Horizontal Baffle Research Articles

Numerical Simulation of Sloshing in Roll Motion on Multiple Tanks with Vertical and Horizontal Baffle Using Smoothed Particle Hydrodynamics

Numerical Simulation of Sloshing in Roll Motion on Multiple Tanks with Vertical and Horizontal Baffle Using Smoothed Particle Hydrodynamics

Numerical Study on the Anti-Sloshing Effect of Horizontal Baffles in a Cargo Hold Loaded with Liquefied Cargo

Sloshing of liquefied bulk granular cargoes weakens the stability of cargo carriers when at sea. Using the horizontal rectangle baffle is a promising way to restrain its sloshing motion. But the location height and optimal baffle area rate to achieve a better anti-sloshing effect should be studied first. The discrete element method was adopted to establish the simulation model, and the direct shear test was used for verification. Through the static tilt tests, the definite relationship between the effects of moisture content on cargo motion and particle friction coefficients was acquired. Then, liquefied cargo motion in a cargo hold without baffles and with one and two pairs of horizontal baffles was simulated. Based on variations in the cargo gravity center offset and the sloshing-induced force on the cargo hold, the anti-sloshing effect of different settings of the baffles was compared. Results show that the baffles have the ability to restrain cargo sloshing, and this is important for sea transportation safety. The anti-sloshing effect is better when the baffle plane is right on the cargo top surface compared to the other location heights. Further, there is an optimal length–width combination, e.g., a single baffle plane with a length of 0.26 L and a width of 0.46 B, at which a better anti-sloshing effect could be achieved with the smallest baffle area rate. This study could be useful for the practical application of horizontal baffles for bulk granular cargo carriers.

A new method for solids residence time distribution measurement in continuous fluidized beds

Accurate measurement of solids residence time distribution (RTD) is an important and challenging issue in developing fluidized bed reactors with continuous solids feeding and discharging. In this study, we proposed a new method for measuring solids residence time distribution, where coked bulk material was used for solids tracer and high-precision element analyzers were used to determine solids tracer fraction. A calibration procedure was established to achieve high-accuracy measurement of solids tracer fraction. The following validation tests had successfully proved the pseudo-CSTR solids flow pattern under different operating conditions and the staging effect of an inserted horizontal baffle in a small laboratory-scale fluidized bed cold model, which demonstrate the feasibility and advantages of this new solids RTD measurement method.

Enhanced solar energy utilization of thermal energy storage tanks with phase change material and baffle incorporating holes

In response to the pressing need for more efficient thermal energy storage solutions, this study investigates the strategic implementation of baffles in phase change material (PCM) tanks to enhance thermal performance. PCM offers a promising solution for efficient thermal energy storage (TES); however, ensuring uniform temperature distribution inside the tanks remains challenging. Horizontal baffles with holes of varying diameters were introduced in Tanks 02, 03, and 04, while an inclined baffle with holes was used in Tank 05. The Tank 06 benefitted from an inclined baffle with holes of different diameters. A comprehensive analysis of all Tanks was evaluated by assessing PCM and water heat flux, PCM and water static enthalpy, Richardson number, velocity vectors, temperature, and liquid fraction contours. The results demonstrated that significant improvements were achieved with the addition of baffles. Tank 01, without a baffle, exhibited a melting time of 2860 s. However, the introduction of baffles resulted in reduced melting times for Tanks 02 to 06: 2360 s (17.48 %), 2350 s (17.83 %), 2400 s (16.08 %), 2320 s (18.88 %), and 2240 s (21.67 %), respectively; which led to enhance TES efficiency, and a quicker energy storage process. The study also includes a comprehensive economic analysis, evaluating the total cost (Ctotal) and performance-economic ratio (Pc). Tank 06 shows superior economic performance, with a Pc value of 0.26 despite a slightly higher cost than Tank 01 by $2 USD. These findings highlight the baffle design’s effectiveness in achieving better heat transfer and uniform temperature distribution within PCM tanks, making them more efficient for TES applications.

CFD simulation and geometric optimization of a novel baffle heat sink for power electronics cooling

The electric drivetrain of an electric vehicle typically has two fluid circuits: an oil circuit for lubrication and a water-glycol circuit for cooling. Eliminating the water-glycol circuit can result in a more compact and lighter drivetrain. However, this requires the drivetrain components to be cooled with oil as coolant, which has inferior heat transfer properties compared to water-glycol mixtures. This is particularly challenging for the power modules in the power electronics unit, which exhibit some of the highest heat fluxes in the drivetrain. This study focusses on the design and optimization of a novel type of heat sink for laminar flows with baffles to guide the flow in four different directions. This has two main advantages: the baffles act as fins and increase the heat transfer area and they introduce a swirling motion in the oil thereby disturbing the boundary layers continuously. Computational fluid dynamics simulations using Ansys Fluent are performed to evaluate the thermohydraulic performance of the heat sink. The influence of design parameters such as the height and thickness of both fins and baffles and the baffle spacing in horizontal, upward and downward direction was evaluated by simulations with several combinations of the design space, considering manufacturing constraints. The optimization of the design showed that the fin thickness, horizontal baffle spacing and baffle length should be as small as possible, while there were optimal values for fin height, upward and downward baffle spacing, streamwise baffle spacing and baffle thickness. The simulations show that the thermal resistance of the baffle heat sink can be 19% lower than that of a benchmark pin fin heat sink at equal pumping power.

Numerical investigation on smoke control with new‐style horizontal smoke baffle in an immersed road tunnel

AbstractTo investigate the improvement induced by horizontal smoke baffles during lateral smoke exhaust, an immersed road tunnel with various horizontal smoke baffles positioned below the lateral exhaust vent was studied numerically. Together with the velocity field characteristics, the temperature distribution was investigated near the lateral smoke exhaust vent, followed by the analysis of lateral smoke exhaust efficiency under different horizontal smoke baffles. Results showed that after installing the horizontal smoke baffle, there was a significant decrease in the extracted cold air, while the high‐temperature smoke in the exhaust vent increases, indicating the plug‐holing is effectively suppressed. It is known that the efficiency of smoke exhaust increases when the length exceedance ratio of the horizontal smoke baffle is smaller than 100%, while it changes slightly when the baffle length continues to increase. When the width ratio of horizontal baffle is smaller than 40%, the efficiency of smoke exhaust increases with the baffle width and then changes slightly with a wider smoke baffle. With a larger aspect ratio, the wider and shorter lateral exhaust vent is beneficial for improving the lateral smoke exhaust. Under the current conditions, the case shows the optimal smoke exhaust performance with a horizontal baffle length exceedance ratio of 100%, a baffle width ratio of 40%, and exhaust vent aspect ratio of 3:1. Finally, an empirical model is developed to describe the improvement of smoke exhaust efficiency caused by horizontal smoke baffle. These outcomes are helpful to the design of lateral smoke extraction system in road tunnels.

Effects of seismic characteristics and baffle damping on liquid sloshing

The present work concentrates on liquid sloshing in tanks under real seismic excitations with various frequency contents [the ratio of peak ground acceleration (PGA) to peak ground velocity (PGV)] by a finite-difference turbulent model. The turbulence is modeled by the large eddy simulation, and the fluid–structure interaction is resolved by the Virtual Boundary Force method. Thirteen seismic records, covering the low, intermediate and high frequency contents, are adopted to excite nonlinear sloshing waves. Both sloshing wave and hydrodynamic pressure are recorded, and their correlations with the filling level, PGA, PGV and frequency content have been identified. The findings suggest that (1) the sloshing responses are in general positively correlated with the filling level; (2) the sloshing height strongly relates to PGV and frequency content, and the seismic excitation of low frequency and meantime with a larger PGV can trigger more violent sloshing waves than others; and (3) the dynamic pressure along the tank sidewall decreases from the bottom up, which is dominated by PGA at the lower part but the stronger correlation is established with PGV and frequency content at the upper part. Finally, to damp severe sloshing waves, the horizontal, vertical and coupled horizontal and vertical baffles are introduced, and their inhibiting effects are discussed. The present work may guide the design of partially filled storage tanks under seismic excitations.

Thermal Performance Improvement of a Spiral Channel Solar Air Heater: Numerical and Experimental Investigation in the Desert Climate of Gabes Region

Abstract This study focuses on improving the thermal performance of a solar air heater (SAH) using a single-pass spiral-shaped ducts. The SAH is designed and tested under prevailing weather conditions of Gabes, Tunisia (33°52.8876′ N,10°5.892′ E). The experimental measurements are carried out over 4 days. Similarly, a computational fluid dynamics (CFD) model was developed to study the fluid flow and the heat transfer inside the SAH using the commercial software ansys fluent 2021 R1”. The discrete ordinate (DO) radiation model and the k-ω shear stress transport (SST) turbulence model are used to study the radiative heat transfer and the turbulent flow in the SAH, respectively. The numerical model is validated against experimental data, and the average error does not exceed 3.6%. To improve the heat transfer phenomena, the ratio of horizontal baffle spacing “d” to vertical baffle spacing “p” (d/p) is numerically investigated. Moreover, the highest air outlet temperature during the test days reached 81.1 °C under a mass flowrate of 0.0077 kg/s. The maximum efficiencies are 57%, 54%, 49%, and 46% for the configurations d/p = 1.5, d/p = 2, d/p = 1, and d/p = 0.5 under a mass flowrate of 0.02 kg/s, respectively. The SAH design with d/p = 1.5 is about 4–10% more efficient than the standard design with d/p = 1 under a mass flowrate ranging from 0.0077 kg/s to 0.025 kg/s.

Enclosure fire extinguishment with water mist and nitrogen as affected by fire size, obstruction and ventilation

Fire tests were conducted to evaluate the efficacy of incorporating nitrogen to enhance water mist's fire-extinguishing capability in an obstructed, naturally-ventilated 1.22 × 0.61 × 1.22 m high enclosure. Water mist and nitrogen were applied from the enclosure ceiling in the respective ranges of 0.35–3.89 lpm and 0.113–0.283 m3/min, with median droplet sizes ranging from 16 to 35 μm. The obstruction was facilitated with horizontal baffles with various vertical spacings to force the transport of water mist and nitrogen to follow an alternating path to a 76- or 152-mm heptane pan fire sitting on the enclosure floor. The enclosure ventilation was provided with a 0.23 × 0.15 m high base opening centered on the enclosure's front wall, together with a 0.33 × 0.05 m high opening centered on the enclosure's front wall or on the enclosure's back wall at the respective elevations of 0.36 m and 0.81 m above the enclosure floor, or with the presence of these two elevated openings. The tests showed that incorporating nitrogen in the water mist application did improve water mist’ fire-extinguishing capability in the enclosure. However, the improvement was highly affected by the fire size, obstruction and ventilation conditions.

Numerical modelling of dual function tanks for fire suppression and tuned liquid damper applications

Exceeding serviceability limits due to wind-induced motions in tall buildings can cause discomfort for residents and adversely affect auxiliary building services, such as elevator operations. A tuned liquid damper (TLD) is an attractive type of dynamic absorber because of its simplicity and affordability. However, its dimensions and geometry can be limited by available floor space. Utilizing dual-purpose water tanks for both damping and fire suppression purposes can be a feasible resolution to fire code requirements and building motion control. Several design criteria need to be considered to accommodate the fire code requirements and the proper tuning of the TLD. Consequently, in this study, a TLD tank is fitted with a perforated floor to divide it into two compartments that allow water transmission to meet fire code requirements. However, the sloshing motion within the tank is complex and computationally expensive to capture when using traditional simulation models. This paper presents a 2D ISPH code equipped with a macro-level model to capture the effect of the perforated floor on the overall sloshing response of the tank. The model is first evaluated using existing results from previous studies on tanks with horizontal baffles. Next, the ISPH model is used to numerically model the perforated floor using the Ergun resistance (ER) macro-level model. In addition, the perforated floor is also explicitly micro-level modelled using rigid boundary particles to validate the proposed ER model. A numerical analysis is then conducted under different excitation amplitudes and frequencies, with both time history and frequency response results being presented. A structure-TLD model is subsequently used to capture the structure-TLD system response under random excitation. Results show that the ER model can efficiently model tanks with dual functions under both harmonic and random excitation and across a wide range of amplitudes and frequencies, with appreciable computational time savings. The proposed tank with a perforated floor is found to be effective in serving as a dual-purpose TLD and storage tank for fire suppression in buildings.

Research on the sloshing characteristics of the ship tank with baffles under rolling motion based on smoothed particle hydrodynamics method

The problem of liquid sloshing is widespread in the field of naval architecture and ocean engineering. During the sloshing process, the liquid will produce a large slamming force on the bulkhead. At the same time, the coupled sloshing of the liquid in tank and the hull will also affect the floating state and stability of the hull, and even induce safety accidents. The tank sloshing simultaneous with baffles and under rolling excitation is particularly focused in this paper, which is rarely concerned preciously. Based on the theory of fluid dynamics, the program of tank sloshing under large-amplitude rolling conditions by the smoothed particle hydrodynamics method is compiled, and the accuracy of the numerical model is validated through existing experimental results. Furthermore, the slamming pressure and the wetted height of the tank wall are studied for the cases of different excitation amplitudes and excitation frequencies. Then, the dynamic response characteristics of the sloshing tank with vertical and horizontal baffles are studied, and the effects of different baffle lengths are analyzed. The result shows that under rolling excitation the vertical baffle longer than the water depth can mitigate sloshing to some extent, but the vertical baffle whose length is less than the water depth and the horizontal baffles cannot play a role in mitigating the sloshing.

A comprehensive analysis method of building luminous and indoor thermal environment based on orthogonal analysis

Good design strategies can help reduce energy consumption and ensure proper natural lighting. In the process of building design, this paper uses orthogonal analysis to identify design elements that correspond optimally to light levels. The visible light transmission ratio, horizontal sunshade baffle depth, sunshade angle, horizontal sunshade height from the window, and heat transfer coefficient were selected as influencing factors. The design elements corresponding to the lowest energy consumption were found. The test points are representative, and the number of tests is small.

A two-dimensional semi-analytic solution on two-layered liquid sloshing in a rectangular tank with a horizontal elastic baffle

A semi-analytic study on two-layered liquid sloshing in a horizontal excited two-dimensional rectangular tank with a horizontal elastic baffle was performed. The present work is a further development of the semi-analytical technique for solving the single-layer liquid sloshing problem. The horizontal elastic baffle was located in the lower liquid or upper liquid. First, the complex liquid domain in a baffled tank was divided into several simple sub-domains to solve the analytic solution. The wet mode of a horizontal baffle was presented according to the Eulerian Bernoulli beam. The continuity boundary condition on the interfaces between two liquids and the virtual interfaces was given. Then, the formal solution was derived for each sub-domain and a horizontal baffle using the superposition principle and the method of separation of variables. Then, the total velocity potential subject to lateral excitation was summed over the container potential function and the liquid disturbance potential. The dynamic response equation for two-layered liquid sloshing was established. Multiple methods verified the semi-analytic solution's correctness and agreed well with other methods. Finally, the numerical analysis mainly shows that the density ratio becomes more significant for the coupled frequency when the baffle is in the upper liquid. A large baffle's width suppresses the liquid flow in the baffled tank effectively. Furthermore, adjusting the baffle and the layered liquid parameters can significantly suppress layered liquid sloshing. For the seismic response, the elevation energy is mainly located after 2.5 s.

Design of Intermediate-Depth Tuned Liquid Damper with Horizontal Baffles for Seismic Control and Carbon Footprint Reduction of Buildings

Design of Intermediate-Depth Tuned Liquid Damper with Horizontal Baffles for Seismic Control and Carbon Footprint Reduction of Buildings

Effect of Retrofit Design Modifications on the Macroturbulence of a Three-Phase Flotation Tank-Flow Characterization Using Positron Emission Particle Tracking (PEPT).

Turbulence in stirred tank flotation tanks impacts the bulk transport of particles and has an important role in particle-bubble collisions. These collisions are necessary for attachment, which is the main physicochemical mechanism enabling the separation of valuable minerals from ore in froth flotation. Modifications to the turbulence profile in a flotation tank, therefore, can result in improvements in flotation performance. This work characterized the effect of two retrofit design modifications, a stator system and a horizontal baffle, on the particle dynamics of a laboratory-scale flotation tank. The flow profiles, residence time distributions, and macroturbulent kinetic energy distributions were derived from positron emission particle tracking (PEPT) measurements of tracer particles representing valuable (hydrophobic) mineral particles in flotation. The results show that the use of both retrofit design modifications together improves recovery by increasing the rise velocity of valuable particles and decreasing turbulent kinetic energy in the quiescent zone and at the pulp-froth interface.

Investigation of Sloshing with Vertical and Horizontal Baffle in the Prismatic Tank using Meshfree CFD

Sloshing is a phenomenon where the tank experiences an external oscillating motion due to the interaction of fluid with tank. The most appropriate way to prevent instability from the sloshing movement is to add baffles or anti-sloshing. This paper was conducted with the 3D simulation of sloshing roll motion on the prismatic tank with a simulation time of 28 seconds. Vertical and Horizontal baffles were used to mitigate sloshing in the prismatic tank. The ratio of baffle height and water depth is 0.7, 0.8 and 0.9. Moreover, horizontal baffle position is 0.1, 0.2, 0.3, and 0.4 respectively, with the tank filling water ratio is 25%. The numerical study was carried out using meshfree CFD, i.e., Smoothed Particle Hydrodynamics. In addition, advanced post-processing was conducted with Blender. The aims of this study were found out the effective baffle configuration ​​to reduce sloshing using vertical and horizontal in the prismatic tank. The results showed the most effective baffle variation for roll motion is 0.9 for vertical baffle and a horizontal baffle height is 0.1 from the water surface. It showed baffles effectively reduces dynamic pressure, hydrodynamic force and free surface deformation

Simulation of a composite latent heat storage tank with horizontal baffles and two phase-change temperatures

A composite latent heat storage tank (CLHST) is fabricated using baffles and two phase-change materials (PCMs) with different phase-change temperatures. The performance of the tank is optimized based on both structure and material. This optimization approach is a new integrated method differing from those developed in previous studies, where only a single aspect of the structure/material is considered. Experimental verification and simulation analysis are used to analyze the difference between the integrated and single-structure/material optimization methods and their influence on the thermal properties of the traditional latent heat storage tank (TLHST). The results show that the CLHST exhibits the best characteristics. Compared with the TLHST, the CLHST’s charging quantity increases by 13.6%, the outlet temperature can be increased by 6.5°C, and the utilization rate of PCM exceeds 85%. Moreover, the PCM in the CLHST melts more completely than unilaterally adding baffles. The charging and discharging quantities of the CLHST increase by more than 10% than just using two PCMs. Furthermore, adding baffles can increase the charging quantity by 11% compared to using two PCMs. Evidently, the tank design must be improved considering several aspects, and structural optimization plays a more important role in improving tank performance.

Magnetic-Mixed Convection in Nanofluid-Filled Cavity Containing Baffles and Rotating Hollow-Cylinders with Roughness Components

Mixed convective heat transfer in a nanofluid-filled lid-driven square cavity equipped with a rotating cylinder, horizontal baffles, and an external magnetic field is numerically examined in this study. A cylinder with triangular components is set at the centre of the cavity while two horizontal baffles are fixed to its vertical walls. The cavity is under the impact of the external magnetic field. Modified Maxwell’s model is taken into consideration to estimate the thermal conductivity of nanofluids. Galerkin FEM is applied to simulate nondimensional governing equations. The computations are carried out for specific ranges of physical parameters, and the results are illustrated through streamlines, isotherms, and average Nusselt number bar charts. Contours plotting indicate that flow circulation and distribution of temperature are significantly affected by the speed of a rotating rough cylinder. The fluid velocity remarkably increases with an increase in speed ratio and Reynolds number but it declines with Hartmann number, baffle length, and volume fraction. Heat transfer rate is substantially augmented by increasing the rotational speed of the rough cylinder, heights of triangular components, and suspended-nanoparticles which are also optimized for increasing baffle’s length and its horizontal arrangement. The findings of this investigation can be applied to improve the cooling efficiency of engineering equipment such as heat exchangers, energy storage systems, electronic equipment, solar collectors, and nuclear reactor safety devices.

Numerical modelling of nonlinear baffles on sloshing suppression of rectangular tanks under horizontal excitation

Sloshing in a tank refers to the movement of a free liquid surface. It can create resonant liquid vibrations, which can damage tank walls structurally. The horizontal baffles can disperse sloshing energy by reducing impact forces acting on container walls. This work studies the effectiveness of nonlinear baffles on sloshing characteristics. The two-dimensional numerical investigations under horizontal excitation are performed using the Volume of Fluid(VoF) technique. In addition to the nonlinear baffles designed using sine and cosine curves, the conventional horizontal baffle is tested for their effectiveness in suppressing sloshing characteristics. The base computational model is validated with the published data, and the effectiveness of each nonlinear baffle on sloshing characteristics is compared in terms of pressure exerted on the walls of the container. The nonlinear baffles are tested for different excitation amplitudes, fill levels, excitation frequencies and submergence depths is studied. In addition, the variation in the baffle parameters, namely baffle amplitude, the number of baffle cycles and the inclination of baffles, are also considered. The negative amplitude cosine baffles with 2 cm wave amplitude fixed at 0.02m submergence depth possessed the superior suppression on sloshing response among all other nonlinear baffles considered.

Mitigation of liquid sloshing by multiple layers of dual horizontal baffles with equal/unequal baffle widths

Present work aimed to discover the inhibiting efficacy of multiple layers of dual horizontal baffles (multiple DHBs) on liquid sloshing under harmonic and seismic excitations by applying a Navier-Stokes solver. The multiple DHBs with equal/unequal baffle width (EBW/UBW) were considered, where that of UBW was divided into two categories — oblique and concave UBW schemes. Their damping effects were illustrated by estimating the free surface and pressure results, and the velocity and vortex fields were also discussed. The results showed that the EBW scheme with wider width was better than the narrow one. Both UBW schemes could effectively inhibit the resonant sloshing wave and were also superior to the EBW scheme in damping the sloshing amplitude and hydrodynamic load at lower parts of the tank sidewall. Overall, all baffle schemes could effectively suppress the total forces acting on the tank sidewall. Finally, El Centro earthquake was imposed on the charging system to guarantee a violent sloshing wave, and the damping efficacy of various baffles on such wave was numerically investigated.