Longitudinal Baffles Research Articles

The suppression effect of a vertical baffle on three-dimensional swirling and chaotic sloshing in a laterally excited square-based tank

In order to systematically investigate the suppression effect of a vertical baffle on three-dimensional (3D) swirling and chaotic sloshing in a square-based tank subjected to horizontal harmonic excitation, hundreds of experiments are conducted in a clean tank and baffled tanks with three different configurations. Specifically, the vertical baffle is mounted on the tank bottom parallel to the longitudinal direction, the transverse direction, or the diagonal direction. This experimental work finds that there are four sloshing wave regimes in a clean tank—planar, square-like, swirling, and chaotic—which can be described by the asymptotic multimodal theory. Furthermore, there are only two wave regimes in a longitudinal-baffle tank, the planar and swirling regimes, and the occurrence of swirling requires that the excitation amplitude is sufficiently large. It is confirmed that the longitudinal baffle has a significant suppression effect on the swirling and chaotic motions of the sloshing waves, even though it is parallel to the direction of tank movement. Furthermore, the suppression effect of the diagonal baffle is similar to but somewhat smaller than that of the longitudinal baffle. However, when the transverse baffle is mounted on the bottom of the tank, it is difficult to excite the rotation of the sloshing wave. Therefore, the suppression effect of a bottom-mounted baffle depends largely on the included angle between the vertical baffle and the tank movement direction.

Effect of the baffle's type on thermal performance of solar air heaters

To determine the optimal baffle's type (longitudinal and transverse baffles) and the number of baffles, two computational fluid dynamics (CFD) models for solar air heaters (SAHs) were developed by using "ANSYS Fluent" software. The computational results closely aligned with the experimental data. As the width of the air channel in SAHs with transverse baffles was narrower than in those with longitudinal baffles under the same number of baffles, the heat transfer coefficient of SAHs with transverse baffles was greater than those with longitudinal baffles. Thus, for the airflow rate (m˙) range of 0.013 kg s−1 to 0.078 kg s−1, SAHs with transverse baffles exhibited 2.34 %–6.97 % higher collection efficiency compared to those with longitudinal baffles. An analysis of the impact of the number of transverse baffles (N) on the flow and heat transfer characteristics in SAHs revealed that both the size and intensity of the vortex zones increased with an increase in N, thereby influencing the heat transfer between the air and the absorber plate. Specifically, among the studied values of N (2, 4, 6, and 8), at = 0.026 kg s−1, N = 4 achieved the peak effective efficiency at 54.32 %. Conversely, for m˙ = 0.039 kg s−1, 0.052 kg s−1, 0.065 kg s−1, and 0.078 kg s−1, the highest effective efficiency was observed at N = 6, with values of 60.03 %, 63.78 %, 64.39 %, and 64.38 %, respectively.

Dynamics of tank trucks with barters for transportation of viscous liquids

The article deals with the issues related to the safety of transportation of viscous liquids in tanks on motor transport. The special attention in the process of research is paid to the forms of partitions and their influence on the slippage of liquid and, accordingly, on the load transfer in the roll and pitch planes. On the basis of the obtained results, an optimized design of longitudinal baffles is proposed, which allows to provide the reduction of transverse force and roll moment. Keywords tank, partition, roll, viscous fluid, pitching

An Analysis of Fuel Oil Sloshing in Partially Filled Cargo Tanker Trucks under Cornering Conditions Using Various Baffle Systems

Ethiopia imports all fuel and crude oils from abroad at high cost, and transportation of these fluids has been carried out by using various capacity of road transportation heavy-duty truck vehicle. Most tanker truck accidents happen during turning because of the fluid splashing in partially loaded tanks and of the uniqueness of the carrying liquids. This is a result of the fact that current baffle configurations are effective at reducing sloshing when braking or accelerating but ineffective at doing so when turning. Consequently, the primary goal of this thesis work is to investigate how different baffle systems affect lateral sloshing reduction. In this work, the optimal baffle configuration and its arrangements for modified oval tanks at 50% and 80% fill levels were tried, and the dynamic analysis of tanker trucks was researched. The tanker truck and baffle system are designed in CATIA V5 for the numerical analysis, and the CFD study is completed in ANSYS Fluent 2021. R2 and the dynamic analysis are carried out in ANSYS LS-DYNA to study the stability of truck. The computational simulation is carried out as a tank with eight types of baffle systems such as existing baffles (TB), TB with BMLB, UMLB, CLB, 2HLB, 2VHLB, 4HLB, and 4VHLB with similar meshing resolution, similar turbulence modeling, similar boundary conditions, and also similar solution strategies. Transverse baffles with bottom-mounted four holes longitudinal baffle with hole-varying position (4VHLB) are discovered to be the best baffle type after evaluating all baffle designs. This suggests that the quantity of sloshing is reduced as the number of holes with small diameters increases. Maximum lateral force and roll moment are reduced by the most, by 47.76% and 58.66%, respectively, at 50% fill level and by 58.08% and 22.52%, at 80% fill level. Consequently, the case tanker truck’s use of this revised design baffle will be crucial for enhancing rollover stability while cornering.

COMPUTATIONAL FLUID DYNAMIC (CFD) SIMULATION ON REDESIGN BAFFLES OF YOGYAKARTA INTERNATIONAL AIRPORT TRAIN FUEL TANK

The tank is one of the most important components in the train which serves as a place to store train fuel. However, so far the tank has been a component that has gone unnoticed, even though there is a very important issue to consider, namely how the fluid moves in the tank due to the movement of the train while moving. The free movement of the liquid fluid in a tank is called sloshing. Sloshing in the tank can be reduced by adding anti-sloshing in the tank called component baffles. So it is necessary to simulate the sloshing due to the movement of the train by taking into account the value of the vehicle subsystem of the train and the variation of the baffles design used. There are several models of fuel tank baffles used in this study, namely fuel tanks without baffles; longitudinal baffles (2) lateral baffles (1) - existing baffles; longitudinal baffles (3) lateral baffles (3) with circular perforations; and horizontal (2) lateral (1) baffles with circular perforations. This study aims to provide a baffles design configuration that can optimally reduce the sloshing that occurs. So in this study, a simulation of the fuel tank with variations in the baffles was carried out by applying the Computational Fluid Dynamic (CFD) method. From the simulation results, it is concluded that the configuration of longitudinal baffles (3) lateral baffles (3) has the best performance with an effectiveness of 34.33% in reducing sloshing.

CFD study of a dual-passage solar collector with longitudinal and transverse baffles for enhanced thermal performance

The focus of this research is to investigate the heat transfer performance of a solar flat plate collector by utilizing CFD simulation. To accomplish this, a 3-D model of the collector with an air inlet was created using ANSYS Workbench, and the grid was generated through ANSYS ICEM, ANSYS FLUENT, and ANSYS CFX were then used to obtain comprehensive results. The primary objective of this study is to enhance the efficiency of the solar collector by introducing two fluid-flow paths and comparing the results with those reported in existing literature. These findings will aid in the development of advanced solar collector designs and promote sustainable use of solar energy. Furthermore, the insights gained from this study may inspire further research in the renewable energy technology field. Overall, this re-search explores the potential of improving the performance of solar flat plate collectors and sheds light on how the use of CFD simulation can facilitate the development of innovative and sustainable energy solutions.

Analysis and hydraulic improvement of a maturation pond using Computational Fluid Dynamics

Especially in small communities, little attention is paid to the hydraulic characteristics of wastewater treatment systems. Motivated by this problem, and using the ANSYS fluid dynamics software, the hydrodynamic evaluation of the residual water flow in a rural plant maturation pond was carried out. For the stationary modeling of the velocity and turbulence fields, the standard k-ε model was used; and for transient modeling of virtual tracer transport, the species transport model without chemical reaction was used. Subsequently, the analysis of the distribution of retention times was carried out, in order to obtain the flow patterns that govern the hydrodynamics of the pond. The results revealed the presence of hydraulic short circuits, stagnant zones, and recirculations, due to design deficiencies and operating conditions over the years. Given this situation, and by bibliographic recommendation, new modified geometries were proposed with longitudinal and transverse baffles at 70 and 90% in relation to the width and length of the pond. As a result, the hydraulic characteristics improved notably in all cases; however, the models configured at 90% achieved higher efficiency.

Study on Behavior of the Heat Exchanger with Conically-Corrugated Tubes and HDD Baffles

Baffles with holes in different diameters (or HDD baffles) and conically-corrugated tubes are respectively longitudinal flow baffle and high-efficiency heat exchange tubes proposed by the author. In this paper, vibrations of tube bundles with HDD baffles and fluid flow as well as heat transfer inside conically-corrugated tubes were numerically simulated, and the heat exchanger with conically-corrugated tubes and HDD baffles was tested for the heat transfer efficiency. It is found that compared with the traditional segmental baffles, tube bundle vibrations in heat exchangers, if using the HDD baffles, can be significantly reduced. Regarding heat transfer efficiency, conically-corrugated tubes are much better than smooth tubes and even better than other high-efficiency heat transfer tubes. Compared with the traditional heat exchangers, heat exchangers constructed with conically-corrugated tubes and the HDD baffles can provide better heat transfer efficiency and less tube bundle vibration.

Performance enhancement of a baffle-type solar heat collector through CFD simulation study

The application of solar energy conversion has been extensively utilized as an alternative energy source to generate heat. This approach would be a step towards sustainable energy development particularly in the manufacturing industry with energy-intensive process. In this paper, thermal enhancement on the key component of a solar energy device – solar heat collector (SHC), has been evaluated by proposing a baffle-type SHC with various geometric configuration in the air passage namely longitudinal baffle and transversal baffle. The performance of SHC is evaluated in term of efficiency, temperature distribution, airflow pattern and pressure drop across the collector outlet through Computational Fluid Dynamic (CFD) investigation. It was observed that maximum collector efficiency was achieved in the Longitudinal-SHC (L-SHC), with a value of 46.2 % followed by Transversal-SHC (T-SHC) and without baffles. Maximum drying temperature at the collector outlet was 332.43 K for L-SHC, showing temperature rise of 0.35 % and 4.21 % from T-SHC and without baffles, respectively. The velocity vector indicated that turbulence flow was created in the T-SHC which consequently improved the heat transfer. Whereas in L-SHC, enhancement was achieved through the prolonged heating time in the passage. Considering the thermo-hydraulic performance factor evaluated, these enhancement features had diminished the effect of pressure drop.

VENTILATION METHOD FOR LONG BLIND DRIFTS WITH LONGITUDINAL BAFFLES

The study focuses on aerodynamic processes in long blind drifts ventilated owing to ejection effect generated thanks to construction of longitudinal baffles. The numerical modeling of air distribution at the junction with a blind drift with a longitudinal baffle is implemented in ANSYS. The change in the local air drag in case of forward and reverse air flows is shown. The velocity variation in air flow in a long blind drift with adjustment of ventilation efficiency by alteration of the opening angle of the longitudinal baffle flap is estimated. Based on the obtained results, the author shows that construction of longitudinal baffles allows efficient ventilation in long blind drifts owing to the ejection effect, without forced ventilation arrangement.

Numerical study of the thermo-energy of a tubular heat exchanger with longitudinal baffles

The work undertaken in this paper presents a computational study of the flow and heat transfer characteristics in a tubular heat exchanger with longitudinal baffles attached to its inner wall, which is maintained at a constant temperature Tw = 343 k. This study is carried out for a Reynolds number, Re ranging from 2 × 104 to 3 × 104, and was devoted first to the case of a smooth tube (without baffles), then to the case of a tube provided with longitudinal baffles of rectangular cross-section, and finally to the case of a tube provided with longitudinal baffles of triangular cross-section. The system of equations governing the thermohydraulic phenomenon consists of the continuity equation (for mass conservation), the Navier-Stokes equations (for momentum conservation), and the first principle equation (for energy conservation). The system of equations thus formulated is a hyperbolic system, which has been solved numerically over the entire domain, using the finite volume approach for its discretization, and the two-equation model (K-ε) for the modeling of turbulence terms. The SIMPLE algorithm is thus used to overcome the problem of velocity–pressure coupling. To meet the needs of aerothermal users. The two fields, thermal and aerodynamic, were analyzed, the friction factor, the Nusselt number, and the thermal efficiency. Finally, the study undertaken was finalized by comparative analysis to identify the relevant parameters in the aerothermal phenomenon and deduce the optimal form to be proposed to aerothermal energy users. The results obtained show that the longitudinal inclusion of the rectangular section baffles improves the thermal performance by 32.37% for the triangular section, and by 44.37% for the case of rectangular section baffles.

Effect of the inner-surface baffles on the tangential acoustic mode in the cylindrical combustor

Abstract The combustion instability in a propulsion system is a ubiquitous problem. The radial baffles usually installed on the injector faceplate eliminate the combustion instability (acoustic pressure oscillation) in the propulsion system. In this article, the longitudinal baffles are installed on the inner surface of the combustor wall to control the combustion instabilities. The first-order and second-order tangential modes are induced in the experiments. The effects of the parameters of the baffle on the acoustic pressure oscillation in the cylindrical combustor are investigated. The effect of the combustor nozzle on the tangential modes has been systematically investigated. It is concluded that the eigen-frequency and amplitude of the first-order tangential mode decline with the increase in the longitudinal baffle number and height. For the second-order tangential mode, the eigen-frequency and amplitude monotonically increase until a maximum value (four baffles), subsequently decrease with the increase in the baffle number and height. The combustor without the nozzle obtains a lower frequency than that with the nozzle, especially for the low baffle height in the combustor.

Stratification and equalization cycles in shallow maturation ponds with different operational configurations and at different periods of the year

Abstract This study aimed at evaluating the occurrence of stratification/equalization cycles in two full-scale shallow maturation ponds in Brazil, with different operational configurations and different periods of the year, through monitoring of temperature and other constituents in the vertical profile of the ponds. The study comprised two operational phases: one phase in which both ponds had no baffles and operated in parallel (one pond had sludge accumulated on the bottom while the other did not); and another phase in which the ponds operated in series, the first pond without baffles and with accumulated sludge on the bottom while the second pond had two longitudinal baffles, a shallower depth and no accumulated sludge. Overall, there were systematic daily periodic events of thermal stratification followed by temperature equalization and vertical mixing in both ponds and operating phases. Vertical temperature gradients were predominantly in the 0–7 °C m−1 range. Statistical tests showed a significant positive correlation between the thermal gradient in the pond and air temperature, but not between the thermal gradient and wind speed. Data suggested that ponds remained 56% of the time under thermal stratification and 44% in vertical mixing. The data also highlighted the importance of sludge in the thermal balance of ponds.

Enhancement of convective heat transfer in smooth air channels with wall-mounted obstacles in the flow path

The topic is of paramount importance. Heating, cooling, or solar air ducts are used in several sectors and in very diverse fields. The improvement in their performance has been and is still of major concern to theorists and practitioners. The issue of exchanging heat between fluid and the heated surfaces within a smooth air channel relies mainly on the value of the heat transfer coefficient. This coefficient is a mine of factors that affect the heat exchange between working fluid and heated walls. Therefore, it is an ambitious attempt to work on such a topic. Obstacles, such as staggered or in-line, transverse, or longitudinal baffles, fins, or ribs have long been utilized in several thermal systems like shell-and-tube heat exchangers with segmental baffles, compact heat exchangers, flat-plate solar air collectors, microelectronics, and various other industrial applications, because of their high thermal loads and reduced structural parameters. The channels, through which the cooling or heating fluid is supplied, are generally mounted with several obstacles in order to increase the cooling or heating level. This configuration is mostly used in designing heat exchangers and solar air collectors. Through this contribution, we present a comprehensive literature review of the various heat transfer strategies used to improve the performance of smooth air channels (SACs). Various research works were made on (SACs) either numerical or experimental in order to improve their performance. Different models and configurations of obstacles are reviewed and discussed, including attached, semiattached, or detached; parallel, orthogonal or inclined; solid, perforated, or porous; and simple, corrugated, or shaped, of various sizes, positions, attack angles, perforations, porosities, arrangements, and orientations. In these studies, the obstacles are principally used to change the direction of the flow field, to modify the distribution of the local heat transfer coefficient, and also to increase the turbulence levels, thus resulting in larger heat transfer between the fluid and the heated walls.

Characteristic of a multi-pass membrane separator for hydrogen separation through self-supported Pd[sbnd]Ag membranes

Dense PdAg membranes have shown immense potential to achieve high hydrogen purity required for proton exchange membrane (PEM) fuel cell. However, high hydrogen recovery and flux at lower transmembrane partial pressure is still a concern. In current study self-supported dense PdAg membranes were used to study the hydrogen recovery in a multi-pass membrane separator. Performance of a single and four collective membranes are tested in a single (without baffle) and multi-pass (with longitudinal baffles) membrane separator. Further, array of membrane configurations were tested experimentally by using longitudinal baffles and placing membranes at different locations. The hydrogen recovery for each configuration was measured experimentally. Experiments were performed using binary gas mixture 50H2:50N2 (v/v) at 3 bar pressure, 673 K temperature and gas-hourly space velocity (GHSV) 43 h−1. The best assembly was further tested with typical methanol reformate gas composition by using simulated gas mixture of 50H2:30N2:18CO2:2CO (v/v) at same operating condition. Numerical simulations were performed by using commercial software ANSYS 14.5 to understand the flow dynamics inside the separator with and without baffle. The results demonstrate that a multi-pass membrane separator enables to control hydrogen partial pressure radially along the length of reactor. This resulted in 33% enhancement in hydrogen recovery with multi-pass in comparison to single pass membrane separator.

NUTRIENT REMOVAL IN A WET DETENTION POND WITH BAFFLE DIKE - A CASE STUDY OF THE CEDAR RIVER PROJECT

The City of Jacksonville, Florida USA is in the midst of an important program to reduce nutrient load from its municipal storm water system. New regulations promulgated by the US EPA and State of Florida have targeted nutrient reduction within the St. Johns River watershed which includes most of the City of Jacksonville. In order to reduce overall nutrient loads to the St. Johns River, the City of Jacksonville and its consultant team have begun a construction program to build a series of wet detention storm water reservoirs designed to attenuate storm runoff and reduce nutrient discharge. One such facility lies within the Cedar River watershed which is connected downstream to the St. Johns River. This paper describes the layout of the facility and its nutrient removal performance over a period of more than one year. The storage and treatment facility is unique in its design since it includes a longitudinal baffle dike designed to extend the flow path and increase the overall residence time of the facility. The actual nutrient removal performance of the specially-designed facility greatly exceeded its design goals and outperformed other typical wet detention facilities in Florida as well as many storm water treatment wetlands. Overall, the pond removed approximately 31% of total nitrogen, 59% of total phosphorus, and 83% of total suspended solids during the study period.

Realization of Design of Multipass Tubes for Rigid Shell-and-Tube Heat Exchangers

A procedure for camera laying out of holes in heat exchanger tubesheets where the holes are located at the vertices of equilateral triangles is described. The procedure can be used for heat exchangers of any diameter from 159 to 3000 mm and any heat exchanger tube diameter from 16 to 57 mm. An algorithm has been developed for determining the position of longitudinal baffles for realizing multipass performance of the tubes. It is proved that the angular coordinate of longitudinal baffles does not depend on absolute dimensions of the exchanger and is determined only by the scheme of fluid passage through the tubes in the apparatus. The schemes for realizing tubeside multipasses z = 2–10 are analyzed. A numerical example for z = 10, which indicates that the results are satisfactory for engineering practice, is given.

Simulação computacional do comportamento hidrodinâmico em lagoas facultativas com chicanas

Wastewater facultative ponds are used extensively to provide wastewater treatment in Brazil. While understanding the hydraulics of facultative ponds is critical to their optimization, there is a poor understanding of the behavior of the flow that exists within them. The objective of this study is to apply Computational Fluid Dynamics (CFD) modeling on waste stabilization ponds with many configurations including baffling. From the comparison of the results the following conclusions were drawn: (1) the flow for the geometry without baffles was characterized by high levels of short-circuiting and large re-circulation regions; (2) the use of baffles creates flow fields in the tanks which reduce short-circuiting and the re-circulating regions. Particularly, the results show that ponds with two longitudinal baffles are more effective in terms of hydrodynamic behavior because the use of baffles creates flow fields with significant volumes of “plug flow” and the regions with very low velocities are significantly diminished. Keywords: facultative ponds; baffling; hydrodynamic behavior; hydraulics

Coupled multimodal fluid-vehicle model for analysis of anti-slosh effectiveness of longitudinal baffles in a partially-filled tank vehicle

An efficient model is formulated for analysis of a coupled fluid slosh-vehicle dynamic system to study the effects of different baffle designs on directional dynamic performance of a partially-filled tank vehicle. A multimodal model of fluid sloshing within a baffled cylindrical tank is initially formulated using potential flow equations and linearized free-surface boundary condition considering maneuver-induced vehicle motions along the lateral, vertical and roll axes. Natural slosh modes/frequencies, hydrodynamic coefficients and Stokes-Joukowski potential associated with the multimodal model are then obtained by solving the eigenvalue problem of free fluid sloshing using a higher order boundary element method. Significant improvement in computational time is achieved by reducing the generalized eigenvalue problem to a standard one involving only the velocity potentials on the half free-surface length using the zoning method. The hydrodynamic force and moment obtained from the multimodal model are subsequently coupled with the TruckSim vehicle dynamic simulation platform through a MATLAB/Simulink model to obtain dynamic responses of a partially-filled tank vehicle with and without baffles under step-turn and double-lane change maneuvers. Two different designs of longitudinal baffles are considered: bottom- and top-mounted baffles. The validity and efficiency of the present boundary element method is demonstrated by comparing the results with those obtained using the boundary element method employing linear elements. The effective mass moment of inertial of the fluid in a clean-bore tank is also obtained as a function of fill ratio and compared with the reported analytical solutions for a half-full tank to further verify the model. The results suggest that directional dynamic responses of partly-filled tank vehicles can be efficiently analyzed using the coupled multimodal slosh-vehicle models with significantly lower computational effort than the methods employing computational fluid dynamic (CFD) fluid slosh models. The results further reveal that top-mounted baffles are most effective in suppressing the fluid slosh force under more likely loading conditions in road tankers.

A numerical study of the effects of the longitudinal baffle on nickel ore slurry sloshing in a prismatic cargo hold

The nickel ore slurry sloshing in a rolling partially loaded prismatic cargo hold with a longitudinal baffle is investigated. A numerical model based on the volume of fluid (VOF) method and the non-Newtonian Herschel-Bulkley and Bingham equations is proposed to study the dynamic behavior of nickel ore slurry sloshing. The numerical model is solved by using the finite volume approximations and the dynamic mesh technique is utilized to handle the cargo hold's motion. After taking grid and time step independence study, the numerical results are compared with experimental data. Comparisons show good agreement in the cases investigated. Further, the relationship between the moment amplitude induced on the hold boundary and the excitation frequency is checked numerically. The ratio of baffle height to the initial cargo depth has been changed in the range of 0.0 ≤ hB/d ≤ 1.2. The variation of the sloshing-induced moment and the deformation of the free surface under different baffle heights have been obtained and discussed. To clearly understand the sloshing behavior of nickel ore slurry, the sloshing of liquid water has also been carried out. Meanwhile, the dynamic viscosity of the nickel ore slurry is monitored. The critical baffle height with regard to the sloshing-induced moment and the elevation difference of the free surface at two sides of the cargo hold has also been presented and discussed.