The Experts below are selected from a list of 123 Experts worldwide ranked by ideXlab platform
Ezio Spessa - One of the best experts on this subject based on the ideXlab platform.
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benefits of hydraulic layout over driving system in piezo injectors and proposal of a new concept cr injector with an integrated minirail
Applied Energy, 2013Co-Authors: Alessandro Ferrari, Antonio Mittica, Ezio SpessaAbstract:Abstract The prediction capability of an advanced Common Rail (CR) piezoelectric injection-system mathematical model has been upgraded and applied to the analysis of transient flows inside injectors. The predicted time histories of the sac-, delivery- and Control-Chamber pressures, of the pilot- and needle-valve lifts, and of the mass flow-rates through the Z and A holes, as well as through the bypass, have been analyzed to explain the differences in performance between piezoelectric and solenoid injectors. The objective was to study the influence exerted by the different hydraulic and mechanical setups in order to assess the effective benefits that could be obtained from the replacement of the solenoid driving system with the piezoelectric one. Then, the upgraded mathematical model has been applied to the design of new-concept injectors. First, specific attention was given to the effects that variations in the peak current values could have on the injected flow-rate. Furthermore, numerical simulations were performed to comprehend the effects that remarkable increments in the injector internal accumulation volume could have on injection system performance. A prototype of the new-concept injector with a small integrated accumulator (Minirail) has also been tested on the hydraulic rig.
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numerical experimental study and solutions to reduce the dwell time threshold for fusion free consecutive injections in a multijet solenoid type cr system
Journal of Engineering for Gas Turbines and Power-transactions of The Asme, 2009Co-Authors: Andrea Catania, Alessandro Ferrari, Ezio SpessaAbstract:In "multijet" common rail (CR) diesel injection systems, when two consecutive injection current pulses approach each other, a merging of the two injections into a single one can occur. Such an "injection fusion" causes an undesired excessive amount of injected fuel, worsening both fuel consumption and particulate emissions. In order to avoid this phenomenon, lower limits to the dwell-time values are introduced in the Control unit maps by a conservatively overestimated threshold, which reduces the flexibility of multiple-injection management. The injection fusion occurrence is mainly related to the time delay between the electrical signal to the solenoid and the nozzle opening and closure. The dwell-time fusion threshold was found to strongly decrease particularly with the nozzle closure delay. A functional dependence of the nozzle opening and closure delays on the solenoid energizing time and nominal rail pressure was experimentally assessed, and the injection temporal duration was correlated to the energizing time and rail pressure. A multijet CR injection-system mathematical model that was previously developed, including thermodynamics of liquids, fluid dynamics, mechanics of subsystems, and electromagnetism equations, was applied to better understand the cause and effect relationships for nozzle opening and closure delays. In particular, numerical results on the time histories of delivery- and Control-Chamber pressures, pilot- and needle-valve lifts, and mass flow rates through Z and A holes were obtained and analyzed to highlight the dependence of nozzle opening and closure delays on injector geometric features, physical variables, and valve dynamics. The nozzle closure delay was shown to strongly depend on the needle dynamics. Parametric numerical tests were carried out to identify configurations useful for minimizing the nozzle closure delay. Based on the results of these tests, a modified version of a commercial electroinjector was built, so as to achieve effectively lower nozzle closure delays and very close sequential injections without any fusion between them.
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Numerical-Experimental Study and Solutions to Reduce the Dwell-Time Threshold for Fusion-Free Consecutive Injections in a Multijet Solenoid-Type CR System
Journal of Engineering for Gas Turbines and Power, 2008Co-Authors: Andrea Catania, Alessandro Ferrari, Ezio SpessaAbstract:In ‘Multijet’ Common Rail (C.R.) diesel injection systems, when two consecutive injection current-pulses are approached to each other, the fusion of the two injections can occur. This causes undesired excessive amount of injected fuel, which leads to worsening of particulate emissions and fuel consumption. In order to avoid such a phenomenon, lower limits to the values of dwell time are introduced in the Control unit maps, by means of a conservatively overestimated threshold, limiting the flexible management of multiple injections and C.R. system capability to perform a larger number of injection shots. The reason of the injection fusion is mainly due to the time delay between the electrical signal to the solenoid and the needle lift at both valve opening and closure. In particular, the dwell-time range inside of which injection fusion occurs was shown to decrease by reducing the nozzle closure delay. Experimental tests were carried out on a high-performance Moehwald-Bosch MEP2000/CA4000 test bench for determining the functional dependence of nozzle closure and opening delays on solenoid energizing time and nominal rail pressure. Besides, a mathematical relation between the solenoid energizing time and the injection time interval was determined. A Multijet C.R. injection system mathematical model, that was previously developed, including thermodynamics of liquids, fluid dynamics, subsystem mechanics, and electromagnetism equations, was applied to better understand the cause and effect relationships for nozzle opening and closure delays. In particular, numerical results on the time histories of delivery- and Control-Chamber pressures, pilot- and needle-valve lifts, mass flow rates through Z and A holes, were obtained and analyzed in order to highlight the dependence of nozzle opening and closure delays on electro-injector internal geometric features and on the needle dynamics. For all the considered operating conditions, the model predictions were compared to the experimental injection flow-rate patterns and to the pressure data taken at the injector inlet, for assessment. The nozzle closure delay was shown to strongly depend on the needle dynamics. Parametric tests were carried out with the numerical code by changing needle and Control plunger mass, needle spring preload and stiffness, maximum needle stroke, in order to identify configurations useful for minimizing the nozzle closure delay. On the basis of the indications derived from these numerical tests, a modified version of the commercial electro-injector was realized so as to achieve effectively reduced nozzle closure delays and very close sequential injections without any fusion between them.Copyright © 2006 by ASME
Alessandro Ferrari - One of the best experts on this subject based on the ideXlab platform.
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benefits of hydraulic layout over driving system in piezo injectors and proposal of a new concept cr injector with an integrated minirail
Applied Energy, 2013Co-Authors: Alessandro Ferrari, Antonio Mittica, Ezio SpessaAbstract:Abstract The prediction capability of an advanced Common Rail (CR) piezoelectric injection-system mathematical model has been upgraded and applied to the analysis of transient flows inside injectors. The predicted time histories of the sac-, delivery- and Control-Chamber pressures, of the pilot- and needle-valve lifts, and of the mass flow-rates through the Z and A holes, as well as through the bypass, have been analyzed to explain the differences in performance between piezoelectric and solenoid injectors. The objective was to study the influence exerted by the different hydraulic and mechanical setups in order to assess the effective benefits that could be obtained from the replacement of the solenoid driving system with the piezoelectric one. Then, the upgraded mathematical model has been applied to the design of new-concept injectors. First, specific attention was given to the effects that variations in the peak current values could have on the injected flow-rate. Furthermore, numerical simulations were performed to comprehend the effects that remarkable increments in the injector internal accumulation volume could have on injection system performance. A prototype of the new-concept injector with a small integrated accumulator (Minirail) has also been tested on the hydraulic rig.
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numerical experimental study and solutions to reduce the dwell time threshold for fusion free consecutive injections in a multijet solenoid type cr system
Journal of Engineering for Gas Turbines and Power-transactions of The Asme, 2009Co-Authors: Andrea Catania, Alessandro Ferrari, Ezio SpessaAbstract:In "multijet" common rail (CR) diesel injection systems, when two consecutive injection current pulses approach each other, a merging of the two injections into a single one can occur. Such an "injection fusion" causes an undesired excessive amount of injected fuel, worsening both fuel consumption and particulate emissions. In order to avoid this phenomenon, lower limits to the dwell-time values are introduced in the Control unit maps by a conservatively overestimated threshold, which reduces the flexibility of multiple-injection management. The injection fusion occurrence is mainly related to the time delay between the electrical signal to the solenoid and the nozzle opening and closure. The dwell-time fusion threshold was found to strongly decrease particularly with the nozzle closure delay. A functional dependence of the nozzle opening and closure delays on the solenoid energizing time and nominal rail pressure was experimentally assessed, and the injection temporal duration was correlated to the energizing time and rail pressure. A multijet CR injection-system mathematical model that was previously developed, including thermodynamics of liquids, fluid dynamics, mechanics of subsystems, and electromagnetism equations, was applied to better understand the cause and effect relationships for nozzle opening and closure delays. In particular, numerical results on the time histories of delivery- and Control-Chamber pressures, pilot- and needle-valve lifts, and mass flow rates through Z and A holes were obtained and analyzed to highlight the dependence of nozzle opening and closure delays on injector geometric features, physical variables, and valve dynamics. The nozzle closure delay was shown to strongly depend on the needle dynamics. Parametric numerical tests were carried out to identify configurations useful for minimizing the nozzle closure delay. Based on the results of these tests, a modified version of a commercial electroinjector was built, so as to achieve effectively lower nozzle closure delays and very close sequential injections without any fusion between them.
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Numerical-Experimental Study and Solutions to Reduce the Dwell-Time Threshold for Fusion-Free Consecutive Injections in a Multijet Solenoid-Type CR System
Journal of Engineering for Gas Turbines and Power, 2008Co-Authors: Andrea Catania, Alessandro Ferrari, Ezio SpessaAbstract:In ‘Multijet’ Common Rail (C.R.) diesel injection systems, when two consecutive injection current-pulses are approached to each other, the fusion of the two injections can occur. This causes undesired excessive amount of injected fuel, which leads to worsening of particulate emissions and fuel consumption. In order to avoid such a phenomenon, lower limits to the values of dwell time are introduced in the Control unit maps, by means of a conservatively overestimated threshold, limiting the flexible management of multiple injections and C.R. system capability to perform a larger number of injection shots. The reason of the injection fusion is mainly due to the time delay between the electrical signal to the solenoid and the needle lift at both valve opening and closure. In particular, the dwell-time range inside of which injection fusion occurs was shown to decrease by reducing the nozzle closure delay. Experimental tests were carried out on a high-performance Moehwald-Bosch MEP2000/CA4000 test bench for determining the functional dependence of nozzle closure and opening delays on solenoid energizing time and nominal rail pressure. Besides, a mathematical relation between the solenoid energizing time and the injection time interval was determined. A Multijet C.R. injection system mathematical model, that was previously developed, including thermodynamics of liquids, fluid dynamics, subsystem mechanics, and electromagnetism equations, was applied to better understand the cause and effect relationships for nozzle opening and closure delays. In particular, numerical results on the time histories of delivery- and Control-Chamber pressures, pilot- and needle-valve lifts, mass flow rates through Z and A holes, were obtained and analyzed in order to highlight the dependence of nozzle opening and closure delays on electro-injector internal geometric features and on the needle dynamics. For all the considered operating conditions, the model predictions were compared to the experimental injection flow-rate patterns and to the pressure data taken at the injector inlet, for assessment. The nozzle closure delay was shown to strongly depend on the needle dynamics. Parametric tests were carried out with the numerical code by changing needle and Control plunger mass, needle spring preload and stiffness, maximum needle stroke, in order to identify configurations useful for minimizing the nozzle closure delay. On the basis of the indications derived from these numerical tests, a modified version of the commercial electro-injector was realized so as to achieve effectively reduced nozzle closure delays and very close sequential injections without any fusion between them.Copyright © 2006 by ASME
Andrea Catania - One of the best experts on this subject based on the ideXlab platform.
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numerical experimental study and solutions to reduce the dwell time threshold for fusion free consecutive injections in a multijet solenoid type cr system
Journal of Engineering for Gas Turbines and Power-transactions of The Asme, 2009Co-Authors: Andrea Catania, Alessandro Ferrari, Ezio SpessaAbstract:In "multijet" common rail (CR) diesel injection systems, when two consecutive injection current pulses approach each other, a merging of the two injections into a single one can occur. Such an "injection fusion" causes an undesired excessive amount of injected fuel, worsening both fuel consumption and particulate emissions. In order to avoid this phenomenon, lower limits to the dwell-time values are introduced in the Control unit maps by a conservatively overestimated threshold, which reduces the flexibility of multiple-injection management. The injection fusion occurrence is mainly related to the time delay between the electrical signal to the solenoid and the nozzle opening and closure. The dwell-time fusion threshold was found to strongly decrease particularly with the nozzle closure delay. A functional dependence of the nozzle opening and closure delays on the solenoid energizing time and nominal rail pressure was experimentally assessed, and the injection temporal duration was correlated to the energizing time and rail pressure. A multijet CR injection-system mathematical model that was previously developed, including thermodynamics of liquids, fluid dynamics, mechanics of subsystems, and electromagnetism equations, was applied to better understand the cause and effect relationships for nozzle opening and closure delays. In particular, numerical results on the time histories of delivery- and Control-Chamber pressures, pilot- and needle-valve lifts, and mass flow rates through Z and A holes were obtained and analyzed to highlight the dependence of nozzle opening and closure delays on injector geometric features, physical variables, and valve dynamics. The nozzle closure delay was shown to strongly depend on the needle dynamics. Parametric numerical tests were carried out to identify configurations useful for minimizing the nozzle closure delay. Based on the results of these tests, a modified version of a commercial electroinjector was built, so as to achieve effectively lower nozzle closure delays and very close sequential injections without any fusion between them.
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Numerical-Experimental Study and Solutions to Reduce the Dwell-Time Threshold for Fusion-Free Consecutive Injections in a Multijet Solenoid-Type CR System
Journal of Engineering for Gas Turbines and Power, 2008Co-Authors: Andrea Catania, Alessandro Ferrari, Ezio SpessaAbstract:In ‘Multijet’ Common Rail (C.R.) diesel injection systems, when two consecutive injection current-pulses are approached to each other, the fusion of the two injections can occur. This causes undesired excessive amount of injected fuel, which leads to worsening of particulate emissions and fuel consumption. In order to avoid such a phenomenon, lower limits to the values of dwell time are introduced in the Control unit maps, by means of a conservatively overestimated threshold, limiting the flexible management of multiple injections and C.R. system capability to perform a larger number of injection shots. The reason of the injection fusion is mainly due to the time delay between the electrical signal to the solenoid and the needle lift at both valve opening and closure. In particular, the dwell-time range inside of which injection fusion occurs was shown to decrease by reducing the nozzle closure delay. Experimental tests were carried out on a high-performance Moehwald-Bosch MEP2000/CA4000 test bench for determining the functional dependence of nozzle closure and opening delays on solenoid energizing time and nominal rail pressure. Besides, a mathematical relation between the solenoid energizing time and the injection time interval was determined. A Multijet C.R. injection system mathematical model, that was previously developed, including thermodynamics of liquids, fluid dynamics, subsystem mechanics, and electromagnetism equations, was applied to better understand the cause and effect relationships for nozzle opening and closure delays. In particular, numerical results on the time histories of delivery- and Control-Chamber pressures, pilot- and needle-valve lifts, mass flow rates through Z and A holes, were obtained and analyzed in order to highlight the dependence of nozzle opening and closure delays on electro-injector internal geometric features and on the needle dynamics. For all the considered operating conditions, the model predictions were compared to the experimental injection flow-rate patterns and to the pressure data taken at the injector inlet, for assessment. The nozzle closure delay was shown to strongly depend on the needle dynamics. Parametric tests were carried out with the numerical code by changing needle and Control plunger mass, needle spring preload and stiffness, maximum needle stroke, in order to identify configurations useful for minimizing the nozzle closure delay. On the basis of the indications derived from these numerical tests, a modified version of the commercial electro-injector was realized so as to achieve effectively reduced nozzle closure delays and very close sequential injections without any fusion between them.Copyright © 2006 by ASME
Mulatu Geleta - One of the best experts on this subject based on the ideXlab platform.
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enhancing neoplasm expression in field pea pisum sativum via intercropping and its significance to pea weevil bruchus pisorum management
Frontiers in Plant Science, 2016Co-Authors: Abel Teshome, Tomas Bryngelsson, Esayas Mendesil, Salla Marttila, Mulatu GeletaAbstract:Neoplasm formation, a non-meristematic tissue growth on young field pea (Pisum sativum L.) pods is triggered in the absence of UV light and/or in response to oviposition by pea weevil (Bruchus pisorum L.). This trait is expressed in some genotypes (Np genotypes) of P. sativum and has the capacity to obstruct pea weevil larval entry into developing seeds. In the present study, 26% of the tested accessions depicted the trait when grown under greenhouse conditions. However, UV light inhibits full expression of this trait and subsequently it is inconspicuous at the field level. In order to investigate UV light impact on the expression of neoplasm, particular Np genotypes were subjected to UV lamp light exposure in the greenhouse and sunlight at the field level. Under these different growing conditions, the highest mean percentage of neoplastic pods was in the Control Chamber in the greenhouse (36%) whereas in single and double UV lamp Chambers, the percentage dropped to 10% and 15%, respectively. Furthermore, when the same Np genotypes were grown in the field, the percentage of neoplastic pods dropped significantly (7%). In order to enhance neoplastic expression at the field level, intercropping of Np genotypes with sorghum was investigated. As result, the percentage of neoplastic pods was threefold in intercropped Np genotypes as compared to those without intercropping. Therefore, intercropping neoplastic genotypes with other crops such as sorghum and maize can facilitate neoplasm formation, which in turn can minimize the success rate of pea weevil larvae entry into developing seeds. Greenhouse artificial infestation experiments showed that pea weevil damage in neoplastic genotypes is lower in comparison to wild type genotypes. Therefore, promoting neoplastic formation under field conditions via intercropping can serve as part of an integrated pea weevil management strategy especially for small scale farming systems.
Antonio Mittica - One of the best experts on this subject based on the ideXlab platform.
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benefits of hydraulic layout over driving system in piezo injectors and proposal of a new concept cr injector with an integrated minirail
Applied Energy, 2013Co-Authors: Alessandro Ferrari, Antonio Mittica, Ezio SpessaAbstract:Abstract The prediction capability of an advanced Common Rail (CR) piezoelectric injection-system mathematical model has been upgraded and applied to the analysis of transient flows inside injectors. The predicted time histories of the sac-, delivery- and Control-Chamber pressures, of the pilot- and needle-valve lifts, and of the mass flow-rates through the Z and A holes, as well as through the bypass, have been analyzed to explain the differences in performance between piezoelectric and solenoid injectors. The objective was to study the influence exerted by the different hydraulic and mechanical setups in order to assess the effective benefits that could be obtained from the replacement of the solenoid driving system with the piezoelectric one. Then, the upgraded mathematical model has been applied to the design of new-concept injectors. First, specific attention was given to the effects that variations in the peak current values could have on the injected flow-rate. Furthermore, numerical simulations were performed to comprehend the effects that remarkable increments in the injector internal accumulation volume could have on injection system performance. A prototype of the new-concept injector with a small integrated accumulator (Minirail) has also been tested on the hydraulic rig.