The Experts below are selected from a list of 194694 Experts worldwide ranked by ideXlab platform
Gherhardt Ribatski - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation of the heat transfer coefficient during convective boiling of r134a in tubes with twisted tape insert
International Journal of Refrigeration-revue Internationale Du Froid, 2018Co-Authors: Andrey V Shishkin, Fabio Toshio Kanizawa, Gherhardt Ribatski, Stanislav E Tarasevich, A B YakovlevAbstract:Abstract This paper addresses experimental results for heat transfer coefficient and flow patterns during R134a convective boiling inside horizontal tubes containing twisted tape inserts. The experimental database comprises results for twist ratios ranging from 3 to 14, tubes with internal diameters of 10.0, 12.7 and 15.9 mm, mass flux from 75 to 1000 kg/m²s, saturation temperature between 5 and 25 °C, vapor quality between 0.01 and 0.95, and heat flux ranging from 5 to 250 kW/m². The influence of distinct parameters on the heat transfer coefficient is parametrically analyzed, and the data are compared with Predictive Methods available in the literature. The dominant heat transfer mechanisms are identified according to the operational conditions. A Predictive Method for the heat transfer coefficient for high heat (≥ 100 kW/m²) and mass (≥ 400 kg/m²s) fluxes is proposed.
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Void fraction Predictive Method based on the minimum kinetic energy
Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2016Co-Authors: Fabio Toshio Kanizawa, Gherhardt RibatskiAbstract:This paper presents a new void fraction Predictive Method for two-phase gas–liquid flows inside tubes for horizontal and vertical upward flows based on the principle of minimum kinetic energy. Non-uniformities of the velocity profiles are taken into account in the development of the Method through empirical factors defined by the momentum coefficients ratio. A regression analysis to correlate the momentum coefficients ratio based on a broad databank gathered from the literature covering horizontal and vertical upward flows is performed. The proposed Method has proven more accurate than the current Methods available in the literature, as it predicts 92 and 85 % of the experimental data for horizontal and vertical saturated flows, respectively, within a ±10 % error band. The experimental database includes results for saturated flow and covers mass velocities ranging from 70 to 800 kg/m^2 s and from 37 to 4500 kg/m^2 s and tube internal diameters from 0.5 to 13.8 mm and 6 to 89 mm for horizontal and vertical upward flows, respectively.
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a new model for flow boiling heat transfer coefficient inside horizontal tubes with twisted tape inserts
International Journal of Refrigeration-revue Internationale Du Froid, 2016Co-Authors: Fabio Toshio Kanizawa, Taye Stephen Mogaji, Gherhardt RibatskiAbstract:Abstract This paper presents a new Method to predict the heat transfer coefficient during flow boiling inside horizontal tubes containing twisted tape inserts. The Method was developed based on the database presented by Kanizawa et al. This database comprises flow boiling results for horizontal tubes with internal diameters of 12.7 and 15.9 mm, twisted-tape ratios of 3, 4, 9 and 14, mass velocities ranging from 75 to 200 kg m −2 s −1 , heat fluxes of 5 and 10 kW m −2 and saturation temperatures of 5 and 15 °C. The Method is flow-pattern based and considers flow boiling, dryout and mist flow regions. The Predictive Method also takes into account the physical picture of the swirl flow phenomenon by considering swirl flow effects promoted by the twisted tape insert. The proposed Method provides satisfactory predictions and captures the main heat transfer trends of the data of Kanizawa et al. and also of independent data from literature.
Fabio Toshio Kanizawa - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation of the heat transfer coefficient during convective boiling of r134a in tubes with twisted tape insert
International Journal of Refrigeration-revue Internationale Du Froid, 2018Co-Authors: Andrey V Shishkin, Fabio Toshio Kanizawa, Gherhardt Ribatski, Stanislav E Tarasevich, A B YakovlevAbstract:Abstract This paper addresses experimental results for heat transfer coefficient and flow patterns during R134a convective boiling inside horizontal tubes containing twisted tape inserts. The experimental database comprises results for twist ratios ranging from 3 to 14, tubes with internal diameters of 10.0, 12.7 and 15.9 mm, mass flux from 75 to 1000 kg/m²s, saturation temperature between 5 and 25 °C, vapor quality between 0.01 and 0.95, and heat flux ranging from 5 to 250 kW/m². The influence of distinct parameters on the heat transfer coefficient is parametrically analyzed, and the data are compared with Predictive Methods available in the literature. The dominant heat transfer mechanisms are identified according to the operational conditions. A Predictive Method for the heat transfer coefficient for high heat (≥ 100 kW/m²) and mass (≥ 400 kg/m²s) fluxes is proposed.
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Void fraction Predictive Method based on the minimum kinetic energy
Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2016Co-Authors: Fabio Toshio Kanizawa, Gherhardt RibatskiAbstract:This paper presents a new void fraction Predictive Method for two-phase gas–liquid flows inside tubes for horizontal and vertical upward flows based on the principle of minimum kinetic energy. Non-uniformities of the velocity profiles are taken into account in the development of the Method through empirical factors defined by the momentum coefficients ratio. A regression analysis to correlate the momentum coefficients ratio based on a broad databank gathered from the literature covering horizontal and vertical upward flows is performed. The proposed Method has proven more accurate than the current Methods available in the literature, as it predicts 92 and 85 % of the experimental data for horizontal and vertical saturated flows, respectively, within a ±10 % error band. The experimental database includes results for saturated flow and covers mass velocities ranging from 70 to 800 kg/m^2 s and from 37 to 4500 kg/m^2 s and tube internal diameters from 0.5 to 13.8 mm and 6 to 89 mm for horizontal and vertical upward flows, respectively.
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a new model for flow boiling heat transfer coefficient inside horizontal tubes with twisted tape inserts
International Journal of Refrigeration-revue Internationale Du Froid, 2016Co-Authors: Fabio Toshio Kanizawa, Taye Stephen Mogaji, Gherhardt RibatskiAbstract:Abstract This paper presents a new Method to predict the heat transfer coefficient during flow boiling inside horizontal tubes containing twisted tape inserts. The Method was developed based on the database presented by Kanizawa et al. This database comprises flow boiling results for horizontal tubes with internal diameters of 12.7 and 15.9 mm, twisted-tape ratios of 3, 4, 9 and 14, mass velocities ranging from 75 to 200 kg m −2 s −1 , heat fluxes of 5 and 10 kW m −2 and saturation temperatures of 5 and 15 °C. The Method is flow-pattern based and considers flow boiling, dryout and mist flow regions. The Predictive Method also takes into account the physical picture of the swirl flow phenomenon by considering swirl flow effects promoted by the twisted tape insert. The proposed Method provides satisfactory predictions and captures the main heat transfer trends of the data of Kanizawa et al. and also of independent data from literature.
Jose Rodriguez - One of the best experts on this subject based on the ideXlab platform.
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model Predictive torque ripple reduction with weighting factor optimization fed by an indirect matrix converter
Electric Power Components and Systems, 2014Co-Authors: Muslem Uddin, Saad Mekhilef, Marizan Mubin, Marco Rivera, Jose RodriguezAbstract:Abstract—Model Predictive control has emerged as a powerful control tool in the field of power converter and drive's system. In this article, a weighting factor optimization for reducing the torque ripple of induction machine fed by an indirect matrix converter is introduced and presented. Therefore, an optimization Method is adopted here to calculate the optimum weighting factor corresponding to minimum torque ripple. However, model Predictive torque and flux control of the induction machine with conventionally selected weighting factor is being investigated in this article and is compared with the proposed optimum weighting factor based model Predictive control algorithm to reduce the torque ripples. The proposed model Predictive control scheme utilizes the discrete phenomena of power converter and predicts the future nature of the system variables. For the next sampling period, model Predictive Method selects the optimized switching state that minimizes a cost function based on optimized weighting fact...
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Predictive current control applied to a matrix converter an assessment with the direct transfer function approach
International Conference on Industrial Technology, 2010Co-Authors: R Vargas, Jose Rodriguez, Christian A Rojas, Patrick WheelerAbstract:The objective of this study is to compare the performance between a model-based Predictive control technique and the established direct transfer function (DTF) approach for matrix converters. Both Methods are analyzed in simulations and based on experimental results, reaching to conclusions in terms of the benefits and disadvantages of each control strategy. The Predictive Method achieves a better performance in terms of input- and load-current THD, PF control and is less affected by a polluted AC grid. The DTF approach, on the other hand, presents benefits during overmodulation, diminished in the implemented practical validation by its greater sensitivity to distorted mains.
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Predictive current control of a voltage source inverter
IEEE Transactions on Industrial Electronics, 2007Co-Authors: Jose Rodriguez, C Silva, Patricio Cortes, P Correa, Pablo Lezana, U AmmaAbstract:This paper presents a Predictive current control Method and its application to a voltage source inverter. The Method uses a discrete-time model of the system to predict the future value of the load current for all possible voltage vectors generated by the inverter. The voltage vector which minimizes a quality function is selected. The quality function used in this work evaluates the current error at the next sampling time. The performance of the proposed Predictive control Method is compared with hysteresis and pulsewidth modulation control. The results show that the Predictive Method controls very effectively the load current and performs very well compared with the classical solutions
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Predictive current control of a voltage source inverter
Power Electronics Specialists Conference, 2004Co-Authors: Jose Rodriguez, J Pontt, C Silva, Patricio Cortes, U Amman, S ReesAbstract:This work presents the application of Predictive current control in a voltage source inverter. The Method uses a discrete-time model of the system to predict the future value of the load current for all possible voltage vectors generated by the inverter. The voltage vector which minimizes the current error at the next sampling time is selected. The performance of the proposed Predictive control Method is compared with hysteresis and PWM control. The results show that the Predictive Method controls very effectively the load current and compares very well with the classical solutions.
U Amma - One of the best experts on this subject based on the ideXlab platform.
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Predictive current control of a voltage source inverter
IEEE Transactions on Industrial Electronics, 2007Co-Authors: Jose Rodriguez, C Silva, Patricio Cortes, P Correa, Pablo Lezana, U AmmaAbstract:This paper presents a Predictive current control Method and its application to a voltage source inverter. The Method uses a discrete-time model of the system to predict the future value of the load current for all possible voltage vectors generated by the inverter. The voltage vector which minimizes a quality function is selected. The quality function used in this work evaluates the current error at the next sampling time. The performance of the proposed Predictive control Method is compared with hysteresis and pulsewidth modulation control. The results show that the Predictive Method controls very effectively the load current and performs very well compared with the classical solutions
Taye Stephen Mogaji - One of the best experts on this subject based on the ideXlab platform.
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a new model for flow boiling heat transfer coefficient inside horizontal tubes with twisted tape inserts
International Journal of Refrigeration-revue Internationale Du Froid, 2016Co-Authors: Fabio Toshio Kanizawa, Taye Stephen Mogaji, Gherhardt RibatskiAbstract:Abstract This paper presents a new Method to predict the heat transfer coefficient during flow boiling inside horizontal tubes containing twisted tape inserts. The Method was developed based on the database presented by Kanizawa et al. This database comprises flow boiling results for horizontal tubes with internal diameters of 12.7 and 15.9 mm, twisted-tape ratios of 3, 4, 9 and 14, mass velocities ranging from 75 to 200 kg m −2 s −1 , heat fluxes of 5 and 10 kW m −2 and saturation temperatures of 5 and 15 °C. The Method is flow-pattern based and considers flow boiling, dryout and mist flow regions. The Predictive Method also takes into account the physical picture of the swirl flow phenomenon by considering swirl flow effects promoted by the twisted tape insert. The proposed Method provides satisfactory predictions and captures the main heat transfer trends of the data of Kanizawa et al. and also of independent data from literature.
