scholarly journals Effect of molten salt properties on internal flow and disk friction loss of molten salt pump

2020 ◽  
Vol 24 (4) ◽  
pp. 2347-2356
Author(s):  
Yong-Xin Jin ◽  
De-Sheng Zhang ◽  
Xi Sheng ◽  
Lei Shi ◽  
Wei-Dong Shi ◽  
...  
Keyword(s):  
Shear Stress ◽  
Molten Salt ◽  
Pure Water ◽  
Friction Loss ◽  
Effect Of Temperature ◽  
Fluid Viscosity ◽  
Fluid Density ◽  
Working Fluids ◽  
Pump Performance ◽  
Disk Friction

Computational fluid dynamics is used to study the effect of temperature on flow structure and disk friction loss for different working fluids in a high temperature molten salt pump, which is used for concentrating solar power, the velocity profile and pressure distribution in the first stage of the pump model and the effect of the fluid property on the ring leakage, disk friction loss as well as the shear stress distribution on shroud are analyzed for the pure water and the molten salt with temperature 300?C and 565?C respectively. The main findings can be concluded as: the working fluids have little effect on pump performance and internal velocity distribution whereas the pressure of the flow field would increase with the fluid density, with the increase of the fluid viscosity, the shear stress inside the ring also increases and the total leakage can be eliminated evidently, the increase of the fluid density and viscosity show the significant responsibility for the disk friction loss, in which the fluid viscosity also increases the disk friction loss, and the viscosity is one of the most influential factors for the shroud shear stress and it can be observed that the shear stress on front shroud is higher than that on the rear shroud. It is believed that the present work can deep the understandings of the fluid structures inside the molten salt pump, which can provide some guidelines to improve the pump performance and optimize the pump structure.

scholarly journals Numerical analysis of flow structure and energy loss in an impeller side chamber of a molten salt pump

2019 ◽  
Vol 23 (4) ◽  
pp. 2333-2341
Author(s):  
Yong-Xin Jin ◽  
De-Sheng Zhang ◽  
Rui-Jie Zhao ◽  
Lei Shi ◽  
Wei-Dong Shi
Keyword(s):  
Energy Loss ◽  
Molten Salt ◽  
Flow Structure ◽  
Flow Rate ◽  
Thermal Power ◽  
Tangential Velocity ◽  
Friction Loss ◽  
Total Energy Consumption ◽  
Core Flow ◽  
Disk Friction

The internal flow structure and the energy loss in the first stage impeller side chamber of a molten salt pump for solar thermal power generation were investigated numerically. The flow field in the model pump was simulated based on the RANS equation using the standard k-? turbulence model. The results indicate that the rotating speed of core flow in the front impeller side chamber is higher than the tangential velocity at the maximal radius of the front shroud. However, the core flow in the rear impeller side chamber gives an opposite trend. Meanwhile, the radial velocity at the boundary-layer separation point on the front impeller side chamber stationary wall decreases initially and then increases with the radius while it only decreases in the rear impeller side chamber. For the energy loss, the percentage of the disk friction loss to total energy consumption reduces as the flow rate increases, while the absolute value of disk friction loss on the front shroud keeps almost constant and the loss on the rear shroud decreases with the increasing flow rate.

Calculated Design Data for the Multiple-Disk Pump Using Incompressible Fluid

1974 ◽  
Vol 96 (3) ◽  
pp. 274-282 ◽  
Author(s):  
M. E. Crawford ◽  
W. Rice
Keyword(s):  
Incompressible Fluid ◽  
Design Process ◽  
Pressure Change ◽  
Friction Loss ◽  
Pump Efficiency ◽  
Design Data ◽  
Dimensionless Parameters ◽  
Pump Performance ◽  
Fluid Properties ◽  
Disk Friction

Earlier analyses of the laminar radically outward flow of Newtonian incompressible fluid between parallel corotating disks have been used to calculate the performance of multiple-disk pumps using such flow passages as the rotor. Such pumps are characterized by certain dimensionless parameters and a large number of computerized calculations have enabled preparation of pump performance maps for pumps idealized as having no losses external to the rotor; these maps show the quantitative dependence of pump efficiency, pressure change and required power on the pump geometry, speed, and on fluid properties. Conventional loss information for the pump entrance and diffuser flows, and conventional bearing, seal, and “disk friction” loss information, must be applied in the design process to provide prediction of actual pump performance and comparison with conventional pumps. The design information is also applicable to low-pressure gas blowers.

Combined effects of viscosity and surface roughness on electric submersible pump performance

2017 ◽  
Vol 231 (4) ◽  
pp. 303-316 ◽  
Author(s):  
MH Siddique ◽  
Abdus Samad ◽  
Afzal Husain
Keyword(s):  
Surface Roughness ◽  
Skin Friction ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Numerical Approach ◽  
Friction Loss ◽  
Fluid Viscosity ◽  
Submersible Pump ◽  
Pump Performance ◽  
Electric Submersible Pump

An electric submersible pump that lifts crude oil from well bore is a type of multi-stage centrifugal pump. The unexpected wellbore conditions like change in pumping fluid viscosity and sand production severely affect pump performance and eventually lead to breakdown. The present study proposes a numerical approach to understand the effects of fluid viscosity and surface roughness of the flow passages in an electric submersible pump at design and off-design conditions. A three-dimensional numerical analysis was carried out by solving Reynolds-averaged Navier–Stokes equations with shear stress transport turbulence model to characterize performance of the pump. The pumping fluids, i.e., water and crude oils of different viscosities were analyzed for different surface roughness ( Ks) values. The model predictions were compared with a theoretical one-dimensional model for the effect of viscosity and surface roughness. It was found that the disc-friction and the skin-friction losses are sensitive hydraulic losses of which the disc-friction loss increases with increase in viscosity, whereas skin-friction loss decreases with increase in surface roughness at high viscosity. The combined effect of viscosity and roughness showed a complicated behavior and eventually an improvement in pump performance at a higher surface roughness compared to a smoother and lowers surface roughness.

Density and Drag Reduction With Hollow Glass Additives

2014 ◽  
Author(s):  
Bahri Kutlu ◽  
Evren M. Ozbayoglu ◽  
Stefan Z. Miska ◽  
Nicholas Takach ◽  
Mengjiao Yu ◽  
...  
Keyword(s):  
Drag Reduction ◽  
Rheological Behavior ◽  
Drilling Fluid ◽  
Hydraulic Drag ◽  
Effect Of Temperature ◽  
Survival Ratio ◽  
Fluid Density ◽  
Hollow Glass ◽  
Glass Spheres ◽  
Reduction Effect

This study concentrates on the use of materials known as hollow glass spheres, also known as glass bubbles, to reduce the drilling fluid density below the base fluid density without introducing a compressible phase to the wellbore. Four types of lightweight glass spheres with different physical properties were tested for their impact on rheological behavior, density reduction effect, survival ratio at elevated pressures and hydraulic drag reduction effect when mixed with water based fluids. A Fann75 HPHT viscometer and a flow loop were used for the experiments. Results show that glass spheres successfully reduce the density of the base drilling fluid while maintaining an average of 0.93 survival ratio, the rheological behavior of the tested fluids at elevated concentrations of glass bubbles is similar to the rheological behavior of conventional drilling fluids and hydraulic drag reduction is present up to certain concentrations. All results were integrated into hydraulics calculations for a wellbore scenario that accounts for the effect of temperature and pressure on rheological properties, as well as the effect of glass bubble concentration on mud temperature distribution along the wellbore. The effect of drag reduction was also considered in the calculations.

scholarly journals Performance Improvement of a Liquid Molten Salt Pump: Geometry Optimization and Experimental Verification

Symmetry ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 423 ◽  
Author(s):  
Kai Wang ◽  
Xin Lu ◽  
Yu Li ◽  
Xianghui He ◽  
Houlin Liu ◽  
...  
Keyword(s):  
Molten Salt ◽  
Performance Improvement ◽  
Pressure Fluctuation ◽  
Geometry Optimization ◽  
Internal Flow ◽  
Experimental Methods ◽  
Sharp Corner ◽  
Hydraulic Efficiency ◽  
Low Velocity ◽  
Pump Performance

In order to enhance the hydraulic efficiency of a liquid molten salt pump, the improvement on the pump was carried out through numerical and experimental methods. The internal flow field obtained by the numerical simulation was analysed. The results show that there are low-velocity area in the scroll region and large curvature of the streamline at the outlet. Geometric modification was made by trimming the back-blades of the impeller and filleting the sharp corner of the outlet pipe. The modified pump performance was verified by the experiments. The hydraulic efficiency, the pressure fluctuation, vibration characteristics between the original and modified pump were compared. The results showed that the hydraulic efficiency of the modified pump increased 7.4%. In addition, the pressure fluctuation and vibration intensity were also reduced compared with the original pump. This result shows that the geometric modification improves not only the hydraulic performance but also the structural properties.

scholarly journals Protein Denaturation Zero Entropy Temperature, and the Structure of Water Around Hydrophobic and Amphiphilic Solutes

2020 ◽  
Author(s):  
kazimieras Tamoliūnas ◽  
Nuno Galamba
Keyword(s):  
Protein Denaturation ◽  
Structural Information ◽  
Pure Water ◽  
Hydrophobic Effect ◽  
Hydrophobic Hydration ◽  
Bulk Water ◽  
Solvent Accessible Surface Area ◽  
Effect Of Temperature ◽  
Structure Of Water ◽  
Zero Entropy

The hydrophobic effect plays a key role in many chemical and biological processes, including protein folding. Nonetheless, a comprehensive picture of the effect of temperature on hydrophobic hydration and protein denaturation remains elusive. Here, we study the effect of temperature on the hydration of model hydrophobic and amphiphilic solutes through molecular dynamics aiming at getting in sight on the singular behavior of water concerning the zero entropy temperature TS and entropic convergence also observed upon protein denaturation. We show that, similar to hydrocarbons and proteins, polar amphiphilic solutes exhibit a TS, although strongly dependent upon solute-water interactions, opposite to hydrocarbons. Further, the temperature dependence of the hydration entropy normalized by the solvent accessible surface area is shown to be nearly solute size independent for hydrophobic but not for amphiphilic solutes, for similar reasons. These results are further discussed in the light of information theory (IT) and the structure of water around hydrophobic groups The latter shows that the tetrahedral enhancement of some water molecules around hydrophobic groups, associated with the reduction of water defects, leads to the strengthening of the weakest hydrogen bonds, relative to bulk water. However, a larger tetrahedrality is found in low density water populations, demonstrating that pure water has encoded structural information similar to that associated with hydrophobic hydration, consistent with IT assumptions. The source of the differences between Kauzmann's "hydrocarbon model" on protein denaturation and hydrophobic hydration is also discussed with relatively large amphiphilic hydrocarbons displaying a more similar behavior to globular proteins, than aliphatic hydrocarbons.<br>

An experimental performance comparison of Newtonian and non-Newtonian fluids on a centrifugal blood pump

2022 ◽  
pp. 095441192110576
Author(s):  
Ahmet Onder ◽  
Rafet Yapici ◽  
Omer Incebay
Keyword(s):  
Flow Rate ◽  
Rotational Speed ◽  
Performance Test ◽  
Newtonian Fluids ◽  
Friction Reduction ◽  
Blood Pump ◽  
Actual Performance ◽  
Centrifugal Blood Pump ◽  
Working Fluids ◽  
Pump Performance

The use of substitute fluid with similar rheological properties instead of blood is important due to ethical concerns and high blood volume consumption in pump performance test before clinical applications. The performance of a centrifugal blood pump with hydrodynamic journal bearing is experimentally tested using Newtonian 40% aqueous glycerin solution (GS) and non-Newtonian aqueous xanthan gum solution of 600 ppm (XGS) as working fluids. Experiments are performed at four different rotational speeds which are 2700, 3000, 3300, and 3600 rpm; experiments using GS reach between 8.5% and 37.2% higher head curve than experiments using the XGS for every rotational speed. It was observed that as the rotational speed and flow rate increase, the head curve difference between GS and XGS decreases. This result can be attributed to the friction reduction effect when using XGS in experiments at high rotation speed and high flow rate. Moreover, due to different fluid viscosities, differences in hydraulic efficiency were observed for both fluids. This study reveals that the use of Newtonian fluids as working fluids is not sufficient to determine the actual performance of a blood pump, and the performance effects of non-Newtonian fluids are remarkably important in pump performance optimizations.

scholarly journals Influence of clearance flow on disk friction loss in low specific speed hydraulic machines

2019 ◽  
Vol 240 ◽  
pp. 032043
Author(s):  
Ryutaro Ujiie ◽  
Asuma Ichinose ◽  
Yohei Nakamura ◽  
Kazuyoshi Miyagawa ◽  
Takeshi Sano
Keyword(s):  
Friction Loss ◽  
Hydraulic Machines ◽  
Clearance Flow ◽  
Disk Friction ◽  
Low Specific Speed ◽  
Specific Speed

Flow Behaviors of Commercial Food Thickeners Used for the Management of Dysphagia: Effect of Temperature

2012 ◽  
Vol 8 (2) ◽  
Author(s):  
Se-Ra Hong ◽  
Dong-Soo Sun ◽  
Whachun Yoo ◽  
Byoungseung Yoo
Keyword(s):  
Shear Stress ◽  
Yield Stress ◽  
Flow Behavior ◽  
Effect Of Temperature ◽  
Rheological Parameters ◽  
High Shear ◽  
Flow Properties ◽  
Different Temperatures ◽  
Management Of Dysphagia ◽  
Arrhenius Temperature

Gum-based food thickeners are widely used to care for patients with dysphagia in Korea. In this study, the flow properties of commercially available gum-based food thickeners marketed in Korea were determined as a function of temperature. The flow properties of thickeners were determined based on the rheological parameters of the power law and Casson models. Changes in shear stress with the rate of shear (1-100 s-1) at different temperatures (5, 20, 35, and 50 oC) were independent of the type of thickener. All thickeners had high shear-thinning behavior (n=0.08-0.18) with yield stress at the different temperatures tested. In general, apparent viscosity (na,50) values progressively decreased with an increase in temperature. In addition, the consistency index (K) and Casson yield stress (σoc) values did not change much upon an increase in temperature from 5 to 35 oC, except for sample B. In the temperature range of 5-50 oC, the thickeners followed an Arrhenius temperature relationship with a high determination coefficient (R2=0.93-0.97): activation energies (Ea) for the flow of thickeners were in the range of 2.44 - 10.7 kJ/mol. Rheological parameters demonstrated considerable differences in flow behavior between the different gum-based food thickeners, indicating that their flow properties are related to the type of thickener and the flow properties of gum.

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