Baffle Plate Research Articles

Thermal hydraulic performance of a tubular heat exchanger with in‐line perforated baffle with shutter type saw tooth turbulator

AbstractThis experimental investigation aimed to analyze the impact of a unique design of swirl generator airflow on the performance of a tubular heat exchanger operating with axial flow. To conduct the experiment, we utilized a custom‐built apparatus containing eight sawtooth air deflectors with differing space height ratios (e/h). These deflectors were oriented in a uniform manner (shutter type) and positioned at various inclination angles. Circular baffle plates, housing these deflectors, were equidistantly spaced at different pitch ratios. The arrangement of tubes within the heat exchanger remained constant throughout the study, while the Reynolds number ranged from 16,000 to 30,000. In addition, a consistent heat flux condition was maintained on the surface of the tubes. The research outcomes indicated that incorporating a deflector baffle plate with an inclination angle of 30°, an e/h ratio of 0.4, and a pitch ratio of 1.2 led to an average increase of 1.36 in the thermal enhancement factor when compared to a heat exchanger lacking a baffle plate, tested under similar conditions.

Modelling and simulation of fuel tank with increased capacity and improving its location for better stability of three wheeled vehicle

In the automotive industry, the fuel tank is an essential component of the vehicle. It is; designed as an integral part of the fuel system to transport the fuel and deliver it to the engine via the fuel filter and fuel pump. In Ethiopia, it is observed that due to the smaller fuel tank of three-wheeled vehicles, more frequent visits to fuel stations result in a lot of time being wasted waiting in long queues at fuel stations. In addition, the current location of the fuel tank causes some stability problems. Subsequently, the method, location, installation techniques and stability analysis of the three-wheeled vehicle are carried out. This study includes a new design of fuel tanks for three-wheeled vehicles in which the capacity is doubled and the rollover stability; of the vehicle is maintained. The SOLIDWORKS software and the CFD software ANSYS FLUENT for the sloshing analysis were used for the modeling of this work. The CFD results of the comparative sloshing analysis of partially filled (50% level) fuel tanks with and without baffles are performed; and conclusions are drawn. It is concluded that a baffle plate for the fuel tank offers the greatest advantage in reducing the effects of sloshing. The newly developed part is mounted on the underside of the passenger seat. A bottom-mounted fuel tank optimizes the vehicle's center of gravity, as the height of the vehicle's center of gravity is lowered by 30 mm. This increases the rollover safety of the vehicle. According to the analysis, the mileage of the filled existing and new tanks is 136 km and 272 km respectively. To refuel once, the driver waits an average of 5 h and works about two days for the existing tank and four days for the new tank.

Improved high shear mixers enhance fast halogenation reactions of alcohols

In the view of green and sustainable synthesis, there is still a broad space for improvement with respect to the halogenations of the alcohol, which is facing up with the problems of high input and low yield. Herein, high shear mixers (HSM) were exploited first to enhance the bromination of tert-butyl alcohol by improving the mixing performance. Notably, the baffle plate (BP) was first proposed to facilitate the in situ separation of the product from the reaction system, promoting the reversible reaction equilibrium to shift toward the right direction. The influences of the molar ratio of reactants, temperature, feed rate, rotor speed, and height of BP were investigated on the reaction performance, which provides a facile and cost-efficient intensified technology to prepare 2-bromo-2-methylpropane. The maximum yield is achieved as 94.8% using HSM, obviously higher than that using CST (82.6%) and HST-Impeller (87.6%), and the reaction time can be shortened by 75%. Furthermore, such HSM and BP-HSM can successfully improve the yields of some fast alcohol halogenations with shorter reaction time. This ingenious exploration of BP in HSM provides valuable guidance on design new technology to intensify some fast organic chemical reactions with the products immiscible to the reactants.

Study the effect of axially perforated baffle plate with multiple opposite-oriented trapezoidal flow deflectors in an air–water tubular heat exchanger

Purpose The research focused on analysing a unique type of heat exchanger that uses swirling air flow over heated tubes. This heat exchanger includes a round baffle plate with holes and opposite-oriented trapezoidal air deflectors attached at different angles. The deflectors are spaced at various distances, and the tubes are arranged in a circular pattern while maintaining a constant heat flux. Design/methodology/approach This setup is housed inside a circular duct with airflow in the longitudinal direction. The study examined the impact of different inclination angles and pitch ratios on the performance of the heat exchanger within a specific range of Reynolds numbers. Findings The findings revealed that the angle of inclination significantly affected the flow velocity, with higher angles resulting in increased velocity. The heat transfer performance was best at lower inclination angles and pitch ratios. Flow resistance decreased with increasing angle of inclination and pitch ratio. Originality/value The average thermal enhancement factor decreased with higher inclination angles, with the maximum value observed as 0.94 at a pitch ratio of 1 at an angle of 30°.

Low-Reynolds-number turbulent forced-convection flow over graded baffle plates

The thermo-hydraulic behaviors of turbulent forced-convection heat transfer flow over a rectangular cross section baffled channel are numerically examined in various graded baffle plate ratio configurations ‘GBR = 0.10, 0.11, 0.12, 0.13, 0.14, and 0.15) at different Reynolds numbers, ranging from 12,000 to 32,000. The governing equations that describe the flow are integrated by the finite volumes method, in two dimensions, employing the Commercial CFD software FLUENT 6.3 with low-Reynolds-number k-E model to describe the turbulence. The velocity and pressure terms of momentum equations are solved with SIMPLE-algorithm. In particular, axial velocity, turbulence intensity, pressure, and temperature fields, average Nusselt number and friction loss are obtained. The numerical runs are carried out for different values of Reynolds numbers and graded baffle ratios at constant wall temperature condition along the top and bottom walls. Results were compared with available experimental data from the literature and good agreement is obtained.

THERMO-FLUID PERFORMANCE COMPARISON OF AN IN-LINE PERFORATED BAFFLE WITH OPPOSITELY ORIENTED RECTANGULAR-WING STRUCTURE IN TURBULENT HEAT EXCHANGER

This research study examined the effects of a novel swirl airflow design on the rate of heat transfer in a tubular heat exchanger with axial flow. The novel design consisted of 16 rectangular air deflectors placed in opposite directions, positioned at varying angles of inclination. These deflectors were embedded on circular perforated baffle plates, which were spaced equidistantly apart at different pitch ratios. Hot water was supplied to heat exchanger tubes whose arrangement remained constant throughout the experiment, while atmospheric air is flown over tube bundle at Reynolds number that ranged from 16 × 10<sup>3</sup> to 3 × 10<sup>4</sup> . The effect of pitch ratio and inclination angle on the thermal enhancement factor was experimentally analyzed. The findings demonstrated that using an opposite-oriented deflector baffle plate with an inclination angle of 30 deg and a pitch ratio of 1 resulted in an average improvement of 1.17 in the thermal enhancement factor compared to a heat exchanger without a baffle plate, tested under similar conditions.

Mitigation of gas entrainment in swirling free surface flows

Gas entrainment presents a safety challenge within sodium-cooled fast reactors. This problem is similar to two-phase free surface interactions in a Taylor–Couette flow characterized by a large annulus gap (small radius ratio, η≈0.333) and highly turbulent swirling flows (Re≈105). The aim of the current work is to test strategies that could mitigate this phenomenon. A three-dimensional numerical model of the primary sodium pump annulus region involved in gas entrainment due to shaft rotation was developed, and turbulent swirling flow that occurs in the annular gap between the vessel and the shaft is investigated. The influence of baffle plates mounted on the stationary vessel with and without porosity was examined during the study. The simulation results revealed that submerged porous plates placed on the outer cylindrical wall both delayed vortex breakdown and suppressed shear waves near the surface. Both these effects substantially delayed gas entrainment into the liquid.

Computational fluid dynamics analysis for improving the uniformity of flow field in heat air drying kilns

Because the uniformity of the wind speed flow field in the hot air drying kiln directly affects the distribution of the temperature field in the kiln, to improve the uniformity of air distribution in the existing wood hot air drying kiln, CFD software was used to analyze the three-dimensional flow field of each improved scheme. A combination of visual comparison and analysis methods and data comparison and analysis methods be used, to serve as the basis for assessing the feasibility and rationality of the improvement schemes. Without adding baffle plates or altering the structure to incorporate right-angle surfaces, the kiln's structure was optimized by adjusting the position of the air outlet and installing airflow distribution chambers. This paper innovatively introduces the Theory of Inventive Problem Solving?TRIZ ?to analyze and solve the flow field optimization problem in the kiln. The difference between this method and the existing research methods is that the solution process is more logical and the solution to the fundamental problem is more accurate. The experimental results show that when the air supply speed of scheme S8 is 3m/s~7m/s, the flow field of kiln Zone C (material drying area) meets the ideal range of 1m/s~3m/s. In addition, under the same working condition (3m/s), the velocity differences of scheme S8 is closer to 0 than that of scheme S0, and the velocity unevenness coefficient is reduced by 18.44%.

Performance analysis and comparison study of liquid cooling-based shell-and-tube battery thermal management systems

To meet the temperature control requirements of lithium-ion batteries (LIBs) under high rate discharge conditions, this study designed two structurally similar shell-and-tube battery thermal management (BTM) schemes, namely air-cooled/liquid cooled coupling scheme and phase change material (PCM)/liquid cooled coupling scheme. By applying simulation methods to analyze and compare the battery temperature control performance of two schemes under different working conditions, and adopting structural optimization and heat dissipation strategies to decrease the maximum temperature and temperature difference of the battery. It can be concluded that the maximum temperature of the batteries in both cooling schemes remains below 333 K after the number of baffle plates is increased from 2 to 6 during 5C discharge. Among them, the PCM/liquid cooling scheme demonstrates superior temperature control capabilities. However, the air cooling/liquid cooling scheme can also effectively reduce the temperature difference of the battery pack to 4.7 K by frequently switching the ventilation direction. The temperature difference of the battery can be further reduced by enhancing the thermal conductivity of composite phase change materials (CPCM). It is worth noting that increasing the liquid cooling flow rate to 2.5 m/s no longer improves the cooling effect of the battery. Additionally, during each discharge stage of cyclic charging and discharging, intermittently turning off the water pump for 9 min results in the battery exhibiting favorable temperature cycling characteristics.

Bronx-Whitestone Bridge: Vertical median barrier extension enhances aerodynamics

The Bronx-Whitestone Bridge was designed during the 1930s in an era of suspension bridges with decks stiffened by shallow plate girders, many of which were subsequently found to be vulnerable to aerodynamic instabilities such as vortex shedding and flutter. Following the occurrence of mild and benign wind-induced oscillations in the first several years after opening in 1939, the bridge has undergone a series of retrofits, from structural solutions such as stay cables, stiffening trusses, and a steel orthotropic deck, to aerodynamic enhancements such as a tuned mass damper and wind fairings. Wind tunnel studies in 2015 confirmed the improved aerodynamic performance due to the recently installed wind fairing system and stiffer orthotropic deck. A subsequent rehabilitation project gave the opportunity to assess measures to further improve the aerodynamic performance of the bridge. A 3 ft (0.91 m) tall solid screen added on top of the median barrier was found to act as an above-deck vertical baffle plate, disrupting the alternating pattern of vortices, reducing the susceptibility of the bridge to instabilities. This led to the conceptual design of a Median Barrier Extension (MBE) comprised of 3 ft (0.91 m) solid transparent acrylic panels fixed to the top of the existing median barrier posts, supported by a tubular steel frame. To ensure this unique barrier modification met current industry safety standards, the MBE design was iterated through a crash analysis study using non-linear finite element models before the final design proceeded to a full-scale physical crash testing program to MASH Test Level 4. This paper presents the full timeline of this innovative retrofit project, from conception during wind tunnel testing, through to design, crashworthiness studies and final construction in 2020. This project has demonstrated that a vertical extension to a median barrier can act as a simple and cost-effective enhancement to the aerodynamic performance of existing bridges.

Inlet baffle structural optimization and reforming performance of exhaust gas-fuel reformer for marine LNG engine

The structural and boundary conditions are pivotal factors influencing the performance of the reformer. However, previous research primarily relied on tailored theoretical boundary conditions specific to the research requirements, often conducted in low airspeed conditions ranging from 700 ℃ to 1000 ℃. There is a lack of research focused on the complex and dynamic process of reforming hydrogen production process in reformers that handle exhaust gas components with high flow rates, high dilution, complex compositions, and low to medium temperatures (300 °C–600 °C) as boundary conditions. The objective of this study is to optimize the structure of the reformation reactor while exploring its hydrogen reforming characteristics. Therefore, this study focused on the simulation-based optimization design of an EGR reformer for marine natural gas engines. A comprehensive model was developed by coupling fluid flow, heat transfer, and surface reactions on a nickel-based catalyst. The accuracy of the model was validated through experimental data from a single-tube fixed-bed catalytic reforming experiment. The results highlighted the importance of the reformer design, with the optimal configuration incorporating two baffle plates positioned at angles of 15° and 35°. This design achieved the most uniform flow field and minimal pressure drop among the six investigated configurations. Furthermore, the study emphasized the significance of reforming gas composition in achieving high performance. The optimal reforming gas composition was found to have an M/O value of approximately 2 and an S/M value of approximately 1. This resulted in an outlet hydrogen concentration of approximately 18.8%, hydrogen yield of approximately 46.1%, methane conversion rate of approximately 66.2%, and an energy efficiency of 71%. It was observed that increasing the EGR rate led to a decrease in performance indicators, with a more pronounced effect observed at an M/O value of 1. This study provides valuable insights into the performance optimization of EGR reformers for marine natural gas engines. The findings offer guidance on selecting operational parameters to enhance efficiency and hydrogen production.

The effect of triangular shutter type flow deflector perforated baffle plate on the thermofluid performance of a heat exchanger

AbstractThe study aimed to investigate the heat transfer (HT) properties of a tubular heat exchanger (HX) by using innovative baffle plate arrangements. The newly designed baffle plate was circular with triangular openings and adjustable triangular flow deflectors. These deflectors were strategically placed at the inlet of the HX to create a swirling flow downstream. Three baffle plates were installed along the flow direction with different length‐to‐diameter ratios (pitch ratios) to assess their impact on HT, pressure drop, and thermal enhancement factor. The study compared these results with a smooth channel under varying Reynolds numbers (16,500–29,500). The findings revealed that both the pitch ratio (0.6–1.2) and the inclination angle of the deflectors (30⁰–50⁰) significantly affected the HX's performance. Notably, the baffle plate with a deflector inclination angle of 30° and a pitch ratio of 1 showed a remarkable average improvement of 36.5% compared to other angles and ratios.

Experimental Investigations on Single-Phase Heat Transfer Enhancement in an Air-To-Water Heat Exchanger with Rectangular Perforated Flow Deflector Baffle Plate

Experimental analysis was conducted to investigate the turbulent heat transfer behaviors within a tubular heat exchanger, incorporating a novel baffle plate design. The new design includes a perforated circular baffle plate with a rectangular flow deflector that can be adjusted to different inclination angles. The baffle plate is strategically positioned at the entrance of the heat exchanger, resulting in a swirling flow downstream. To assess the impact of the baffle plate design, three baffle plates were placed longitudinally along the flow, with varying pitch ratios (l/D). The effects of pitch ratio (ranging from 0.6 to 1.2), deflector inclination angle (ranging between 30⁰ to 50⁰), and Reynolds numbers (ranging between 16000 to 29000) were examined. The outcomes highlighted the substantial impact of pitch ratio and inclination angle on the thermal enhancement factor. In particular, compared to single segmental baffle plates working under similar operating conditions. The result indicates that an inclination angle of 30° and a pitch ratio of 1 exhibited an average 41.49% augmentation in thermal-fluidic performance compared with an exchanger with a segmental baffle plate.

On abnormal noise generated from steam gas heater

When a steam gas heater set up in a town was operated, an abnormal noise with a sound pressure level (SPL) of 120 dB was generated at 32% of the rated flow rate. In order to solve this problem, We conducted a field survey to investigate the relationship between the operating conditions and the noise. First, I identified the source of noise and next, the noise level and the mode of sound pressure level (SPL) in a duct were measured and the FFT analysis was carried out to determine the dominant frequency. The results revealed that the abnormal noise was not a mere resonance but rather a self-sustained tone due to the interference of the vortex and the sound field. Furthermore, we measured the SPL outside the gas heater duct and found that the SPL was highest at the center of the gas heater duct. Typically, the first pressure mode should be minimum at the center and maximum at both ends, but the reason for this deviation was clarified in this paper. To address the issue, multiple baffle plates were inserted in a tube array and as a result, the abnormal noise completely disappeared. It was also found that the baffle plate should be inserted at the position where the particle velocity exceeds half of the maximum value.

Mechanism and risk assessment of baffle-jetting-induced vibrations in fuel rods

As nuclear reactor cores approach the end of their lifespans, it is a crucial aspect to ensure that the structural integrity of the reactor internals is not affected. The baffle-former bolts are subjected to significant mechanical stress and neutron irradiation from the reactor core during the plant operation. These circumstances can cause the bolts to degrade and lose some of their load-bearing capacity over the reactor lifespan. The degraded baffle-former bolts can lead to separation/openings between the baffle plates which cause water jet cross-flow injecting through these openings. This phenomenon is called baffle jetting. This jet flow can induce the vibration of fuel rods located near the baffle gaps, resulting in grid-to-rod fretting and, in extreme cases, fuel rod failures.This paper investigates the risk of baffle jetting-induced fluidelastic instability in fuel assemblies. A 6 × 5 axisymmetric flexible rod bundle having a prototypical nuclear fuel assembly is designed and fabricated to simulate a part of a fuel assembly under combined axial flow and baffle jetting. A special displacement mechanism is used to vary the position of jet flow relative to the array (i.e. jet eccentricity). Two cases, the jet-gap aligned case, and the jet-rod aligned case, are investigated to determine the variation of critical jet velocity with the jet eccentricity. In addition, three axial flow velocity cases, VAxial = 1.0 m/s, 1.5 m/s, and 2.0 m/s are tested in order to determine the stability effect of axial flow velocity on jet-induced instability. The experiments show that the mock-up array response resembles fluidelastic instability behavior. The stability threshold of the mock-up array depends strongly on the relative position of the jet flow with respect to the array centerline. In the jet-rod aligned case, the axial flow shows a strong effect on the combined flow-induced instability.

Flow characteristics of radial inflow in impeller rear cavity with baffle plate

The research purpose of this paper is to explore the influence of the baffle plate on the airflow in the rear cavity of the centrifugal impeller and optimize the performance of the secondary air system's air bleed section. In this paper, a comprehensive experimental study was carried out on the flow characteristics in the impeller rear cavity with baffle plate. The windage torque, flow structure and pressure drop between inlet and outlet were measured respectively. The experiment was carried out with the condition that the range of rotational Reynolds number was from 8.33 × 105 to 22.2 × 105 and the range of mass flow rate coefficient was from 0.92 × 104 to 2.92 × 104. The results show that the static cavity and the narrow stator-rotor cavity formed by the baffle plate effectively suppress the overall swirl coefficient in the cavity. Thus, the static pressure and total pressure drop in the rotor–stator cavity were reduced. The influence of the baffle plate on the windage torque of the rotary disk is related to the turbulence parameters. Under large turbulence parameters, the windage torque would be reduced with baffle plate, while under small turbulence parameters, the baffle plate would increase with baffle plate. In general, the baffle plate can improve the flow capacity and optimize the bleed air performance with proper structure and operation conditions.

The influence of geometrical and operational parameters on thermofluid performance of discontinuous colonial self‐swirl‐inducing baffle plate in a tubular heat exchanger

AbstractAn exploratory investigation was conducted to analyze a tubular heat exchanger's turbulent heat transfer characteristics using an innovative baffle plate design. The design incorporated a perforated conical baffle plate and an adjustable rectangular deflector. The strategic placement of this baffle plate at the heat exchanger inlet facilitated a swirling flow downstream. To assess the impact of this design, three baffle plates with varying pitch ratios (l/D) were positioned in the direction of the flow. The study examined the effects of pitch ratio (ranging from 0.6 to 1.2), deflector inclination angle (ranging from 30° to 50°), and Reynolds numbers (ranging from 16,500 to 29,500). Moreover, the size of the conical baffle plate (H/D) was altered (from 0.25 to 0.15). The findings highlighted the substantial influence of pitch ratio, inclination angle, and height ratio on the heat exchanger's performance. Notably, the configuration featuring an inclination angle of 50° and height ratio of 0.15 exhibited an average performance improvement of 22% compared to other height ratios, inclination angles, and pitch ratios.

Experimental Investigation on the Correlation Between Total Pressure and Swirl Distortions

Abstract To lay the foundations of establishing low-cost methods, which can predict characteristics of swirl distortion inexpensively, experimental investigations on the correlation between total pressure and swirl distortions of an S-duct intake model are implemented. A baffle plate is installed at the inlet of the intake model to generate strong inlet flow distortions, and the flow field at the outlet of the duct is measured using five-hole probes, which are calibrated using zonal calibration algorithm. Total pressure and swirl distortions associated with the baffle plate installed at the upper part of the intake model show no correlations. When baffle plate is installed at left/right part of the intake model, strong total pressure and swirl distortions will interact with each other, and both strength and circumferential location of the two types of distortion are well correlated by linear relationships. When baffle plate is installed at the lower part of the intake model, strong total pressure and paired swirl distortions are induced, and strength of the two types of distortion is well correlated by linear relationship.

Effectiveness of a tubular heat exchanger and a novel perforated rectangular flow-deflector type baffle plate with opposing orientation

Purpose The purpose of this experimental research was to examine a novel axial heat exchanger featuring swirling air movement over heated tubes. This apparatus is designed with perforated circular baffle plates complemented by rectangular air deflectors operating at different inclination angles. The tubes were arranged in a consistent layout parallel to the longitudinal airflow. The deflector’s heightened air-side turbulence initiates the frenzied motion, escalating the surface heat transfer rate. Design/methodology/approach The tubes maintained a constant heat flux condition over the surface. In each baffle plate, eight deflectors with identical inclination angles were devised in a reverse position, forming a rotation of air inside a circular duct that held tubes (carrying hot water) which elevated air-side turbulence, thereby enhancing the rate of heat transference on the surface. The baffle plates were equally situated from each other at changing pitch ratios. The Reynolds quantity was preserved in the scope of 16,000–30,000. The performance of the heat exchanger considering pitch ratios and inclination angles was examined. Findings The research indicates that when examined under similar conditions, an exchanger with a deflector baffle plate shows a strong dependence on the pitch ratio and inclination angle with a mean rise of 0.19 times in thermal enhancement factor at an inclination angle of 30° and a pitch ratio of 1.2 contrasted with an exchanger with segmental baffle plates. Originality/value The result shows the dependence of pitch ratio, Reynolds number and inclination on the heat transfer and friction factor rate.

Validation of modeling scheme implementing MULTID component of MARS-KS code to predict shell-side pressure drop in shell-and-tube type heat exchangers

A modeling scheme to predict the pressure drop on the shell side of the shell-and-tube type heat exchanger is developed, which is using the system thermal hydraulic code, MARS-KS. In the present scheme, the shell side of the heat exchanger is modeled by the MULTID component in rectangular shape in which, the part blocked by the segmental baffle plate and the opening part by the baffle cut are modeled by separate nodes. The form loss coefficients and its distribution for the junctions of the shell side are estimated by the assumption of the same pressure drop in each cross pass of the shell and then finalized by iterative calculation. To prove the validity of the modeling scheme, calculations are made to simulate the experiments conducted at the test heat exchanger having a size used in the industries. It is discussed whether each effect of the size of inlet/outlet nozzle and the height of the baffle cut on the overall pressure drop of the heat exchanger is properly predicted and consistent with the experimental observations. Also, the effectiveness of consideration of leakage at the clearance between the shell and the segmental baffle plates is discussed in resolving the problem of over-predicted pressure drops in the high flow region. For the simplification, the use of one-dimensional modeling to this problem is attempted. The applicability of the present method and results to the different heat exchangers is also discussed.