Inlet Position Research Articles

Swirl-Bypass Nozzle for CO2 Two-Phase Ejectors: Numerical Design Exploration

In this work, a novel ejector design concept of a swirl-bypass nozzle is proposed to improve off-design performance of CO2 two-phase ejectors. The swirl-bypass nozzle allows part of the flow to bypass into the ejector mixing chamber to generate swirl. The design of such a device is investigated using a 3D multiphase CFD model. An extensive experimental test campaign is conducted to validate the baseline homogeneous equilibrium CFD model. The model’s prediction motive mass flow rate within 2–12% error and suction mass flow rate was predicted with 3–50% error. Based on the tested ejector geometry, simulations of different ejector swirl-bypass inlets are conducted. The results show that, for the current design, total entrainment of the ejector is reduced by 2–20% with the swirl-bypass inlet. The axial position of the bypass inlet plays a primary role in the bypass inlet flow rate, and, consequently, in suction flow reduction. This is found to be due to the bypass flow blocking off the suction mass flow rate, which has a net negative impact on performance. Finally, several design improvements to improve future designs are proposed.

Computational fluid dynamics predicts the nanoparticle transport in gas aggregation cluster sources

In a typical sputter-based gas aggregation cluster source (GAS), nanoparticles (NPs) are created from supersaturated vapours of the target material. The NPs then escape from the source with the expanding gas through an exit orifice. The carrier gas flow profile is one of the most critical parameters, which strongly affects the NP losses on the walls and determines the efficiency of the NP transport to the substrate. In this work, computational fluid dynamics (CFD) simulations are performed to understand the flow of the carrier gas inside the aggregation chamber. We focus on the impact of the inlet and outlet geometry on the carrier gas flow and, therefore, on the NP transportation. Two types of GAS with either a conventional planar magnetron or a cylindrical magnetron are considered. In the planar configuration, the working gas inlet is from behind the magnetron, and the gas flows around the target towards the orifice along the system axis, which may cause some vertices. The situation is even more critical for the cylindrical magnetron, where the gas inlet position and geometry have a drastic influence on the gas flow. Brownian diffusion is found to prevail for NPs smaller than 5 nm, regardless of the gas flow. This leads to their losses on the walls. Larger NPs experience a stronger drag force from the carrier gas flow, which should exceed 10 m s−1 to prevent loss of NPs on the walls and keep NP transport efficient. Therefore, the CFD simulations help to visualise the motion of the NPs and optimise the geometry of the GAS for future applications.

Optimization on Secondary Flow and Auxiliary Entrainment Inlets of an Ejector by Using Three-Dimensional Numerical Study.

In this paper, by using three-dimensional numerical simulations, the optimization of the cross-sectional area and angle of the secondary flow inlet is first conducted. Then, to further improve the ejector performance, an auxiliary entrainment is proposed and the optimization of the relative position, cross-sectional area and angle of the auxiliary entrainment inlet is accordingly performed by using three-dimensional methods. The results show that: (1) the performance of the ejector with the secondary flow in a vertical direction to the primary flow is slightly better than that in a parallel direction to the primary flow; (2) the effect of the cross-sectional area of the secondary flow has a relatively evident influence on ER, but its effect becomes ignored when the inlet area increases to a certain value; (3) the relative position and axial width of the auxiliary entrainment inlet are important factors influencing ejector performance, and after the optimization of these two geometries, the ejector ER can be increased by 97.7%; and (4) the optimization of the auxiliary entrainment inlet has a substantial effect on the ejector performance as compared to that of the secondary flow inlet. The novelty of this study is that the effect of an auxiliary entrainment on the ejector’s performance is identified by using a three-dimensional numerical simulation for the first time.

Cooling performance of battery pack as affected by inlet position and inlet air velocity in electric vehicle

Numerical simulation on the U-shaped channel with various inlet positions using air cooling is investigated to solve heat dissipation issue of battery pack in electric vehicle. The mechanism of the influences of inlet position and inlet air velocity on the cooling performance of battery pack is revealed. The results show that the maximum temperature of battery pack decreases by 4.17 K at inlet position of 30 mm compared with that of 20 mm due to the increase of airflow velocity in the second half of the battery pack caused by flow around effect. The maximum temperature of battery pack decreases by 8.5–18.5 K with increasing inlet air velocity from 2 m/s to 5 m/s. The cooling performance improves because of flow around effect and high convective heat transfer using reasonable matching between inlet position (10–30 mm) and inlet air velocity (3–6 m/s). This paper provides valuable guidelines for cooling design of battery pack in electric vehicle.

Computational Analysis of Polymer Melt Filling in a Medical Mold Cavity During the Injection Molding Process

This study describes the results of a mold filling simulation analysis of a medical syringe performed during the thermoplastic injection molding process, which was performed using a computational Fluid Dynamic Simulation (CFD) with the Volume of Fluid Method (VOF). ANSYS Fluent was used for analysis and data collection. Medical grade polypropylene (PP) is considered in this study. The studies consider physical parameters (such as inlet position and syringe thickness) of the injection molding process. The outlet vent must be placed as far away from the inlet as possible to root out entrapped air and allow the molten PP to occupy the mold cavity. The findings revealed that syringe thicknesses ranging from 0.75 mm to 1.00 mm resulted in increased flow velocity, shorter filling time, and faster flow front advancement.

Mathematical analysis of flow passing through a rectangular nozzle

Practically speaking, fluid flow in round and noncircular nozzle is a very regular occurrence. The cold and hot water used in our homes is delivered to us via pipes. Water is delivered throughout the city via large pipe networks. Large pipelines carry natural gas and oil hundreds of kilometres from one place to another. During the operation of an engine, cooling water is carried by hoses to the radiator’s pipes, in which it is cooled as it travels. Experimentally, we detected the results of the model because there is no restriction on the application of experimental research to a certain sector or kind of concept. It may be used for a broad range of events and circumstances. Under parabolic velocity conditions, fluid (Water Pr 6.9) flows from the inlet position. The top and bottom walls of the rectangular nozzle are also moving at the same velocity as they are at the inlet position. Due to the movement of the walls, fluid is compressed in the particular region and also exhibits the same parabolic behavior. The solution of the coupled equations is determined by using the Finite Volume Method (FVM). When partial differential equations are expressed as algebraic equations, the FVM may be used to evaluate them. It can be used to evaluate elliptic, parabolic, and hyperbolic partial differential equations. Using FVM, it is necessary to know the values (and derivatives) of multiple variables at the cell faces, when the values (and derivatives) of these variables are only known at the cell centres. When determining these variables for convective terms, it is common to take the direction of the flow into consideration. The numerical results of the velocity and the pressure could be seen in the rectangular nozzle.

Study on Microscopic Water Flooding in Porous Carbonate Reservoirs by Numerical Simulation

The study on the flow behaviors of oil and water two phases in porous media and their influencing factor is very important to adjust the porous carbonate reservoir development strategy and enhance the oil recovery. Based on the CT (computed tomography) scanning of real carbonate reservoir core sample, the micropore structure was reconstructed, and the effects of different factors (injection rate, oil-to-water viscosity ratio, and contact angle) and secondary development methods (higher injection rate and water displacement direction optimization) on the flow behavior of oil and water two phases were explored by numerical simulation in this paper. It is found from the study that the pores in the porous carbonate reservoirs have good structural connectivity. During the displacement process, the oil-water interface mainly resides at the pore throat junction with a large change of pore size, and the Haines jumps exist in the oil-water movement; the areal sweep efficiency of the water phase is jointly affected by the viscosity effect, interfacial tension, pore structure, and injection rate. Under the minimum injection rate and oil-to-water viscosity ratio, the maximum oil recovery can be obtained, and the oil recovery is 52.62% and 57.01%, respectively. The recovery efficiency and swept area are better in a water-wet system than oil-wet system. During the secondary development, the remaining oil is hardly displaced even with the injection rate increased by a factor of 50, and it shows improvement after 250 times of initial injection rate. Changing the position of water inlet and the produced fluid outlet results in better recovery since the remaining oil near the new inlet and outlet can be effectively produced.

Performance analysis of auxiliary entrainment ejector used in multi-evaporator refrigeration system

• Effect of diffuser angle on auxuiliary ejector performance is identified. • Effect of diffuser angle on auxiliary inlet position, angle and, ER is investigated. • An optimal parameters (θ = 4°, LR = 1.9, and γ = 45°) of the new-type ejector exists. • An optimal operating scheme exists under different evaporating temperatures. In this paper, a numerical method is used to maximize the performance of an auxiliary entrainment ejector used in multi-evaporator refrigeration system developed for refrigerated trucks in tropical and humid climates. The Computational Fluid Dynamics model based on the previous study is developed to discuss the effects of key design parameters of an auxiliary entrainment ejector. The simulation model is validated against experimental data of an R134a test rig. The numerical models agree fairly well with the experiments. In order to maximize the efficiency of the auxiliary inlet, the diffuser angle is considered critically. The influence of diffuser angle on the optimal position and angle of the auxiliary inlet is then discussed. As well, the effect of secondary flow and auxiliary flow at varying temperatures on the efficiency of auxiliary entrainment ejector is analyzed. The main results are given as follows: (1) optimal auxiliary inlet position as well as angle and entrainment ratio depend on diffuser angle, and optimum parameters combination (length ratio of 1.9, inlet angle of 45°, and diffuser angle of 4°) of the new-type ejector exists; (2) with the secondary flow working temperature of −10 °C, the entrainment ratio reaches its maximum value of 0.658, and the corresponding entrainment ratio at secondary inlet is 2.60; (3) the auxiliary entrainment ejector can only function if the auxiliary flow working temperature is between −30 °C to −22 °C; (4) it is best to connect the secondary inlet to the medium temperature evaporator, with the auxiliary inlet to the low temperature evaporator, when using the secondary and auxiliary inlet connections to separate evaporators with varied operating temperatures.

Effect of precursor gas inlet position relative to hot wire cells in HWC-IP-PECVD systems for low-temperature graphene growth

ABSTRACT Graphene growth at low temperatures was investigated by integrating a hot wire cell made from coil-shaped tungsten into a plasma-enhanced chemical vapour deposition (PECVD) system. It was found that the suitable position of the hot wire was such that the precursor gas comes out of the end of the gas pipeline and directly flows into the hot wire along its axis. This position puts the gas pipeline outside of plasma area, yielding uninterrupted plasma. The obtained films, which were grown at a low temperature between 290 °C to 300 °C, showed the presence of sharp G band in Raman spectra, indicating the presence of graphitic carbon structure and was confirmed by X-Ray Diffraction data. Also, sharp D band was detected in Raman spectra, which indicated that the film contains many defects. In addition to the nature of ion bombardment in the PECVD process, the defects were due to the addition of O-H functional groups and the formation of sp3 C-H in the samples, as shown in the FTIR spectra. Due to these defects, the Raman spectra obtained of the films showed very weak 2D bands, suggesting that our samples were in the form of graphene oxide.

A review of the research status of scroll expander

In order to solve the problem of energy crisis and take the road of sustainable development, the development of renewable energy and recycling of low-grade waste heat have attracted more and more attention. As a new type of volumetric energy conversion device, scroll expander is wi dely used in Organic Rankine Cycle (ORC) waste heat recovery, because of its advantages such as small size and so on. Scroll profile is one of the main factors affecting scroll expander performance. Compared with the traditional constant section scroll profile with same suction volume, volume ratio and shell size, the new type of variable section scroll profile could reduce scroll tooth height, better mechanical properties and improve efficiency, therefore making it more suitable for working under complex operating conditions. In order to reduce the head invasion rate, airflow friction factor, the power loss at the air inlet, and improve the pneumatic power conversion efficiency, a new head correction method is proposed. Although R123, R134 and R245 are the most commonly used working medium in scroll fluid machinery, the selection of working medium in scroll expander is still a key problem. The overall performance of the scroll expander can be improved by designing different inlet shapes and positions or double-symmetrical exhaust ports. The radial leakage caused by axial clearance of scroll expander can be improved by developing new scroll profile to reduce the length of radial leakage line and optimizing the design of scroll top sealing mechanism. The tangential leakage caused by radial clearance can be improved by enhancing the manufacturing precision and installation accuracy of scroll plate and designing the radial variable mechanism. At present, fewer research has been carried out on the leakage of scroll expander. Therefore reducing the leakage loss to improve the performance of scroll expander is of great significance in the future research.

A Geometry Optimization of Spiral Grain Selector During Directional Solidification of Nickel‐Based Superalloy

A spiral grain selector with excellent geometric parameters can ensure qualified single-crystal (SX) is selected while decreasing lesser thermal gradient (G) during casting of SX nickel-based superalloy . In this paper, three configurations of spiral grain selectors with different height of starter block (H = 18, 25, 35 mm) and same spiral passage are adopted. Based on the quantitative analysis of orientation distribution of grains in starter block, it is found that the deviation of <001> oriented grains in the projection zone of spiral passage inlet (circle with a diameter of 4 mm) are smaller than grains of overall cross-section (circle with a diameter of 10 mm), which verify that starter block with smaller diameter have better optimization effect of grain orientation. Moreover, the average deviation of <001> oriented grains decreases to a range of 6.6–10.8° when the height of starter block is 18–27 mm, and SX selection is completed on the position of less than half turn in spiral passage regardless of the number of grains in the inlet position. Finally, a modified spiral grain selector is designed from the perspective of practical production, of which total height is reduced by at least 15 mm, and can decrease lesser G at some extent during casting .

Efficient heat extraction from the storage zone of solar pond by structurally improved spiral pipes; numerical simulation/experimental validation

Various semi-O/O-shape dimple patterns were applied on the flat spiral pipes as a regional contorting policy. In this method only the critical regions that may cause significant effect on the improvement of the hydrothermal performance can be subjected to structural modification. The all-round geometrical modifications causes excessive pressure drop while this method can solve this problem to some extent. Archimedean spiral geometry of spiral pipe makes uneven hydraulic-thermal characteristics along the pipe, so regional geometrical modification allows to pinpoint the optimal model. Using semi-O or O-shape dimples or combination of both on the inner or outer (or on both wall) leads to obtain unique cases. Constant wall temperature of 360 K was applied for the outer wall of all cases to evaluate the strength of each case based on heat extraction potential. The effect of arrangement, position, and type of dimples was taken under consideration. To get elaborate comprehension about the frictional and thermal behavior of each design, several criteria including Nusselt number (Nu), friction factor (f), thermal performance factor (TPF), temperature efficiency (ɛ), and J-factor were employed. Moreover, the effect of flow inlet position on the said was explored. All investigations were done in the flow velocity range of 0.1–0.6 m/s. The findings showed that case “c” (spiral pipe with dimples on the inner wall) has the highest heat extraction potential and improves heat extraction by 27% compared to the smooth spiral pipe. Also, case “c” makes the lowest pressure drop. Hence, by owning said two positive features case “c” provided the highest TPF, ɛ, and J-factor. Heat transfer improves when flow enters from the innermost turn.

Effect of Vibration and Noise Measuring Points Distribution on the Sensitivity of Pump Cavitation Diagnosis

Cavitation is an essential factor in the deterioration of the hydraulic performance of centrifugal pumps. The study of cavitation fault diagnosis can help avoid or reduce the damage it causes. The vibration and noise analysis method can predict the incipient cavitation more accurately. In order to improve the accuracy of cavitation fault diagnosis, this paper studies the distribution of vibration and noise measuring points for centrifugal pump cavitation diagnosis. The research object is a centrifugal pump with an inducer and splitter blades. Vibration acceleration sensors and hydrophones were used to collect structural vibration and liquid-borne noise signals at different positions of the pump unit. Root-mean-square (RMS) and fast Fourier transform (FFT) methods were used to construct spectrums of vibration and noise signals with different NPSH and compare the sensitivity of different measuring points to the inception and development of cavitation. In addition, the SST k-ω turbulence model and Zwart cavitation model were used to study the cavitation volume distribution in the pump under different cavitation stages. By setting monitoring points at the impeller outlet, the frequency domain signal distribution of pressure pulsation was studied. The results show that the vibration acceleration measuring points at the pump inlet flange and pump axial position, and liquid-borne noise measuring point at the inlet position, are more sensitive to the diagnosis of cavitation fault. Motor current is also the basis for judging the inception of cavitation. Moreover, as the cavitation intensifies, the dominant frequency signal of the pressure pulsation in the pump is partially shifted.

Analysis on Flow and Temperature Field of High-Power Magnetorheological Fluid Transmission Device

Aiming to solve the problem of high-power magnetorheological fluid transmission heat dissipation, a new type of magnetorheological fluid drive disk is designed. The characteristics of the flow field and temperature field of high power MR fluid transmission devices are analyzed. Meanwhile, the influence of factors, such as rotating speed, inlet velocity, inlet position, diameter and number of magnetic columns, on the flow field are also investigated. Furthermore, the distribution characteristics of the ultimate slip power and the transient temperature field are obtained. The experimental platform of an MR fluid transmission device was established, and the torque transfer performance and heat dissipation performance were tested. The experimental results show that the device has good heat dissipation performance and can transfer high-power torque.

Dynamic two-phase flow behaviors in permeable network integrated with microchannel

The performance of a direct methanol fuel cell greatly depends on the two-phase flow behaviors in the anode gas diffusion layer and flow channel. However, complex and opaque nature of gas diffusion layer poses a grand challenge for deep insight into the two-phase flow behaviors. Therefore, a homogeneous permeable network integrated with a microchannel was put forward to simulate the anode gas diffusion layer and microchannel in the present study, by which the dynamic two-phase flow behaviors were visually studied with the help of adaptive image enhancement method. The influence of the position and number of the gas inlet, and the gas and liquid flow rates on the two-phase flow behavior were analyzed. The results showed that the liquid saturation decreased and the number of the position for bubble generation increased with increasing the gas flow rate in case the gas was suppled from only one gas supply orifice. When two gas supply orifices simultaneously supplied the gas, the liquid saturation was between the cases using a single one gas supply orifice. For given liquid and gas flow rates of 0.1 mL/min and 0.5 mL/min, the liquid saturation was about 84%, which was between 83% and 92% for the single-one cases. Besides, the two-phase flow exhibited strong periodicity at low gas flow rates. The obtained results provide a deep understanding of the two-phase flow behaviors in such a simulated structure, helping better design and operation of direct methanol fuel cells.

Investigation of displacement ventilation performance under various room configurations using computational fluid dynamics simulation

The performance of a ventilation system affects air quality, thermal comfort, and energy consumption in indoor environments. To evaluate the performance of displacement ventilation under various room configurations, steady Reynolds Averaged Navier–Stokes (RANS) Computational Fluid Dynamics (CFD) simulations were used. The CFD model was validated using measurements of a full-scale test room. The age of air concept was used to evaluate the ventilation performance regarding indoor air quality. The PD index was used to control the case studies for draft risk. Twelve cases with different configurations were systematically studied and compared with the reference case. The configurations included plan aspect ratio, exhaust opening position, inlet position and geometry, and internal heat gains. The results showed that the overall ventilation performance of a room is less sensitive to room configurations compared with local ventilation performance around the occupants. However, almost in all cases, the occupants were exposed to better-than-average air quality in most cases. The results also indicated that when internal heat gains are small, displacement ventilation should be used with caution. Practical application: Any HVAC system design is based on assumptions made for ventilation performance. Comprehensive knowledge of the influential factors is critical for an efficient design. Regarding the architecture and interior design, the architects are also involved in the ventilation systems since they have an axial role in decision making for room configuration, including but not limited to room geometry, the position of inlet and outlet air terminals, and heat/pollutant sources. Consequently, the impact of room configuration on ventilation performance is of practical importance in the architecture, engineering, and construction industry.

Numerical investigations on temperature and flow field performance of octagonal culture tank under different physical parameters for fish growth based on computational fluid dynamics

• Both velocity and temperature fields within octagonal rearing tank jointly solved by theory and CFD. • Effects of seven different physical parameters of rearing tank numerically studied. • Average and STD of temperature and velocity for seven horizontal planes used quantitatively to evaluate effects. • Completely mixing flow field & obvious secondary flow existing with increasing inlet velocity by 0.5 m/s. Both velocity and temperature field performance of fish octagonal rearing tank played an important role in the recirculating aquaculture system (RAS). To maintain the water temperature and velocity distributions in the optimal growth conditions for fish, particularly juvenile fish, is a great challenge. To solve this problem, computational fluid dynamics (CFD) was employed to investigate the dynamic temperature and velocity fields in the juvenile fish rearing tank. In this study, a full-scale CFD benchmark model of octagonal rearing tank based on real situation has been firstly validated by comparing on-site measurement data with simulation results. Following that, the effects of several different physical parameters of rearing tank, including inlet flow temperature and velocity, inlet position on the culturing tank wall, water flow inlet diameter and ambient air temperature around RAS on both velocity and temperature field performance were numerically studied, respectively. Meanwhile, average temperature and velocity as well as standard deviation (STD) of temperature and velocity for seven different horizontal plane have been employed to quantitatively evaluate the effects of aforementioned physical parameters on velocity and temperature field performance. Some key findings are found that 1) Benchmark scenario with inlet temperature of 25 °C and inlet velocity of 0.1 m/s could establish dynamic homogeneous temperature and velocity fields, which is suitable for fish growth; 2) Increasing inlet temperature will increase STD of horizontal plane temperature and achieve a maximum approximately 55% at the height of inlet position with inlet temperature of 28 °C; 3) As the inlet diameter increases up to 101.6 mm with inlet velocity 0.1 m/s, which is not only beneficial to clean the solid waste; but also could provide a suitable juvenile fish growth conditions.

Numerical Study on the Effect of Nozzle Incident Angle on the Overall Performance of Gas Wave Refrigerator

Gas wave refrigerator (GWR) is a new type of refrigeration machinery that uses pressure waves to transfer energy between gases. In this paper, the flow characteristics and refrigeration mechanism in the wave rotor are numerically simulated. The nozzle angle is introduced to improve the overall refrigeration performance and expand the efficient operating range of the equipment. After verifying the model and method, the potential mechanism of refrigeration loss in the oscillating tube and the effect of loss on refrigeration efficiency are discussed in detail. Then the influence of incident angle on flow loss, refrigeration temperature drop, and power consumption are discussed. The association model of velocity development pattern and the maintenance of pressure performance at the inlet position of the oscillating tube is established during the high-pressure gas incident. The obtained numerical results show that flow loss and shock intensity loss are the main energy loss factors in the wave rotor. The incident angle determines the loss of the refrigeration process. The optimal incident angle of the device at the working point is obtained. The "balance" of velocity distribution in the oscillating tube can effectively reduce vortex loss. Arranging nozzles in the same rotation direction as the wave rotor can reduce work consumption, and the variation law is approximately negative linear correlation. Furthermore, based on the current simulation results, a set of nozzle design methods are obtained. It laid the foundation for the subsequent experimental research and optimization of GWR equipped with adaptive nozzles.

Study on the mass and heat transfer characteristics of the drying process of spent nuclear fuel cladding with nitrogen assisted

The spent nuclear fuel cladding needs to be cooled in water for a long time before being compressed. The water attached to the solid must be dried before compressing the spent nuclear fuel cladding. In this paper, based on the heat and mass transfer process inside the porous medium, a coupled heat and mass transfer model for the nitrogen-assisted drying of the waste cladding porous medium is established. The influence of nitrogen flow rate, temperature and inlet position on the heat and mass transfer characteristics of the porous medium in the nitrogen-assisted drying of waste cladding is analyzed. The results show that the calculated results of the model are in good agreement with the experimental results. According to the temperature change on the surface of the waste cladding, the gas-assisted drying process can be divided into three stages: the initial stage of drying, the accelerated drying stage and the latter stage of drying. In addition, the nitrogen flow rate has the greatest impact on the accelerated drying stage in the drying process, and the change of the nitrogen flow rate only changes the heat transfer rate between the liquid and solid phases. Nitrogen temperature affects the drying time by changing the heat transfer coefficient between the gas and liquid phases during the drying process. The inlet position of nitrogen affects the drying time by changing the convection effect between the gas and liquid phases in the drying process. The above research provides reference for the study of the heat and mass transfer characteristics and the mechanism of the drying process in the process of nuclear fuel solid waste treatment. It can also provide an important reference for the application research of key equipment in the reprocessing of spent fuel in nuclear power plants.

Simulasi Pengaruh Ketebalan Elektroda Terhadap Potensial Elektrolit dan Molaritas Spesies Vanadium Redox Flow Battery (VRFB)

Vanadium Redox Flow Battery (VRFB) is a relative new type of secondary battery that has ability as Energy Storage System (ESS) for renewable energy power plants such as solar cell. 2D VRFB single cell was modeled using COMSOL Multiphysics software and simulated numerically by using Nernst-Planck, secondary current distribution, tertiary current distribution and Buttler-Volmer principle. Simulation was conducted at 293,15 K, with electrode thickness variations of 1 mm (L1), 2 mm (L2), 3 mm (L3), 4 mm (L4) and 5 mm (L5). According to the simulation results, it is known that electrolyte potential in negative electrode is higher than positive electrode and the distribution is tend to decrease for all variations. Surface concentration near collector is dominant during charging compare inlet position and the reverse phenomenon occur during discharging process. VRFB L1 show weak performance and VRFB L2 show the best performance in term of electrolyte potential and species molarity in the electrode surface.