This study presents a numerical investigation of flow structure (FS) and heat transfer (HT) characteristics in a square duct heat exchanger (SD-HX) equipped with an X-V baffle (XVB) acting as a vortex generator for HT enhancement. The effects of key geometric and flow parameters, including flow blockage ratio (B-R = 0.05-0.30), pitch spacing ratio (P-R = 1-2), flow attack angle (20 degrees, 30 degrees, and 45 degrees), and air-flow direction (AF-D) (+x and-x), are systematically examined under turbulent flow conditions with Reynolds numbers ranging from 3000 to 16000. The governing equations are solved using the finite volume method. The results reveal that the installation of XVB induces flow blockage, creating pressure differentials across the baffle that generate strong longitudinal vortices. These vortical structures impinge on the heat transfer surface, disrupt the thermal boundary layer (T-BL), and enhance convective heat transfer while promoting effective fluid mixing between core and near-wall regions. Vortex intensity increases with increasing blockage ratio, Reynolds number, and attack angle, whereas it decreases with increasing pitch ratio. The maximum heat transfer enhancement, expressed as Nu/Nu0, reaches 5.95 within the investigated range. Thermal performance is evaluated based on the constant pumping power criterion using the thermal enhancement factor (TEF). The maximum TEF of 1.44 is obtained at an attack angle of 20 degrees, B-R = 0.10, and P-R =1 for the-x flow direction, indicating an optimal balance between heat transfer enhancement and frictional penalty. Although higher attack angles yield greater heat transfer rates, they are accompanied by substantially increased pressure losses, resulting in reduced overall performance. To ensure the reliability and robustness of the numerical results, a comprehensive validation procedure is conducted. The numerical model is validated against established correlations and previously published data for smooth duct configurations under similar flow conditions, showing good agreement within acceptable deviation ranges. A grid independence test is also performed to confirm that the predicted results are insensitive to mesh resolution. In addition, all boundary conditions and numerical schemes are carefully implemented following standard computational fluid dynamics (CFD) practices. The consistency between the predicted flow structures and well-known physical mechanisms of vortex-induced heat transfer further supports the accuracy and credibility of the present simulations. Overall, the findings demonstrate that the XVB configuration is an effective technique for enhancing heat transfer in square duct heat exchangers. The validated numerical framework and the identified optimal parameter ranges provide valuable design guidelines for the development and optimization of advanced heat exchanger systems.

This study proposes a novel vortex generator, referred to as a discrete X-V baffle (DXVB), for enhancing heat transfer (H-T) in a square cross-section tube heat exchanger. The DXVB is developed by integrating the design concepts of a V-baffle and a V-orifice. A numerical approach based on the finite volume method is employed to investigate the thermal-hydraulic characteristics under turbulent flow conditions, with Reynolds numbers ranging from 3000 to 16,000. The effects of DXVB thickness and installation clearance are systematically examined. In addition, both co-current flow (+x direction) and counter-current flow (-x direction) configurations are considered. The results are presented in terms of dimensionless parameters, along with detailed analyses of flow structures (F-S), H-T characteristics, and the underlying physical mechanisms occurring within the heat exchanger system. The findings reveal that the incorporation of DXVB significantly enhances the H-T rate, achieving a maximum increase of up to 6.29 times compared to a plain tube without inserts. Furthermore, the thermal enhancement factor (TEF), representing the overall performance, reaches a maximum value of 1.32.

This study investigates the airflow dynamics and heat transfer (HT) profiles in a circular heat exchanger tube (CHET) mounted with a modified V-orifice (MVO) acting as a turbulator/vortex generator, which is a passive technique to enhance HT. A numerical modeling approach based on the finite volume method using a commercial software package was employed to provide detailed insights into the air flow profile, which is essential for the design of both the turbulator and the CHET system. The MVO is a turbulator derived from the orifice concept, an established engineering device, and has been adapted in combination with a V-shaped structure to effectively generate vortices and enhance HT. Key parameters expected to influence the flow and HT behavior were investigated. These include the ratio of the MVO thickness, b, to the CHET diameter, D (referred to as the blockage ratio, B-R), which was studied in the range of 0.05–0.30, and the ratio of the MVO spacing, P, to the CHET diameter (pitch ratio, P-R), which was considered at values of 1, 1.5, and 2. Attack angles of 30°, 45°, and 60° were examined for both + x and–x flow directions. The study covered turbulent flow conditions corresponding to Reynolds numbers in the range of 3,000–16000, representative of the operating conditions at the CHET inlet. The results indicate that MVO installation in the CHET acts as a flow obstruction, generating a pressure difference that induces vortex formation. These vortices play a key role in modifying the HT behavior, resulting in increased convective HT coefficients. The outcomes are summarized in forms of dimensionless variables. The highest observed HT enhancement reached 9.93 times that of the plain CHET, while the maximum thermal enhancement factor (TEF) was 1.92, obtained at an attack angle of 30°, P-R = 1, B-R = 0.25, in the +x fluid-flow direction at Re = 3,000.

This study explored the use of diffuser shapes to enhance the performance of a solar updraft tower. A diffuser-shaped vortex generator, a simple device requiring no structural modifications to the tower, was installed at the chimney outlet. The generator transformed crosswind into a vortex, increasing the updraft velocity. This study employed finite element methods and numerical models to validate the results alongside physical experiments. Both approaches focused on the crosswind velocity and vortex generator height to determine an optimal semi-opening angle for the diffuser shape. The experimental results revealed that an 8° diffuser-shaped vortex generator with a height of hvg = 2D achieved the greatest updraft enhancement, increasing the speed by 86.89% compared to the prototype tower. The enhancement was found to increase proportionally with the generator’s angle and height.

This study numerically investigates the enhancement of heat exchanger performance using a passive technique based on vortex generation. The proposed enhancement device, termed a diamond-shaped orifice (DSO), is a modified configuration that combines a conventional orifice plate with a conical ring. The DSO is inserted into a circular tube to modify the flow structure and induce strong vortices, thereby promoting convective heat transfer and improving the overall thermal performance. The effects of key geometric parameters, including the attack angle (α = 20°, 30°, and 45°), flow blockage ratio (FBR = 0.05–0.30), and pitch ratio (PRT = 1–2), are systematically examined under turbulent airflow conditions with Reynolds numbers ranging from 3,000 to 20,000. The results reveal that incorporating the DSO generates intense swirling flow, which effectively disrupts the thermal boundary layer and enhances the convective heat transfer coefficient. The maximum Nusselt number improvement reached 7.16 times that of a plain tube, while the highest thermal enhancement factor (TEF) attained was 1.77, indicating a substantial improvement in heat exchanger performance without additional active energy input.

The research presents an investigation into airflow configuration, thermal behavior, and convective heat transfer enhancement in a circular heat exchanger tube fitted with turbulence generators. These turbulence generators, referred to in this study as X‐V baffles (XVBs), were developed to generate swirling flow within the heat exchanger tube, which is directly related to the enhancement of heat transfer rates and the overall performance of the heat exchanger. Additionally, the XVBs were designed with consideration for practical application and ease of maintenance in real‐world industrial settings. The study examines the variables influencing airflow topology and thermal structure, including the blockage ratio ( g / D = 0.05–0.20), pitch ratio ( P / D = 1–2), flow direction (FD‐VD and FD‐VU), and types of turbulence generators (Type S and Type T XVBs). The research was conducted within the turbulent flow regime, with Reynolds numbers ranging from 3000 to 12,000 (Re = 3000–12000). The results are presented in terms of observed flow behavior within the test tube, such as cross‐flow streamlines, streamwise flow streamlines, Nusselt number distribution, and fluid temperature distribution. The findings clearly show the formation of swirling flow in the heat exchanger tube when XVBs are installed. An increase in the blockage ratio and a decrease in the pitch ratio lead to a more intense swirling flow. The intensity of this swirling flow is directly correlated with the degree of disturbance in the thermal boundary layer (TH‐BL). The maximum enhancements in Nusselt number and friction factor due to XVB installation are 7.24 and 58.01 times greater, respectively, compared to a smooth tube without XVBs. The maximum thermal enhancement factor (TEF) achieved is 2.27, obtained from the case with the Type T XVB at a blockage ratio of g / D = 0.05, a pitch ratio of P / D = 1, and a flow direction in the FD‐VD configuration.

This research presents a numerical study on flow structures, heat transfer, and thermal performance evaluation in a square duct heat exchanger (SDHX) equipped with combined vortex turbulators (CVTs). The aim of installing CVTs is to create vortex flow, impinging flow, and disrupt the thermal boundary layer, thereby enhancing the convective heat transfer coefficient and increasing the heat transfer ability and SDHX performance. V-shaped ribs and rectangular winglets are selected as CVTs due to their effectiveness in enhancing heat transfer rates. The study investigates the effects of CVT height (the values of a/H and b/H range from 0.05 to 0.20.), flow direction (V-apex pointing downstream (V-Downstream) and V-apex pointing upstream (V-Upstream)), and CVT arrangement (in-line and staggered arrangements) on flow structure and heat transfer characteristics. A comparison between V-shaped ribs and rectangular winglets is presented in terms of CVT types (A and B). The study focuses on turbulent flow with Reynolds numbers ranging from 3000 to 20,000. The results demonstrate that the flow behavior aligns with the proposed hypotheses, leading to increased heat transfer rates, which are 1.24 to 7.71 times greater than those of the empty duct. For thermal performance evaluation, the highest thermal enhancement factor (TEF) value of 1.77 is observed with type A CVT, in a staggered arrangement, and with the V-Upstream flow direction, when considering a Reynolds number (Re) of 3000. Additionally, the results of the study are presented in the form of TEF contours and correlations to assist in the design of vortex turbulators for heat exchange systems.

Numerical simulations of laminar air flow, heat transfer behavior (thermal structure), and thermal performance evaluation in a square duct with combined vortex generators (CVGs) are presented. The CVG configuration consists of a combination of rectangular winglets and V-shaped baffles. The thermal performance of two types of CVGs is compared. Type I includes a set of rectangular winglets placed on the upper and lower walls, with a V-shaped baffle in the middle. Type II features V-shaped baffles placed on the upper and lower walls, with a rectangular winglet in the middle. The purpose of the CVGs is to induce vortex flows, impinging flows, swirling flows, and to disturb the viscous sublayer over the duct surfaces, thereby improving the convective heat transfer coefficient and thermal efficiency. Based on the finite volume method, numerical modeling is used to analyze the effects of the position and height of CVGs on fluid and thermal characteristics for Reynolds numbers ranging from 100 to 2000. Thermal assessments of the CVGs are presented in terms of the Nusselt number ratio, friction factor ratio, and thermal enhancement factor. It is found that Type II outperforms Type I, showing the best Nusselt number ratio of 19.36 when b1/H = b2/H = 0.20 in the positive x-direction. However, Type I exhibits the greatest thermal enhancement factor, 4.39, which is higher than Type II when the blockage ratios are b1 = 0.15H and b2 = 0.05H in the +x FFD.

This research is an extension study that applies a vortex generator previously developed and tested under laminar flow conditions to investigate its performance under turbulent flow conditions, covering the operating range of various heat exchanger systems. This type of vortex generator is called the discrete X-V inducing turbulator (DXVIT), which is derived from the V-baffle, known for its high heat transfer enhancement efficiency, combined with the structure of an orifice that provides durability and stability when installed in heat exchanger systems. The DXVIT is installed to modify the primary flow structure and disrupt the thermal boundary layer (ThBL), resulting in an increase in the convective heat transfer coefficient. This study examines the effects of DXVIT size, installation spacing, flow direction, and DXVIT type on the heat transfer and flow behavior under turbulent flow conditions with Reynolds numbers ranging from 3000 to 16,000. The investigation is conducted using numerical simulation methods. The results are presented in terms of flow and heat transfer behavior, along with an analysis of thermal performance using dimensionless parameters. The findings indicate that the heat transfer rate increases up to 5.29 times, and the thermal performance factor reaches 2.65 under the same pumping power conditions.

A round tube heat exchanger (RTHE) with combined vortex generators (CVGs) is subjected to numerical assessments of its airflows and thermal characteristics. The CVGs are V-shaped ribs and rectangular winglets. The effects of CVG arrangement (A-1, A-2, and B), blockage ratio ( b 1 / H and b 2 / D ), and airflow direction (+ x , − x ) on airflow and thermal behavior are considered. To solve the numerical problem, a commercial program’s finite volume technique is chosen. Presenting streamlines, fluid temperature distributions, and local Nusselt number contours (on the tube wall) are the numerical findings obtained in the RTHE fitted with the CVG. The study presents the performance analysis of RTHE using dimensionless variables, including the thermal enhancement factor (or thermal performance factor), averaged friction factor, and averaged Nusselt number. The numerical results indicate that the general flow configuration in the RTHE is dramatically altered by the CVG. The mixing quality of the fluid seems to be enhanced. The vortex flows are found through the RTHE. As a result of the vortex flows impinging on the RTHE wall, the thermal boundary layer (T-BL) over the heat transfer surfaces changes. Enhancing the convective heat transfer coefficient, heat transfer ability, and thermal performance in the RTHE is mostly because of the reduction of the T-BL thickness. When compared to a smooth round tube, the maximum enhanced heat transfer of the RTHE fitted with the CVG is 13.83 times greater. Furthermore, at Re = 2000, type B, b 1 / D = 0.15, b 2 / D = 0.05, and V-Upstream scenario, the optimal TEF is 3.81.

The increasing global demand for energy has stimulated innovation aimed at optimizing energy usage for both efficiency and cost-effectiveness. Heat exchangers (HTEX) have consequently become a central focus of research, as enhancing their performance is essential for improving overall energy efficiency. Passive heat transfer enhancement techniques, such as the use of vortex turbulators, have attracted considerable attention because they can improve heat transfer without incurring additional energy consumption costs.This study proposes the development of a novel vortex turbulator for a square cross-section HTEX duct by integrating the advantages of existing turbulator designs. The design also considers applicability and operational feasibility for real-world implementation. The resulting device, termed the modified-orifice vortex turbulator (MOVT), is intended to enhance the heat transfer rate (HTR) and overall thermo-hydraulic performance of heat transfer systems. The study investigates the influence of MOVT shapes, categorized into three types: X, Y, and Z. It also examines the MOVT size, defined by the ratio of its thickness (a) to the duct height (H), a/H = 0.05–0.20. Furthermore, the effects of flow direction variations (+x, -x) are analyzed. The entire study is conducted under turbulent flow conditions, with inlet Reynolds numbers ranging from 3000 to 16,000. The numerical simulation results indicate that the HTR increases by up to 4.19 times compared to a plain tube without the MOVT. The best optimum transfer enhancement ratio at similar pumping force or the highest thermal enhancement factor (TEF) of 1.42 is observed with the Y-type MOVT at a thickness-to-height ratio (a/H) of 0.05.

This study presents the implementation of discrete X-V vortex inducers (DXVVI) as a passive heat transfer enhancement technique in circular heat exchanger tubes. The DXVVI devices are introduced to improve the convective heat transfer coefficient, heat transfer rate, and thermal performance. Numerical simulations using a commercial CFD code were employed to investigate the flow structure and thermal behavior within the heat exchanger system. The DXVVI concept is developed based on a combination of the V-Orifice and V-shaped baffle, aiming to retain the thermal performance of the V-shaped baffle while maintaining the structural strength of the V-Orifice. The discrete configuration was selected to enhance turbulence levels and reduce pressure drop. Two DXVVI design groups, referred to as "GROUP 1" and "GROUP 2", were proposed. Key parameters influencing the flow and thermal characteristics were investigated, including the pitch ratio (PRT), defined as the ratio of the longitudinal pitch or pitch distance (P) to the circular tube diameter (D), i.e., P/D, and the flow-blockage ratio (BKRT), defined as the ratio of the DXVVI thickness (b) to the circular tube diameter, i.e., b/D. The simulations were conducted under turbulent flow conditions with Reynolds numbers (Re) ranging from 3000 to 20,000, considering both co-flow (+x) and counter-flow (-x) directions. In GROUP 2, small gaps were introduced in various configurations to enhance turbulence intensity, increase the number of vortex cores, and further reduce pressure drop-leading to improved heat exchanger performance. The numerical model was validated using appropriate academic standards, confirming its reliability in predicting thermal and flow behaviors. The numerical results are performed in terms of fluid-flow structure (e.g., streamline plots in transverse planes and 3D flow visualizations) and thermal characteristics (e.g., fluid-temperature contours in cross-sectional planes and Nusselt number distributions on the tube surface). Performance evaluation was also carried out using dimensionless metrics, including the Nusselt number ratio (Nu/Nu0), the friction factor ratio (f/f0), and the thermal enhancement factor (TEF) under equal pumping power conditions. The best heat transfer rate augmentation was observed to be up to 8.07 times greater than the reference case (smooth tube). The highest TEF, equal to 3.14, was observed in GROUP 2 for configuration 5B5G5B with a pitch ratio (PRT) of 1.

A numerical investigation is conducted into the airflow topologies and thermal structures of a circular tube heat exchanger (CTHX) fitted with combined vortex producers (CVP), including winglets and V-profile ribs. The CVP installation is necessary to produce vortex flows in the CTHX, which bounce over the CTHX wall, significantly altering the thermal boundary layer. This change affects the local convective heat transfer coefficient and heat transfer rate. Moreover, producing vortex flow can improve air mixing quality, further augmenting the heat transfer rate and thermohydraulic efficiency. The effects of CVP heights (b1/D and b2/D), CVP types (X-1, X-2, and Y), and airflow directions on flow topology and thermal structure are considered. The airflow velocity, in terms of the Reynolds number from 100 to 2000 (considered from the entry settings), is examined. The current numerical challenge is resolved using a commercial application and the finite volume technique. To improve the dependability of the numerical findings, the computational model of the CTHX equipped with the CVP is verified. The numerical results are explained by streamlines in the CTHX, the local Nusselt number over the CTHX wall, and fluid temperature distributions. A summary is also provided for the dimensionless variables (averaged Nusselt number, friction factor, and thermal enhancement factor) of the CTHX with the CVP. The numerical results reveal that CVP insertion significantly enhances the heat transfer rate due to vortex flow generation. The maximum heat transfer rate is 15.29 times higher than that of a smooth circular tube, with the best thermal enhancement factor of 3.74 observed within our investigated range.

Given the escalating energy demands today, improving the efficiency of engineering equipment is crucial for optimizing energy use. This study focuses on enhancing heat exchanger performance through passive methods, particularly by installing vortex turbulators. Passive techniques can effectively manage energy costs while enhancing efficiency. The research examines thermal profiles and airflow structures within a square channel heat exchanger (SCHE) equipped with staggered vortex turbulators (SVTs). SVTs feature a unique design combining rectangular winglets and V-pattern baffles. The installation of SVTs aims to intensify vortex strength, thereby increasing SCHE efficiency, convective heat transfer coefficients, and overall heat transfer potential. The study investigates the effects of SVT dimensions (b(1)/H and b(2)/H), airflow directions (+x and -x), installation patterns (pattern no. 1 and 2), pitch to height ratios (P/H = 1, 1.5, and 2), and flow attack angles (alpha = 20 degrees, 30 degrees, and 45 degrees). Computational simulations using the finite volume method with a commercial code (FLUENT) under laminar flow conditions (Reynolds number of 100-2000) provide insights into thermal profiles, fluid temperature distributions, and flow configurations within the SCHE. Staggered arrangement and gap spacing are employed to reduce pressure loss and enhance airflow strength. The results highlight flow structures and heat transfer characteristics in the heat exchanger channels, elucidating the underlying mechanisms of the heat exchange process. Understanding these behaviors is crucial for developing more efficient heat exchangers and vortex generators in the future. Simulation findings demonstrate that SVTs significantly enhance convective heat transfer over smooth channels due to increased vortex strength. Notably, pattern no. 2 SVTs (b(1)/H = b(2)/H = 0.20) achieve the highest Nu/Nu(0) of 19.21 in the +x flow direction at Re = 2000, alpha = 30 degrees, and P/H = 1. In conclusion, the study identifies a maximum thermal enhancement factor of 4.38. It underscores the potential of pattern no. 2 SVTs for optimizing heat exchanger performance, offering valuable insights for future developments in thermal management technologies.

This research presents an improvement to the traditional solar updraft tower, which relies solely on solar energy and cannot operate continuously throughout the day. The enhancement involves a hybrid energy approach by installing a vortex generator at the top of the tower to convert crosswinds into a vortex flow at the chimney’s top. This modification induces an updraft within the tower, enabling it to generate electricity continuously, even at night when there is no sunlight. The aim is to enable the solar updraft tower to harness crosswind energy without altering the tower’s main structure. This involves developing a vortex generator from a unidirectional wind intake design to a three-directional intake, enhancing the feasibility of commercial installation. Additionally, various designs and heights of vortex generators were developed, considering different crosswind speeds (2, 4, 6, and 8 m/s). The research utilizes the finite element method, along with real model construction, to validate the reliability of the study’s findings. The results indicate that the updraft speed is directly proportional to the crosswind speed. From a physical standpoint, the vortex generator with a height equal to D produced the best results in all experiments. The square, cylindrical, and diffuser shapes increased the wind speed inside the chimney by 60%, 41%, and 48%, respectively. These results from various shapes provide effective design and development guidelines for the future commercial use of vortex generators.

Thermal performance improvement in a heating tube (HT) using discrete X-V baffle (DXVB) as turbulators is presented. The DXVB is designed with three main goals: 1. To decrease the pressure drop in the tested tube and 2. To increase the mixing quality in the heat exchanger tube and 3. To produce powerful vortex flows. Lower pressure drop, generated vortex flows and higher mixing quality will augment a heat transfer rate and thermo-hydraulic efficiency. This study examines effects of DXVB structures, DXVB distances and placements on laminar air flow and thermal structure with Reynolds number from 100 to 2000. The current problem is numerically investigated using the finite volume technique of a commercial program/code (ANSYS-FLUENT V.2022). The created model of the HT fitted with the DXVB is numerically validated. From the numerical results, the DXVB installed affects the air flow structure in the tested tube. The vortex streams are observed. The change in fluid flow influences thermal characteristics. The vortex streams destroy some parts of the thermal boundary layer and help to increase mixing quality. These perturbed thermal boundary layer (TB-layer) and better mixing quality are two important factors that contribute to convective heat transfer enhancement. In addition, the maximum heat transfer rate and pressure loss are 10.17 and 45.75 times upper than that in the circular plain tube, respectively, while the best thermal enhancement factor (TEF) of 3.09 is observed at 15b5g, +x at Re = 2000.

This work presents a numerical study on flow configurations and pressure distribution of cylindrical towers attached with different shapes of vortex generators. The vortex-generator attachment is done with the main aim of reducing the energy of ventilation for the cylindrical tower. The two different types of vortex generators, namely, a cylindrical-shaped vortex generator and a diffuser-shaped vortex generator, are compared with an original square-shaped vortex generator. The effects of air velocity (2, 4, 6, and 8 m/s) and vortex generator size (D/2, D, and 2D) on flow structure are considered. The finite element method (a commercial code) is selected for the main problem-solving. The numerical models of the cylindrical towers attached with various vortex generators are validated to confirm the reliability of the numerical results. From the numerical results, it was found that the suctioned updraft speed in the tower was proportional to the crosswind speed. In addition, the vortex generator with h=2D performs the highest updraft speed, which leads to the best efficiency for ventilation.

A novel design of “X–V rib” turbulators is proposed to improve fluid blending and to perturb thermal boundary layer (TBL) in a heat exchanger (HX) duct. Better fluid blending and more highly disturbed TBL are the two important factors for the improvement of HX performance. Effects of X–V rib geometrical parameters including rib height ratios (b/H = 0.05–0.20), rib arrangements (V-tip pointing upstream called “V-Upstream (VU)” and V-tip pointing downstream called “V-Downstream (VD)”) and rib types (I, II and III) on air stream and thermal mechanisms are numerically investigated in a 3D model. The numerical model is solved with the finite volume method (a commercial code) and a commercial program. Laminar air flow (inlet conditions with Re = 100–2000) is a selected range of the present investigation. Firstly, the created numerical model for the ribbed duct is validated with two significant topics: 1. Plain duct validation and 2. Optimum grid elements (grid independence). The validated results show that the ribbed-duct model has great reliability to simulate air stream and thermal characteristics. According to the numerical results, the disturbed TBL is obviously found in all rib types. Moreover, it is observed that the core flow disturbance occurs and improves fluid blending. The outcomes from the present investigation point out that the knowledge about flow structure and thermal mechanism are important guidelines for the development of vortex turbulators and HX improvement. For the thermal assessments, it is found that the best Nusselt number ratio (Nu/Nu0) is 11.80 for the type III X–V rib with b/H = 0.20 in the VD-direction. Additionally, the maximum thermal enhancement factor within our investigated range is 3.48 at Re = 2000, b/H = 0.20, type II X–V rib in the VU-direction.