CFD Analysis Research Articles

CFD Analysis of Improving Air Conditioning System Performance By Adding SiO2 Nanoparticles To The Compressor Oil

The overall performance of air-conditioning systems is necessary to evaluate the comfort conditions and equipment life. in order not to varnish energy. The aim of this study is to improve performance of air conditioning by adding nanoparticles to oil of compressor. The research applied computational fluid dynamics CFD to simulate the use of SiO2 nanoparticles in air-conditioning systems. Silicon dioxide (SiO2) nanoparticles have better thermal properties than pure oil and can also significantly enhance the performance of compressor oils as well as heat transfer capability in HVAC systems. This research investigates the reactions between (0.1%, 0.4%, and %0.7) of SiO2 nanoparticles with compressor oil, to determine their impacts on heat dissipation, lubricant efficiency as well as performance overall. Results show that the addition of nanoparticles to the oil lubricant increases the COP of the air conditioning system.

Numerical Analysis and Design of New Exhaust Section Downstream of Constant Volume Combustor

Abstract Pressure gain combustors (PGC) exploit either their isochoric or detonative combustion increasing the theoretical thermal efficiency of a gas turbine cycle. On this basis, a constant-volume combustor (CVC) is developed operating with rotary valves while the chamber is fed with mixture of air and liquid iso-octane. This work describes the numerical design of a new exhaust section after the CVC. First, the design parametrization of the transition duct and the resulting design of experiments (DOE) of 81 samples are introduced. Every case is numerically tested and the election of the best sample is based on the pressure losses and the oscillations characterization. In the last part, the LS89-VKI vane is added at the aft part of the best transition duct and the ensemble exhaust system is analyzed with the help of transient CFD analysis. Every component is evaluated in terms of pressure losses and oscillations, while the operation of the vane is investigated in details. The results of the stator's performance are discussed and compared with steady experimental data. During a CVC period, the cycle average outlet flow angle remains close to the outlet metal angle denoting promising results for the future numerical analysis of the subsequent rotor.

Accelerated pump tube concept for hypersonic ground testing

This paper examines a new hypersonic wind tunnel concept which is referred to here as an ‘accelerated pump tube’ (APT). The facility can be considered a hybrid between a gun tunnel and an expansion tube. Like a gun tunnel, the test gas is isentropically compressed with a piston to raise its pressure and temperature; like an expansion tube, the compressed test gas is subject to an unsteady expansion to further increase its enthalpy and stagnation pressure. State-to-state analytical calculations incorporating high temperature equilibrium chemistry are presented which demonstrate that the APT is theoretically able to simulate a wide hypersonic terrestrial flight envelope from Mach 5–14, with significant capacity for pressure-length scaling. Potential practical benefits of this concept include relatively simple internal flow processes, removal of the need for a film secondary diaphragm and helium as a driver gas, and a reduction in experimental uncertainty through better defined internal boundary conditions and relatively low mechanical complexity. To assess the feasibility of the APT concept in a practical context, the paper considers how an APT based around a 25 m long, 600 mm diameter pump tube should be configured for a Mach 10 test flow. One-dimensional Lagrangian CFD analysis is used to compute piston dynamics for three different pump tube compression ratios and the associated test flows are characterised. The CFD results suggest that the concept should be viable in practice, and also validate the Mach 10 state-to-state calculations.

Innovative-serpentine cooling method of batteries: Both thermal and statistical method approach

Renewable energy, in particular, is critical for a sustainable world. Effective storage of energy is at the heart of all systems. While energy storage allows us to preserve the beauties offered by nature, it also requires innovative solutions that push the limits of technology. The most important factor affecting the performance of batteries is their temperature. For this reason, the serpentine cooling model, which is an innovative battery cooling method, was evaluated in this study. Generally, in the literature, batteries are considered as heat masses and given a certain heat flux and their temperature distributions are examined. In this study, batteries were connected to each other with busbars as in reality and thermal analyses were performed. In addition, a serpentine cooling method, which has never been used before, was tried as a cooling method in batteries. While all these evaluations were made, statistical analyses were performed for the priority order of the parameters used. All of these situations show how innovative the study is. The NTGK model was used in CFD analyses. 5 different parameters were considered. These are the discharge rate (0.5C, 1C, 1.5C, 2C and 2.5C), the type of refrigerant (air and water), the speed at which the refrigerant enters the model (0.01 m/s, 0.03 m/s and 0.05 m/s), the ambient temperature (293K, 298K and 300K), and the SOH value (50 %, 65 %, 75 %).Water has been shown to be a better refrigerant than air. As the inlet speed of the refrigerant was increased, the discharge rate was reduced, and the SOH value decreased, the temperature values obtained by the model were lower. The temperature values of the batteries according to their location in the model were also examined. 5-factor, 2-level experiments were conducted to examine statistically. It was checked whether the created values fit the distributions and it was seen that the most effective parameter used in the model was the type of refrigerant. In addition, the most statistically effective working conditions were also determined.

On the termination of an emerging droplet from a capillary tube over a flat surface by a wetting slug: A one-dimensional quasistatic model and CFD analysis

The problem of ejection of a droplet from a pore opening into a reservoir appears in many fields including pharmaceutical, food, chemical, and several other industries. In this work, we are interested in investigating the onset of dislodgment of such an emerging droplet. A one-dimensional model is developed that describes the dynamics of this process under quasistatic assumptions. Fluid inertia, the dynamic nature of the contact angle, as well as the entrance and exit hydrodynamic effects are ignored. Fluid inertia may be important at the very early stage of the displacement process, after which its effect diminishes. It is hypothesized that the emerging droplet will dislodge the surface when the two contact lines associated with the two interfaces meet. The forces acting on this system include external pressures, viscous and capillary forces. The flow rate is influenced by the capillary pressure of the emerging nonwetting fluid when the advancing interface reaches the exit of the tube and starts to develop, then by the two interfaces when the wetting fluid starts to displace the wetting one. At the onset of dislodgment, the capillary pressure across the two interfaces equalizes. A computational fluid dynamics (CFD) study has been conducted to confirm the stated hypothesis and to provide a framework for the validation and verification of the developed model. The CFD model depicts the whole spectrum of processes involved from the start of injection of the nonwetting fluid towards the ejection of the droplet. The model, however, only considers the system when the wetting fluid starts to emerge from the exit of the tube into the reservoir. Comparisons between the model and the CFD analysis show a good match, which builds confidence in the modeling approach. Interesting results are obtained, particularly when the interfaces reach the exit of the tube.

Modeling gas holdup in a multiphase oxygen slurry bubble column reactor for Cu-Cl hydrogen production using CFD

The hydrodynamics of the oxygen bubble column reactor is investigated numerically using CFD analyses to predict the values of the gas holdup using Eulerian model and k−ε turbulence method. It is shown that, at any given static liquid height and solid concentration, increasing the superficial gas velocity leads to a higher gas holdup. Also, the gas holdup reduces when the static liquid height increases and/or the solid concentration increases at any given superficial gas velocity. All gas holdup findings were verified by experimental results from prior literature, showing excellent agreement and validating the models' applicability to this kind of a slurry bubble column system. Profiles of gas holdup obtained from CFD simulations were shown to generally under-predict the experimental data. Also, it is shown that CFD models accurately anticipated the experimental effects of the superficial gas velocity, static liquid height, and solid concentration on gas holdup.

Improved Heat Transfer Capabilities of Nanofluids—An Assessment Through CFD Analysis

AbstractConventional fluids used in fission‐based water‐cooled nuclear reactors have lower heat transfer coefficients (HTCs) and thermal conductivity, which has led researchers to explore high‐performance fluids that can enhance heat transfer in routine operation and prevent core meltdown in the case of accidents. It is important to investigate a wide range of fluids that can help designers improve thermal hydraulic characteristics, such as HTC, critical heat flux, and minimum departure from nucleate boiling ratio (MDNBR). In this study, the effectiveness of nanofluids in enhancing heat transfer parameters, including thermal conductivity and heat capacity, was investigated. Four different nanofluids (Al2O3–H2O, ZrO2–H2O, Ag–H2O, and Si–H2O) with pure water as the primary coolant in an HPR‐1000 nuclear reactor were compared using computational methods. Due to computational limitations, only the flow channel among four fuel rods with the highest power density in the core was simulated using Eulerian computational fluid dynamics. The results of this study show that silver water (Ag–H2O) nanofluid outperformed other nanofluids and pure water. It had a higher average HTC and MDNBR, with a 67.15 % and 45.23 % improvement, respectively, compared to pure water. The fuel rod wall temperature was also reduced by 28.5 K with Ag–H2O compared to water. Comparison of current simulated results with literature data shows a good agreement.

CFD Analyses of Density Gradients under Conditions of Supersonic Flow at Low Pressures.

This paper deals with CFD analyses of the difference in the nature of the shock waves in supersonic flow under atmospheric pressure and pressure conditions at the boundary of continuum mechanics for electron microscopy. The first part describes the verification of the CFD analyses in combination with the experimental chamber results and the initial analyses using optical methods at low pressures on the boundary of continuum mechanics that were performed. The second part describes the analyses on an underexpanded nozzle performed to analyze the characteristics of normal shock waves in a pressure range from atmospheric pressure to pressures at the boundary of continuum mechanics. The results obtained by CFD modeling are prepared as a basis for the design of the planned experimental sensing of density gradients using optical methods, and for validation, the expected pressure and temperature courses from selected locations suitable for the placement of temperature and pressure sensors are prepared from the CFD analyses.

Immersion cooling of a cylindrical battery module: An optimum configuration using CFD, NSGA-II and desirability function approach

Immersion cooling offers promising advantages for cylindrical battery modules, particularly in applications where compact design, efficient thermal management, and enhanced safety are critical factors. In this study, the geometric, thermal, and dynamic parameters of an immersion-cooled battery module with 14 NCM cylindrical cells are analyzed using CFD methods. The developed battery model is experimentally validated, establishing the constraints through numerical analysis of the impact of design parameters on response values. The design parameters are optimized using a multi-objective optimization technique. The study models the battery module with mineral oil cooling and examines the impact of each parameter on variables such as maximum battery module temperature (Tmax), pressure drop (ΔP), maximum temperature variance (ΔTmax), and battery module mass index (Im). A Design of Experiment set, created with Central Composite Design (CCD), is solved using CFD methods, and quadratic correlation equations are derived using backward regression. The regression models for Tmax, ΔTmax, ΔP, and Im show high accuracy with R2 values close to 1.0. Optimization is performed using the entropy weight-based composite desirability function approach, yielding optimum values for cell center spacing (t), coolant mass flow rate (ṁc), and coolant inlet temperature (Ti) at 20.606 mm, 1.5 kg/s, and 23 °C, respectively. The optimized design sets are validated through CFD analysis, showing a maximum deviation of 4.27 %. Reducing t boosts thermal performance but lowers hydraulic performance, while the reverse occurs for ṁc. As Ti decreases, effective cooling improves, but temperature uniformity suffers.

Investigating the Effectiveness of Vortex Generators in Aviation through High-Fidelity CFD Analysis

Investigating the Effectiveness of Vortex Generators in Aviation through High-Fidelity CFD Analysis

CFD and ray tracing analysis of a discrete nozzle for laser metal deposition

CFD and ray tracing analysis of a discrete nozzle for laser metal deposition

Comprehensive Investigation of the Thermal Performance of an Electrically Heated Double-Glazed Window: A Theoretical and Experimental Approach

The thermal performance of windows is an important area of research to reduce the energy consumption of buildings and improve indoor comfort. The application of innovative glazing technologies can improve the energy performance of windows and transparent facades, resulting in significant energy savings. This paper presents research results on the energy performance of electrically heated windows. A comprehensive CFD and experimental analysis of the heat transfer processes in a window space depending on the size, power, and location of an electric heater was performed. The convective gas flows in the gas gaps and in the boundary layer were also analysed, and it is shown that a window with an electric heater can reduce the energy consumption of a room by 10–12%. This study is a pilot study to assess the feasibility and cost-effectiveness of electric local heating of a window or facade to minimise heat loss before full-scale implementation. The results of numerical modelling and experimental studies confirm the potential of the new technologies.

Experimental research and CFD analysis on engine fins with varied geometries

Experimental research and CFD analysis on engine fins with varied geometries

Three Phase Oil Separator Simulation Using CFD Analysis: A Review Study

Three Phase Oil Separator Simulation Using CFD Analysis: A Review Study

Three Phase Oil Separator Simulation Using CFD Analysis: A Review Study

Three Phase Oil Separator Simulation Using CFD Analysis: A Review Study

Comparative CFD Analysis of Angles of attack to increase aerodynamics properties

Abstract In the contemporary landscape, discussions of turbulence often lead to thoughts of incompressible fluids and their behaviour in nature. However, as the pursuit of energy efficiency and performance takes precedence in major aviation and automotive industries, safety and comfort remain achievable. Spoilers on sedan cars, designed to counteract lift and enhance grip, also increase drag. Aerofoils play a vital role in reducing drag while increasing lift force. This study compares three different angles of attack to identify the one that generates the best performance, based on its aerodynamic coefficients. In a world focused on ecological preservation and fuel efficiency, these studies become essential.

Performance optimization of a neon turboexpander based on the Kriging model and genetic algorithm

The rapid development of high-temperature superconducting (HTS) technology has increased demand for stable and reliable cooling sources, with the neon refrigerator emerging as a favorable solution for HTS applications, among which neon turboexpander is the core component. This paper proposes an optimal design method tailored for the neon turboexpander, which combines a one-dimensional mean-line design, three-dimensional CFD analysis, adaptive Kriging surrogate model, and the genetic algorithm. The meridional contour of the turboexpander impeller is geometrically parameterized, and the three most critical structural parameters are selected through Sobol sensitivity analysis, and then the response surface analysis is carried out to analyze the coupling relationship between the structural parameters. After optimization, the total-to-static efficiency and output power of the neon turboexpander increased by 3.98% and 6.12%, respectively. Notably, the flow separation phenomenon within the optimized impeller is significantly improved, resulting in reduced flow loss. Furthermore, the optimized impeller demonstrates robust performance in a wide range of variable operating conditions. Therefore, the optimization design method has been proven effective, and the optimal turboexpander impeller structure can be obtained quickly and accurately.

6DoF CFD Analysis for High-Speed Small Craft in Free Running Conditions

ABSTRACT CFD simulations of a high-speed small craft are performed with 6DoF motions. The hull form and propulsor are scaled to match a deep V fishing boat (DVFB). The on water experimental data of the DVFB was used for qualitative validation. Many captive and free running conditions are considered including some most critical conditions, such as 2DoF captive motion, free running self-propulsion, turning circles in calm water and waves, acceleration, and avoidance line tests. The present work is the first known CFD study for the free running of high-speed small craft with 6DoF motions and is exploratory in nature. The accuracy and performance of the gear case and propeller models are evaluated with the issues identified. Other issues are also discussed including the optimum grid sizes, submerged depth of the gear case, and instabilities. All of these can be provided as recommendations for the future research improvements.

Study on Traction Characteristics of Point Contact State under Oil–Air Lubrication

Oil–air lubrication technology is commonly utilized in the lubrication design of traditional components to reduce friction between contact pairs. This study focuses on testing the point-contact friction pairs of two quantitative valves using a self-made oil–air lubrication traction force machine with a G95Cr18 disk and ball as the friction pairs. The test data are analyzed using a four-parameter exponential model. Additionally, a calculation model of the oil–air lubrication flow field is established, defining boundary conditions and conducting flow field simulation analysis. The results of the ball and disk test show that the traction coefficient increases with load and decreases with entrainment speed. Furthermore, when the air-speed is 12 m/s, the traction coefficient is lower for the oil supply of 6 mL/min than for the oil supply of 1.5 mL/min. According to CFD analysis, the volume fraction of the oil phase in the contact area increases with the increase of entrainment speed when the slip–roll ratio is 0.1. The theoretical values from the four-parameter exponential model align well with the experimental results, and the fitting accuracy is higher than 0.95.

CFD analysis of mixed convection and entropy generation in vented curved cavity under the radiation effects

CFD analysis of mixed convection and entropy generation in vented curved cavity under the radiation effects