A numerical study on mechanisms of energy dissipation in a pump as turbine (PAT) using entropy generation theory

Ghorani, Mohammad Mahdi; Haghighi, Mohammad Hadi Sotoude; Maleki, Ali Reza; Riasi, Alireza

doi:10.1016/j.renene.2020.08.102

Cited by 115 publications

(39 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The turbulent flow in the multiphase pump is very complex, three-dimensional, random, and irregular, and changes with time and space, carrying countless vortices with different sizes and shapes depending on the geometric space of the flow field. In order to simulate such a flow accurately and efficiently, the RANS (Reynolds averaged Navier-Stokes) equations combined with k-ω SST (Shear Stress Transport) turbulence models were employed in this research, because of their good stability and applicability and which have been confirmed in a large number of examples in engineering practice and scientific research [34,35]. As the pump is one of rotating machinery, a two-dimensional simulation will reduce the accuracy of the results and lose lot information of the flow field, so a fully three-dimensional simulation is carried out in the present study as most researchers have done.…”

Section: Governing Equations Numerical Methods and Boundary Conditionsmentioning

confidence: 99%

Effect of Flow Rate on Turbulence Dissipation Rate Distribution in a Multiphase Pump

et al. 2021

View full text Add to dashboard Cite

The turbulence dissipation will cause the increment of energy loss in the multiphase pump and deteriorate the pump performance. In order to research the turbulence dissipation rate distribution characteristics in the pressurized unit of the multiphase pump, the spiral axial flow type multiphase pump is researched numerically in the present study. This research is focused on the turbulence dissipation rate distribution characteristics in the directions of inlet to outlet, hub to rim, and in the circumferential direction of the rotating impeller blades. Numerical simulation based on the RANS (Reynolds averaged Navier–Stokes equations) and the k-ω SST (Shear Stress Transport) turbulence model has been carried out. The numerical method is verified by comparing the numerical results with the experimental data. Results show that the regions of the large turbulence dissipation rate are mainly at the inlet and outlet of the rotating impeller and static impeller, while it is almost zero from the inlet to the middle of outlet in the suction surface and pressure surface of the first-stage rotating impeller blades. The turbulence dissipation rate is increased gradually from the hub to the rim of the inlet section of the first-stage rotating impeller, while it is decreased firstly and then increased on the middle and outlet sections. The turbulence dissipation rate distributes unevenly in the circumferential direction on the outlet section. The maximum value of the turbulence dissipation rate occurs at 0.9 times of the rated flow rate, while the minimum value at 1.5 times of the rated flow rate. Four turning points in the turbulence dissipation rate distribution that are the same as the number of impeller blades occur at 0.5 times the blade height at 0.9 times the rated flow rate condition. The turbulence dissipation rate distribution characteristics in the pressurized unit of the multiphase pump have been studied carefully in this paper, and the research results have an important significance for improving the performance of the multiphase pump theoretically.

show abstract

Section: Governing Equations Numerical Methods and Boundary Conditionsmentioning

confidence: 99%

Effect of Flow Rate on Turbulence Dissipation Rate Distribution in a Multiphase Pump

et al. 2021

View full text Add to dashboard Cite

show abstract

“…A finite element procedure can be applied to solve the system of equations. The -turbulence model is used to predict the flow behavior in the mass regions [42].…”

Section: Governance Equations and Boundary Conditionsmentioning

confidence: 99%

Characteristic Curve Prediction of a Commercial Centrifugal Pump Operating as a Turbine Through Numerical Simulations

Vásquez

Graciano-Uribe

Río

2021

ARFMTS

View full text Add to dashboard Cite

In this work, we seek to predict the characteristic curve of a commercial centrifugal radial flow pump operating as a turbine, applying a novel methodology based on the state of the art. Initially, the characteristic curve in pump mode is validated through numerical simulations. The results obtained are approximate to the points awarded by the manufacturer, with an error of less than 7% at the best efficiency point. Subsequently, the characteristic curve is generated in turbine mode, obtaining an error of less than 10% respect to mathematical model. Then, velocity and pressure contours are evaluated to validate the fluid dynamic behavior. Finally, the site operating conditions for electricity generation are obtained. With this, it is proposing a methodology for the selection of these turbomachines, applying an economic technology for zones that do not have access to the electrical energy, since it was not found a method that is being applied for its correct election in the hydroelectric generation at low scale.

show abstract

“…e calculation of Reynolds stress in this model is based on the Bossinger hypothesis in the following equation [17]:…”

Section: Z(ρkmentioning

confidence: 99%

“…It was found that the entropy dissipation theory can not only accurately calculate the loss of each part of the turbine, but also determine the location and mode of water loss. Ghorani et al [17] studied the energy loss mechanism of a pump as turbine for the first time from the perspective of entropy generation theory and the second law of thermodynamics and pointed out that the turbulent term in entropy generation is the main factor causing the energy loss in the turbine. Li et al [18] pointed out that mass flow mainly affects the position of pressure fluctuation peak, and the number of blades mainly affects the main frequency of pressure fluctuation.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation on the Influence of Rotating Speed on the Hydraulic Loss Characteristics of Desalination Energy Recovery Turbine

Stankovic

Zhang

et al. 2021

Shock and Vibration

View full text Add to dashboard Cite

The performance of energy recovery turbine (ERT) directly determines the cost and energy consumption of reverse osmosis desalination. In order to study the performance and loss mechanisms of ERT under different conditions, the external characteristics and the losses of different components were quantitatively analyzed. The loss mechanisms of each component in the turbine were revealed through the comparative analysis of the internal flow field. The results show that the efficiency is 2.2% higher than that at the design speed when turbine runs at n = 22000 r/min. The impeller losses account for more than 67% of the total losses. The impeller loss is mainly observed at the leading edge. The vortex on the pressure side of the leading edge is caused by the impact effect, while the vortex on the suction side of the leading edge is caused by the flow separation. With the increase in the rotating speed, the loss caused by flow separation in impeller decreases obviously. The volute loss is mainly observed near the tongue, which is caused by the flow separation at the tongue. The design of the tongue is very important to the performance of the volute. The turbulent kinetic energy (TKE) and loss decrease with the increase in the rotating speed. The loss in the draft tube is mainly observed at the inlet core. With the increase in the rotating speed, the turbulence pulsation and the radial pressure fluctuation amplitude reduce. Therefore, the turbine can be operated at the design or slightly higher than the design rotating speed under the condition that both the hydraulic condition and the intensity are satisfied, which are conducive to the efficient utilization of energy.

show abstract

A numerical study on mechanisms of energy dissipation in a pump as turbine (PAT) using entropy generation theory

Cited by 115 publications

References 48 publications

Effect of Flow Rate on Turbulence Dissipation Rate Distribution in a Multiphase Pump

Effect of Flow Rate on Turbulence Dissipation Rate Distribution in a Multiphase Pump

Characteristic Curve Prediction of a Commercial Centrifugal Pump Operating as a Turbine Through Numerical Simulations

Numerical Simulation on the Influence of Rotating Speed on the Hydraulic Loss Characteristics of Desalination Energy Recovery Turbine

Contact Info

Product

Resources

About