Transfer Drop Research Articles

Numerical Investigation of Microchannel Heat Sink with Trefoil Shape Ribs

The present study investigates the thermo-hydraulic characteristics of a microchannel sink with novel trefoil Shaped ribs. The motivation for this form of rib shape is taken from the design of lung alveoli that exchange oxygen and carbon dioxide. This study has been conducted numerically by using a code from the commercially available Fluent software. The trefoil shaped ribs were mounted on the centerline of different walls of the microchannel in three different configurations. These consisted of base wall trefoil ribs (MC-BWTR), sidewall trefoil ribs (MC-SWTR), all wall trefoil ribs (MC-AWTR) and smooth channel (MC-SC) having no ribs on its wall. The streamline distance between the ribs was kept constant at 0.4 mm, and the results were compared by using pressure drop (∆p), Nusselt number (Nu), thermal resistance (Rth) and thermal enhancement factor (η). The results indicated that the addition of trefoil ribs to any wall improved heat transfer characteristics at the expense of an increase in the friction factor. The trends of the pressure drop and heat transfer coefficient were the same, which indicated higher values for MC-AWTR followed by MC-SWTR and a lower value for MC-BWTR. In order to compare the thermal and hydraulic performance of all the configurations simultaneously, the overall performance was quantified in terms of the thermal enhancement factor, which was higher than one in each case, except for MC-AWTR, in 100 < Re < 200 regimes. The thermal enhancement factor in the ribbed channel was the highest for MC-SWTR followed by MC-BWTR, and it was the lowest for MC-AWTR. Moreover, the thermal enhancement factor increases with the Reynolds number (Re) for each case. This confirms that the increment in the Nusselt number with velocity is more significant than the pressure drop. The highest thermal enhancement factor of 1.6 was attained for MC-SWTR at Re = 1000, and the lowest value of 0.87 was achieved for MC-AWTR at Re = 100.

Numerical Study on Influences of Drag Reducing Additive in Supercritical Flow of Kerosene in a Millichannel

To improve the performance of a high-pressure refueling liquid oxy-kerosene engine, the influence of drag-reducing additive on the heat transfer characteristics in the supercritical flow of kerosene in a microchannel for regenerative cooling is explored. The finite-volume CFD numerical simulation method is applied using the RNG k-ε turbulence model and enhanced wall function. The current work faithfully represents the effect of the drag-reducing additive in kerosene through numerical calculations by combining a 10-component model for the physical properties of the kerosene and the Carreau non-Newtonian fluid constitutive model from rheological measurements. Results suggest that the 10-component kerosene surrogate can describe the supercritical physical properties of kerosene. The inlet temperature, inlet velocity, and the heat flux on the channel wall are driving factors for the supercritical kerosene flow and heat transfer characteristics. The pressure influence on the heat transfer is negligible. With polymer additives, the loss in pressure drop and heat transfer performance of supercritical kerosene flow decrease 46.8% and 37.5% respectively. The enhancement of engine thrust caused by reduction in pressure drop is an attractive improvement of concern.

Local Measurements in Heat Exchangers: A Systematic Review and Regression Analysis

It is widely known that most of the heat transfer and pressure drop measurements in heat exchangers are global measurements that are based on surface averaged parameters that do not measure the growth of the hydraulic and thermal boundary layer. Recent local heat transfer coefficient investigations on hydrocarbon condensation in plate heat exchangers suggest that the mean heat transfer coefficients obtained from local measurements are 10–20% higher than those obtained from studies based on a uniform wall heat flux assumption. Consequently, process heat exchangers which were rated by global measurements could be underrated. This systematic review presents a meta-analysis and regression analysis of the available pressure drop and heat transfer data for both single-phase and two-phase flows in enhanced heat exchangers. Data was compiled from studies in the last decade for similar Reynolds, Prandtl, Dean, Weber, and boiling numbers, pitch/diameter ratio, and other parameter ratios for statistical analysis and correlation development. State-of-the-art local measurement techniques like liquid crystal thermography are also discussed. Both practicing engineers and graduate students should benefit from this study.

Equivalent Parallel Strands Modeling of Highly-Porous Media for Two-Dimensional Heat Transfer: Application to Metal Foam

A new geometric modeling of isotropic highly-porous cellular media, e.g., open-cell metal, ceramic, and graphite foams, is developed. The modelling is valid strictly for macroscopically two-dimensional heat transfer due to the fluid flow in highly-porous media. Unlike the current geometrical modelling of such media, the current model employs simple geometry, and is derived from equivalency conditions that are imposed on the model’s geometry a priori, in order to ensure that the model produces the same pressure drop and heat transfer as the porous medium it represents. The model embodies the internal structure of the highly-porous media, e.g., metal foam, using equivalent parallel strands (EPS), which are rods arranged in a spatially periodic two-dimensional pattern. The dimensions of these strands and their arrangement are derived from equivalency conditions, ensuring that the porosity and the surface area density of the model and of the foam are indeed equal. In order to obtain the pressure drop and heat transfer results, the governing equations are solved on the geometrically-simple EPS model, instead of the complex structure of the foam. By virtue of the simple geometry of parallel strands, huge savings on computational time and cost are realized. The application of the modeling approach to metal foam is provided. It shows how an EPS model is obtained from an actual metal foam with known morphology. Predictions of the model are compared to experimental data on metal foam from the literature. The predicted local temperatures of the model are found to be in very good agreement with their experimental counterparts, with a maximum error of less than 11%. The pressure drop in the model follows the Forchheimer equation.

Study on thermal-hydraulic characteristics of hybrid heat exchangers with interpolated etched plates

The Supercritical carbon dioxide (S-CO2) Brayton cycle can be used to recover the exhaust heat energy of marine diesel engines. The hybrid heat exchanger is one of the potential solutions for heat exchange between flue gas and S-CO2, but there is no good design theory and design method at present. The traditional hybrid heat exchanger has an one-to-one correspondence between the fin and the etched plate. However, under special requirements, it is necessary to insert etched plates in the hybrid heat exchanger to improve the thermalhydraulic characteristics. In this study, four CFD models of the hybrid heat exchangers with interpolated etched plates were established. When the total mass flow rate and the total mass velocity are constant, the thermalhydraulic characteristics of the hybrid heat exchanger are analyzed by Fluent. The results show that regardless of the constant mass flow rate or the constant mass velocity, inserting etched channels into the hybrid heat exchanger will increase the total heat transfer coefficient. When the total mass flow rate of the cold and hot fluids is unchanged, the heat transfer coefficient and pressure drop of the etched channel decrease with the increase of the inserted etched channel. When the total mass velocity of the hybrid heat exchanger is unchanged, the insertion of the etched channel causes the pressure drop and the convective heat transfer coefficient of the fin channel to increase. Meanwhile, the pressure drop and convective heat transfer coefficient of the etched channels are reduced, but the total heat transfer coefficient is increased. The study can provide guidance for the design of the hybrid heat exchangers.

Using radial basis function network to model the heat transfer and pressure drop of water based nanofluids containing MgO nanoparticles

Present study is focused on feasibility of predicting the thermal and fluid properties of MgO/water nanofluid using radial based function (RBF) type artificial neural networks (ANNs). To design the ANN, Reynolds number and volume fraction of nanoparticles (ϕ) were considered as ANN inputs and in principle independent parameters and on the other hand, the parameters of relative pressure drop and relative heat transfer coefficient were considered as the outputs of this ANN. One of the important innovations in the present study is the attempt to simultaneously predict the relative pressure drop as undesirable and the relative heat transfer coefficient as undesirable parameters. The designed ANN using the radial basis function (RBF) was able to predict the laboratory parameters of relative pressure drop and relative heat transfer coefficient (RHTC) with 99.3% and 99.5% accuracy, respectively. It can drastically reduce the time and financial costs of laboratory methods. Based on the obtained results in ϕ = 0.125%, the unfavorable parameter (relative pressure drop) has a significant supremacy over the optimal parameter (RHTC) and therefore the ϕ is not suitable for use in thermal cycles. But on the other hand, with ϕ = 0.5%, the optimal parameter (RHTC) has a significant supremacy over the undesirable parameter (relative pressure drop), and therefore for MgO/water nanofluid, ϕ>0.5% are suitable for using in thermal cycles.

Performance score based multi-objective optimization for thermal design of partially filled high porosity metal foam pipes under forced convection

Optimization study in flow through metal foams for heat exchanging applications is very much essential as it involves variety of fluid flow and structural properties. Moreover, the identification of best combinations of structural parameters of metal foams for simultaneous improvement of heat transfer and pressure drop is a pressing situation. In this work, six different metal foam configurations are considered for the enhancement of heat transfer in a circular conduit. The foam is aluminum with PPI varying from 10 to 45 and almost the same porosity (0.90-0.95). The aluminum foams are chosen from the available literature and they are partially filled in the conduit to reduce the pressure drop. For a constant heat flux condition, the goal is to find out the efficient metal foam and configurations when air is considered as a working fluid. A special attention is paid to the preference between pressure drop and heat transfer enhancements. That is why TOPSIS optimization techniques with five different criteria (contains the combination of the weightage/priority of heat transfer and pressure drop) is used. Based on the numerical results of heat and fluid flow in conduit, it is found that when an equal importance is given to both heat transfer and friction effect, 30 PPI aluminum foam with 80% filling on the inner lateral of the pipe provides the best score as 0.8197. The best configuration and PPI for different preferences between friction and heat transfer enhancements is discussed in details. The Reynolds number varies from 4500 to 16500.

Experimental study on the thermal-hydraulic performance of a fluttering split flag in a channel flow

The use of flags as vortex generators inside heat sinks has been successfully demonstrated as a heat transfer enhancement technique. However, their thermal-hydraulic performance is usually diminished by the blocking effect induced by the fluttering phenomenon. To tackle this problem, with the expectation to maximize the fluid mixing while minimizing the pressure drop, we report a simple and direct design by splitting a flag into multiple strips. Flags with different strip widths were compared with a full flag on the performance of pressure drop and heat transfer. A high-speed camera is used to investigate their fluttering motion. A piezoelectric plate is attached to the wall to measure the flag's flutter frequency. The results show that the performance of a flag with multiple strips outperforms that of the full flag for its lower pressure drop and higher heat dissipation effect. The performance of split flag is not linear with the strip number and the optimal way in our study is to split the full flag into 4 strips. The maximum thermal-hydraulic performance factor of the split flag is 1.91, which is 26% higher than that of the full flag. Besides, the split flag starts fluttering at a lower wind velocity. All these results demonstrate that the split strategy of a flag acting as a vortex generator is of great potential for improving the heat sink performance.

Self-Excited Counterflow Disturbance and Heat Transfer Characteristics of –Water Nanofluids

A numerical study of the heat transfer and flow resistance performance of –water nanofluids in self-oscillating hot runners with different chamber lengths was performed. The control volume method based on the Semi-Implicit Method for Pressure Linked Equations (SIMPLE) algorithm was used to numerically solve the governing equations of the two-dimensional computational domain. The inlet flow rate was determined according to the Reynolds number (), and the uniform temperature was applied to the wall of the hot runner. The effects of chamber length and volume fraction on the heat transfer performance of nanofluids vortex pulsation were described by temperature, thermal boundary-layer thickness, pulsation frequency, Nusselt number, pressure drop, and heat transfer performance evaluation index. The simulation outcomes indicated that the counterflow vortex can reduce the thermal boundary-layer thickness and increase the mixing degree between the central mainstream region and the wall. It was also observed that the heat transfer performance increases with the increase of the chamber length. When , the heat transfer performance is the highest, and the main frequency () at the center of the chamber corresponds to the pressure pulsation amplitude of 35,982.6 Pa.

Fluid flow and convective heat transfer in a rotating rectangular microchannel with various aspect ratios

The features of flow fluid and convective heat transfer have been investigated numerically in a rotating rectangular U-shaped microchannel for various aspect ratios (AR). Pure water is used as working fluid and 3D steady simulations are performed for Reynolds number of 400. The effects of aspect ratio (AR = 0.25–4), slip/no-slip conditions, rotational speeds in the range of 0–300 rad/s on the velocity profiles/contours, heat transfer, pressure drop, Nusselt number, and thermal performance coefficient are studied. The results show that an increase in AR (for AR>1) or a decrease in AR (for AR<1) provided an increase in pressure drop and heat transfer. Besides, contrary to hydrophilic microchannel, the heat transfer and pressure drop decrease in microchannel with the hydrophobic surfaces for all ARs considered. In addition, the thermal performance coefficient (E) is used as a balance between heat transfer augmentation and the power consumed. It is found that the E is higher for microchannel with hydrophobic surface than that of with hydrophilic one for all ARs examined. Moreover, the rotating microchannel is more efficient in respect to heat transfer enhancement than that of the stationary case, especially at AR = 1. Moreover, the results for two thermal boundary conditions of constant heat transfer and constant wall temperature conditions are compared at AR = 1 and it is found that the total Nusselt number is higher for constant wall temperature case than that of constant heat flux case in rotating microchannel while it is contrary in stationary one.

Design optimization and experimental investigation of CPU heat sink cooled by alumina-water nanofluid

In this study, an experimental evaluation on the use of Al2O3 nanoparticles in a circular structure of minichannel heat sink is conducted for heat dissipation from electronic components such as Central Processing Unit (CPU). The experiments are prepared for various hydraulic diameter of channels and different values of coolant flow rates. After a hydro-thermal analysis on the obtained data, as a main outcome, findings indicate that decreasing the channel diameter and increasing the flow rate of Al2O3-water as working fluid are the most effective approaches to improve the cooling performance of heat sinks. An optimization study using Response Surface Methodology (RSM) based on Central Composite Design (CCD) is performed due to complex effect of channel size, nanofluid volume flow rates and channel numbers on pressure drop and heat transfer to reach the best operating design.

Numerical analysis and optimization on flow and heat transfer performance of a steam-cooled ribbed channel

It aims to enhance the heat transfer performance and reduce the pressure loss of the steam-cooled ribbed channels in the gas turbine blades. Numerical calculations were performed to analyze the flow and heat transfer characteristics in the steam-cooled ribbed channel for different inlet Reynolds number (10,000 ≦ Re ≦ 90,000), rib angle (30° ≦ α ≦ 90°), rib height ratio (0.05 ≦ e/D ≦ 0.15) and rib pitch ratio (0.5 ≦ P/D ≦ 1.5). The flow and heat transfer analysis, response surface analysis, significance analysis and parameter optimization were performed by using the Response Surface Methodology. The results show that the variations of Re, α, e/D and P/D change the size, shape and swirling strength of the secondary flows in different extent, leading to the change of flow and heat transfer characteristics in the steam-cooled ribbed channel. Increasing Re and e/D, and decreasing P/D at the low-medium level of e/D obviously enhance the Nu/Nu0; Decreasing Re and e/D, and increasing P/D result in a reduction in the f/f0. An increment in α first increases and then decreases both the Nu/Nu0 and f/f0. Among the four influence parameters Re, α, e/D and P/D, Re is the most significant parameter affecting the Nu/Nu0, followed by e/D, α and P/D; e/D has the most significant influence on the f/f0, followed by α, Re and P/D. The multi-objective optimization for lower pressure drop and higher heat transfer is achieved at Re of 90,000, α of 41.5152, e/D of 0.1157 and P/D of 0.9747. Compared with the reference channel, the optimized channel has a 86.19% enhancement in heat transfer coefficient and a 38.32% improvement in comprehensive thermal coefficient, at the same Reynolds number (Re = 90,000).

3D Printed PEI Containing Adsorbents Supported by Carbon Nanostructures for Post-combustion Carbon Capture From Biomass Fired Power Plants

Processes that utilize solid adsorbents to capture CO2 are promising alternatives to state-of-art Amine based technologies for capturing CO2 from large point sources. Although the energy needs of solid sorbent-based processes are low, the process footprint and consequently the capital cost connected to its implementation can be large due to the relatively long cycle times needed to get the required purity and recovery of the CO2 product. To overcome this challenge, processes having structured adsorbents like laminates, monoliths etc. are needed due to their low pressure drop and better mass transfer characteristics. The aim of this multiscale study is to evaluate the process-based performance of a 3D printed sorbent containing polyethyleneimine (PEI) and multiwalled carbon nanotubes (MWCNT) for capturing CO2 from a biomass fired power plant flue gas. A 6-step vacuum swing adsorption (VSA) cycle was simulated and optimized using equilibrium and kinetics data obtained from volumetry and breakthrough experiments. The optimization study showed that it was possible to achieve purity values &amp;gt;95% and recovery values &amp;gt;90% from dry CO2 feed streams containing 10 and 15% CO2 respectively. The minimum specific energy values were 0.94 and 0.6 MJ/kg and maximum productivity values were 0.8 and 2.2 mol/m3 ads s, respectively, for the two scenarios.

Features of Filler Wire Melting and Transferring in Wire-Arc Additive Manufacturing of Metal Workpieces.

In this paper, we present the results of a study on droplet transferring with arc space short circuits during wire-arc additive manufacturing (WAAM GMAW). Experiments were conducted on cladding of single beads with variable welding current and voltage parameters. The obtained oscillograms and video recordings were analyzed in order to compare the time parameters of short circuit and arc burning, the average process peak current, as well as the droplets size. Following the experiments conducted, 2.5D objects were built-up to determine the influence of electrode stickout and welding torch travel speed to identify the droplet transferring and formation features. Moreover, the current–voltage characteristics of the arc were investigated with varying WAAM parameters. Process parameters have been determined that make it possible to increase the stability of the formation of the built-up walls, without the use of specialized equipment for forced droplet transfer. In the course of the research, the following conclusions were established: the most stable drop transfer occurs at an arc length of 1.1–1.2 mm, reverse polarity provides the best drop formation result, the stickout of the electrode wire affects the drop transfer process and the quality of the deposited layers. The dependence of the formation of beads on the number of short circuits per unit length is noted.

Heat Transfer and Friction Factor Characteristics of Turbulent Flow through a Conical Heat Exchanger

In this present energy demand scenario, the use of a waste heat recovery device like regenerator, recuperator, reheaters in the industrial processes is gaining much more importance due to improvement in thermal efficiency, and consequently reduction in thermal pollution. In the power plant, the waste heat carried by hot flue gases through the chimney remains untapped which can be recovered through the use of a conical heat exchanger at the inner portion of the chimney. Also, few customized designs of the conical coil heat exchanger can have the potential to be used to recover the waste heat in other industrial processes like chemical reactors, electrical contractors, HVAC applications, condenser, boiler, and evaporator, etc. In the present study, different arrangements of the conical coil heat exchanger are analyzed using a numerical technique. A conical coil of different geometrical configurations viz. at three different cone angles 45°, 90°and 135°, and at three different pitches 20 mm, 25 mm, and 30 mm are considered. The results for heat transfer and friction factor are presented for the flow of fluid of different Reynolds numbers. The impact of geometrical parameters as well as flow parameters on pressure drop and heat transfer under constant wall heat flux conditions are presented. The average heat transfer and pressure drop values are observed to be 175 to 225% more than the smooth tube values with increased pressure drop. Also, the results indicate that there is a nonlinear increase in both Nusselt number and friction factor with the increase in cone angle and pitch of conical coil.

Water recovery efficiency improvement using the enhanced structure of the mist eliminator

Thermal power plants are users of high water consumption, and the water consumption of cooling towers accounts for more than half of the total water consumption of the whole plant. Therefore, water saving of cooling towers is the key to water saving in thermal power plants. Wave-plate demister as a component of cooling tower influences the performance of entire system. Demister realizes the collection of liquid droplets with the penalty of extra pressure loss. Curved bends and drainage hooks are proposed as enhancing structures of demister to increase separation efficiency and reducing pressure loss simultaneously. Computational result shows that interaction between curved bend and hooks improves the overall performance of demister. Moreover, effect of enhancing parameters on the performance is presented, specifically, Euler number and separation efficiency are correlated as functions of curved bend radius and hook length. Most importantly, an experiment is conducted on a real cooling tower. It shows that the overall thermal capacity is lowered with the presence of demister. Pressure drop, separation efficiency and heat transfer of the entire system are tested with and without demisters, based on which a new criterion is proposed to evaluate the influence of demister on the overall performance of cooling tower in terms of thermal efficiency and droplets collection. Performance indexes as functions of enhancing parameters and droplets dynamic are plotted. Therefore, a quick design of demister can be realized in achieving an optimal performance of cooling tower.

Anti-thrombogenic Surface Coatings for Extracorporeal Membrane Oxygenation: A Narrative Review.

Extracorporeal membrane oxygenation (ECMO) is used in critical care to manage patients with severe respiratory and cardiac failure. ECMO brings blood from a critically ill patient into contact with a non-endothelialized circuit which can cause clotting and bleeding simultaneously in this population. Continuous systemic anticoagulation is needed during ECMO. The membrane oxygenator, which is a critical component of the extracorporeal circuit, is prone to significant thrombus formation due to its large surface area and areas of low, turbulent, and stagnant flow. Various surface coatings, including but not limited to heparin, albumin, poly(ethylene glycol), phosphorylcholine, and poly(2-methoxyethyl acrylate), have been developed to reduce thrombus formation during ECMO. The present work provides an up-to-date overview of anti-thrombogenic surface coatings for ECMO, including both commercial coatings and those under development. The focus is placed on the coatings being developed for oxygenators. Overall, zwitterionic polymer coatings, nitric oxide (NO)-releasing coatings, and lubricant-infused coatings have attracted more attention than other coatings and showed some improvement in in vitro and in vivo anti-thrombogenic effects. However, most studies lacked standard hemocompatibility assessment and comparison studies with current clinically used coatings, either heparin coatings or nonheparin coatings. Moreover, this review identifies that further investigation on the thrombo-resistance, stability and durability of coatings under rated flow conditions and the effects of coatings on the function of oxygenators (pressure drop and gas transfer) are needed. Therefore, extensive further development is required before these new coatings can be used in the clinic.

Investigation on effects of varying geometrical configurations on thermal hydraulics flow in a 3D corrugated pipe

In this numerical investigation, the flow behavior, pressure drop, and heat transfer enhancement for the fluid in a corrugated pipe with varying geometrical configurations arrangements by supporting the computational simulation technique are analyzed. Also, correlations expressions for friction factor (f) and Nusselt number (Nu) with different corrugated geometrical parameters are developed. The numerical modeling is applied using computational fluid dynamics (CFD), and flow field patterns with different structural parameters are predicted. The numerical simulation results are validated with available experimental data. The numerical approach combined with the varying qualitatively and quantitatively analysis are used. The computational investigations are carried out for a different range of Reynolds numbers (Re) with varying corrugated geometrical configurations, including corrugated pipe ratio (PCR) of 20, 40, 60, 80, and 100%, a number of the corrugated ring (NCR) of 2, 3 and 4 as well as the corrugated diameter ring (CDR) of 1, 2 and 3 mm respectively. The outcomes illustrate that as in similar Re number increases, the Nu number increases. When the corrugated geometrical increases, the mixing, and recirculation flow regions start to high rise along the corrugated pipe. Then the flow becomes more undisturbed near and closes to the corrugated rings, and hence the pressure drop (PD), Turbulent kinetic energy (TKE), and vorticity also increase. Moreover, as the PCR increases, the friction factor increases and the f for PCR of 100% is considerably higher than other models. The friction factor for PCR is higher than other models by about 7.05, 24.3, 40.7, and 67.1%. Furthermore, the performance evaluation factor is greater than unity.

Study of Pressure Drops and Heat Transfer of Nonequilibrial Two-Phase Flows

Currently, there are no universal methods for calculating the heat transfer and pressure drop for a wide range of two-phase flow parameters in mini-channels due to changes in the void fraction and flow regime. Many experimental studies have been carried out, and narrow-range calculation methods have been developed. With increasing pressure, it becomes possible to expand the range of parameters for applying reliable calculation methods as a result of changes in the flow regime. This paper provides an overview of methods for calculating the pressure drops and heat transfer of two-phase flows in small-diameter channels and presents a comparison of calculation methods. For conditions of high reduced pressures pr = p/pcr ≈ 0.4 ÷ 0.6, the results of own experimental studies of pressure drops and flow boiling heat transfer of freons in the region of low and high mass flow rates (G = 200–2000 kg/m2 s) are presented. A description of the experimental stand is given, and a comparison of own experimental data with those obtained using the most reliable calculated relations is carried out.

CFD modelling of mixing vane spacer grids for ALLEGRO relevant gas cooled reactor fuel geometry

The main objective of this paper is to present a newly developed CFD modelling method, suitable for the simulation of Mixing Vane spacer Grids (MVGs) that are designed for Gas Cooled Fast Reactors (GFRs). In order to prove the reliability of the model, a thorough validation is necessary. However, the available experimental data concerning the fluid dynamics of the ALLEGRO reactor, is limited to bare subchannel models.CFD models have been developed with a domain, that contains one spacer grid with mixing vanes. The mesh sensitivity study of ALLEGRO MVG CFD models was extended to transient calculations. Five different mesh densities were used/applied to get mesh independent results. The key parameters were crossflow factor, pressure drop, and heat transfer coefficient enhanced by the MVGs.We investigated the performance of different mixing vane types in gas cooled fuel rod bundles. The chosen vanes were of type split, advanced split, swirl and twisted mixing vanes. The different types were ranked by performance.According to our research, the twisted type mixing vane is the most efficient vane type for the ALLEGRO assembly. Calculations were performed in search of the optimal geometry in which the vane angle was modified between 15° and 40°.With the optimised twisted vanes, a full active length ALLEGRO fuel assembly CFD model was created, and the performance of different MVG arrangements was compared in three different CFD models. All the calculations were carried out using ANSYS CFX 17 code.