fault detection by means of plant-wide mass and energy balances
05/01175 Analysis of an unconventional cycle as a new comparison standard for practical heat engines: the circular/ elliptical cycle in T-S diagram
05•01180 vehicle
Sahin, B. et al. International Journal of Energy Research, 2004, 28, (13), 1159-1175. An unconventional cycle analysis in the T-S diagram has been carried out and the cycle characteristics such as thermal efficiency, work density (defined as the ratio of the network output to the maximum volume in the cycle), maximum volume and maximum pressure are determined. The obtained results for the unconventional cycle are compared with those of the Carnot cycle. It is proposed that the analysed unconventional cycle may be used as a better comparison standard than the Carnot cycle for practical heat engines when both size and thermal efficiency are considered.
05/01176 CFD analysis and overheating control of a turbine Aulisa, E. et al. International Journal of Thermal Sciences, 2004, 43, (11), 1119-1124. The thermal analysis of a turbine stack discharging exhaust gases to the atmosphere is presented. The examined turbine stack belongs to a gas lift plant for oil extraction located in the Gulf area. The analysis has been performed because an overheating of the anchor flange/bolts and of the concrete foundation occurred and caused small cracks in the upper layer of the foundation. A qualitative thermal analysis of the stack has pointed out that the main cause of the overheating was the thermal radiation in the air-filled region underneath the stack bottom plate. Detailed calculations performed by using a computational fluid dynamics code (Fluent ver. 6.0.12), cross-checked with measurements taken from site, have shown that a significant reduction of the heat flux to the foundation could be obtained by filling the above mentioned air region with an insulating material. The benefits of this solution are prevailing over those achievable with the installation of external fins on the stack shell.
05/01177 Comparative performance analysis of irreversible Dual and Diesel cycles under maximum power conditions Parlak, A. Energy Conversion and Management, 2005, 46, (3), 351-359. In this study, a comparative performance analysis and optimization based on maximum power and maximum thermal efficiency criteria have been performed for irreversible Dual and Diesel cycles. Optimal performance and design parameters, such as pressure ratio, cut-off ratio and extreme temperature ratio, of the cycles has been derived analytically and compared with each other based on maximum power (MP) and the corresponding thermal efficiency criteria. The effects of the internal irreversibilities of the cycles on overall performance in terms of isentropic efficiencies for the compression and expansion processes are also investigated. The obtained results may provide a general theoretical tool for the optimal design and operation of real engines.
05/01178 Current status of actual fuel-consumptions of petrol-fuelled passenger vehicles in Japan Kudoh, Y. et al. Applied Energy, 2004, 79, (3), 291-308. An actual fuel-consumption (FC) database with hierarchic structure was established based upon voluntary reported fuel-consumption log data collected through an internet-connected mobile-phone system. The current status of the actual FC in Japan has been investigated by the database and CO2 emissions from petrol-fuelled passenger vehicles (PVs) were estimated. It was confirmed that there lies a statistically significant difference between actual FC and Japanese 10.15 mode FC and that the actual FCs differ by geographical and social aspects. In addition, the estimated actual FC-based COz emissions were consistent with the present COz emissions. Since a large amount of CO2 emissions mitigation in the transportation sector is expected by improving the FC of motorcars, the following items are required to significantly reduce the COz emissions in the motorcar sector: (1) comprehensive measures to reduce CO2 emissions regarding actual FC, (2) R&D of motorcars with high actual FC and (3) endorsement and execution of environmentally-friendly driving to improve actual FC.
Sunde, S. and Berg, O. Progress in Nuclear Energy, 2003, 43, (1-4), 97104. A plant-wide mass and heat balance model was fitted to 39 values of temperature, pressure and flow for a turbine cycle supplied by steam from a BWR. The calculated results were in good agreement with the measurements. For example, deviations between calculated and measured feed-water flow were usually in the order of 2 kg/s. The quality of the fitted results may be expressed as an overall assessment index Q stating directly the probability that the process is free of faults. The results are discussed with respect to the inclusion versus exclusion of the turbines' flow passing characteristics in the plant model.
Development of a hybrid pneumatic-power
Huang, K. D. and Tzeng, S.-C. Applied Energy, 2005, 80, (1), 47-59. Many complex technologies have been developed and applied to improve the energy efficiency and exhaust emission of an engine under different driving conditions. The overall thermal efficiency of an internal-combustion engine, however, can be maintained at only about 20-30%, with aggravated problems in the design and development, such as overall difficulty, excessive time consumption or excessively high cost. For electric cars, there is still no major technological breakthrough for the rapid recharging of a large capacity battery and detection of remaining power in it. Although all currently available hybrid-power engines are able to lower the amount of exhaust emissions and the fuel consumption of the engine, they are still unable to achieve a stable and optimal running condition immediately after ignition; hence the engine's thermal-efficiency remains low. To solve the aforementioned problems, an innovative concept - a hybrid pneumatic power-system (HPPS), which stores 'flow work' instead of storing electrochemical energy of the battery - is introduced. This innovative power system not only ensures that the internal-combustion ensures optimally but also recycles the exhaust flow to propel the vehicle. The optimization of the internal-combustion and recycling of the exhaust energy can increase the vehicle's efficiency from an original 15% to 33%, an overall increase of 18%.
05/01181 Effect of turbocharging system on the performance of a natural gas engine Kesgin, U. Energy Conversion and Management, 2005, 46, (1), 11-32. The effect of the turbo-charging system on the performance of the gas engine family, which is used in combined power plants, is investigated. These investigations show a clear improvement potential for the future of the engine series optimized here. To do this, a computational model in which zero-dimensional phenomena within the cylinder and onedimensional phenomena in the engine inlet and exhaust system are used is verified. Using this engine model, the effects of the parameters of the exhaust and turbo-charging system on the engine performance are obtained. In particular, the following parameters are chosen: diameter of the exhaust manifold, diameter of the pipe at the turbine exit, efficiency of the turbocharger, location of the turbocharger, back pressure at the turbine exit and pressure losses (resistances) before the compressor. This paper presents the results of these investigations.
05•01182 Effects of anti-freeze concentration in the engine coolant on the cavitation temperature of a water pump Huang, K. D. et al. Applied Energy, 2004, 79, (3), 261-273. Improvements in engine-manufacturing technology have gradually increased the thermal efficiencies of engines as well as the burning temperature and pressure of fuels within the cylinders. Accordingly, greater heat dissipation are required. However, the volume of the radiators is constrained by the configuration of the engines, leading to excessive internal resistance in the engine-cooling system. Therefore, water pumps in engines are prone to cavitation, and air bubbles are likely to permeate into the anti-freeze, thereby severely reducing the performance, reliability and service life of the engines. Ethylene glycol (EG) is added to the radiator of some vehicles in cold areas to reduce the solidification point of the coolant and prevent freezing. This study probes the effects of the percentage of anti-freeze added to the cooling water in a water pump in an engine on the water-supply capability and cavitation temperature, whether air or burnt gas is present in the system. The results of this study have revealed that engines have a higher tolerance to air bubbles at lower rates of rotation. At a given fixed rotational speed, the tolerable cavitation temperature of an engine's water pump will fall slowly as the amount of air bubbles increases.
05/01183 Emission characteristics of diesel engine running on vegetable oil with elevated fuel inlet temperature Nwafor, O. M. I. Biomass and Bioenergy, 2004, 27, (5), 507-511. The world energy demand has, for the last two decades, witnessed uncertainties in two dimensions. Firstly, the price of conventional fossil fuel is too high and has added burden on the economy of the importing nations. Secondly, combustion of fossil fuels is the main culprit in
Fuel and Energy Abstracts
May 2005
177
05/01179 Data reconciliation and fault detection by means of plant-wide mass and energy balances
05/01175 Analysis of an unconventional cycle as a new comparison standard for practical heat engines: the circular/ elliptical cycle in T-S diagram
05•01180 vehicle
Sahin, B. et al. International Journal of Energy Research, 2004, 28, (13), 1159-1175. An unconventional cycle analysis in the T-S diagram has been carried out and the cycle characteristics such as thermal efficiency, work density (defined as the ratio of the network output to the maximum volume in the cycle), maximum volume and maximum pressure are determined. The obtained results for the unconventional cycle are compared with those of the Carnot cycle. It is proposed that the analysed unconventional cycle may be used as a better comparison standard than the Carnot cycle for practical heat engines when both size and thermal efficiency are considered.
05/01176 CFD analysis and overheating control of a turbine Aulisa, E. et al. International Journal of Thermal Sciences, 2004, 43, (11), 1119-1124. The thermal analysis of a turbine stack discharging exhaust gases to the atmosphere is presented. The examined turbine stack belongs to a gas lift plant for oil extraction located in the Gulf area. The analysis has been performed because an overheating of the anchor flange/bolts and of the concrete foundation occurred and caused small cracks in the upper layer of the foundation. A qualitative thermal analysis of the stack has pointed out that the main cause of the overheating was the thermal radiation in the air-filled region underneath the stack bottom plate. Detailed calculations performed by using a computational fluid dynamics code (Fluent ver. 6.0.12), cross-checked with measurements taken from site, have shown that a significant reduction of the heat flux to the foundation could be obtained by filling the above mentioned air region with an insulating material. The benefits of this solution are prevailing over those achievable with the installation of external fins on the stack shell.
05/01177 Comparative performance analysis of irreversible Dual and Diesel cycles under maximum power conditions Parlak, A. Energy Conversion and Management, 2005, 46, (3), 351-359. In this study, a comparative performance analysis and optimization based on maximum power and maximum thermal efficiency criteria have been performed for irreversible Dual and Diesel cycles. Optimal performance and design parameters, such as pressure ratio, cut-off ratio and extreme temperature ratio, of the cycles has been derived analytically and compared with each other based on maximum power (MP) and the corresponding thermal efficiency criteria. The effects of the internal irreversibilities of the cycles on overall performance in terms of isentropic efficiencies for the compression and expansion processes are also investigated. The obtained results may provide a general theoretical tool for the optimal design and operation of real engines.
05/01178 Current status of actual fuel-consumptions of petrol-fuelled passenger vehicles in Japan Kudoh, Y. et al. Applied Energy, 2004, 79, (3), 291-308. An actual fuel-consumption (FC) database with hierarchic structure was established based upon voluntary reported fuel-consumption log data collected through an internet-connected mobile-phone system. The current status of the actual FC in Japan has been investigated by the database and CO2 emissions from petrol-fuelled passenger vehicles (PVs) were estimated. It was confirmed that there lies a statistically significant difference between actual FC and Japanese 10.15 mode FC and that the actual FCs differ by geographical and social aspects. In addition, the estimated actual FC-based COz emissions were consistent with the present COz emissions. Since a large amount of CO2 emissions mitigation in the transportation sector is expected by improving the FC of motorcars, the following items are required to significantly reduce the COz emissions in the motorcar sector: (1) comprehensive measures to reduce CO2 emissions regarding actual FC, (2) R&D of motorcars with high actual FC and (3) endorsement and execution of environmentally-friendly driving to improve actual FC.
Sunde, S. and Berg, O. Progress in Nuclear Energy, 2003, 43, (1-4), 97104. A plant-wide mass and heat balance model was fitted to 39 values of temperature, pressure and flow for a turbine cycle supplied by steam from a BWR. The calculated results were in good agreement with the measurements. For example, deviations between calculated and measured feed-water flow were usually in the order of 2 kg/s. The quality of the fitted results may be expressed as an overall assessment index Q stating directly the probability that the process is free of faults. The results are discussed with respect to the inclusion versus exclusion of the turbines' flow passing characteristics in the plant model.
Development of a hybrid pneumatic-power
Huang, K. D. and Tzeng, S.-C. Applied Energy, 2005, 80, (1), 47-59. Many complex technologies have been developed and applied to improve the energy efficiency and exhaust emission of an engine under different driving conditions. The overall thermal efficiency of an internal-combustion engine, however, can be maintained at only about 20-30%, with aggravated problems in the design and development, such as overall difficulty, excessive time consumption or excessively high cost. For electric cars, there is still no major technological breakthrough for the rapid recharging of a large capacity battery and detection of remaining power in it. Although all currently available hybrid-power engines are able to lower the amount of exhaust emissions and the fuel consumption of the engine, they are still unable to achieve a stable and optimal running condition immediately after ignition; hence the engine's thermal-efficiency remains low. To solve the aforementioned problems, an innovative concept - a hybrid pneumatic power-system (HPPS), which stores 'flow work' instead of storing electrochemical energy of the battery - is introduced. This innovative power system not only ensures that the internal-combustion ensures optimally but also recycles the exhaust flow to propel the vehicle. The optimization of the internal-combustion and recycling of the exhaust energy can increase the vehicle's efficiency from an original 15% to 33%, an overall increase of 18%.
05/01181 Effect of turbocharging system on the performance of a natural gas engine Kesgin, U. Energy Conversion and Management, 2005, 46, (1), 11-32. The effect of the turbo-charging system on the performance of the gas engine family, which is used in combined power plants, is investigated. These investigations show a clear improvement potential for the future of the engine series optimized here. To do this, a computational model in which zero-dimensional phenomena within the cylinder and onedimensional phenomena in the engine inlet and exhaust system are used is verified. Using this engine model, the effects of the parameters of the exhaust and turbo-charging system on the engine performance are obtained. In particular, the following parameters are chosen: diameter of the exhaust manifold, diameter of the pipe at the turbine exit, efficiency of the turbocharger, location of the turbocharger, back pressure at the turbine exit and pressure losses (resistances) before the compressor. This paper presents the results of these investigations.
05•01182 Effects of anti-freeze concentration in the engine coolant on the cavitation temperature of a water pump Huang, K. D. et al. Applied Energy, 2004, 79, (3), 261-273. Improvements in engine-manufacturing technology have gradually increased the thermal efficiencies of engines as well as the burning temperature and pressure of fuels within the cylinders. Accordingly, greater heat dissipation are required. However, the volume of the radiators is constrained by the configuration of the engines, leading to excessive internal resistance in the engine-cooling system. Therefore, water pumps in engines are prone to cavitation, and air bubbles are likely to permeate into the anti-freeze, thereby severely reducing the performance, reliability and service life of the engines. Ethylene glycol (EG) is added to the radiator of some vehicles in cold areas to reduce the solidification point of the coolant and prevent freezing. This study probes the effects of the percentage of anti-freeze added to the cooling water in a water pump in an engine on the water-supply capability and cavitation temperature, whether air or burnt gas is present in the system. The results of this study have revealed that engines have a higher tolerance to air bubbles at lower rates of rotation. At a given fixed rotational speed, the tolerable cavitation temperature of an engine's water pump will fall slowly as the amount of air bubbles increases.
05/01183 Emission characteristics of diesel engine running on vegetable oil with elevated fuel inlet temperature Nwafor, O. M. I. Biomass and Bioenergy, 2004, 27, (5), 507-511. The world energy demand has, for the last two decades, witnessed uncertainties in two dimensions. Firstly, the price of conventional fossil fuel is too high and has added burden on the economy of the importing nations. Secondly, combustion of fossil fuels is the main culprit in
Fuel and Energy Abstracts
May 2005
177