Inlet Velocity Research Articles

Numerical Investigation of Flow Inside a Channel with Elastic Vortex Generator and Elastic Wall for Heat Transfer Enhancement

In the present investigation, a detailed numerical investigation of the flow and heat transfer characteristics of a channel with an elastic fin (vortex generator) and an elastic wall has been carried out using finite element method. The Fluid-Structure Interaction (FSI) model is used to capture the interaction between the fluid and the solid structure. A sinusoidal time dependent velocity profile has been imposed at the inlet of the channel and the right half of the upper wall of the channel is heated and exposed to constant temperature boundary condition. Due to the sinusoidal velocity profile at the inlet, the elastic fin oscillates periodically and act as a vortex generator, which causes more turbulence in the flow. The obtained results showed that the Nusselt number over the heated wall is affected by the position of the flexible fin, height of flexible fin and elasticity modulus of elastic fin. Moreover, due to the elasticity of the elastic wall and sinusoidal behavior of the inlet velocity, the elastic wall oscillates periodically upward and downward. The Nusselt number values over the heated wall are increased with decrease of the elastic modulus value of the elastic wall. However, the decrease in elastic modulus value of the elastic wall contributes to an increase in the pressure drop inside the channel. It should be added that the interplay between the fluid motion and the deformable structures leads to enhanced turbulence, as the flexible fin and elastic wall introduce additional disturbances and fluctuations into the flow regime. Consequently, this heightened turbulence level has profound implications for heat transfer processes within the system.

Thermal hydraulic and material analysis of upgraded flat-type Graphite divertor mock-up for Pakistan Spherical Tokamak (PST)

The design of a divertor is critically dependent on managing power deposition, erosion effects, and plasma configuration. An upgraded double-null divertor configuration has been developed for the Pakistan Spherical Tokamak (PST), featuring graphite targets that are actively cooled and designed to withstand a peak heat flux of 0.3 MW/m² at a pressure of 0.1 MPa. This paper presents a comprehensive thermal-hydraulic and material analysis for the upgraded flat-type divertor mock-up system, covering aspects such as material surface heat load, peak temperature rise (∆T °C) on the mock-up, and surface temperature increase in the cooling channel. The analysis includes total deformation (mm) and equivalent strain for the inner vertical target (IVT), outer vertical target (OVT), and dome structure, along with material comparison. The recommended SST K-ω turbulence model is utilized in the pressure-based transient analysis, with an inlet velocity of 1.5 m s-1 and an inlet temperature of 16.8 °C. A comparative study of the material and thermal-hydraulic analyses was performed using CFD and RELAP5. The findings reveal that graphite is more suitable than tungsten for the PST's upgraded divertor system, demonstrating its effectiveness as the preferred surface material to address heat enhancement challenges in the PST.

Numerical investigation on the thermohydraulic performance of a solar air heater duct featuring parabolic rib turbulators on the absorber plate

Solar power is a clean and sustainable energy option, widely accessible and capable of driving the creation of more sustainable systems in the future. A specialized device called the Solar Air Heater harnesses solar energy for various applications. In the current study, a novel quadratic shape ribs affixed to the absorber plate in different orientations with a transverse pattern to the flow, and one straight side and one curved side are subjected to a compressive analysis using numerical methods. The two rib orientations are shown individually, with one side being straight and the other quadratic curve. Ansys Fluent is used to examine the impacts of a number of variables on SAH performance, including rib characteristics (pitch and height) and airflow inlet velocity. The range of Reynolds numbers used for the investigation is 3400–20000, with a rib pitch ratio ranging from 6.66 to 20. The contours of pressure, temperature, and velocity are displayed to elucidate the physics of fluid flow and heat transfer. A notable enhancement is achieved, wherein an optimized case with parabolic rib turbulator SAH and rib roughness pitch of 16.66 yields a Thermal Enhancement Ratio (TER) of 2.14.

Prediction and Analysis of Borosilicate Glass Surface Deformation Induced by Flame Jet

To address the issues of low processing efficiency, poor forming accuracy, and internal damage in glass material processing, this study proposes the use of flame jet forming. However, the mechanism of flame jet processing requires further elucidation. This research investigates the relationship between the indentation morphology on the glass surface and the inlet velocity of the flame jet. A theoretical model was established through mathematical analysis to reflect this relationship. The model’s accuracy was validated using numerical simulation methods. By comparing experimental data with theoretical model results, surface tension was incorporated, and the model was iteratively optimized using MATLAB R2024a. The final optimized model demonstrated an absolute error range of 0.009 to 0.069 mm. This study confirms the feasibility of flame jet processing and enriches the understanding of its mechanism, providing a novel, efficient, and precise method for processing glass materials.

Investigation of aerodynamic processes in porous materials based on triply periodic minimal surfaces

RELEVANCE: The relevance of this work lies in the study of new porous materials for use in compact, highly efficient heat exchange devices. PURPOSE: To investigate the hydro-aerodynamic properties of flows passing through porous inserts based on triply periodic minimal surface (TPMS) topologies. To develop a methodology for studying porous materials with ordered structures. To identify potentially suitable TPMS-based porous materials for application in heat exchange equipment. METHODS: Numerical (CFD) and experimental methods were used to address the research objectives. Ansys Fluent 2019 R3 software was utilized for numerical modeling. Experimental samples for the physical experiments conducted on the VENT-08-7LR-01 laboratory setup were fabricated using SLA additive technologies. The porosity of the samples ranged from 0.73 to 0.89. The experiment was conducted with inlet velocities ranging from 0.3 to 4.5 m/s. RESULTS: New empirical dependencies of pressure drop on flow velocity were obtained for inserts based on the surfaces: Primitive (P), Fischer Koch S (FKS), Neovius (N), and Schoen's I-WP (IWP). The airflow through the N structure showed the highest pressure drop, while the P structure had 8 times less pressure drop at the same velocity. Stagnation zones, which can negatively impact heat transfer, were identified in the porous inserts. Changes in local flow velocity in the porous inserts were determined to correlate with the insert's transparency. CONCLUSION: The research results can be used for designing cooling systems with TPMS-based ribbing. Based on the analysis of the velocity vector field distribution and pressure drops, the FKS and IWP structures have potential applications in heat exchange equipment.

Numerical Investigation of Solar Collector Performance with Encapsulated PCM: A Transient, 3D Approach

This study presents a comprehensive numerical investigation into the thermal performance of solar collectors integrated with encapsulated phase change materials (PCMs) using a transient three-dimensional (3D) approach. The performance of two distinct PCMs—paraffin wax and RT60—was evaluated under varying operational conditions, including seasonal variations, inlet pipe velocities, and inlet temperatures. The results indicate that paraffin wax exhibits a higher peak temperature, reaching approximately 360 K, compared to RT60’s peak of 345 K, making paraffin wax more effective for consistent thermal energy storage. Paraffin wax also maintained higher fluid fractions, with a maximum of 0.9 in summer, indicating superior heat absorption and retention capabilities. In contrast, RT60 demonstrated a quicker phase transition, fully liquefying at a lower fluid fraction, which is advantageous for rapid heat release. Seasonal variations significantly impacted system efficiency, with the highest efficiency observed in June at 365 K and the lowest in December at 340 K. The study also found that lower inlet velocities (e.g., 0.25 L/s) significantly improved heat retention, resulting in higher outlet temperatures, while increasing the inlet temperature from 290 K to 310 K led to a marked increase in outlet temperatures throughout the day. These findings underscore the importance of optimizing PCM selection, inlet velocity, and temperature in enhancing the performance of solar thermal systems, offering quantitative insights that contribute to the development of more efficient and reliable renewable energy solutions.

Influence of inlet velocity on the separation performance of a combined hydrocyclone

Hydrocyclone separation exploits centrifugal force to differentiate particles based on their sizes and densities, yet challenges arise when small, dense particles and large, low-density ones settle at similar velocities. To address this, we propose a two-stage combined hydrocyclone for accurate separation. Using numerical simulations, we examine the internal flow field and performance of this system. Our findings reveal that the primary hydrocyclone achieves size-dependent classification, while the secondary one achieves density-dependent sorting. Increasing inlet velocity enhances separation efficiency and accuracy by improving flow field dynamics, albeit at the cost of increased energy consumption and material residence time. Thus, optimizing inlet velocity is vital for maximizing the separation performance and operational efficacy of the combined hydrocyclones.

Computational Fluid Dynamics (CFD) in Arteriovenous (AV) Graft Implantation Through End-to-Side Anastomosis with Varying Tube Diameters Across Different Vascular Access Locations for Dialysis Treatment.

Background/Objectives: Arteriovenous (AV) graft is a procedure for hemodialysis performed in the arm. Optimizing AV graft design is vital to enhance haemodialytic efficiency in patients with kidney disease. Despite being a standard procedure, making it work optimally is still difficult due to various graft diameters and anastomosis configurations, which have limited studies. This research aims to find the ideal AV graft tube diameter on blood flow and pressure gradients and the ideal body site for AV graft implantation and to study their angles for dialysate flow. Methods: Nine models were designed in Autodesk Fusion 360 with 40°, 50°, and 60° angles each having 2 mm, 5.1 mm, and 14.5 mm diameters, all following specific equations on continuity, momentum (Navier-Stokes Equation)), and the Reynolds Stress Model (RSM). The CFD simulation of these models was performed in ANSYS Fluent with an established parameter of 0.3 m/s inlet velocity and stiff/no-slip graft and artery wall boundary condition. Results: As a result, the design with a diameter of 14.5 mm and a 40° angle was overall the most ideal in terms of minimal wall shear stress and turbulence. Conclusions: Thus the brachiocephalic area or the forearm is calculated to be the most optimal implantation site. Additionally, varying angles do affect dialysate flow, as smaller values cause less stress.

Experimental investigation of dodecanoic acid–tetradecanoic acid–dodecanol ternary mixture based nanoparticle enriched-phase change material for food preservation applications

In this research, a novel phase change material (PCM), containing dodecanoic acid-tetradecanoic acid-dodecanol ternary mixture, designated as pure mixture, dispersed with two carbon-based nanoparticles, i.e., graphene nanoplatelets - multiwall carbon nanotube and graphene nanoplatelets-titanium dioxide, with 1% weight fraction, is prepared and is designated as nanoparticle-enriched-phase change material. The chemical and thermal analysis of pure ternary mixture and nanoparticle-enriched-phase change material was conducted using X-ray diffraction, Scanning electron microscopy, Differential scanning calorimetry, Fourier transform infrared, Thermo gravimetric analyser and Thermal conductivity analyser techniques. The pure mixture possess melting and freezing temperature of 15.6°C and 8.4°C with a melting-freezing latent heat (LH) of 131.5 J/g and 125.4 J/g, respectively. The thermal conductivity exhibited a significant increase of 187.6% in the case of pure mixture with graphene nanoplatelets- multiwall carbon nanotube and 41.7% for pure mixture with graphene nanoplatelets-titanium dioxide. Moreover, the PCM remained thermally stable in both cases, even with the incorporation of nanoparticles. The melting as well as freezing LHs were reduced by about 18.17% and 18.02% for graphene nanoplatelets- multiwall carbon nanotube dispersed PCM and, 12.49% and 9.49% for graphene nanoplatelets- titanium dioxide dispersed PCM, respectively, in comparison with the pure mixture. Similarly, the melting/freezing temperatures, gets also reduced by 9.6%/8.3% and 10.9%/8.3%, respectively, for both mixtures. The pure mixture with graphene nanoplatelets- multiwall carbon nanotube exhibited a substantial decrease in both charging and discharging times, with reductions of 28.48% and 18.73%, respectively, in comparison to pure mixture, at an air inlet velocity of 3 m/s.

Enhancing convergence speed with feature enforcing physics-informed neural networks using boundary conditions as prior knowledge

This research introduces an accelerated training approach for Vanilla Physics-Informed Neural Networks (PINNs) that addresses three factors affecting the loss function: the initial weight state of the neural network, the ratio of domain to boundary points, and the loss weighting factor. The proposed method involves two phases. In the initial phase, a unique loss function is created using a subset of boundary conditions and partial differential equation terms. Furthermore, we introduce preprocessing procedures that aim to decrease the variance during initialization and choose domain points according to the initial weight state of various neural networks. The second phase resembles Vanilla-PINN training, but a portion of the random weights are substituted with weights from the first phase. This implies that the neural network’s structure is designed to prioritize the boundary conditions, subsequently affecting the overall convergence. The study evaluates the method using three benchmarks: two-dimensional flow over a cylinder, an inverse problem of inlet velocity determination, and the Burger equation. Incorporating weights generated in the first training phase neutralizes imbalance effects. Notably, the proposed approach outperforms Vanilla-PINN in terms of speed, convergence likelihood and eliminates the need for hyperparameter tuning to balance the loss function.

Direct MultiSearch optimization of TPMS scaffolds for bone tissue engineering

BackgroundScaffolds designed for tissue engineering must consider multiple parameters, namely the permeability of the design and the wall shear stress experienced by the cells on the scaffold surface. However, these parameters are not independent from each other, with changes that improve wall shear stress, negatively impacting permeability and vice versa. This study introduces a novel multi-objective optimization framework using Direct MultiSearch (DMS) to design triply periodic minimal surface (TPMS) scaffolds for bone tissue engineering. MethodThe optimization algorithm focused on maximizing the permeability of the scaffolds and obtaining a desired value of average wall shear stress (which ranges between the values that promote osteogenic differentiation of 0.1 mPa and 10 mPa). Multiple fluid inlet velocities and target wall shear stress were analyzed. The DMS method successfully generated Pareto fronts for each configuration, enabling the selection of optimized scaffolds based on specific structural requirements. ResultsThe findings reveal that increasing the target wall shear stress results in a greater number of non-dominated points on the Pareto front, highlighting a more robust optimization process. Additionally, it was also demonstrated that the tested Schwartz diamond scaffolds had a better permeability-wall shear stress relation when compared to Schoen gyroid geometries. ConclusionsDirect MultiSearch was proven as an effective tool to aid in the design of tissue engineering scaffolds. This adaptable optimization framework has potential applications beyond bone tissue engineering, including cartilage tissue differentiation.

A liquid-cooled plate based on bionic flow channels evolved from the shape of leaf veins and tree roots

With the rapid development of lithium-ion (Li-ion) batteries, battery thermal management (BTMS) is increasingly essential for the temperature control of Li-ion batteries. The energy required to control temperature is coming into focus. In order to consume less energy to control temperature and improve temperature uniformity, the liquid-cooled plate (LCP) based on bionic flow channels evolved from the shape of leaf veins and tree roots is proposed. In this BLCP, different from the others BLCPs, it is divided into a reinforced heat exchange area located in the middle and back part of the plate and a normal area located in the front part of the plate. Firstly, 16 sets of orthogonal tests are conducted based on four parameters: the distance of the hexagon from the outlet (a), the distance from the inlet (b), the distance between two adjacent hexagons (c) and the size of the hexagon (d). Secondly, Optimization was investigated based on NSGA-II for two objectives: temperature and pressure drop. The simulation results are analyzed based on the optimized structural parameters (a = 30 mm, b = 8 mm, c = 50 mm and d = 90 mm). After Comparing the optimization results with the simulation results, the temperature and pressure drop errors were 0.56 percent and 3.8 percent, respectively. The effects of flow rate and thickness of the fluid domain on temperature and pressure drop are next discussed separately. Finally, after comparing the optimized bionic liquid cooling plate (BLCP) with the conventional liquid cooling plate (CLCP) based on temperature pressure drop, velocity, and synergy angle, conclusions are made at the same inlet width, height, flow rate, and velocity (V = 0.2 m/s). This leads to the criterion of energy loss becoming only the pressure drop. The BLCP for pressure drop is 14.2 percent lower than the CLCP, which means less energy loss. The maximum temperature of the BLCP is 0.7 °C lower than that of the CLCP. Furthermore, the former has a better ability to suppress the rate of temperature rise and better temperature uniformity. In addition, this proposed new structure and research methods can be applied to the subsequent study of LCP.

Experimental Study on the Combustion Characteristics of Ultralow-Concentration Methane in Divergent Porous Media Burner

ABSTRACT To improve the stable combustion characteristics of ultralow-concentration methane (Concentration of 3.5%-5.0%), a series of combustion experiments were carried out by filling alumina spheres with different particle sizes (i.e. 5 mm, 10 mm and 15 mm) in a divergent burner, and the effects of divergent angle (i.e. 10°, 20° and 30°) and pore distribution on the flame propagation and stable combustion characteristics of ultralow-concentration methane were revealed. The results show that larger particle sizes and methane flow rates lead to the double flame surface phenomenon, and increasing angle and decreasing particle size can help to improve the preheating efficiency of the burner. Moreover, the inlet flow rates corresponding to the steady combustion of ultra-low concentrations methane are between 0.225 m/s and 0.308 m/s, the increase in inlet velocity, particle size, and angle will reduce the stability of the flame and make the shape of the flame surface developed in the order of “V→W→∧.” The burner with 10 mm particles and 30° angle has a wider stable combustion range, and the burner filled with smaller pore distribution help to improve the utilization of the lower concentration methane premixed.

Numerical and artificial neural network inspired study on step-like-plenum battery thermal management system

This study leverage numerical simulation (NS) and artificial neural network (ANN) capabilities to carry out additional investigations on step-like plenum battery thermal management system (BTMS). Different cooling strategies have been developed over the years in BTMSs’ design. Yet, air-cooling strategies still remains relevant, especially in battery-powered aircrafts, where light-weight is important and air is the preferred cooling fluid. Hence, additional study become necessary especially on the step-like plenum design to provide more insight on the performance of the design by considering several number of step, varied air inlet temperature and velocity. Computational fluid dynamics (CFD) approach was employed to obtained results for different number of step; Ns = 1, 3, 4, 7, 9, 15 and 19, varied air inlet temperature; Ti = 278, 298 and 318 K, and varied air inlet velocity; Vi = 3, 3.5, 4, 5 and 6 m/s. Artificial Neural Network (ANN) approach was then employed to predict the BTMSs’ performance for additional values of Ti and Vi. Minimum temperature (Tmin), maximum temperature (Tmax), maximum temperature difference (ΔTmax) and pressure drop (ΔP) were computed. By comparing the CFD results with the result predicted by the ANN, the percentage difference, for the entire dataset were 0.01 %, 0.005 %, 1 % and 0.14 % for Tmax, Tmin ΔTmax and ΔP, respectively. Based on the optimum design parameters predicted using ANN, for Tmax = 299.24 comprises Ns = 4, Vi = 6 m/s and Ti = 278 K, while for ΔP, comprises Ns = 1, Vi = 3 m/s and Ti = 318 K.

Numerical Simulation of Fixed-Free End Beam’s Modal Behaviour using Two-Way Coupled Fluid-Structure Interaction Approach

The fluid flow velocity stands as a pivotal parameter with a great influence on the mutual interaction between the fluid domain and structure. This paper focuses on structural deformation, structural velocity, von-Mises stress and frequency response of a fixed-free end beam using two-way coupled fluid-structure interaction within ANSYS Workbench. The parameters such as deformed fluid pressure and velocity were analysed across three diverse flow regimes: laminar, transitional and turbulent – each aligned with distinct fluid velocities. The outcomes show that the total deformation, velocity and von-Mises stress distribution of the fixed-free end beam increase as the inlet fluid velocity increases. As a result, the pressure and velocity distribution in the fluid flow which receiving the resultant or leftover structure deflection also increases as the incoming fluid velocity increases. Furthermore, the analysis probes the frequency response in turbulent flow conditions reveals higher values compared to laminar and transitional flows, albeit within the same natural frequency domain. This observation marks significant vibrational characteristics found in the presence of turbulent flow dynamics.

In Situ Conductive Heating for Thermal Desorption of Volatile Organic-Contaminated Soil Based on Solar Energy

A novel conductive heating method using solar energy for soil remediation was introduced in this work. Contaminated industrial heritage sites will affect the sustainable development of the local ecological environment and the surrounding air environment, and frequent exposure will have a negative impact on human health. Soil thermal desorption is an effective means to repair contaminated soil, but thermal desorption is accompanied by a large amount of energy consumption and secondary pollution. Therefore, a trough solar heat collection desorption system (TSHCDS) is proposed, which is applied to soil thermal desorption technology. The effects of different water inlet temperature, water inlet velocity and soil porosity on the evolution of soil temperature field were discussed. The temperature field of contaminated soil can be numerically simulated, and a small experimental platform is built to verify the accuracy of the numerical model for simulation research. It is concluded that the heating effect is the best when the water entry temperature is the highest, at 70 °C, and the temperature of test point 4 is increased by 50.71% and 1.42%, respectively. When the inlet water flow rate is increased from 0.1 m/s to 0.2 m/s, the heating effect is significantly improved; when the inlet water flow rate is increased from 0.5 m/s to 1.5 m/s, the heating effect is not significantly improved. Therefore, when the flow rate is greater than a certain value, the heating effect is not significantly improved. The simulation analysis of soil with different porosity shows that larger porosity will affect the thermal diffusivity, which will make the heat transfer effect worse and reduce the heating effect. The effects of soil temperature distribution on the removal of petroleum hydrocarbon C6–C9 and trichloroethylene (TCE) were studied. The results showed that in the thermal desorption process of petroleum hydrocarbon C6–C9-contaminated soil, the removal rate of pollutants increased significantly when the average soil temperature reached 80 °C. In the thermal desorption of trichloroethylene-contaminated soil, when the thermal desorption begins, the soil temperature rises rapidly and reaches the target temperature, and a large number of pollutants are removed. At the end of thermal desorption, the removal of both types of pollutants reached the target repair value. This study provides a new feasible method for soil thermal desorption.

Numerical study of proton exchange membrane water electrolyzer performance based on catalyst layer agglomerate model

In this work, a two-dimensional two-phase model of proton exchange membrane water electrolyzer (PEMWE) is developed, in which the catalyst layer (CL) is represented using agglomerate model. The effects of CL composition, porous transport layer (PTL) material properties and operating conditions on PEMWE performance are investigated. The results indicate that small size of catalyst agglomerate around 0.25 μm would benefit PEMWE performance. Appropriate increase of catalyst loading, porosity and ionomer volume fraction in the CL improves PEMWE performance, but their further increment leads to high mass transfer resistance, limiting the improvement of electrolyzer performance. The porosity and ionomer volume fraction of the catalyst layer are suggested to be lower than 0.5 and 0.6, respectively. The catalyst loading should be lower than 1.5 mg cm−2 when the CL porosity is higher than 0.3. The PTLs with high permeability, porosity and low contact angle is beneficial for the gas–liquid two-phase flow and avoiding the overheat and water shortage in the electrolyzer. Increasing the inlet velocity accelerates the bubble removal process, but might results in significant temperature drop, degrading the PEMWE performance. The most suitable temperature of inlet liquid is around 353.15 K. The results provide important guidance for the optimization design of high-performance PEMWE.

Stabilized equal lower-order finite element methods for simulating Brinkman equations in porous media

This paper demonstrates the mixed formulation of the Brinkman problem using linear equal-order finite element methods in porous media modelling. We introduce Galerkin least-squares (GLS) and least-squares (LS) finite element methods to address the incompatibility of finite element spaces, treating velocity, pressure, and vorticity as independent variables. Theoretical analysis examines coercivity and continuity, providing error estimates. Demonstrating resilience in theoretical findings, these methods achieve optimal convergence rates in the L 2 norm by incorporating stabilization terms with low-order basis functions. Numerical experiments validate theoretical predictions, showing the effectiveness of the GLS method and addressing finite element space incompatibility. Additionally, the GLS method exhibits promising capabilities in handling the Brinkman equation at low permeability compared to the LS method. The study reveals an increase in the average pressure difference in the Brinkman problem compared to the Stokes equations as the inlet velocity rises, providing insights into the behaviour of Brinkman equations.

Effect analysis on the low-temperature preheating performance of a novel micro-combustor air preheater for the cold start of the Li-ion battery packs

In this work, a micro-combustor (MC) air preheater as the heat source is developed. This novel air preheater has a compact size and outputs hot air with a wide range of temperatures with high temperature uniformity, which can well meet the preheating needs of Li-ion batteries in cold environments. Numerical studies are carried out to investigate the effects of baffle height, number of fins Nfin, hot air inlet velocity, cold air inlet velocity and combustor inlet velocity on the performance of the air preheater. The heating power of the air preheater can be adjusted by changing combustor inlet velocity Vcombustor, the outlet temperature can be easily adjusted by changing cold air inlet velocity Vcold and hot air inlet velocity Vhot, and the addition of baffles makes the outlet temperature very uniform. The results show that the height of the baffle of 20 mm and 30 mm makes ΔTair not exceed 1.5 K. The air preheater performance is better with fin number 6, and the maximum air temperature of 309.8 K is obtained with fin number and Vhot of 6 and 0.3 m/s respectively. Tair can vary between 287.8 K and 309.8 K when Vcombustor=12 m/s.

Research on water droplet interception mechanism of sheet-type drift eliminator based on three-dimensional transient numerical simulation

A three-dimensional transient numerical study was conducted on the sheet-type drift eliminator single-channel to reveal the droplet interception mechanism, using a mechanical draft wet cooling tower (MDWCT) as a typical operating environment. The droplet-air, droplet-droplet, droplet-film, and film-air interactions were considered comprehensively from the aerodynamics and heat transfer. The results indicate the existence of two distinct types of droplet escape: primary escape and secondary escape. The Stokes number (St) ≤ 1 for the vast majority of primary escaped droplets, whereas the secondary escaped droplets exhibit a considerable range of St. The correlation curves between the escape rate and the Stokes number (Stin) is similar under different inlet velocities (vin). The escape rate first decreases and then increases as Stin increases. There is a safety zone (Stin from 0.83 to 18.62) where the escape rate is near zero. For the studied eliminator, the specific safety zone is 65∼190 μm. The mass flow rate of escaped droplets first decreases and then increases as vin increases. The secondary escape dominates instead of primary escape when vin ≥ 7 m/s. This paper provides theoretical support for improving interception efficiency of eliminator while extending the methods for drift reduction and water savings.