Baffle Position Research Articles

Design and Test of Precise Regulation System for Process Parameters of Double-Layer Tea Winnowing Machine

Conventional winnowing machines rely on manual operation and adjust their parameter settings based on experience. These problems have led to poor wind sorting results. In order to improve the sorting accuracy and efficiency of the tea winnowing machine, a double-layer automatically controlled winnowing machine has been designed in this study. Firstly, an automatic control system based on a programmable logic controller is established. Secondly, the AC motor control technology is used to achieve the automatic adjustment of the baffle position. The prototype tests show that the control input voltage of the vibrating feeder is 2 V for Lan tea and 1.5 V for pan-fried green tea material. The frequencies of the upper fan are 30 Hz and 25 Hz, respectively, while those of the lower fan are 35 Hz and 30 Hz, respectively. For Lan tea, the No. 3 baffle moves to the right by 5 cm, and the positions of the No. 5 and No. 6 baffles remain unchanged. The main outlet of the double-layer winnowing machine contains 3.72% impurities. As for pan-fried green tea, the position of the No. 3 baffle remains unchanged, the No. 5 baffle moves 5 cm to the right, and the No. 6 baffle moves 4.5 cm to the right. The main outlet of the winnowing machine contains 4.28% impurities. The experiments indicate that the double-layer winnowing machine is more effective than the single-layer one and can provide a reference for an efficient and accurate winnowing machine.

Numerical and experimental study of thermal efficiency of the transversal rectangular baffles with incline angle inside of solar air collector

ABSTRACT This study aims to improve the thermal and hydraulic performance of the solar air collector through rectangular baffles perpendicular to the air inside the channel (duct). In the latter, four cases were examined for the number and position of baffles (6 b, 10 b, 14 b, 18 b) with a fixed inclination angle of 135° in the Reynolds range from Re = 5038 to Re = 10635 using Computational Fluid Dynamic (CFD) (Ansys Fluent 18.1). The turbulence model RNG k-ε was chosen because it gave closer results to the standard correlations of Dittus-Boelter and Modified Blasius, compared to the rest of the models. The validity of the CFD simulation was confirmed based on the experimental investigation. The study -of these cases shows that the increase in the number of baffles increases the average Nusselt number as well as the friction coefficient, where the highest value of Nusselt was recorded in the case of 18 baffles Nu = 49.40 at Re = 10257. The relationship between the positioning of the baffles and the local heat transfer coefficient was also concluded. The last three cases (10 b, 14 b, 18 b) gave a very close thermal-hydraulic performance factor (THPF), while the first case (6 b) is significantly greater than theirs by a significant percentage, where the highest value recorded THPF = 0.557 at Re = 5368. Throughout this work, the effect of baffles on the heat transfer from the absorber plate to the air was understood through the local heat transfer coefficient along the channel and the velocity fields and their rays. This said heat transfer was also perceived by adding this form of baffles in the four cases and their impact on the hydraulic and thermal performance of the collector.

Effect of baffles on hydrodynamic ram and damage of storage tank under fragment impact

PurposeFragment impact is one of the main threats for the safety of storage tank in aircraft. This study aims to investigate the influence of inserted baffle on hydrodynamic ram (HRAM) and damage of storage tank to optimize the protective performance of storage tank under fragment impact.Design/methodology/approachThe characteristics of initial shock wave, cavity evolution, velocity attenuation of fragment and anti-penetration performance of baffle-inserted tanks were evaluated by experimental and numerical methods.FindingsResults indicated that the inserted baffle in tank could significantly increase the velocity attenuation rate of fragment in water. The volume of the second cavity caused by the inserted baffle rapidly decreased with the baffle position moving backward. For the baffle-inserted tank, the deformation of the front and rear walls was substantially weakened, and the alleviating effect for front wall was more significant. Comparing with the ordinary storage tank, the inserted baffle at normalized position 0.25, 0.5 and 0.75 in tank made the ballistic limit velocity of storage tank increasing by 118.3%, 20.0% and 54.0%, respectively.Originality/valueThe findings of this work illustrating the HRAM history and damage map of storage tanks after inserted baffle could provide a convenient approach to improve the anti-penetration performance of storage tanks effectively.

A new combination approach for optimal design of sedimentation tanks based on hydrodynamic simulation model and machine learning algorithms

The current study aims to propose a novel approach to design rectangular primary sedimentation tanks using computational fluid dynamics (CFD) and artificial intelligence. Hybrid adaptive neuro-fuzzy inference system and particle swarm optimization algorithm (ANFIS-PSO) is trained using CFD model's results. ANFIS-PSO is coupled with two multi-objective algorithms to optimize two objectives: Mean velocity and baffles' configurations. For the single-baffle tank, the optimal baffle position regarding flow velocity was approximately at 0.13 of the basin length, with the height ratio (ratio of baffle height to weir height) of 0.21, but the most cost-effective design was obtained when the single baffle was placed at about 0.06 of total length, with the height ratio of 0.17. Using two baffles could enhance the tank's hydraulic performance, especially when the first and second baffles were at 0.11 and 0.25 of the tank's length, respectively, with the height ratio of 0.33 and 0.22, respectively.

The effect of trapezoidal baffles on heat and flow characteristics of a cross-corrugated triangular duct

The cross-corrugated triangular duct is a common flow channel in plate heat exchangers. To further improve the heat transfer in the cross-corrugated triangular duct, trapezoidal baffles were inserted in the flow channel in this study. The apex angle and baffle position on heat and flow characteristics of the flow channel are investigated. The flow fields, velocity contours, and temperature contours were obtained through calculation. Numerical results of friction factor (f), Nusselt number (Nu), and Performance Evaluation Criterion (PEC) for various channel structures were analyzed. The variations of apex angle and baffle position make the field more complex in the flow channel than that of without baffles. For various apex angles, the f of flow channels with an apex angle of 60° or 90° are close in value, higher than that of 120°. The same trend is found for Nu. When the baffles are in the center of the upper half of the channel, the flow duct owns the highest f, Nu, and PEC values. When the Reynolds number is less than 1000, the PEC value for the flow channel with a particular baffle position at the apex angle of 120° may be lower than that of without baffles.

The performance analysis of a high-efficiency dual-channel Trombe wall in winter

In order to improve the thermal efficiency of Trombe wall in winter conditions, a novel system of high-efficiency dual-channel Trombe wall was proposed in this paper. The influence of different baffle shapes (that is corrugated C-shaped baffle and flat baffle) and their location on the thermal performance of the novel system were studied experimentally. In addition, the mathematical model of the dual-channel Trombe wall system was established and validated. The optimal configuration and position of the insulation baffle were discussed by simulation. Experimental results showed that the heating effect was the best when the total channel thickness was 0.5 m, and the baffle was 0.2 m apart from the glass cover. For dual-channel Trombe wall with corrugated C-shaped baffle, the temperature difference between the inlet and outlet, the indoor air temperature, the maximum thermal efficiency, and the maximum volume flow rate were 8.1 °C, 21.7 °C, 58.1%, and 240.9 m³/h, respectively, which were 4.9 °C, 5.6 °C, 5.1 times, and 98% higher than that of the traditional Trombe wall. Similar conclusions can be obtained for dual-channel Trombe wall with flat baffle, which was also superior to traditional Trombe wall. The simulation results indicated that the thermal efficiency would be optimal when the thickness ratio of outer air channel to total air channel was 0.3–0.4, 0.4 to 0.5 for dual-channel Trombe wall with corrugated C-shaped baffle and flat baffle, respectively. Furthermore, both the ambient temperature and solar radiation intensity had positive effect on thermal efficiency. The results could provide beneficial effect on the development of the improved Trombe wall.

자율형 소화모니터 노즐의 분사 성능에 대한 실험 연구

A systematic experimental study is carried out for the fire fighting monitor nozzle of 65A diameter to design and manufacture a new nozzle with better water spray performance than available domestic nozzles. The nozzle inlet pressure, flow rate and reach for the discharged water from the nozzle are measured by utilizing the experimental facility consisting of two pumps and piping system with a flow meter and pressure gauges. It was found that the baffle position and baffle head chamfering were the most sensitive design factors to be remarkably changed in the flow rate of the discharged water. Also, It was confirmed that the baffle position and the water exit area had the significant effect on the change in reach distance. The results obtained from this study are expected to be used effectively to design new nozzles with excellent spray performances and also to validate numerical analysis results for evaluating the water spray performance of fire fighting monitor nozzles.

Fluid-Structure Interaction Analysis in Natural Convection Heat Transfer Inside a T-Shaped Cavity with a Flexible Baffle

The purpose of this paper is to investigate the free convection flow through a flexible baffle in a T-shaped enclosure. This study is established in two-dimensional space. The 2D numerical analysis is performed with Comsol Multiphysics on the basis of the finite element method. The effect of all parameters influencing the convection heat transfer and the deformation baffle are rigorously studied. Results obtained show that the convection heat transfer and the warp baffle deformation are improved by increasing the Rayleigh and Prandtl numbers. By cons, the convection heat transfer is reduced by increasing the elasticity modulus of the flexible baffle and increasing the length of baffle. However, the stress over the baffle is improved. The variation of baffle position is not an important factor that affects the convection heat transfer inside the cavity; by contrast, the stress over the baffle is more important with a higher baffle position.

Numerical Investigation of an Optimum Ring Baffle Design to Optimize the Structural Strength of a Tank Subjected to Resonant Seismic Sloshing

This article numerically investigates the sloshing dynamics and structural response of baffled cylindrical tanks subjected to lateral resonant as well as seismic excitations. The study focuses on suppressing the sloshing forces and fluid movement by increasing the tank structural strength with the help of a baffle and explores the optimum baffle design from among various ring baffle designs. Two approaches have been used for the evaluation of effective positions and design: the modal approach and the fluid–structure interaction (FSI) approach. The numerical model is validated using the tank design code Eurocode-8. Based on the detailed fluid and structural analysis of sloshing pressure and fluid velocity, the structural stress optimum baffle position and design are achieved, which change the structural characteristics of the tank positively. Furthermore, the effectiveness of the selected design is also tested against the El-Centro and Kocaeli earthquakes. It is found that the optimum design increases the tank structural strength by up to 2.5 and 4 times under resonant and seismic excitations, respectively.

Effects of the Design and Optimization of Trapezoidal Channels and Baffles (Number and Position) on the Net Power Density of Proton-Exchange Membrane Fuel Cells.

The effects of the design and optimization of trapezoidal channels and baffles on the net power density of proton-exchange membrane fuel cells (PEMFCs) are studied. The significant effects of the length of upper and lower sides of the trapezoidal cross section and the number and position of baffles on the net power density of PEMFC have been investigated. It is found that at the same flow rate, changing the effective contact surface between the flow channel and the gas diffusion layer can tremendously improve the current density of fuel cells; moreover, the performance of a PEMFC based on the addition of a baffle can be further improved. The results show that the trapezoidal cross-sectional flow channel with baffles has higher efficiency and better overall performance compared with a basic straight flow channel. In addition, the response surface was used to optimize the trapezoidal cross-sectional flow channel by considering the power loss of output power and the flow rate. The optimal result was obtained with an upper side length of 1.234 mm, a lower side length of 1.8 mm, and a baffle from the entrance at 9.5 mm, increasing the net power density by 4.347%.

Research on the Dust Suppression Effect of Three Types of Baffles on the Particle Flow Horizontal Projectile Falling Process in Transverse Airflow

Industrial progress is the source of social development. As one of the important links in the industrial production process, industrial particulate transportation systems such as coal, cement, mineral materials and food transportation cause a large number of dust diffuse problems, which have become the pollution source of the deterioration of the environment quality in the workplace. In the production process, the initial velocity of the conveyor belt makes the particle flow form a horizontal projectile motion, which causes the dust pollution and transverse airflow often further aggravates the dust diffusion. Firstly, the author verified the applicability of Discrete Phase Model by using experimental result. Then, this paper studies the control effect of dust emission in the particles flow horizontal projectile fall process with different types baffle and different baffle positions under transverse airflow. The results show that the semicircular baffle has a better dust suppression effect, followed by the V-shaped baffle, the straight baffle is the worst. The semicircular and V-shaped baffles are moved closer to the particles source out, the better the dust suppression effect. The dust suppression effect of the straight baffle gradually improves as the distance increases, and reaches the best at a distance of L=1 m. The research results provide a theoretical basis for ventilation dust removal design of industrial particulate transport systems.

Augmentation of Heat Transfer in a Circular Channel with Inline and Staggered Baffles

This numerical investigation presents the effects of the position of baffles in the shape of a circle’s segment placed inside a circular channel to improve the thermal and flow performance of a solar air heater. Three different baffles’ positions with Reynolds number varying between 10,000 to 50,000 were investigated computationally. The k-omega SST model was used for solving the governing equations. Air was taken as the working fluid. Three pitch ratios (Y = 3, 4, and 5) were considered, while the height of the baffles remained fixed. The result showed an enhancement in Nusselt number, friction factor, j-factor, and thermal performance factor. Staggered exit-length baffles showed maximum enhancement in heat transfer and pressure drop, while inline inlet-length baffles showed the least enhancement. For a pitch ratio of Y = 3.0, the enhancement in all parameters was the highest, while for Y = 5.0, the enhancement in all parameters was the least. The highest thermal performance factor of 1.6 was found for SEL at Y = 3.0.

Numerical Investigation of Shallow Liquid Sloshing in a Baffled Tank and the Associated Damping Effect by BM-MPS Method

Understanding the damping mechanism of baffles is helpful to make more reasonable use of them in suppressing liquid sloshing. In this study, the damping effect and mechanism of vertical baffles in shallow liquid sloshing under a rotational excitation are investigated by an improved particle method. By incorporation of a background mesh scheme and a modified pressure gradient model, the accuracy of impact pressure during sloshing is significantly enhanced. Combined with the advantages of the particle method, the present numerical method is a wonderful tool for the investigation of liquid sloshing issues. Through the analysis of impact pressure, the influences of baffle height and baffle position on the damping mechanism are discussed. The results show that the damping effect of vertical baffles increases with the increase of the elevation of baffle top and decreases with the increase of the elevation of the baffle bottom. Moreover, the resonance characteristics of sloshing are altered when static water is divided into two parts by the vertical baffle. The dominant damping mechanism of vertical baffles depends on the configurations.

Buoyant Convective Flow and Heat Dissipation of Cu–H2O Nanoliquids in an Annulus Through a Thin Baffle

This article numerically investigates the buoyant convective flow and thermal transport enhancement of Cu–H2O nanoliquid in a differentially heated upright annulus having a thin baffle. For the analysis, the outer and inner cylinders are cooled and heated respectively through insulated top and lower boundaries. Also, the baffle temperature is assumed to be that of the hot cylinder. The finite difference based numerical technique is used to solve the system of equations governing the physical processes. The findings are accessible in terms isotherms, streamlines and Nu number for wider ranges of baffle positions and lengths, Rayleigh numbers, and by considering different nanofluid (NF) volume fractions. The average Nu number is enhanced in addition of the Cu nanoparticle to the base liquid and it is also found the liquid flow and heat transport can be successfully controlled via the appropriate selection of baffle location and length. Principally, the baffle length having 20% of annular width placed at 80% of the annular height has been found to produce higher thermal transport rates as compared to other choices of baffle lengths and positions.

Control of buoyant flow and heat dissipation in a porous annular chamber using a thin baffle

This paper reports the numerical simulations on buoyant thermal transfer inside the finite porous cylindrical annular region with a thin circular baffle attached to inner cylinder. The main objective of this investigation is to provide a detailed impact of baffle on flow and heat transport rates due to the direct relevance of this problem to the design of heat exchangers. The side walls of annular enclosure are maintained at uniform, but different temperatures, while the top and bottom walls are insulated. The Brinkman-extended Darcy model is adopted for the momentum equations, and simulations of the governing PDEs are performed using the ADI and SLOR algorithms. The predictions from the present simulations detected that the size and position of baffle has predominant impact on buoyant flow and thermal transport characteristics. It has been detected that the thermal dissipation rates could be enhanced by positioning the baffle near the upper boundary, while increasing the baffle length leads to the reduction of thermal transport. The size and location of baffle emerges out as an important quantity in regulating the global thermal transfer through modifying the flow regimes in the annular geometry. Interestingly, the magnitude of flow circulation enhances with an increase in Rayleigh and Darcy numbers for any baffle length and position.

Effect of Baffles Position on Thermo-Hydraulic Efficiency of a Solar Air Heater

Providing artificial irregularity in the form of baffles on the bottom plate of a solar air heater improves the thermal performance of the heater, whereas it reduces the hydraulic efficiency due to friction losses. To optimize the thermo-hydraulic performance of a rectangular duct solar air heater, a thermo-hydraulic performance factor (THPF), dependent on shape, position and size of baffles, is considered in this study. The performance of the heater in various configurations related to the position of the baffles was evaluated considering Renormalization group k-£ model to simulate the fully turbulent flow for a forced convection condition. At a constant value of heat flux of 1000 W/m2 on the absorber plate and a fixed value of Reynolds number as 2350, pitch between the baffles was varied from 15mm to 75mm. Further, the distance of 1st row of baffles from the inlet was varied from 200mm to 500mm and the optimum configuration was figured out. For pitch value of 60mm between the baffles and the distance of 1st row of baffles as 200mm from the inlet, the highest value of THPF was obtained as 0.9339. The fluid behavior in presence of baffles was analyzed together with its influence on the thermo-hydraulics parameters.

Erratum to: MHD natural convection and thermal radiation of diamond–water nanofluid around rotating elliptical baffle inside inclined trapezoidal cavity

In this work, we study the natural convection and thermal radiation heat transfer of diamond–water nanofluid around rotating elliptical baffle inside inclined trapezoidal cavity under Lorentz forces effect in the presence of uniform heat generation/absorption. The trapezoidal cavity lateral walls are uniformly cooled, and the top and bottom walls are kept adiabatic. The interior rotating elliptical baffle is uniformly heated. Our numerical study is realized by the software Comsol Multiphysics based on the on the finite element method. The results extracted show that an increment on the convection heat transfer is reached by increasing Rayleigh number, the radiation parameter and the elliptical baffle horizontal radius; however, the increment of Hartmann number reduces it. The effect of cavity inclination on the convection heat transfer depends on the baffle position. The presence of uniform heat generation increases the temperature field inside cavity and improves the convection flow, but the presence of uniform heat absorption reduces it. Using nanoparticles with higher shape factor improves more the convection heat transfer.

Energy dissipation in stepped spillways using baffled stilling basins

ABSTRACT Stepped spillways have become increasingly popular due to the low-cost of construction and high efficiency. A stepped spillway is a hydraulic structure that is an integral part of the dam that allows the safe passage of overtopping flows. In this paper, an experimental study was employed to investigate the stepped spillway with four steps of 32 cm height and 54 cm width contracted by wing wall width (C) = 0.2 from the width of the flume. Eighteen runs were carried out considering different positions, heights, and widths of the baffle to increase the energy dissipation resulting from this contraction stepped spillway. The results indicated that the best position of baffles was (a/y2 ) = 1.4, the relative baffles height was (hb/y1 ) = 0.95, and the best relative baffles widths (wb/W) = 0.68, compared with cases of contraction stepped spillway without baffles. The results showed that the baffles on the stilling basin downstream stepped spillway increase the energy dissipation. Simple formulae were also deduced to evaluate the energy parameters.

The Apex Angle and Baffle Position on Heat and Flow Characteristics of a Cross-Corrugated Triangular Duct with Trapezoidal Baffles

The Apex Angle and Baffle Position on Heat and Flow Characteristics of a Cross-Corrugated Triangular Duct with Trapezoidal Baffles

Numerical and experimental investigation on thermal stratification characteristics affected by the baffle plate in thermal storage tank

The aim of this study was to analyze the thermal stratification characteristics affected by the central hole-type baffle plate in heat storage tank. The response surface method was used to optimize the structure parameters. Experiments were conducted to investigate the thermal stratification characteristics of a hot water storage tank with a baffle plate during the charging process. The temperature field and flow field inside the storage tank were calculated by numerical simulation, and the effects of different structural parameters on the mixing number, stratification number, and the Richardson number were analyzed. The results showed that the three evaluation indices correspond to different optimal parameter combinations. The interaction factors that have a crucial influence on the three evaluation indices are baffle aperture and inlet velocity, baffle position and inlet velocity, and baffle position and baffle aperture. Taking the Richardson number with the highest precision of the regression model as the optimization objective, the optimal parameter combination optimized by the expected function is a baffle position of 0.79, aperture of 0.80, and inlet velocity of 0.2 m/s.