Commercial Computational Fluid Dynamics Research Articles

Validation of Effectiveness Factor Correlations for Steam Methane Reforming in Ni-Based Washcoat Catalyst Layers Using Commercial Computational Fluid Dynamics Software

Validation of Effectiveness Factor Correlations for Steam Methane Reforming in Ni-Based Washcoat Catalyst Layers Using Commercial Computational Fluid Dynamics Software

Thermal enhancement of PEM fuel cell cooling with novel configurations of Tesla valve and hybrid nanofluids: A numerical study

The operating temperature and thermal distribution play a significant role in the appropriate performance of the proton exchange membrane fuel cell (PEMFC). A suitable cell cooling method can guarantee uniform temperature distribution and preservation of membrane water content under harsh conditions in a PEMFC. The compact structure of PEM fuel cells and the size of the cooling system impose a great challenge to achieve a proper design of cooling plate. In this numerical study, four designs of the multi-stage Tesla valve with straight and reverse configuration are proposed to be employed as a cooling channel in which three different hybrid nanofluids such as TiO2–Cu, Al2O3–CuO, and Ag–MgO dispersed in water and Ethylene glycol flow inside the channels. A validated numerical model is developed using a commercial computational fluid dynamics (CFD) code to investigate the effect of inlet temperatures and mass flow rates of cooling fluid and volume fraction of nanoparticles on heat transfer coefficient, pressure drop, index of uniform temperature (IUT), and performance evaluation criteria (PEC). The results demonstrated that the reverse configuration of the Tesla valve (CASE E) experienced outstanding uniform thermal distribution while the heat transfer coefficient increased by 15% in this case compared to the straight-line cooling channel. The Ag–MgO hybrid nanoparticles showed better thermal performance than the two other nanoparticles with a 4% reduction in temperature difference in the cooling plate.

Turbulent Particle Flow in Spent Nuclear Fuel Storage Systems

Deposition models are being developed with the commercial computational fluid dynamics software STAR-CCM+ to evaluate particulate deposition on spent nuclear fuel (SNF) canisters. The primary particulate of concern is chloride salts, which are dispersed in the atmosphere and then deposited onto the canisters. During dry storage, the primary degradation process is likely to be chloride-induced stress corrosion cracking (CISCC) at the heat-affected zones of the canister welds. It is known that stainless steel canisters are susceptible to CISCC; however, the rate of chloride deposition onto the canisters is poorly known, based on sparse field data from a small number of sites. This paper describes work looking at various approaches to modeling turbulence, such as Reynolds-averaged Navier Stokes (RANS) and large eddy simulation (LES), and its impact on particle flow and deposition within a ventilated SNF storage system. The deposition rate is determined for a vertical canister system and a horizontal canister system. LES has the potential to simulate turbulent flows more accurately versus RANS, but is much more computationally expensive. A k-omega version of the RANS turbulence model was used for this study. The computational efficient RANS steady-state model predicted a similar canister deposition result as the LES simulation for a vertical canister storage system. For a horizontal storage system, the RANS steady-state model predicted more particles depositing on the canister than the LES simulation, providing a conservative estimation for particle deposition. A wall correction factor was added to the RANS model to dampen the turbulence fluctuation normal to a surface that left undamped, leads to the RANS model overpredicting deposition along a surface for smaller particles. This work was done to further development of deposition models that could be used to plan and inform SNF canister aging management programs with predictive models for the timing and occurrence of canister CISCC. This work is part of a larger effort tasked with understanding the likelihood of canister degradation due to CISCC. These models are still under development, and testing is needed for validation. However, these models are being presented now to demonstrate to canister vendors, utilities, regulators, and stakeholders the value of this type of modeling.

Transient evolution of thermal stratification and passive flow guidance inside a heat exchanger immersed thermal energy storage tank

Thermal stratification is being studied globally for thermal storage tanks while natural convection motion has a high impact on the phenomenon. Therefore, in this work, a conical guide geometry is introduced as a passive flow modifier to enhance the thermal stratification inside a cylindrical tank that is used for thermal storage purposes. The tank also has an immersed spiral coil heat exchanger in it. Transient evolution of thermal stratification inside the thermal storage tank is monitored for different charge flowrates and temperatures. The experimental data is used to benchmark a commercial computational fluid dynamics code relying on finite volume method. After seeing that the code simulates the transient thermal stratification with acceptable discrepancies, a conical guide geometry above the immersed heat exchanger is examined via the computational code for dimensional variations. The dimensions of the cone guide are defined based on thermal storage tank dimensions in order to have some degree of universality. The best performing cone guide in the simulations is then tested experimentally. It is validated that the proposed cone guidance enhanced thermal stratification evolution in the tank. An increase of 3.85 °C is obtained in the average tank temperature with the use of the cone guide after 3 h of charging. Approximate effectiveness of the heat exchanger coil is found about 90 % while a 7.6 % increase is realized by the utilization of the guide.

A computational fluid dynamics study of the influence of sleeper shape and ballast depth on ballast flight during passage of a simplified train

The paper assesses the effect on the air flow regime underneath a simplified high-speed train of changing the ballast depth and the sleeper shape, with regard to its potential for causing ballast flight or pickup. The study was carried out numerically using the commercial Computational Fluid Dynamics (CFD) software AnSys Fluent. The flow profile beneath the underbody of the train was generated by means of a moving wall above the track. The Delayed Detached Eddy Simulation (DDES) with the SST [Formula: see text] turbulence model was used to simulate turbulent flow, and the ballast bed roughness was applied parametrically using the wall roughness feature when resolving the boundary layer. CFD simulations were validated for flow over a cube, showing good agreement with experimental results. Up to three different depths to the ballast surface and three different sleeper profiles were investigated. Velocity profiles and aerodynamic forces on cubes placed between or on top of the sleeper blocks were used to assess the propensity of individual ballast grains for movement. For a standard G44 sleeper, increasing the ballast depth and/or the ballast bed roughness was found to reduce aerodynamic loads on an individual ballast grain. A ballast grain on top of the sleeper is more prone to uplift than a grain on the surface of the ballast bed in the crib. A curved upper surface to the sleeper is beneficial in that it prevents ballast from settling on top, the most vulnerable position. However, the reduced flow separation associated with the curved top may increase the likelihood of ballast pickup from the crib. Hence new sleeper shapes intended to reduce the potential for ballast flight should not only prevent ballast from settling on top, but also increase flow separation through the provision of a sharp surface. A prismatic sleeper shape that achieves both is suggested.

An In-Depth Comparison of Straight and Wavy Microchannel Heat Exchangers

Abstract This paper presents extensive fluid flow and Heat-Transfer studies conducted using a commercial computational fluid dynamics (CFD) package known as CFD-ACE® to elaborate and expand on the reference studies available for ceramic-compact counterflow microchannel heat exchangers (MCHEs). The computational 3D model was developed using an experimentally tested MCHE and validated with experimental data with 3–5% variation for hot fluid and 6–12% variation for cold fluid for the entire design of experiments (DoEs). This study aimed to identify the performance of novel microchannel shapes using numerical analysis. The MCHE has good heat exchange properties, a compact design at industrial throughput, and a lower inner volume. During the study and identification of novel channel shapes, the segmented wavy MCHE was evaluated. The results were compared with those of the same volume and area straight MCHE baseline design under various identical operating conditions. Although the performance in terms of effectiveness is increased up to ∼12–25% in wavy MCHE with respect to straight MCHE simultaneously, the pressure drop is also increased by ∼60–80% under the same operating conditions. Therefore, performance and trade-offs are required to make the correct decision regarding feasibility. The effectiveness of the heat-transfer enhancement was also evaluated by plotting the heat-transfer coefficient ratio with respect to the pressure ratio of the two designs under identical operating conditions. This numerical study clearly indicates that wavy channels are better from the thermal performance point of view, whereas straight channels are better from the pumping power point of view, and the quantitative values are presented in graphical form.

Hydrodynamic characteristics of wing-in-ground effect oscillating hydrofoil on power extraction performance

The energy contained in the tidal motion of the seas and oceans has the potential to be a significant source of renewable energy. The oscillating hydrofoil current-energy turbine has a good performance to extract energy from the coupling of its heaving and pitching motions. In the present study, the wing-in-ground (WIG) effect has been considered to improve the power-extraction performance of the oscillating hydrofoils. The overset grid in the commercial computational fluid dynamic (CFD) software STAR CCM+ is applied to study the flapping hydrofoil with dynamic WIG effect between two hydrofoils. The simulation results show that the WIG effect can greatly improve the power extraction performance of the flapping hydrofoil. The WIG effect is asymmetric over the course of the foil moving toward or leaving from the symmetry plane. The distance of the gap has a major influence on the hydrodynamic performances of the flapping hydrofoil. For a moderate gap, the positive pressure on the lower surface enhances as the hydrofoil departs from the symmetry plane and causes an improvement of lift and moment coefficients. As the gap decreases further, the increasing negative pressure between the leading edge and the symmetry plane plays an essential role improving the power extraction as the hydrofoil approaches the symmetry plane. Compared to the case without the WIG effect, the power-extraction efficiency has an increment of 16.34% in the present study.

Investigation of the thermal performance of a spiral fin-and-tube heat exchanger by numerical methods

Spiral fin-and-tube heat exchangers (SPF HEX) are broadly employed heat transfer (HT) equipment for heating and cooling applications. Therefore, developing a model that predicts the HT characteristics could provide an advantage when selecting the required device considering operation conditions. The efficacy of the HT characteristics of a three-dimensional SPF HEX was examined under various boundary conditions with the help of a commercial computational fluid dynamics (CFD) solver and predicted by employing machine learning (ML) approaches as a rarely studied novel work. Three-dimensional, steady, and incompressible Reynolds-Averaged Navier-Stokes (RANS) formulas, including continuity, momentum and energy were solved to obtain numerical data. k-ε Realizable turbulence model, which has two additional transport equations, was employed. The outlet temperature of water was calculated at various water inlet velocity, air inlet velocity, and air inlet temperature with a constant water inlet temperature. First, the methods of CFD were utilized to obtain sixty cases, then the outlet temperatures of water were obtained at various conditions. The current CFD technique was verified with a work in literature. After collecting a labeled dataset, this data is fed into four recognized ML algorithms: Support Vector Machine (SVM), Linear Regression (LR), Decision Tree Regression (DT), and Random Forest (RF). In the presented results, the SVM algorithm achieved the highest accuracy rate with values of 0.1765 mean squared error (MSE), 0.3294 mean absolute error (MAE), and 0.9940 R-squared (R2). Furthermore, these results indicate that ML algorithms can deliver high prediction performance, potentially reducing the need for many experimental and numerical studies.

Hemodynamic Study of Cerebral Arteriovenous Malformation: Newtonian and Non-Newtonian Blood Flow

ObjectiveArteriovenous malformation is a disease of the vascular system that occurs mainly in the cerebral arteries and spine. Numerical simulation as a powerful method is used to investigate the Cerebral Arteriovenous Malformation hemodynamic after occlusion of the abnormality step by step by embolization. MethodsThe CT Angiographic imaging data of two patients are used and a geometric model is extracted by the Mimics software. Numerical simulation of blood flow is performed in both Newtonian and non-Newtonian models. The Navier–Stokes, and continuity governing equations are solved by finite element method using the COMSOL Multiphysics software (the commercial computational fluid dynamics (CFD) simulation software). To validate the numerical results, the real data on blood flow rate in the feeding artery and draining veins are used, as well as angiographic images at different times. ResultsRegarding the comparison of pressure contours for different occlusions of 0, 30, 50, and 90%, by increasing the amount of occlusion in the nidus, there is an increase in the blood pressure. Regarding the comparison of the blood flow velocity in the feeding artery, draining veins, and inside the AVM nidus for Newtonian and non-Newtonian models, there is a significant difference between these two simulations in vessels with smaller dimensions (such as vessels inside the nidus). ConclusionBy increasing the amount of nidus occlusion, the blood pressure is increased, so the blood supply process is better. According to a significant difference between the Newtonian and non-Newtonian simulations in vessels with smaller dimensions (such as vessels inside the nidus), therefore, non-Newtonian simulation should be done for different occlusions of 30, 50, and 90%.

CFD evaluation of hydrophobic feedstock bench-scale fermenters for efficient high agitation volumetric mass transfer.

A new biomanufacturing platform combining intracellular metabolic engineering of the oleaginous yeast Yarrowia lipolytica and extracellular bioreaction engineering provides efficient bioconversion of plant oils/animal fats into high-value products. However, predicting the hydrodynamics and mass transfer parameters is difficult due to the high agitation and sparging required to create dispersed oil droplets in an aqueous medium for efficient yeast fermentation. In the current study, commercial computational fluid dynamic (CFD) solver Ansys CFX coupled with the MUSIG model first predicts two-phase system (oil/water and air/water) mixing dynamics and their particle size distributions. Then, a three-phase model (oil, air, and water) utilizing dispersed air bubbles and a polydispersed oil phase was implemented to explore fermenter mixing, gas dispersion efficiency, and volumetric mass transfer coefficient estimations (kL a). The study analyzed the effect of the impeller type, agitation speed, and power input on the tank's flow field and revealed that upward-pumping pitched blade impellers (PBI) in the top two positions (compared to Rushton-type) provided advantageous oil phase homogeneity and similar estimated kL a values with reduced power. These results show good agreement with the experimental mixing and kL a data.

NUMERICAL SIMULATION OF TURBULENT FLOW IN A HEAT EXCHANGER EQUIPPED WITH FINS OF DIFFERENT MATERIALS AND GEOMETRIES

The miniaturization of electronic devices causes heat generation in the system. In this scenario, highly effective heat sinks are needed for the electronic devices. The present study focuses on enhancing heat transfer in heat sinks by using pin fins with different geometries (circular, elliptical, triangular, and square), various materials for pin fins (copper, aluminum, magnesium, tungsten, zinc, and steel), and Al<sub>2</sub>O<sub>3</sub>-EG nanofluid. The analysis is carried out by a commercial computational fluid dynamics (CFD) program called Ansys Fluent 14, which was used to numerically solve the governing equations and boundary conditions. The 3D model is subsequently discretized using the ICEM CFD meshing tool. From the analysis, it has been observed that 331.75 W of heat is lost by using copper material in a heat sink, and magnesium recorded 363.7 W of heat loss, whereas aluminum recorded 319.5 W. Moreover, copper is a great material for transferring heat. This means that heat moves quickly through copper and magnesium as they have good thermal conductivity. Elliptical materials conserve materials more than others when the space is limited to one direction. Elliptical shapes record 461.67 W heat loss.

Airfoil Lift Coefficient Optimization Using Genetic Algorithm and IGP Parameterization: Volume 1

The objective of this study is to develop a genetic algorithm that uses the IGP parameterization to increase the lift coefficient (CL) of three airfoils to be used on wings of unmanned aerial vehicles (UAVs). The geometry of three baseline airfoils was modified by developing a genetic algorithm that operates with the IGP parameterization and performs the aerodynamic analysis using XFOIL in the MATLAB environment. Subsequently, a numerical model was made for each baseline and optimized airfoil using a commercial computational fluid dynamics (CFD) code to analyze the behavior of the lift coefficient. An increase in the average CL was obtained for the Eppler 68, MH 70, and Wortmann FX 60-126 airfoils for angles of attack ranging from 0 to 10, obtaining increments of 17.243%, 14.967%, and 10.708%, respectively. Additionally, an average 5.027% uncertainty was obtained in lift coefficient calculations between XFOIL and CFD. The utility of the IGP method and genetic algorithms for parameterizing and optimizing airfoils was demonstrated. In addition, airfoils could be tailored for a specific UAV depending on the mission profile. Volume 2 of this study will include experimental data from wind tunnel.

CFD Study for Wave Run-up Characteristics Around a Truncated Cylinder with Damper

In this study, numerical simulations for a single fixed truncated circular cylinder in regular waves were conducted to investigate the nonlinear wave run-up under various dampers and wave period conditions. The present study used the volume of fluid (VOF) technique to capture the air-water interface. The unsteady Reynolds-averaged Navier–Stokes (URANS) equation with the k– ϵ turbulence model was solved using the commercial computational fluid dynamics (CFD) software STAR-CCM+. First, a systematic spatial convergence study was conducted to assess the performance and precision of the present numerical wave tank. The numerical scheme was validated by comparing the numerical results of wave run-up on a bare truncated cylinder with the experimental results, and a good agreement was achieved. Then, a series of parametric studies were carried out to examine the wave run-up time series around the truncated cylinder with single and dual dampers in terms of the first- and second-order harmonic and mean set-up components. Additionally, the local wave field and the flow velocity vectors adjacent to the cylinder were evaluated. It was confirmed that under short wave conditions, the high position of the damper led to a noticeable increase in the wave run-ups with significant changes in the first- and second-order harmonic components.

Numerical simulation to study mixing vane spacer effects on heat transfer performance of supercritical pressure fluid in an annular channel

The spacer represents an essential part in the nuclear fuel rod. Spacer grid with mixing vanes in fuel rod bundle of nuclear reactor core has a significant impact on heat transfer perfor-mance in downstream to grid spacer. Grid Spacers are located on the nuclear fuel rod as-sembly to hold suitable clearance among the rods in a bundle. The objective of this paper is to study the enhanced heat transfer performance of R134a at supercritical pressure 4.5 MPa near downstream to mixing vane spacer in a vertical channel of annular flow. A spacer of 0.38 blockage ratio with mixing vanes, situated at mid-span of an annular channel is used in the present work. Numerical simulations have been accomplished for spacer with mixing vane and spacer without mixing vane in an annular channel by using commercial CFD (Computa-tional fluid dynamics) code ANSYS Fluent. The present investigation represents the compara-tive study for spacer with mixing vane and spacer without mixing vane effects on heat transfer and flow field characteristics in a downstream direction for mass flow-rate 0.41469 kg/s and heat flux 160 kW/m2. The results indicate that spacer with mixing vane has notable influence on heat transfer performance and flow field characteristics downstream of mixing vane spacer as compared to spacer without mixing vane. Wall temperature fall and increase of coefficient of heat transfer are significantly greater adjacent to spacer downstream. Spacer influence in the improvement of the heat transfer is noted up to distance X/D = 40 downstream and then flow is found as fully developed.

Colourless distributed combustion effects on a pre‐mixed coke oven gas flame

AbstractFuels consisting of high hydrogen concentration can be consumed under colourless distributed combustion (CDC) to suppress flashback tendency in premixed conditions. Higher NOX challenges can also be overcome through CDC. For those purposes, coke oven gas was consumed under CDC within the scope of this study. To achieve CDC, or diluents were introduced into the oxidizer so that oxygen concentration in the oxidizer would be decreased from 21% O2 to its lean blow‐off limits. Excess air ratios were determined as λ = 1.2 and λ = 1.5 along with a thermal power of 10 kW under premixed conditions. A commercial computational fluid dynamics code was used to predict temperature distribution and , CO, and emissions. 162‐step reactions created with GRI‐Mech 3.0 chemical kinetics was integrated to the eddy dissipation concept combustion model. The temperature and profiles predicted were compared with the experimental results. Consistency was achieved at ~95% for temperature profiles, and almost 100% for profiles between the measured and the predicted ones. According to the results, it is concluded that a more homogeneous temperature distribution with the ~21% decrease in the maximum temperature was observed, and there was about 96% decrease in level. It was also demonstrated that using as a diluent is more effective in terms of temperature distribution over the combustor and reduction, while dilution with is more effective in terms about 70% in decrease on CO.

A Hydro-Powered Climate-Neutral Pump: Full Cycle Simulation and Performance Evaluation

This paper presents a parametric study of the multistorey hydro-powered pump, known as ‘Bunyip’, which has demonstrated significant potential in contributing to rural regions. The study is aimed at understanding the underlying physics of the system and ways to enhance its hydraulic performance. A transient three-dimensional model using the commercial Computational Fluid Dynamics (CFD) tool Ansys-Fluent is utilized to gain insights into its fundamental flow mechanics, operational efficiency, standard capacity, and relative delivery. The investigation involves an initial assessment of performance for three Bunyip devices based on manufacturing data. A parametric analysis is conducted for the dataset generated through meticulous application and numerical modelling. The CFD results are validated against experimental data. Three main design configurations are considered, and 58 sets of varied input parameters are examined. The best design configuration is evaluated against five cases of conventional hydro-power pump systems. The results indicate that a smaller diameter of the pressure chamber and a higher supply head lead to higher pressure, achieving a target head of 3 m with 15% efficiency and a flowrate of 11.82 L/min.

Hemodynamic analysis of coil filled patient-specific middle cerebral artery aneurysm using porous medium approach

Cerebral aneurysms are bulges of an artery, which could be life-threatening when ruptured. Depending on their size, shape, and location, they need to be managed either through clipping or an endovascular coiling intervention. When coiled, reduced hemodynamic activity enables the coil to get thrombosed and achieve flow stasis. However, some coils delivered into the aneurysm tend to prolapse into the parent vessel and cause stroke due to obstruction and embolization. The recurrence of an aneurysm after endovascular coiling is of concern in the treatment of wide necked aneurysms. The initial packing density or improper coiling of the aneurysm and its relation to recurrence remains uncertain. This study investigates the influence of reduction in coil fill volume and packing density on the aneurysm recurrence using hemodynamic parameters by analyzing its flow features. Finite element method based commercial computational fluid dynamics solver is employed for performing patient-specific simulations for the coil filled aneurysm. The present approach uses porous medium based formulation. The numerical simulations show that any reduction below the optimal coil fill volume and packing density inside the aneurysm increases the velocity magnitude, wall shear stress, time-averaged wall shear stress, and spatial gradient of wall shear stress and reduces the relative residence time. The hemodynamic parameters and flow features suggest that a reduction in the coil packing density inside the aneurysm increases the chances of aneurysm recurrence. Hence, an assessment on how to achieve optimal coil fill volume and packing density is critical in reducing the risk of aneurysm recurrence.

Investigation of Taylor bubble dynamics in annular conduits with counter-current flow

This study numerically investigates counter-current slug flow by considering the motion of a Taylor bubble in annular conduits with downward-flowing liquids using the Volume-of-Fluid method implemented in the commercial computational fluid dynamics software ANSYS Fluent (Release 19.2). The translational velocity of a counter-current ascending or co-current descending Taylor bubble in vertical concentric annuli and the corresponding distribution parameter (C0) are analyzed. The latter is correlated in terms of Eötvös number (Eo) and inverse viscosity number (Nf) within the range of Eo between 40 and 400 and Nf between 40 and 320. The proposed correlation provides an accurate fit to the numerical data with an average error of 2.64%, and is successfully compared with published numerical findings. In general, the smooth and stable shape of the bubble is disrupted as the counter-current flow velocity (Frl) increases above a critical value, leading to the formation of surface waves and the displacement of the bubble tip away from the annular gap center and towards the outer pipe. C0 increases with Eo and Nf, plateauing at high values of Eo. The effects of annulus inclination (θ) and eccentricity (ε) on bubble rise velocity are examined within the common range of θ and ε encountered during the drilling of oil, gas, or geothermal wells, i.e. 0° ≤ θ ≤ 60° and 0 ≤ ε ≤ 0.7, and their impact on the C0. The increasing Frl and θ lead to a streamlined bubble with pointed nose and thus a reduction in the wrap angle (θwrap), ultimately leading to reduced drag compared to the vertical annulus case and a decrease in C0. As the ε increases, which is accompanied by an increase in the degree of bubble eccentricity, the corresponding C0 decreases. For a constant Eo = 100 and Nf = 160 with inclination angle of θ = 40°and eccentricity of ε = 0.5, the C0 < 1 is observed.

Simulation of co-pyrolysis of coffee ground and waste polystyrene foam in a tilted-slide reactor

Coffee ground is considered one of the promising biomass resources because it is one of the most popular beverages and has higher calorific value than other kinds of biomass. In the previous study on the fast pyrolysis of coffee ground, the viscosity of the pyrolysis oil was found to be very high and it was suggested to mix some amount of alcohol to reduce its viscosity. The quality of the pyrolysis oil also can be improved by mixing synthesis polymer such as polyethylene, polyethylene, or polystyrene as a feedstock. Recently, a tilted-slide reactor for fast pyrolysis was designed with a feeding capacity of 20 kg/h, in which no fluidizing gas is necessary for conveying hot sand. In the previous experiment, the co-pyrolysis of coffee ground and waste polystyrene foam was performed in the tilted-slide reactor. The ratio of waste polystyrene foam in the feedstock mixture was varied from 0% to 100% by weight, and fast pyrolysis was performed near the temperature of 550 °C. In this study, the co-pyrolysis was simulated by a commercial computational fluid dynamics code, and the results were compared with experimental results. A multistep kinetic mechanism was adopted for the pyrolysis of coffee ground and polystyrene. The volatile yields in the simulation approached the pyrolysis oil yields in the experiment by introducing a composite boundary condition to retain the unpyrolyzed polystyrene near the reactor bottom for longer residence time. The elemental composition and moisture contents became similar with measurement when increasing polystyrene blending ratio.

Thermal analysis on the performance of a finned hybrid bi-fluid PVT system

The increase in the temperature of solar panels is a significant issue that leads to low performance of photovoltaic (PV) cells. This numerical investigation aims to perform a transient analysis employing commercial computational fluid dynamics code and improve the electrical energy of the PV panel in a hybrid system by utilizing both water and air and adding fins. The system was cooled from the rear side of the PV/thermal (PVT) module by flowing water at different mass flow rates (ṁw = 0.010 kg/s to 0.020 kg/s) through aluminum tubes adhered to an aluminum absorbent plate. Moreover, the air passes through the channel that contains aluminum fins welded to the absorbent plate and next to the tubes. The objective is to analyze the effects of ṁw and fins on the flow and the thermal efficiency. A comparison was made between two modules of bi-fluid (BF) PVT manifolds: module 1 without fins and module 2 with fins. The effect of the operating temperature rise on the PV panel and the total thermal efficiency was evaluated. The attained results presented a linear decrease in thermal efficiency with the increase of ṁw. The thermal efficiency of modules 1 and 2 at ṁw = 0.010 kg/s is 50% and 60%, respectively. Under the solar irradiance and ṁw = 0.010 kg/s in module 2, an improvement of thermal efficiency of about 5.7% was recorded compared to module 1. The hybrid PVT BF system with fins (module 2) operating with ṁw = 0.010 kg/s has proved that adding fins to the PVT system was very effective in maintaining the system’s thermal efficiency at its highest record.