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1
Chen, Cong, Dongji Xuan, Mingge Wu, Shengnan Liu, and Yunde Shen. "Performance and Parameter Sensitivity Analysis of the PEMFC Flow Channel with Porous Baffles." Applied Sciences 11, no. 24 (December 15, 2021): 11942. http://dx.doi.org/10.3390/app112411942.
Повний текст джерелаАнотація:
In this paper, a method to improve the performance of PEMFCs using porous material as a flow channel baffle is proposed. The results show that PEMFCs with four porous baffles flow channels have better performance at high current density compared with the traditional flow channel. The structural parameters of the flow channel explored in this study include porosity, the thickness of the baffle and the number of baffles, and their influence on the performance of PEMFCs. Sensitivity analysis results show that the performance of the PEMFCs with the porous baffle channel is the most sensitive to baffle thickness, and the thickness and baffle could be appropriately adjusted. The number of plates and porosity of the baffle are adjusted to improve the performance of the PEMFCs.
2
Jeng, Tzer-Ming, and Sheng-Chung Tzeng. "Study of Flow and Heat Transfer Characteristics in Asymmetrically Heated Sintered Porous Heat Sinks With Periodical Baffles." Journal of Electronic Packaging 128, no. 3 (August 18, 2005): 226–35. http://dx.doi.org/10.1115/1.2229220.
Повний текст джерелаАнотація:
This work numerically examined the mechanism of heat transfer in a sintered porous heat sink with baffles. A channel filled with the sintered porous heat sink was asymmetrically heated and metallic baffles were periodically mounted on the heated surface. The fluid medium was air. The results indicate that no recirculation occurred between baffles. The metallic baffle obtained heat from the heated surface by conduction directly from the heated surface and indirectly through the porous media. It dissipated heat to the fluid that passed over the zone above the baffle. The Nusselt numbers in the cases with baffles exceeded those in cases without a baffle. The enhancement in the average Nusselt numbers of sintered porous heat sinks with baffles increased as the Reynolds number (Re) declined; the baffle height (h∕H) increased; the baffle length (w∕H) increased, or the baffle pitch (XL) decreased. However, at Re=500, the average Nusselt number in the case with h∕H=0.3 was higher than those with h∕H=0.7, 0.5, and 0.1. Additionally, the minimum enhancement appeared at around Re=3000 for various h∕H, w∕H, and XL. For the cases with h∕H⩽0.3 and various w∕H as well as XL, at Re>3000, sintered porous heat sinks with baffles insignificantly improved heat transfer.
3
Zhu, Aimeng, Mi-An Xue, Xiaoli Yuan, Feng Zhang, and Wei Zhang. "Effect of Double-Side Curved Baffle on Reducing Sloshing in Tanks under Surge and Pitch Excitations." Shock and Vibration 2021 (February 19, 2021): 1–17. http://dx.doi.org/10.1155/2021/6647604.
Повний текст джерелаАнотація:
Sloshing is associated with the structural safety of liquid storage vessel. Installing the baffles inside the containers would be beneficial for the mitigating the damage due to the severe sloshing. In this study, an innovative type of double-side curved baffle was proposed to evaluate its effect on reducing sloshing in a rectangular tank under surge and pitch excitation. For comparison with conventional baffles, effects of the vertical baffle and the T-type baffle on mitigating sloshing were also studied experimentally and numerically by analyzing the free surface wave elevation as well as the hydrodynamic pressure on the tank wall. The effective stress at the double-side curved baffle along the height direction of the baffle is much smaller than that at the T-type baffle although they have the same mitigation effect on sloshing wave heights. The sloshing-induced effective stress on the double-side curved baffles was analyzed by varying their radian. Findings show that the effective stress on the baffle tends to decrease with the increase in the radian. The velocity field was presented to observe effect of the baffles on sloshing with the aid of ADINA and laboratory experiments conducted on a hexapod motion platform.
4
Yasuo, A., and M. P. Paidoussis. "Flow-Induced Instability of Heat-Exchanger Tubes due to Axial Flow in a Diffuser-Shaped, Loose Intermediate Support." Journal of Pressure Vessel Technology 111, no. 4 (November 1, 1989): 428–34. http://dx.doi.org/10.1115/1.3265700.
Повний текст джерелаАнотація:
In some heat exchangers and steam generators, the flow is predominantly axial, and the external fluid flows between baffled compartments through enlarged holes in the baffles around the heat exchanger tubes. Thus, the tube is subjected to relatively high flow velocities over small portions of its length, in the baffle locations. In this paper, the dynamics of such an idealized system is investigated, involving a cylindrical beam with pinned ends in axial flow, going through a baffle plate of finite thickness at some intermediate point, with small radial clearance. The fluid forces along the tube are formulated in a manner reminiscent of the transfer-matrix technique, since the character of these forces changes drastically along the tube. The fluid forces are determined approximately by means of potential flow theory, and viscous effects are taken into account only in a global sense. It was found that if the flow passage through the baffle plate is diffuser-shaped, negative fluid-dynamic damping is generated therein, destabilizing the system and leading to flutter at relatively low flow velocities. The instability depends critically on the shape of the hole through the baffle and on the clearance; thus a convergent-type flow passage does not lead to instability. The negative fluid-dynamic damping is linearly proportional to the flow velocity through the baffle.
5
Abu-Hijleh, Bassam A/K. "Mixed Convection From a Cylinder With Low Conductivity Baffles in Cross-Flow." Journal of Heat Transfer 124, no. 6 (December 1, 2002): 1064–71. http://dx.doi.org/10.1115/1.1518494.
Повний текст джерелаАнотація:
The problem of laminar mixed convection from an isothermal cylinder with low conductivity baffles in cross flow was solved numerically. The average Nusselt number was calculated at different combinations of number of baffles, baffle height, Reynolds number, and buoyancy parameter. The reduction in the Nusselt number is as much as 75 percent. When using a small number of baffles at low values of buoyancy parameter, an odd number of baffles reduced the Nusselt number more than an even number of baffles, especially at high values of Reynolds number. This is not the case at high values of buoyancy parameter. There is an optimal baffle height, Reynolds number dependent, for maximum heat transfer reduction beyond which an increase in baffle height does not result in further decrease in heat transfer.
6
Menni, Younes, Ahmed Azzi, and A. Chamkha. "Modeling and analysis of solar air channels with attachments of different shapes." International Journal of Numerical Methods for Heat & Fluid Flow 29, no. 5 (May 7, 2019): 1815–45. http://dx.doi.org/10.1108/hff-08-2018-0435.
Повний текст джерелаАнотація:
Purpose This paper aims to report the results of numerical analysis of turbulent fluid flow and forced-convection heat transfer in solar air channels with baffle-type attachments of various shapes. The effect of reconfiguring baffle geometry on the local and average heat transfer coefficients and pressure drop measurements in the whole domain investigated at constant surface temperature condition along the top and bottom channels’ walls is studied by comparing 15 forms of the baffle, which are simple (flat rectangular), triangular, trapezoidal, cascaded rectangular-triangular, diamond, arc, corrugated, +, S, V, double V (or W), Z, T, G and epsilon (or e)-shaped, with the Reynolds number changing from 12,000 to 32,000. Design/methodology/approach The baffled channel flow model is controlled by the Reynolds-averaged Navier–Stokes equations, besides the k-epsilon (or k-e) turbulence model and the energy equation. The finite volume method, by means of commercial computational fluid dynamics software FLUENT is used in this research work. Findings Over the range investigated, the Z-shaped baffle gives a higher thermal enhancement factor than with simple, triangular, trapezoidal, cascaded rectangular-triangular, diamond, arc, corrugated, +, S, V, W, T, G and e-shaped baffles by about 3.569-20.809; 3.696-20.127; 3.916-20.498; 1.834-12.154; 1.758-12.107; 7.272-23.333; 6.509-22.965; 8.917-26.463; 8.257-23.759; 5.513-18.960; 8.331-27.016; 7.520-26.592; 6.452-24.324; and 0.637-17.139 per cent, respectively. Thus, the baffle of Z-geometry is considered as the best modern model of obstacles to significantly improve the dynamic and thermal performance of the turbulent airflow within the solar channel. Originality/value This analysis reports an interesting strategy to enhance thermal transfer in solar air channels by use of attachments with various shapes
7
Habib, M. A., A. M. Mobarak, M. A. Sallak, E. A. Abdel Hadi, and R. I. Affify. "Experimental Investigation of Heat Transfer and Flow Over Baffles of Different Heights." Journal of Heat Transfer 116, no. 2 (May 1, 1994): 363–68. http://dx.doi.org/10.1115/1.2911408.
Повний текст джерелаАнотація:
The phenomenon of flow separation in ducts with segmented baffles has many engineering applications, for example, shell-and-tube heat exchangers with segmented baffles, labyrinth shaft seals, laser curtain seals, air-cooled solar collectors, and internally cooled turbine blades. In the present work, an experimental investigation has been done to study the characteristics of the turbulent flow and heat transfer inside the periodic cell formed between segmented baffles staggered in a rectangular duct. In particular, flow field, pressure loss, and local and average heat transfer coefficients were obtained. The experimental runs were carried out for different values of Reynolds numbers and baffle heights (window cuts) at uniform wall heat flux condition along the top and bottom walls. The results indicate that the pressure loss increases as the baffle height does, for a given flow rate. Also, the local and average heat transfer parameters increase with increasing Reynolds number and baffle height. However, the associated increase in the pressure loss was found to be much higher than the increase in the heat transfer coefficient.
8
Eisinger, F. L., and R. E. Sullivan. "Suppression of Acoustic Waves in Steam Generator and Heat Exchanger Tube Banks." Journal of Pressure Vessel Technology 125, no. 2 (May 1, 2003): 221–27. http://dx.doi.org/10.1115/1.1565079.
Повний текст джерелаАнотація:
Tube banks located in flow channels and exposed to crossflow have a low resistance to acoustic resonance and vibration in general. Such resistance can be increased substantially by placing acoustic baffles inside the tube banks. The locations and the number of baffles play an important role in the degree of their effectiveness of suppressing acoustic waves. One or two baffles placed within a tube bank will raise the threshold to acoustic vibration significantly. Optimum baffle locations suppressing acoustic resonance and vibration or reducing noise levels at resonance can be determined. A general procedure based on acoustic particle velocity mode shape functions is presented for the evaluation of the acoustic baffle effects.
9
Ren, Lv, Yinjie Zou, Jinbo Tang, Xin Jin, Dengsong Li, and Mingming Liu. "Numerical Modeling of Coupled Surge-Heave Sloshing in a Rectangular Tank with Baffles." Shock and Vibration 2021 (May 31, 2021): 1–11. http://dx.doi.org/10.1155/2021/5545635.
Повний текст джерелаАнотація:
Liquid sloshing under coupled surge and heave excitations in a rectangular tank has been numerically investigated by applying a Navier–Stokes solver. Fieriest coupled sloshing was further considered, and the internal baffle was expected to suppress the violent sloshing wave. After getting fully validated against available results from the literatures, the numerical model was applied to research coupled sloshing, and both vertical baffle and horizontal baffle have been considered. Due to the strong vortexes created by the sharper corners of the baffles and the reduction of the effective water bulk climbing through the tank walls, the sloshing was dramatically reduced. The increase of the baffle distance away from the tank bottom led to a decrease in the sloshing wave. It was noted that the baffle near the free surface caused the maximal dissipation. The frequency response of the sloshing wave was accordingly illustrated.
10
Fernandes, Erica Jacqueline, and Sachidananda Hassan Krishanmurthy. "Design and analysis of shell and tube heat exchanger." International Journal for Simulation and Multidisciplinary Design Optimization 13 (2022): 15. http://dx.doi.org/10.1051/smdo/2022005.
Повний текст джерелаАнотація:
The demand for consumption of energy in industries has made designers to build efficient heat transfer exchangers. One of the most used heat exchangers which supports this is the shell and tube heat exchangers which are built for effective heat transfer. These heat exchangers are widely utilized in the HVAC industries especially in chiller plants due to their large surface for heat transfer. So, design of these chillers is influenced by the selection of material. This research paper discusses the design and analysis of shell and tube heat exchangers by considering different material and their ability to transfer heat from the surface. So, baffles play an important role to analyze the performance of the heat exchangers and it is possible to improve their heat transfer capabilities. So, in this research paper baffle spacing and its effect on heat transfer has been analyzed using CFD analysis and compared these results with the theoretical analysis. The Design and modelling of the heat exchanger have been modelled using PTC Creo parametric and using ANSYS Fluent CFD analysis have been carried out considering copper, aluminum, and steel as the materials. From this analysis it can be stated that copper has performed well as compared to aluminum and steel by using minimum baffle spacing.
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Harutyunyan, Davit, Michal Košál, Stanislav Vandlík, Anna Hojná, Martin Schulc, and Stanislav Flibor. "Estimation of material degradation of VVER-1000 baffle." EPJ Web of Conferences 153 (2017): 07019. http://dx.doi.org/10.1051/epjconf/201715307019.
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12
Wang, Jiadong, Jinxing Liu, and Dan Wang. "Coupled Responses in a Partially Liquid-Filled Cylindrical Tank with the Single Flexible Baffle under Pitching Excitations." Shock and Vibration 2019 (July 1, 2019): 1–15. http://dx.doi.org/10.1155/2019/9854187.
Повний текст джерелаАнотація:
Antisloshing baffles are widely used in many engineering fields, including aerospace, ocean engineering, and nuclear engineering. The semianalytical scheme is proposed to explore the effect of the single flexible baffle on the coupled responses in the rigid cylindrical tank partially filled with ideal liquid undergoing the pitching excitation. The function series for the velocity potential, the dynamic deflection of the flexible baffle, and the surface wave height are given by introducing the time-dependent generalized coordinates. The Stokes–Joukowski potentials which are contained in the liquid velocity potential can be solved analytically. According to the dynamic and kinematic equations for the free surface and the coupled vibration equation for the flexible baffle, the coupled dynamic response equations are obtained. The additional damping terms are introduced to account for the sloshing damping. The semianalytical method is validated by the comparison study with the numerical results. Parameter studies are conducted to investigate the effects of the parameters of the flexible baffle on the coupled responses of the system.
13
Thao, Pham Ba, Duong Cong Truyen, and Nguyen Minh Phu. "CFD Analysis and Taguchi-Based Optimization of the Thermohydraulic Performance of a Solar Air Heater Duct Baffled on a Back Plate." Applied Sciences 11, no. 10 (May 19, 2021): 4645. http://dx.doi.org/10.3390/app11104645.
Повний текст джерелаАнотація:
In this paper, a solar air collector duct equipped with baffles on a back plate was numerically investigated. The Reynolds number (Re) was varied from 5000 to 20,000, the angle baffle (a) from 30° to 120°, the baffle spacing ratio (Pr) from 2 to 8, and the baffle blockage ratio (Br) from 0.375 to 0.75 to examine their effects on the Nusselt number (Nu), the friction factor (f), and the thermohydraulic performance parameter (η). The 2D numerical simulation used the standard k-ε turbulence model with enhanced wall treatment. The Taguchi method was used to design the experiment, generating an orthogonal array consisting of four factors each at four levels. The optimization results from the Taguchi method and CFD analysis showed that the optimal geometry of a = 90°, Pr = 6, and Br = 0.375 achieved the maximum η. The influence of Br on all investigated parameters was considerable because as Br increased, a larger primary vortex region was formed downstream of the baffle. At Re = 5000 and the optimal geometry parameters, a maximum η of 1.01 was reached. A baffle angle between 60° and 90° achieved a high Nusselt number due to the impingement heat transfer.
14
Djunur, Lutfi Hair. "Study On Scouring and Protection of USBR-III Type Downstream of Spillway." Jurnal Teknik Sipil dan Perencanaan 24, no. 1 (April 30, 2022): 62–71. http://dx.doi.org/10.15294/jtsp.v24i1.34196.
Повний текст джерелаАнотація:
Abstract. In the downstream part of the spillway building, especially in the flood way, occurs phenomenon of changing flow conditions from super critical to sub critical which causes a hydraulic jump and used by energy absorbers to reduce flow energy. The hydraulic jump in the floodway causes scouring of the bottom, particularly in the unprotected downstream spillway. Using 3 different dimensional baffle block models provides three different discharge variations in four flow simulations. Based on the results of the analysis and planning of the baffle block, it is found that the effectiveness in protecting the downstream scour of the spillway, namely baffle block dimensions of 1:1, 1:3 and 1:5. The three models of baffle blocks are used to determine the change in channel cross-section, scour pattern, scour volume and flow parameters that occur in downstream of spillway. The results showed that without baffle block was 32.80%, 1:1 baffle block was 43, 24%, 1:3 baffle block was 10.01% and 1:5 baffle block was 47.77%. The results of the drainage simulation showed that the higher the water level and the velocity of the flow at the bottom of the channel, the less the flow will be and will not be able to lift the bottom material of the channel
15
Alwan, Dhia Al-Deen H. "An Investigation of Natural Convection Heat Transfer in A Cubic Enclosure with Oriented Partial Partitions at Different Angles." Wasit Journal of Engineering Sciences 2, no. 2 (October 2, 2014): 28–46. http://dx.doi.org/10.31185/ejuow.vol2.iss2.27.
Повний текст джерелаАнотація:
Natural convection heat transfer in an enclosure provided with inclined partitions to the two adiabatic sides, heated from the bottom with uniform heat flux and cooled from the top at constant temperature is studied experimentally and numerically in this work. The inclined partitions is well covered with an insulated material, so that, it can be assumed as parts of the adiabatic walls that places on. The governing parameter, Rayleigh number, is fixed in this work within 2.6x1011, so that the effect of inclination angles of the two side’s partitions can be investigated. The inclination angles of the two baffles range as (0o ≤ and ≥ 150o). In numerical solution the effect of turbulence is modelled using (k-ε) model. Some applications need to use the enclosed fluid layers as insulation, so that one purpose of this work deals with improve the insulating properties of fluid layers. The experimental and numerical works are done in 36 runs, grouped into 6 collections. Each collection with 6 runs done under a fixed inclination angle of one baffle and change the second baffle inclination angle to investigate the enclosure flow field and heat transfer. The result shows that a multi cells forms when the two baffles aboard to each other’s, which is a reason to make a separation between a cold, and hot circulation cells that forms in the enclosure and act as insulator. It is also conclude that for all cases, the long insulated baffle of any inclination angle causes a reduction to the heat exchange inside the enclosure due to the damping cause to the flow field. The less average Nusselt number occurs when the two angles are equals, and the worst case is (θ=β=90o).
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Guo, Wen Yong, Lin Gen Chen, and Yu Cao. "Study on the Optimization of Absorption Baffle with Coating Material." Advanced Materials Research 644 (January 2013): 165–70. http://dx.doi.org/10.4028/www.scientific.net/amr.644.165.
Повний текст джерелаАнотація:
The absorption baffle making of viscoelastic structure with varying material can decrease effectively the sound reflection on the considerable bandwidth of sound-absorbing frequencies. In order to design the varying sectional cylindrical cavity which has better absorption result in more wide bandwidth, the mathematical model of the perforated ratio and optimization algorithm based on the genetic algorithm was designed. The simulation results based on the different rubber materials reveal that the selection of the shape of the cavity depends on the material characteristic. And the result from the optimization algorithm can be regarded as the effective referenced data.
17
Youcef, Ahmed, Rachid Saim, Hakan F. Öztop, and Mohamed Ali. "Turbulent forced convection in a shell and tube heat exchanger equipped with novel design of wing baffles." International Journal of Numerical Methods for Heat & Fluid Flow 29, no. 6 (June 3, 2019): 2103–27. http://dx.doi.org/10.1108/hff-12-2018-0754.
Повний текст джерелаАнотація:
Purpose This work presents a numerical study of the dynamic and thermal behavior of a turbulent flow in a shell and tube heat exchanger equipped with a new design of baffle type wing. The implementation of this type of baffle makes it possible to lengthen the path of the fluid in the shell, to increase the heat flux exchanged on the one hand and is to capture the weakness of the shell and tube heat exchanger with segmental baffles on the other hand. Design/methodology/approach This paper aims to analyze numerically the thermo-convective behavior of water using CFD technique by solving the conservation equations of mass, momentum and energy by the finite volume method based on the SIMPLE algorithm for coupling velocity-pressure. To describe the turbulence phenomenon, the Realizable k–ε model is employed. The analysis is done for different mass flow rates. The parameters studied are: the fluid outlet temperature, the average heat transfer coefficient, the pressure drop, the total heat transfer rate, the effect of the geometric shape of the baffle on the thermal behavior. The purpose of this study is to propose a new design of a shell and tube heat exchanger with a high heat transfer coefficient and a lower pressure drop compared to a shell and tube heat exchanger with transverse and segmental baffles. Findings The results showed that the use of the wing baffles enhanced the heat transfer coefficient significantly and reduced the friction coefficient. Compared with segmental baffles, the wing baffles are 11.67, 18.53 and 11.5 per cent lower in the pressure drop and 1.79, 1.9 and 2.39 per cent higher in the Nusselt number for the three mass flow rates 0.5, 1 and 2 kg/s, respectively. Originality/value The originality of this work lies in proposing a three-dimensional analysis for a novel heat exchanger.
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Abbasian Arani, Ali Akbar, and Hamed Uosofvand. "Improving shell and tube heat exchanger thermohydraulic performance using combined baffle." International Journal of Numerical Methods for Heat & Fluid Flow 30, no. 8 (December 6, 2019): 4119–40. http://dx.doi.org/10.1108/hff-06-2019-0514.
Повний текст джерелаАнотація:
Purpose This paper aims to investigate the fluid flow and heat transfer of a laboratory shell and tube heat exchanger that are analyzed using computational fluid dynamic approach by SOLIDWORKS flow simulation (ver. 2015) software. Design/methodology/approach In this study, several types of baffle including segmental baffle, butterfly baffle, helical baffle, combined helical-segmental baffle, combined helical-disk baffle and combined helical-butterfly baffle are examined. Two important parameters as the heat transfer and pressure drop are evaluated and analyzed. Based on obtained results, segmental baffle has the highest amount of heat transfer and pressure drop. To assess the integrative performance, performance coefficient defines as “Q/Δp” is used. Findings This investigation showed that among the presented baffle types, the heat exchangers equipped with disk baffle has the highest heat transfer. In addition, in the same mass flow rate, the performance coefficient of the shell and tube heat exchanger equipped with helical-butterfly baffle is the highest among the proposed models. Originality/value After combined helical-butterfly baffle the butterfly baffle, disk baffle, helical-segmental baffle and helical-disk baffle show their superiority of 35.12, 25, 22 and 12 per cent rather than the common segmental baffle, respectively. Furthermore, except for the combined helical-disk baffle, the other type of combined baffle have better performance compare to the basic configuration (butterfly and segmental baffle).
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Roberts, E. P. L. "A numerical and experimental study of transition processes in an obstructed channel flow." Journal of Fluid Mechanics 260 (February 10, 1994): 185–209. http://dx.doi.org/10.1017/s0022112094003484.
Повний текст джерелаАнотація:
Incompressible Newtonian flow in a two-dimensional channel with periodically placed sharp edged baffles has been studied both by numerical simulation and by experimental flow visualization. The flow was observed to be steady and symmetric at low Reynolds numbers, with recirculating eddies downstream of each baffle. At a critical Reynolds number (based on channel width and cross-sectional mean velocity) of approximately 100 the flow became asymmetric and unsteady. This transition to unsteadiness led to an eddy shedding regime, with eddies formed and shed successively from each baffle. A stability study suggested that the mechanism for transition to unsteady flow is a Kelvin–Helmholtz instability associated with the shear layer formed downstream of the sharp edged baffles. The frequency of the unsteadiness is, however, dependent on the full flow field, and not only the shear layer characteristics. Experimental observations show that the instability is followed by a secondary transition to three-dimensional disordered flow. Experimentally observed flows in the two-dimensional regime were found to be in close agreement with the numerical simulation for both the steady and unsteady flows.
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Peiravi, Mohammad Mohsen, Javad Alinejad, D. D. Ganji, and Soroush Maddah. "3D optimization of baffle arrangement in a multi-phase nanofluid natural convection based on numerical simulation." International Journal of Numerical Methods for Heat & Fluid Flow 30, no. 5 (July 31, 2019): 2583–605. http://dx.doi.org/10.1108/hff-01-2019-0012.
Повний текст джерелаАнотація:
Purpose The purpose of this study is investigating the effect of using multi-phase nanofluids, Rayleigh number and baffle arrangement simultaneously on the heat transfer rate and Predict the optimal arrangement type of baffles in the differentiation of Rayleigh number in a 3D enclosure. Design/methodology/approach Simulations were performed on the base of the L25 Taguchi orthogonal array, and each test was conducted under different height and baffle arrangement. The multi-phase thermal lattice Boltzmann based on the D3Q19 method was used for modeling fluid flow and temperature fields. Findings Streamlines, isotherms, nanofluid volume fraction distribution and Nusselt number along the wall surface for 104 < Ra < 108 have been demonstrated. Signal-to-noise ratios have been analyzed to predict optimal conditions of maximize and minimize the heat transfer rate. The results show that by choosing the appropriate height and arrangement of the baffles, the average Nusselt number can be changed by more than 57 per cent. Originality/value The value of this paper is surveying three-dimensional and two-phase simulation for nanofluid. Also using the Taguchi method for Predicting the optimal arrangement type of baffles in a multi-part enclosure. Finally statistical analysis of the results by using of two maximum and minimum target Function heat transfer rates.
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Zhang, Wen Wen, Jun Zhao, Yi Lin Cui, Liu Hua Gao, Ming Hui Ge, and Fei Bo Wang. "Simulation on Ice Slurry Cooling High Integrated Electronic Chip as a Functional Material." Advanced Materials Research 531 (June 2012): 256–60. http://dx.doi.org/10.4028/www.scientific.net/amr.531.256.
Повний текст джерелаАнотація:
Traditional cooling methods for electronic chips cannot fully meet the increasing cooling requirement of chips with high heat flux at present, so finding high-efficiency and low-cost cooling functional materials, and cooling methods with high efficiency has been a hot spot to explore. In this article, using Fluent 6, we construct a grooved channel physical model and analyze cooling effects of ethylene glycol/water ice slurry as a functional material on the chips under conditions that baffle lengths are 60mm, 80mm and 90mm, the mass flow rates are 0.4kg/s, 0.3kg/s and 0.2kg/s, and the ice fractions are 15%, 20%, 25% respectively. The results show that the chip cooling rate is increasing effectively and the temperature uniformity is better as well as the utilization rate of the latent heat is increasing as the length of baffles, the mass flow rate and the ice fraction are increasing, but the pressure loss resulted from the local effects of the inlet and corners cannot be ignored. Considering the cooling effect and the uniformity of temperature field, the length of baffles should be 83%-93% of length of flow path. In practical projects, the temperature difference between inlet and outlet should be reduced and the diameter of pipes should be decreased in order to take full advantage of the huge latent heat of the ice slurry while the ice is completely melted. Therefore, ice slurry as a functional material has a great potential to cool high integrated electronic chips.
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Wang, Zhe, Fenghui Han, Yuxiang Liu, and Wenhua Li. "Evolution Process of Liquefied Natural Gas from Stratification to Rollover in Tanks of Coastal Engineering with the Influence of Baffle Structure." Journal of Marine Science and Engineering 9, no. 1 (January 17, 2021): 95. http://dx.doi.org/10.3390/jmse9010095.
Повний текст джерелаАнотація:
During the storage process, liquefied natural gas (LNG) may undergo severe evaporation, stratification, and rollover in large storage tanks due to heat leakage, aging, or charging, causing major safety risks. Therefore, this article theoretically analyzes the causes and inducing factors of the LNG stratification and rollover phenomenon in the storage tank of coastal engineering. The computational fluid dynamics was used to establish a numerical model for the heat and mass transfer of LNG multicomponent materials in the imaginary layered interface of the storage tank, and the evolution process of LNG from spontaneous stratification to rollover was simulated. The accuracy of the mathematical model is verified by comparing numerical results with experimental data from open literature. The effects of the density difference between upper and lower layers, layering parameters, heat leakage parameters, and the baffles structure on the rollover process were studied. The effects of the interfacial surface variations are not included in this study. The results show that different baffle structures will form different boundary velocity fields, which will only affect the severity of the rollover, not the occurrence time. The larger the layering density difference, the earlier the rollover occurs. Under current conditions, the baffle structure that has the best suppression of rollover and the minimum boundary velocity is at 0.5 m above the stratified interface with the installation of the baffle at 5 degrees.
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Frese, Marianne, Matthias Bleck, and Michael Schöner. "DOWNFLOW BAFFLE BREAKWATERS LATEST DEVELOPMENTS AND LESSONS LEARNED." Coastal Engineering Proceedings 1, no. 33 (December 28, 2012): 86. http://dx.doi.org/10.9753/icce.v33.structures.86.
Повний текст джерелаАнотація:
Downflow baffle breakwaters or floating breakwaters are not as common as "full-depth" breakwaters. As a consequence the scientific work on hydraulic performance and loading is limited and most work dates back to the 1960s and 1970s. Several baffle breakwaters were planned and constructed in Germany in the last decades. Their advantages are reduced costs due to less material required and less impact on sediment transport and water quality. Experiences from different case studies and first results of a desk study on hydraulic performance and hydraulic loading will be described.
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Kim, Moonjeong, Jemyung Cha, and Jeung Sang Go. "Ring-Shaped Baffle Effect on Separation Performance of Lithium Carbonate Micro Particles in a Centrifugal Classifier." Micromachines 11, no. 11 (October 30, 2020): 980. http://dx.doi.org/10.3390/mi11110980.
Повний текст джерелаАнотація:
In this work, a centrifugal classifier for separating lithium carbonate particles, used as a cathode material for lithium-ion batteries, was investigated. This work numerically evaluates the internal flow and particle separation performance of the centrifugal classifier. The complex turbulent flow field in the classifier is key to understanding particle motion. A Reynolds stress model, to describe air flow field, and a discrete phase model, to track particle motion, were applied to a numerical simulation. Design parameters such as mass flow rate and rotor speed were investigated, and a ring-shaped baffle, in particular, was designed to investigate the effects of flow and particle separation in the centrifugal classifier. The simple geometry of the baffle changes the movement direction of unseparated particles to the rotor cage region, and increases the local air velocity in the separation zone. The numerical analysis results were verified through a baffle experiment.
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Makhnenko, O., S. Kandala, and M. Cherkashin. "Improving the Methods for Estimating Radiation Swelling and Progressive Dimensional Changes of the Elements of VVER-1000 Internals." Nuclear and Radiation Safety, no. 2(82) (June 6, 2019): 35–42. http://dx.doi.org/10.32918/nrs.2019.2(82).07.
Повний текст джерелаАнотація:
The problem in the computer prediction of radiation swelling in the elements of reactor internals when justifying VVER-1000 safe operation is quite relevant. In this regard, the approaches of the current Standard Program (PM-T.0.03.333-15) for assessing the technical condition and lifetime extension of VVER-1000 internals were considered. The paper presents various models of radiation swelling for 08Х18Н10Т steel of which elements of internals are made. A comparative analysis of the prediction results for various models has been performed. It is shown that the approaches of the current Standard Program, which take into account factors such as the stress-strain state and radiation creep of the material, are the most relevant. The influence of various fuel campaigns and their sequence on the nature of distribution and the maximum value of radiation swelling, as well as on the stress state in the baffle after long-term operation has been investigated. It is determined that the calculated stationary temperature distribution in the baffle may differ significantly depending on the input data on heat release and accumulated fluence, therefore, it must be calculated for each fuel campaign, and the calculation of the input data averaged for all fuel campaigns may lead to significant errors in the results. From the point of view of the reliability, it is also important to take into account the sequence of fuel campaigns, since, depending on the radiation swelling kinetics, the resulting baffle form can significantly change. The consequences of a possible decrease in cooling efficiency on the external surface of the baffle in the case of reducing the gap between the inner cavity and the baffle are considered, which may cause a local temperature increase in the baffle, but does not lead to a noticeable change in the radiation swelling. However, the radial displacement of the baffle due to thermal expansion increases significantly, which can cause an increase in stresses in the contact area, both in the wall of the cavity and in the baffle. According to the results of the computer analysis, recommendations were formulated to improve the approaches to estimating radiation swelling and progressive dimensional changes in the elements of VVER-1000 internals.
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Laroche, S., L. Sun, and J. Pietralik. "NUMERICAL ANALYSIS OF CAVITATION SUSCEPTIBILITY FOR STEAM GENERATOR INTEGRAL PREHEATER TUBES." AECL Nuclear Review 3, no. 01 (June 1, 2014): 37–46. http://dx.doi.org/10.12943/anr.2014.00026.
Повний текст джерелаАнотація:
A new tube degradation mechanism was observed in a recirculating steam generator (SG) with an integral preheater tube at the clearance gap between the tube and the preheater baffle. The general pattern of the damage and material composition in the degraded region suggested that the degradation was cavitation erosion. Cavitation erosion occurs when vapour bubbles exist or form in the flowing liquid and then these bubbles collapse violently in the vicinity of a solid wall. The bubbles collapse when they contact water that is sufficiently subcooled, i.e., below the saturation temperature. In the clearance gap between the tube and the preheater baffle, secondary fluid flow exists due to the pressure difference across the baffle plate. Meanwhile, heat transfer occurs from the primary-side fluid to the secondary-side fluid within this clearance gap, driven by the primary-to-secondary temperature difference. Factors such as the tube position in the baffle hole and fouling may influence the local flow and heat transfer conditions and can cause subcooled boiling that results in cavitation. This paper presents a numerical analysis of flow and heat transfer phenomena to determine the factors contributing to cavitation erosion of tubes in the preheater of a recirculating SG. The analysis used the THIRST code for a 3-dimensional thermalhydraulic simulation of steam generator and the ANSYS Fluent® code for detailed calculations of flow and heat transfer in the clearance gaps. A detailed temperature distribution in the gap was obtained using this analysis to determine the regions where subcooled boiling could occur by comparing the local fluid temperature with its saturation temperature. The susceptibility to cavitation was found to increase with increased inclination (i.e., tilt) and eccentricity (i.e., off-centre) of the tube in the baffle plate gap, and increased fouling on baffle plate surfaces. This methodology could be applied to analyze the cavitation susceptibility for other preheater types with this “tube to baffle plate” gap, as these preheaters might have conditions where boiling followed by the rapid condensation of the steam bubbles are present.
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Liu, Xin Ling, and Kai Zhao. "Tensile and Impact Behavior and Fracture Characteristics of FGH96 Powder Metallurgy Superalloy." Applied Mechanics and Materials 556-562 (May 2014): 389–94. http://dx.doi.org/10.4028/www.scientific.net/amm.556-562.389.
Повний текст джерелаАнотація:
Powder metallurgy (P/M) superalloy has not only been the primary material of turbine disk but also the main material of packing disk, packing ring and baffle plate of the aero-engine. Among these components, some parts are very thin, for example, the thinnest of baffle plate is only 2mm. The thin plate component was subjected to complex load, and the failure mode was synthetical. Some parts of component are subjected to impact load or impact-fatigue load although the nominal load of this component is fatigue load, more than one baffle plates have cracked through fast expansion and burst multiple debris because of the different local load type for the same component. It is very useful to investigate the effect on tensile and impact properties by specimen shape and shot peening. In this article, the different tests were carried out, including different specimen shape, temperature and surfaces. The results indicated that fracture strength σb and elongation δ5 were not affected by shape of specimen of P/M superalloy. Rod or plate specimens may be used to characterize the static properties of material. Shot peening would decrease the elongation,δ5 (at room temperature and 650°C) and impact work, but it did not reduce the fracture strength σb. In order to utilize adequately the component subjected to complicated loads, the surface state of the component may be treated distinctively according to the specific local load.
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Rashkovan, A., G. Ziskind, and U. Bieder. "Baffle jetting modelling." Nuclear Engineering and Design 379 (August 2021): 111233. http://dx.doi.org/10.1016/j.nucengdes.2021.111233.
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Savino, Stefano, and Carlo Nonino. "Header Shape Effect on the Inlet Velocity Distribution in Cross-Flow Double-Layered Microchannel Heat Sinks." Fluids 7, no. 1 (December 24, 2021): 7. http://dx.doi.org/10.3390/fluids7010007.
Повний текст джерелаАнотація:
Counter-flow double-layered microchannel heat sinks are very effective for thermal control of electronic components; however, they require rather complicated headers and flow maldistribution can also play a negative role. The cross-flow configuration allows a much simpler header design and the thermal performance becomes similar to that provided by the counter-flow arrangement if the velocity distribution in the microchannels is not uniform. The aim of this work is to show the possibility of achieving a favorable flow distribution in the microchannels of a cross-flow double-layered heat sink with an adequate header design and the aid of additional elements such as full or partial height baffles made of solid or porous materials. Turbulent RANS numerical simulations of the flow field in headers are carried out with the commercial code ANSYS Fluent. The flow in the microchannel layers is modeled as that in a porous material, whose properties are derived from pressure drop data obtained using an in-house FEM code. It is demonstrated that, with an appropriate baffle selection, inlet headers of cross-flow microchannel heat sinks yield velocity distributions very close to those that would allow optimal hotspot management in electronic devices.
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Ruciński, Adam, Andrzej Grzebielec, Maciej Jaworski, Rafał Laskowski, Grzegorz Niewiński, Adam Baryłka, and Artur Rusowicz. "The Problem of Smog-Particle Removal in Large Cities—Experimental Analysis of Some Filtration Materials." Energies 14, no. 23 (November 30, 2021): 8012. http://dx.doi.org/10.3390/en14238012.
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Air pollution is a significant problem in city centers. According to public health care in Poland, there is a need for local authorities to propose good purification solutions in both outdoor and indoor conditions. The main objective of this study is the development of an appropriate filtration system for public transport, especially for buses and bus stops. Firstly, the authors justify the need for air filtration in the capital of Poland, Warsaw. The average concentration level of PM10 and PM2.5 dust particles in large Polish cities is presented. In addition, it is underlined that PM2.5 dust particles are carriers for coronavirus COVID-19 and easily inhaled by humans. In the next step, the authors introduce an experimental stand used in the examination of different filtration baffles. The filtration efficiency is defined and calculated according to experimental examinations. In these experiments, an antismog cover for air-conditioning split systems, an H13 HEPA filter and a three-stage filtration baffle (active carbon + F5 filter + EPA11 filter) were taken into consideration, and the efficiency of filtration under pressure-drop conditions and the influence of moisture were ascertained. The best filter setup was thereby determined to be the three-stage filtration baffle, being the most efficient in cleaning air on account of having the smallest mass concentration of PM2.5. This indicates that three-stage filtration is the most suitable air-filtration method for public transportation in cities where air pollution is a serious concern.
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Cho, J. R., S. Y. Lee, and M. S. Song. "Dynamic response characteristics of cylindrical baffled liquid storage tank to the baffle number." Journal of Mechanical Science and Technology 33, no. 12 (December 2019): 5979–87. http://dx.doi.org/10.1007/s12206-019-1142-z.
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Wang, Yazhou, Guoliang Qin, Ximeng Ye, and Zhenzhong Bao. "SEM-based numerical framework for non-Darcy mixed convection in a porous cavity with three adiabatic thin baffles on the hot wall." International Journal of Numerical Methods for Heat & Fluid Flow 29, no. 9 (September 2, 2019): 3366–93. http://dx.doi.org/10.1108/hff-12-2018-0820.
Повний текст джерелаАнотація:
Purpose The purpose of this paper is to develop a numerical framework based on the accurate spectral element method (SEM) to simulate the mixed convective heat transfer within a porous enclosure with three adiabatic thin baffles of different lengths in nine cases and analyze the effects of several parameters. Design/methodology/approach The authors develop an improved time-splitting method to solve the Darcy–Brinkman–Forchheimer model. No extra assumptions are introduced for the intermediate velocity, and the final velocity field satisfies the incompressible constraint strictly compared with the classical method. The governing equations are split into a pure convection problem, a Stokes problem and a thermal diffusion problem. The least-squares variation is adopted for the Stokes problem, and the Galerkin variation is used for the other two problems, such that the pressure and velocity can be discretized with the same interpolation order, which benefits the numerical accuracy and program design. Findings Regarding the method, the excellent spectral accuracy, the capability of discretizing complex computational regions and the improved time-splitting methods make SEM an effective tool to accurately predict the non-Darcy convective heat transfer; as for the numerical tests, it is observed that weakened convection and heat transfer are induced by the increasing length of the baffles. The flow and heat transfer in channel 1 is only related to the length of baffle 1 because of the downward-driven right sidewall, and it is more difficult for baffle 3 to form the secondary flow on its tip. Originality/value A novel numerical framework for Darcy–Brinkman–Forchheimer model is developed, expanding the application of SEM for simulating non-Darcy convective heat transfer to improve the numerical accuracy. Numerical results and analysis for flow and heat fields could help designers understand the control of heat transfer using adiabatic baffles better.
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Karimi Chahartaghi, Morteza, Sohrab Nazari, and Mohsen Solimani Babarsad. "Investigating the Effects of the Block Geometries and Sidewall Divergences on the Local Scour Downstream of Baffled Chute Spillways." Advances in Civil Engineering 2020 (October 14, 2020): 1–14. http://dx.doi.org/10.1155/2020/2978602.
Повний текст джерелаАнотація:
Due to the lack of any specific study about the sidewalls and other blocks’ changes in the case of hydraulic and scour downstream, the present study was conducted to investigate this issue. For this purpose, drainage projects and spillway chutes, as well as many baffle block chutes, were designed and constructed with the parallel sidewalls and trapezoidal shape using the U.S. Bureau of Reclamation (USBR) instructions. Three divergence ratios of b 1 / b 2 = 1.45 , 1.75 , and 2.45 , a parallel sidewall of b 1 / b 2 = 1 , and also three geometry blocks including trapezoidal USBR, trihedral, and semicircle blocks were applied and tested in the hydraulic laboratory using a baffle chute with the slope of (2 : 1), (H : V). The material used in this study was sediment sand with a uniform grain size of d50 = 1.2 mm, 15 cm of thickness, and 2 m of length. The experiment was conducted with seven different discharges in lasting condition, and the flow characteristic and scour hole dimensions were measured. The results revealed that in comparison with the USBR blocks, changes in the baffle sidewall and block shape made an approximate 50% reduction in the maximum depth of the scour hole. Thus, increasing the divergence ratio from 1 to 2.45 had a significant effect on reducing the maximum depth and the topographic shape of the scour hole. According to the range mentioned in the literature for the Weber number, the scale effect was negligible for the chute with baffle blocks. Generally, it can be concluded that the sidewall changes also can make a reduction in the number of overbaffle blocks, causing a reduction in the construction cost.
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Cong, Jing, Di Cui, Fei Yu, Jia Yuan Wang, and Li Quan Xie. "Hydromechanical Analysis of Desilting Mechanism of Ecological Arc-Shaped Baffle Fishway." Advanced Materials Research 511 (April 2012): 154–58. http://dx.doi.org/10.4028/www.scientific.net/amr.511.154.
Повний текст джерелаАнотація:
In this paper, we developed a new type of ecological Denil fishway installed with arc-shaped baffles which can split upstream flow to improve the flow condition for fish migration. In fact, the arc-shaped is based on architectonics theory and imitate the mechanism of architectonics.So it has good effectiveness. During the construction course, building materials can be used to improve efficiency.By setting water flow orifices near the V-shaped notch, the energy dissipation can be increased as result of the interaction between the water from the orifices and the water from the notch. The sand or other sediments accumulated on the fishway floor can be washed away by the flow through desilting orifices, meeting the requirement of purificating the fishway and providing a clear environment for fish species. Model tests were conducted to investigate the desilting capability of the ecological arc-shaped baffle fishway and the results agree well with the hydromechanical analysis.
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Surojo, Eko, Raka Pungkas Aji, Triyono Triyono, Eko Prasetya Budiana, and Aditya Rio Prabowo. "Mechanical and Microstructural Properties of A36 Marine Steel Subjected to Underwater Wet Welding." Metals 11, no. 7 (June 22, 2021): 999. http://dx.doi.org/10.3390/met11070999.
Повний текст джерелаАнотація:
Underwater wet welding (UWW) is applied to repair basic offshore structures, underwater pipelines, water transportation, docks, and port equipment. The underwater wet welding method used in the current research was shield metal arc welding (SMAW), and this was conducted on an A36 steel plate. We investigated the effect of a water temperature of 10 ± 5 °C and different types of water flow (without flow, non-uniform flow with baffle bulkhead, and non-uniform flow without baffle bulkhead). The defects found on the specimen included spattering, irregular surfaces, porosity, and undercutting. A high cooling rate led to the formation of more acicular ferrite (AF) phases in the weld metal area than a slow cooling rate. The microstructure of the heat affected zone (HAZ) area led to the formation of finer and small grains. Values of tensile, impact, and hardness strength were greater with higher cooling rates. The highest tensile strength value was 585.09 MPa, and this occurred with non-uniform flow without a baffle bulkhead. The highest values of absorbed energy and impact strength were 41.9 J and 2.05 J/mm2, respectively, and these occurred with a non-uniform flow without a baffle bulkhead. The greatest hardness values were found with a non-uniform flow without a baffle bulkhead in the weld metal area.
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Zhou, Yihui, Xi He, Wang Li, Tao Xu, Dong Xie, Xin Dai, Zhang Liu, Hanqing Wang, and Gang Yu. "Separating paint mist from paint spraying waste gas: mechanism, model and application." Environmental Engineering Research 26, no. 5 (October 16, 2020): 200464–0. http://dx.doi.org/10.4491/eer.2020.464.
Повний текст джерелаАнотація:
The paint spraying waste gas contains a large amount of paint mist, volatile organic compounds (VOCs) and other hazardous materials, which seriously affects human health and atmospheric environment. Paint mist cannot be separated from paint spraying waste gas effectively by the existing dry filtration methods because of the filter blocking. A new separation process and a novel coupling device with high separation efficiency have been developed. A numerical model was established to optimize the structure and operation parameters of the baffle interceptor by hydrodynamics method which verified by the coupling device experiment. From the simulating results, when plate spacing was 20 mm, folding angle was 90° and airflow velocity was up to 8 m/s, the separation efficiency of paint mist with the diameter of 15 μm was 84.7% and the pressure drop of the baffle interceptor was 220.2 Pa. Experiment was conducted under the above-optimized conditions, and the results showed that the pressure drop of the baffle interceptor was 303.33 Pa, and the paint mist separation efficiencies of the baffle interceptor and the interception-filtration coupling device were 78.34% and 96.38%, respectively.
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XIONG, SIYUE, and XUEYE CHEN. "NUMERICAL SIMULATION OF THREE-DIMENSIONAL PASSIVE MICROMIXER WITH VARIABLE-ANGLE GROOVES AND BAFFLES." Surface Review and Letters 28, no. 05 (March 22, 2021): 2150037. http://dx.doi.org/10.1142/s0218625x21500372.
Повний текст джерелаАнотація:
In this paper, we have studied the effect of variable-angle grooves and baffles on the mixing efficiency of the micromixer. In order to explore the influence on the micromixer with different types of grooves and baffles, we designed grooves and baffles with different geometric parameters and placed them in T-channels to interfere with fluid flow. We studied VAM30∘ (variable-angle grooves and baffles micromixer with an angle of 30∘) directions and distributions as well as their different groove depths and baffle heights affect the mixing performance. We tried to divide the grooves and baffles into five groups, and discussed the effects of staggered depth and height on mixing efficiency. The mixing efficiencies of micromixer in the Re (Reynolds number) range of 0.1–100 were calculated, and the fluid flow in the microchannel was analyzed. The simulation results show that VAM30∘ is more favorable for solution mixing. The mixing efficiency of the micromixer could reach 98.9% with the change of different geometric parameters. This is because when the structure changes, the flow state of the fluid is improved, which is conducive to lengthening the residence time of the fluid in the channel. With the increase of Re, it is also conducive to enhancing the chaotic convection and improving the mixing efficiency.
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Jia, Qian, Cun Yi Song, Zhen Song Tong, Dong Hui Zhang, Kai Hua Chen, Xi Ning Lu, and Yue Zhang. "Motion Simulation of Desulfurized Fly Ash in Dense Flow Absorber Based on Computational Fluid Dynamics." Advanced Materials Research 694-697 (May 2013): 621–25. http://dx.doi.org/10.4028/www.scientific.net/amr.694-697.621.
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The motion track of desulfurized fly ash in flue gas was simulated by means of Fluent software. The abrasion and deposition of desulfurized fly ash to inner surface and other internals inside of dense flow absorber were studied. The results show that, under the simulated condition, the flue gas streamline is uniform inside of dense flow absorber which is installed with the equipment of baffle plates and four-layer delta wing plates. The desulfurized fly ash could be distributed uniformly and the pressure loss is approximately 340Pa. The abrasion rate of desulfurized fly ash to No.1 baffle plate is higher and the distribution is relatively concentrated, however, the abrasion rate of desulfurized fly ash to other layers of baffle plate and delta wing plate is lower and the distribution is relatively uniform. Besides, the abrasion rate of the dense flow absorber top and the A-convex surface is higher as well. Most desulfurized fly ash deposits on the bottom of ash hopper and some deposits on parts of baffle plates and delta wing plates. The deposition rate of B-convex surface is higher than that of A-convex surface. In reality, the highly corrosive parts inside of dense flow absorber should adopt wear-resistant materials. Meanwhile, water content of desulfurized fly ash should be controlled to avoid hardening of desulfurized fly ash which is deposited.
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Duan, Zhenya, Feng Shen, Xing Cao, and Junmei Zhang. "Comprehensive effects of baffle configuration on the performance of heat exchanger with helical baffles." Nuclear Engineering and Design 300 (April 2016): 349–57. http://dx.doi.org/10.1016/j.nucengdes.2016.02.010.
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Xi, Yuan, Yong-liang Zhang, Xi-long Zhang, and Yan Dai. "Enhancement of particle collection efficiency considering the structural interplay: particle motion characteristics analysis." Mechanics & Industry 21, no. 6 (2020): 618. http://dx.doi.org/10.1051/meca/2020093.
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The vacuum-blowing cleaning system, utilizing positive and negative pressure mixed-delivery theory, has been adopted for the road sweeper vehicle. To enhance the solid particle separation performance and to evaluate the motion characteristics of inhaled particles under different structural parameters, the gas-solid flow in the vacuum-blowing cleaning system was investigated by using computational fluid dynamics (CFD) technology. The influence of the main structural parameters on the grade dust collection efficiency and average detention time of the inhaled particles was determined, such as suction-inlet diameter, suction-inlet inclination angle, and front baffle inclination angle. And the interplay between them was also investigated. In addition, a dust collection efficiency model was built, based on uniform design (UD) and multiple regression analysis (MRA), and subsequently verified via experiments. The results revealed that the structural parameters have significant influence on the dust collection performance. The suction-inlet diameter, front baffle inclination angle, and suction-inlet inclination angle exerted the highest, second-highest, and lowest influence, respectively. Furthermore, the interaction among structural parameters also influenced the collection performance. The highest, second-highest, and lowest levels of influence were determined for the inlet diameter/baffle inclination angle, inlet inclination angle/baffle inclination angle, and inlet diameter/inlet inclination interactions, respectively. The highest dust collection efficiency (i.e., 96.10%) and a short average detention time of particles in the chamber were realized under the following conditions: suction-inlet diameter and inclination angle: 200 mm and 110°, respectively, and front baffle inclination angle: 105°.
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Feng, Shuangchang, Jie Chen, and Wenhao Shen. "Research on a new designed upward turning comb of escalator." Journal of Physics: Conference Series 2264, no. 1 (April 1, 2022): 012005. http://dx.doi.org/10.1088/1742-6596/2264/1/012005.
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Abstract Escalator is an important transportation method for people in their daily life. The comb fixed at the entrance and exit is an important component of the escalator. Its function is to facilitate the transportation of passengers and prevent the escalator from being damaged by foreign matters to a certain extent. In order to avoid harm to passengers caused by the comb, the end of the comb should be made of easily broken material traditionally such as plastic and aluminum to ensure that the object can be released when clamped. This greatly increases the loss of comb and the repair time of maintenance personnel and leaves potential safety hazards. The article researches a new designed upward turning comb of escalator. The device comprises comb plate, mounting base, guide rod, spring, comb teeth, rotating shaft, upper baffle, chute, notch, mounting hole, long hole, guide hole, lower baffle, positioning block and arc push block. Compared with the prior technology, this new comb has the advantages of simple structure, convenient operation, repeated use, difficult to damage.
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YU, Junquan. "Effect of Baffle-block on Material Flow Velocity during Thin-walled Hollow Aluminum Profile Extrusion." Journal of Mechanical Engineering 48, no. 16 (2012): 52. http://dx.doi.org/10.3901/jme.2012.16.052.
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Čajová Kantová, Nikola, Alexander Čaja, Marek Patsch, Michal Holubčík, and Peter Ďurčanský. "Dependence of the Flue Gas Flow on the Setting of the Separation Baffle in the Flue Gas Tract." Applied Sciences 11, no. 7 (March 25, 2021): 2961. http://dx.doi.org/10.3390/app11072961.
Повний текст джерелаАнотація:
With the combustion of solid fuels, emissions such as particulate matter are also formed, which have a negative impact on human health. Reducing their amount in the air can be achieved by optimizing the combustion process as well as the flue gas flow. This article aims to optimize the flue gas tract using separation baffles. This design can make it possible to capture particulate matter by using three baffles and prevent it from escaping into the air in the flue gas. The geometric parameters of the first baffle were changed twice more. The dependence of the flue gas flow on the baffles was first observed by computational fluid dynamics (CFD) simulations and subsequently verified by the particle imaging velocimetry (PIV) method. Based on the CFD results, the most effective is setting 1 with the same boundary conditions as those during experimental PIV measurements. Setting 2 can capture 1.8% less particles and setting 3 can capture 0.6% less particles than setting 1. Based on the stoichiometric calculations, it would be possible to capture up to 62.3% of the particles in setting 1. The velocities comparison obtained from CFD and PIV confirmed the supposed character of the turbulent flow with vortexes appearing in the flue gas tract, despite some inaccuracies.
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Armaghani, Taher, A. Kasaeipoor, Mohsen Izadi, and Ioan Pop. "MHD natural convection and entropy analysis of a nanofluid inside T-shaped baffled enclosure." International Journal of Numerical Methods for Heat & Fluid Flow 28, no. 12 (December 3, 2018): 2916–41. http://dx.doi.org/10.1108/hff-02-2018-0041.
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Purpose The purpose of this paper is to numerically study MHD natural convection and entropy generation of Al2O3-water alumina nanofluid inside of T-shaped baffled cavity which is subjected to a magnetic field. Design/methodology/approach Effect of various geometrical, fluid and flow factors such as aspect ratio of enclosure and baffle length, Rayleigh and Hartmann number of nanofluid have been considered in detail. The hydrodynamics and thermal indexes of nanofluid have been described using streamlines, isotherms and isentropic lines. Findings It is found that by enhancing Hartmann number, symmetrical streamlines gradually lose symmetry and their values decline. It is found that by enhancing Hartmann number, symmetrical streamlines gradually lose symmetry and their values decline. The interesting finding is an increase in the impact of Hartmann number on heat transfer indexes with augmenting Rayleigh number. However, with augmenting Rayleigh number and, thus, strengthening the buoyant forces, the efficacy of Hartmann number one, an index indicating the simultaneous impact of natural heat transfer to entropy generation increases. It is clearly seen that the efficacy of nanofluid on increased Nusselt number enhances with increasing aspect ratio of the enclosure. Based on the results, the Nusselt number generally enhances with the larger baffle length in the enclosure. Finally, with larger Hartmann number and lesser Nusselt one, entropy production is reduced. Originality/value The authors believe that all the results, both numerical and asymptotic, are original and have not been published elsewhere.
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Kawamura, K., and A. Yasuo. "Turbulence-Induced Vibration of Tube Bundle in Cross and Parallel Jet Mixed Flow." Journal of Pressure Vessel Technology 111, no. 4 (November 1, 1989): 352–60. http://dx.doi.org/10.1115/1.3265691.
Повний текст джерелаАнотація:
In the multi-tube type of heat exchanger, baffle plates are located at appropriate intervals to support the heat transfer tubes. Depending on the baffle plate type employed, the flow field in the tube bundle will consist of a mixture of the cross flow (the fluid flows at right angles to the tube bundle along the baffle plate surfaces) and the parallel jet flow (the fluid streams through channels such as the flow holes of the baffle plates in the form of jets and flows in parallel with the tube bundle). Vibrations induced by the flow can cause fretting wear and fatigue of the heat transfer tubes. Therefore, it it essential to establish a method of evaluating heat transfer tube vibrations induced by the mixed flow for the purpose of evaluating the integrity of heat exchanger tubes. In this paper, three different flows, that is, cross, parallel jet and mixed flows, were simulated in order to clarify the relationships between the flow conditions and vibration of the tube bundle, and to study a method for evaluating tube bundle vibrations induced by turbulence in the mixed flow field by using the vibration characteristics in the cross flow field and the parallel jet flow field.
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V. Harika and Dr. K. Vasantha Kumar. "Modeling and Performance Analysis of AC Plant Heat Exchanger." September 2021 7, no. 09 (September 27, 2021): 35–40. http://dx.doi.org/10.46501/ijmtst0709007.
Повний текст джерелаАнотація:
AC plant Chiller is considered as a shell-and-tube heat exchanger and generally applied in a water-cooled chiller. These days shell and tube heat exchanger (STHX) is the most common type of heat exchanger broadly used in marine ships, due to its high pressure application. The AC plants fitted on-board Marine ships consist of a Chiller i.e. parallel flow heat exchanger with baffles. It is important to improve the performance of a chiller so that the usage of electrical energy can be reduced while the quality of a product can be increased. The water is cooled by using refrigerant in this chiller. This project mainly deals with modeling the prototype of basic geometry of shell and tube heat exchanger using Solidworks and meshing using simulation run using CFD package ANSYS. In this paper, by varying the number of baffles and different fluids they are water, R134a and R410a their performance of the chiller is studied. In this work, effect of the baffle spacing on the performance of a heat exchanger has been examined. Thermal and fatigue analysis is done in ANSYS for two materials Aluminum and Copper for better fluid at from CFD analysis.
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Liu, Jian, and Xiangzhe Zhu. "Chaotic mixing analysis of a novel single-screw extruder with a perturbation baffle by the finite-time Lyapunov exponent method." Journal of Polymer Engineering 39, no. 3 (February 25, 2019): 287–99. http://dx.doi.org/10.1515/polyeng-2018-0037.
Повний текст джерелаАнотація:
Abstract The single-screw extruder with a perturbation baffle is a novel piece of equipment for polymer processing, in which the polymer melts undergo complex chaotic mixing. In this paper, from a new Lagrangian perspective, the fluid transporting mechanism in chaotic flow of the unwound screw channel was analyzed based on the finite element method. Firstly, two-dimensional velocity distributions in the unwound screw channel were calculated based on the mesh superposition technique. Fluid particle evolution processes in the extruder were tracked based on the fourth-order Runge-Kutta scheme. The numerical method used in this paper was validated by grid independence and experiments obtained from literature. Moreover, the finite-time Lyapunov exponent (FTLE) and Poincaré sections were adopted to discuss the chaotic mixing in the novel single-screw extruder. The effects of baffle width and height on the manifold structures in the flow dynamic system were analyzed. The results show that the homoclinic point of the manifold structure can give rise to chaotic mixing in the single-screw extruder. The height of the baffle is an important parameter to control the chaotic strength. In a way, increasing the height of the baffle can enlarge the kink scale and increase the stretching and folding actions, which results in the decrease of regular regions and an increase of the mixing efficiency in the single-screw extruder.
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Manta (Balaş), Oana‐Maria, Radu Balaş, Roman Murzac, Mihaela Ulmeanu, and Cristian Vasile Doicin. "Statical Analysis of Slosh Noise Baffle." Macromolecular Symposia 389, no. 1 (February 2020): 1900119. http://dx.doi.org/10.1002/masy.201900119.
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Ghobadi, Behzad, Farshad Kowsary, and Farzad Veysi. "Optimization of heat transfer and pressure drop of the channel flow with baffle." High Temperature Materials and Processes 40, no. 1 (January 1, 2021): 286–99. http://dx.doi.org/10.1515/htmp-2021-0030.
Повний текст джерелаАнотація:
Abstract In this article, the numerical analysis has been carried out to optimize heat transfer and pressure drop in the horizontal channel in the presence of a rectangular baffle and constant temperature in two-dimension. For this aim, the governing differential equation has been solved by computational fluid dynamics software. The Reynolds numbers are in the range of 2,000 < Re < 10,000 and the working fluid is water. While the periodic boundary condition has been applied at the inlet, outlet, and the channel wall, axisymmetric boundary condition has been used for channel axis. For modeling and optimizing the turbulence, k–ω SST model and genetic algorithm have been applied, respectively. The results illustrate that adding a rectangular baffle to the channel enhances heat transfer and pressure drop. Hence, the heat transfer performance factor along with maximum heat transfer and minimum pressure drop has been investigated and the effective geometrical parameters have been introduced. As can be seen, there is an inverse relationship between baffle step and both heat transfer and pressure drop so that for p/d equal to 0.5, 1, and 1.25, the percentage of increase in Nusselt number is 141, 124, and 120% comparing to a simple channel and the increase in friction factor is 5.5, 5, and 4.25 times, respectively. The results of modeling confirm the increase in heat transfer performance and friction factor in the baffle with more height. For instance, when the Reynolds number and height are 5,000 and 3 mm, the Nusselt number and friction factor have been increased by 35% and 2.5 times, respectively. However, for baffle with 4 mm height, the increase in the Nusselt number and friction factor is 68% and 5.57 times, respectively. It is also demonstrated that by increasing Reynolds number, the maximum heat transfer performance has been decreased which is proportional to the increase in p/d and h/d. Moreover, the maximum heat transfer performance in 2,000 Reynolds number is 1.5 proportional to p/d of 0.61 and h/d of 0.36, while for 10,000 Reynolds number, its value is 1.19 in high p/d of 0.93 and h/d of 0.15. The approaches of the present study can be used for optimizing heat transfer performance where geometrical dimensions are not accessible or the rectangular baffle has been applied for heat transfer enhancement.
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LI Yang, 李洋, 廖志波 LIAO Zhi-bo, 穆生博 MU Sheng-bo, 郭悦 GUO Yue, and 王海超 WANG Hai-chao. "Design of ultra-short embedded baffle." Optics and Precision Engineering 24, no. 11 (2016): 2683–88. http://dx.doi.org/10.3788/ope.20162411.2683.
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