The Experts below are selected from a list of 219 Experts worldwide ranked by ideXlab platform
Ayad Al Jubori - One of the best experts on this subject based on the ideXlab platform.
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Development and optimization of efficient small-scale turbines for organic rankine cycle powered by low-temperature heat sources
2017Co-Authors: Ayad Al Jubori, Ayad Mahmoud SalmanAbstract:In this this research, ORC systems using axial, Radial-inflow and Radial-Outflow turbines are investigated for various low-power generation (1-15 kW) applications like domestic, rural and remote off-grid communities. This work presents a new integrated mathematical model for developing efficient axial, Radial-inflow and Radial-Outflow (centrifugal) turbines with low mass flow rate (0.1-0.5 kg/s) using a range of organic working fluids (R14lb, R1234yf, R245fa, R365mfc, isobutene, n-butane and n-pentane). The new mathematical approach integrates mean-line design and 3D CFD analysis with ORC modelling. RANS equations for three-dimensional steady state and viscous flow were solved with k-ro SST turbulence model to predict 3D viscous turbulent flow and turbine performance. With the aim of enhancing the ORC performance by increasing its pressure ratio, novel small-scale two-stage axial and Radial Outflow turbines are modelled and compared with single-stage axial, Radial-inflow and Radial-Outflow turbines. New performance maps in terms of isentropic efficiency and power output for each turbine configuration are developed in terms of expansion ratio, mass flow rate, rotational speed and turbine size. Novel optimization technique using multi-objective genetic algorithm was applied to optimize small-scale single stage axial, Radial-inflow and Radial-Outflow turbines with this flow rate. Experimental study of the ORC Radial-inflow turbine was carried out.
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New performance maps for selecting suitable small-scale turbine configuration for low-power organic Rankine cycle applications
Journal of Cleaner Production, 2017Co-Authors: Ayad Al Jubori, Raya Al-dadah, Saad MahmoudAbstract:Abstract This paper aims to deliver new performance maps for small-scale organic Rankine cycle (ORC) turbines ( ®17 -CFX was used to perform 3D CFD analysis of all turbine configurations. RANS equations for three-dimensional steady state and viscous flow were solved with a k-ω SST turbulence model. The performance maps in terms of turbine isentropic efficiency and power output for each turbine configuration are presented according to the operating conditions in terms of expansion ratio, working fluid mass flow rate, and rotational speed with turbine size. The results revealed that the two-stage axial and Radial-Outflow turbines’ configurations exhibited a considerably higher turbine performance, with overall isentropic efficiency of 84.642% and 82.9% and power output of 15.798 kW and 14.331 kW respectively, with R245fa as a working fluid. Also, the results exhibited that the maximum ORC thermal efficiency for both two-stage configurations was 13.96% and 12.80% for axial and Radial-Outflow turbines respectively working with R245fa. These results indicated the potential advantages of a two-stage turbine configuration in a small-scale ORC system for the conversion of a low-temperature heat source into electricity as a useful power.
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modelling and parametric analysis of small scale axial and Radial Outflow turbines for organic rankine cycle applications
Applied Energy, 2017Co-Authors: Ayad Al Jubori, Raya Aldadah, Saad Mahmoud, Ahmed M DaaboAbstract:The existing literature pays limited attention to the design and 3D analysis of small-scale axial and Radial–Outflow turbines that can be utilised in Organic Rankine Cycles (ORC) for power generation with a low–temperature (<100°C) heat source and low mass flow rate. Turbine efficiency significantly affects an ORC’s efficiency because the turbine is considered a key component of the ORC. Therefore, obtaining high cycle thermal efficiency requires high turbine efficiency and power output. This work presents an integrated mathematical model for developing efficient axial and Radial-Outflow (centrifugal) turbines using a range of organic working fluids (R141b, R245fa, R365mfc, isobutane and n–pentane). This mathematical approach integrates mean-line design and 3D CFD analysis with ORC modelling. The ANSYSR17CFX is used to predict 3D viscous flow and turbine performance. To achieve accurate prediction, the ORC/turbines model uses real gas formulations based on the REFPROP database. The results showed that the axial turbine performed better, with efficiency of 82.5% and power output of 15.15kW, compared with 79.05% and 13.625kW from the Radial–Outflow turbine, with n-pentane as the working fluid in both cases. The maximum cycle thermal efficiency was 11.74% and 10.25% for axial and Radial-Outflow turbines respectively with n-pentane as the working fluid and a heat source temperature of 87°C. The large tip diameter of the axial turbine was 73.82mm compared with 108.72mm for the Radial-Outflow turbine. The predicted results are better than others in the literature and highlight the advantages of the integrated approach for accurate prediction of ORC performance based on small-scale axial and Radial-Outflow turbines.
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Modelling and parametric analysis of small-scale axial and Radial-Outflow turbines for Organic Rankine Cycle applications
Applied Energy, 2017Co-Authors: Ayad Al Jubori, Saad Mahmoud, Raya Al-dadah, Ahmed M DaaboAbstract:The existing literature pays limited attention to the design and 3D analysis of small-scale axial and Radial–Outflow turbines that can be utilised in Organic Rankine Cycles (ORC) for power generation with a low–temperature (
Richard M. Lueptow - One of the best experts on this subject based on the ideXlab platform.
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The effect of Radial through-flow on the stability of Taylor- Couette flow
2020Co-Authors: Eric Serre, Michael A. Sprague, Patrick Bontoux, Richard M. LueptowAbstract:Linear stability analysis predicts that a Radial through-flow in a Taylor-Couette system will alter the stability of the flow, but the underlying physics for the stabilization of the flow is unclear. We investigate the impact of Radial inflow and Outflow on Taylor vortex flow and wavy vortex flow in a finite-length cavity via direct numerical simulation using a three- dimensional spectral method. The numerical simulations are consistent with linear stability predictions that Radial inflow and strong Radial Outflow have a stabilizing effect, while weak Radial Outflow destabilizes the system slightly. The flow is stabilized when the imposed Radial velocity is similar in magnitude to the maximum Radial velocity of the Taylor vortices, as occurs for inflow and strong Radial Outflow. In this case, the vortical flow is simply dominated by the imposed Radial flow. However, a small Radial Outflow velocity enhances the strength of the Taylor vortices resulting in destabilization of the flow. The Radial flow also alters the stability of higher order transitions to three-dimensional vortical flow including wavy vortex flow.
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Stability of Taylor–Couette flow in a finite-length cavity with Radial throughflow
Physics of Fluids, 2008Co-Authors: Eric Serre, Michael A. Sprague, Richard M. LueptowAbstract:Linear stability analysis predicts that a Radial throughflow in a Taylor–Couette system will alter the stability of the flow, but the underlying physics for the stabilization of the flow is unclear. We investigate the impact of Radial inflow and Outflow on Taylor vortex flow and wavy vortex flow in a finite-length cavity via direct numerical simulation using a three-dimensional spectral method. The numerical simulations are consistent with linear stability predictions in that Radial inflow and strong Radial Outflow have a stabilizing effect, while weak Radial Outflow destabilizes the system slightly. A small Radial Outflow velocity enhances the strength of the Taylor vortices resulting in destabilization of the base flow, whereas strong Radial Outflow and Radial inflow reduce vortex strength, thus stabilizing the system. The transition to wavy vortex flow is unaffected by small Radial Outflow, but is stabilized for Radial inflow. For strong Radial Outflow the wavy vortex flow includes localized dislocatio...
Ennio Macchi - One of the best experts on this subject based on the ideXlab platform.
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field performance evaluation of geothermal orc power plants with a focus on Radial Outflow turbines
Renewable Energy, 2020Co-Authors: Luca Zanellato, Aldo Serafino, Dario Rizzi, Marco Astolfi, Ennio MacchiAbstract:Abstract The calculation of the performance of an ORC (Organic Rankine Cycle) and its components (in particularly the turbine) is generally not a trivial task because of the lack of a proper instrumentation, the inaccuracy of the available measurements and the uncertainty on fluid thermodynamic properties calculation. These limitations can greatly affect the final computed results especially for complex fluids with a small temperature drop in expansion. A strategy to solve the inconsistency of the measured data set is to verify the energy and mass balance of each component and of the overall plant using also information related to the geometry of specific components, primarily the turbine as well as electrical measurements. After a brief description of the Radial Outflow turbine and of its main features, two operating geothermal ORC (Organic Rankine Cycle) plants installed by Exergy Spa in Turkey are described. For both plants a methodology for the consistency check of the experimental data set is presented with a description of the installed instrumentation, the test procedure and methods used to calculate the turbine efficiency as well as the overall power cycle performance.
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Field Performance Evaluation of ORC Geothermal Power Plants Using Radial Outflow Turbines
Energy Procedia, 2017Co-Authors: Luca Zanellato, Aldo Serafino, Dario Rizzi, Marco Astolfi, Ennio MacchiAbstract:This paper, after a brief description of the Radial Outflow turbine and of its main features, discloses the field performances evaluation of two operating geothermal ORC (Organic Rankine Cycle) plants installed by Exergy Spa in Turkey. The work describes the test procedure, the measurements and calculation methods used to obtain the turbine efficiency as well as overall power cycle performance from the set of available experimental data.
Ahmed M Daabo - One of the best experts on this subject based on the ideXlab platform.
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modelling and parametric analysis of small scale axial and Radial Outflow turbines for organic rankine cycle applications
Applied Energy, 2017Co-Authors: Ayad Al Jubori, Raya Aldadah, Saad Mahmoud, Ahmed M DaaboAbstract:The existing literature pays limited attention to the design and 3D analysis of small-scale axial and Radial–Outflow turbines that can be utilised in Organic Rankine Cycles (ORC) for power generation with a low–temperature (<100°C) heat source and low mass flow rate. Turbine efficiency significantly affects an ORC’s efficiency because the turbine is considered a key component of the ORC. Therefore, obtaining high cycle thermal efficiency requires high turbine efficiency and power output. This work presents an integrated mathematical model for developing efficient axial and Radial-Outflow (centrifugal) turbines using a range of organic working fluids (R141b, R245fa, R365mfc, isobutane and n–pentane). This mathematical approach integrates mean-line design and 3D CFD analysis with ORC modelling. The ANSYSR17CFX is used to predict 3D viscous flow and turbine performance. To achieve accurate prediction, the ORC/turbines model uses real gas formulations based on the REFPROP database. The results showed that the axial turbine performed better, with efficiency of 82.5% and power output of 15.15kW, compared with 79.05% and 13.625kW from the Radial–Outflow turbine, with n-pentane as the working fluid in both cases. The maximum cycle thermal efficiency was 11.74% and 10.25% for axial and Radial-Outflow turbines respectively with n-pentane as the working fluid and a heat source temperature of 87°C. The large tip diameter of the axial turbine was 73.82mm compared with 108.72mm for the Radial-Outflow turbine. The predicted results are better than others in the literature and highlight the advantages of the integrated approach for accurate prediction of ORC performance based on small-scale axial and Radial-Outflow turbines.
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Modelling and parametric analysis of small-scale axial and Radial-Outflow turbines for Organic Rankine Cycle applications
Applied Energy, 2017Co-Authors: Ayad Al Jubori, Saad Mahmoud, Raya Al-dadah, Ahmed M DaaboAbstract:The existing literature pays limited attention to the design and 3D analysis of small-scale axial and Radial–Outflow turbines that can be utilised in Organic Rankine Cycles (ORC) for power generation with a low–temperature (
Saad Mahmoud - One of the best experts on this subject based on the ideXlab platform.
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New performance maps for selecting suitable small-scale turbine configuration for low-power organic Rankine cycle applications
Journal of Cleaner Production, 2017Co-Authors: Ayad Al Jubori, Raya Al-dadah, Saad MahmoudAbstract:Abstract This paper aims to deliver new performance maps for small-scale organic Rankine cycle (ORC) turbines ( ®17 -CFX was used to perform 3D CFD analysis of all turbine configurations. RANS equations for three-dimensional steady state and viscous flow were solved with a k-ω SST turbulence model. The performance maps in terms of turbine isentropic efficiency and power output for each turbine configuration are presented according to the operating conditions in terms of expansion ratio, working fluid mass flow rate, and rotational speed with turbine size. The results revealed that the two-stage axial and Radial-Outflow turbines’ configurations exhibited a considerably higher turbine performance, with overall isentropic efficiency of 84.642% and 82.9% and power output of 15.798 kW and 14.331 kW respectively, with R245fa as a working fluid. Also, the results exhibited that the maximum ORC thermal efficiency for both two-stage configurations was 13.96% and 12.80% for axial and Radial-Outflow turbines respectively working with R245fa. These results indicated the potential advantages of a two-stage turbine configuration in a small-scale ORC system for the conversion of a low-temperature heat source into electricity as a useful power.
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modelling and parametric analysis of small scale axial and Radial Outflow turbines for organic rankine cycle applications
Applied Energy, 2017Co-Authors: Ayad Al Jubori, Raya Aldadah, Saad Mahmoud, Ahmed M DaaboAbstract:The existing literature pays limited attention to the design and 3D analysis of small-scale axial and Radial–Outflow turbines that can be utilised in Organic Rankine Cycles (ORC) for power generation with a low–temperature (<100°C) heat source and low mass flow rate. Turbine efficiency significantly affects an ORC’s efficiency because the turbine is considered a key component of the ORC. Therefore, obtaining high cycle thermal efficiency requires high turbine efficiency and power output. This work presents an integrated mathematical model for developing efficient axial and Radial-Outflow (centrifugal) turbines using a range of organic working fluids (R141b, R245fa, R365mfc, isobutane and n–pentane). This mathematical approach integrates mean-line design and 3D CFD analysis with ORC modelling. The ANSYSR17CFX is used to predict 3D viscous flow and turbine performance. To achieve accurate prediction, the ORC/turbines model uses real gas formulations based on the REFPROP database. The results showed that the axial turbine performed better, with efficiency of 82.5% and power output of 15.15kW, compared with 79.05% and 13.625kW from the Radial–Outflow turbine, with n-pentane as the working fluid in both cases. The maximum cycle thermal efficiency was 11.74% and 10.25% for axial and Radial-Outflow turbines respectively with n-pentane as the working fluid and a heat source temperature of 87°C. The large tip diameter of the axial turbine was 73.82mm compared with 108.72mm for the Radial-Outflow turbine. The predicted results are better than others in the literature and highlight the advantages of the integrated approach for accurate prediction of ORC performance based on small-scale axial and Radial-Outflow turbines.
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Modelling and parametric analysis of small-scale axial and Radial-Outflow turbines for Organic Rankine Cycle applications
Applied Energy, 2017Co-Authors: Ayad Al Jubori, Saad Mahmoud, Raya Al-dadah, Ahmed M DaaboAbstract:The existing literature pays limited attention to the design and 3D analysis of small-scale axial and Radial–Outflow turbines that can be utilised in Organic Rankine Cycles (ORC) for power generation with a low–temperature (
