Search

Hydrogen has the potential to produce energy with no emissions, and therefore offers a strategic opportunity for rapid development of renewable energy storage. However, jet flames caused by the leakage of high-pressure hydrogen may cause casualties and damage equipment, so the safety issues associated with hydrogen incidents are a key issue restricting its development. Barrier walls can be an important mitigative action to reduce the hazard of hydrogen jet flames. Previous studies have evaluated the protective effect of different vertical or inclined arrangements of a single barrier wall in the vertical direction. However, in the vertical direction, a single barrier wall is not sufficient to reduce the hazards associated with high-pressure hydrogen jet flames. In this paper, a two-dimensional CFD model of high-pressure hydrogen jet flames are established. A simplified form of the hydrogen real gas equation of state is used to describe the complex behavior of high-pressure hydrogen. This CFD study employs the standard k-ε turbulence model, the eddy dissipation concept (EDC) model, and the discrete ordinate (DO) radiation model. The results display good agreement with the experimentally obtained flame shape and thermal radiation values, which confirms the applicability of the model. Based on this model, the characteristics of high-pressure jet flames are systematically studied under different forms of barrier walls and different pressures of hydrogen storage. Compared with the vertical barrier wall, barrier walls with complex structures can block the flames in front of the wall more effectively. This is proven through a remarkable decline in the vertical flame length and a reduction in the high temperature area. Comparing the five barrier wall patterns for their combined flame shape and flame temperature, it is more preferred to choose 60° Plate. The results of this study will help to better analyze the consequences of hydrogen jet flames and provide guidance for better design of barrier walls for mitigation. [ABSTRACT FROM AUTHOR]

This numerical study presents discharge prediction on range of upstream head levels over a compound rectangular broad crested weir (CR-BCW). The computational domain was built in Ansys workbench, while 3D simulation and postprocessing were performed in CFD based tool Fluent using volume of fluid (VOF) method. Two turbulence models, the Re-Normalization Group (RNG) K-ε and the Shear Stress Transport (SST) K-ω, were considered to check their capability for flow prediction under different upstream head levels. The calculated numerical results initially compared with the published experimental data. The Root Mean Square Error (RMSE) and the Mean Absolute Percent Error (MAPE) were used to check the accuracy of the numerical results. The findings demonstrate that the SST K- ω model presents better agreement with experimental data, indicating its optimal performance for simulating flow characteristics and predicting discharge over the CR-BCW model. This study does not only validate the SST K- ω model's effectiveness, but also highlights the sensitivity of hydraulic parameters to the choice of turbulence model, thus contributing valuable insights for the design and analysis of hydraulic structures. • Numerical study for discharge predictions for compound rectangular broad-crested weir. • SST K-ω model forecast accurate discharge predictions. • VOF method successfully replicates experimental water surface profiles. • Numerical results reveal complex nature of pressure and velocity distribution on compound weir crest. • Investigating discharge coefficient sensitivity across various dimensionless head ratios. [ABSTRACT FROM AUTHOR]

This study provides a comprehensive analysis on the hydraulics of flow over cylindrical weir-gates with and without a flow extender, utilizing a validated numerical model. The model, validated against recent experimental data, examines the effects of various parameters including the angle of flow extender, gate opening, and submergence levels on flow characteristics, energy losses, and discharge reduction factors. The findings indicate that Results show that weir-gates equipped with a flow extender experience a notable reduction in energy losses—up to 35 % for flow extenders with angles between 0° and 10°, compared to only 19 % for weir-gates without a flow extender. While the modest impact of the flow extender on discharge capacity, it effectively minimizes downstream vortices and energy dissipation. Additionally, three distinct submerged flow regimes (Surface Jump, Surface Wave, Deeply Submerged Flow) were identified, illustrating the behavior of flow with varying submergence levels. The modular limit, marking the onset of submerged flow, decreases significantly with larger gate openings, showing a maximum reduction of 64 %. The discharge reduction factor also varies with gate opening, remaining stable under moderate conditions and then sharply declining with increased submergence. These insights are essential for optimizing the design and performance of cylindrical weir-gates across different hydraulic conditions, thereby enhancing their efficiency and effectiveness in practical applications. • The hydraulics of flow over cylindrical weir-gates with a flow extender was tested. • Increasing gate opening generally leads to reduce energy losses. • The modular limit varies significantly with gate opening and discharge. • The discharge reduction factor decreased by 17.5 % up to a specific tailwater level. • The onset of submerged flow decreased by approximately 53 % with larger gate openings. [ABSTRACT FROM AUTHOR]

This paper used convergent-divergent sonic nozzles to describe a theoretical and experimental study on plume formation and thermal oscillations during direct contact with steam condensation in water. Experiments were carried out to understand how plume patterns behaved in restricted spaces, and the results were compared with CFD simulations. The study focused on pressure changes near the plume tail, where fluctuations and instabilities were most noticeable. It also examined how pressure maxima varied along the length of the nozzle. The heat transfer coefficient (HTC) was calculated, ranging from 1 to 3 MW/m2K, to assess the efficiency of the condensation process. The length of the steam plume was measured through experiments, and these findings were validated with semi-empirical models. The experimental results and numerical simulations correlated well, showing how nozzle geometry and steam mass flow rate affected the plume's thermal and flow characteristics. This research helped improve understanding of the condensation process in confined spaces, providing valuable insights to enhance heat transfer and reduce instabilities in various industrial applications. [ABSTRACT FROM AUTHOR]

Previous studies have revealed that major accidents in Chemical Process Industry (CPI) are most commonly due to explosions. Thus, analytical studies of explosion-related risk assessments are performed to predict the consequences of potential explosions. As physical experiments on explosions are very expensive, modelling and simulation techniques using theoretical models are becoming increasingly popular, allowing researchers to replicate the potential explosion scenarios. In this regard, computational fluid dynamics (CFD) models are more than appropriate. Although CFD simulations are widely applied, they have several weaknesses such as high computational costs as well as potential simulation inaccuracies due to inaccurate modelling steps. The weaknesses can be overcome with appropriate techniques such as model simplification, defining the appropriate method, grid design and boundary conditions. Many studies have reported different aspects and perspectives of explosion modelling and simulation techniques, but few evaluate the techniques across every different type of explosion. This subject is critical, as modelling steps and techniques directly affect the accuracy of simulation results. Hence, a review of the assumptions and simulation techniques that are used to reduce the computational costs associated with gas explosion modelling for each of the different explosion types is presented. [ABSTRACT FROM AUTHOR]

This research focuses on an innovative design of a perforated fishing vessel, aiming to precisely and efficiently evaluate its hydrodynamic performance and the characteristics of its internal flow fields. Initially, the boundary element method is employed to tackle the challenge of hydrodynamic responses in structures with arbitrary openings, quantifying added mass, damping effects, and dynamic responses under various filling scenarios. This sets a foundation for assessing structural stability. Subsequently, using the CFD method, based on the Navier–Stokes equations, a deep exploration into the mechanisms of how fluid viscosity and nonlinear effects influence the flow fields inside and outside the culture compartments is conducted. This reveals the impact of detailed flow field features on the fish welfare of fishing vessel design. The CFD method implemented the forced motion of the aquaculture fishing vessel based on FLUENT UDF, with the specific parameters of the moving boundary conditions determined by the results of the BEM method. The frequency-domain results show that the heave motion response is significantly greater than the sway. Compared with the isolated heave flow field results, the coupling heave-roll motion causes obvious vortex phenomena in the fluid on both sides of the perforated fishing vessel. [Display omitted] • Including BEM and CFD method through the dimensionless Ka value. • A new method to the hydrodynamic response of arbitrarily perforated structures. • Motion responses and wave numerical absorption based on fluent UDF. • The viscous and nonlinear effects on the flow field due to coupling heave and roll. • Characteristics of fish welfare in the cabin under wave conditions. [ABSTRACT FROM AUTHOR]

It is necessary to evaluate the released gases distribution (especially hydrogen) to avoid hydrogen accumulation and maintain containment integrity against the pressure loads due to its deflagration or detonation. For this purpose, this work uses coupling of the FLUENT and MELCOR to evaluate the produced gases distribution in the WWER1000/V446 during in-vessel and ex-vessel phases of the Station Black Out (SBO) along with Large Break Loss of Coolant Accident (LBLOCA). The results indicate that 30 cm mesh size is sufficiently fine to evaluate the gases behavior in the containment. Also, driving force of the hydrogen/carbon monoxide (CO) and steam are mainly in the form of the plume due to buoyancy effects and jet flow caused by momentum, respectively. Furthermore, hydrogen accumulates in the upper compartments more than in other areas and its average volume fraction reaches to 12.7% at the end of the calculations. In addition, it can be concluded that steam condensation on the walls increases the hydrogen volume fraction up to 2%. [ABSTRACT FROM AUTHOR]

In order to cope with the frequent fire accidents in modern society, it is crucial to develop efficient fire extinguishing agents to stamp out fires in its early stage. In this work, a new composite ultrafine dry powder extinguishing agent containing ammonium molybdate ((NH4)2MoO4) is prepared, and its fire extinguishing efficiency is studied. The cup burner experimental results show that with the increase of the mass fraction of (NH4)2MoO4, the flame temperature drop and flame height variation rate show a trend of increasing and then decreasing, while the MEC and extinguishing time present a trend of a decrease and then an increase. It is indicated that the composite dry powder has the best fire extinguishing efficiency when the mass fraction of (NH4)2MoO4 is 7%. Besides, in terms of the pyrolysis results of TGA and DSC, it is found that the degree of thermal decomposition is significantly promoted under the condition of 7% addition. Based on the gas-solid two-phase flow theory and multiphase flow model, a simplified simulation model of the cup burner is established by the ANSYS-FLUENT software to analyze the variation of temperature and particle motion trajectory. The simulation results demonstrate that the ultra-fine dry powder mediums have a good dispersibility after entering the cup burner. This can achieve a full submerged state at a faster speed, and the flame temperature of the entire fire suppression stage is consistent with the experimental results. This article mainly develops the application of fire extinguishing media in the field of fire protection from the perspective of process safety. [ABSTRACT FROM AUTHOR]

Improvement of air flow distribution, air velocity and temperature inside a mixed greenhouse dryer was numerically investigated using 3D CFD ANSYS FLUENT code. The study was performed considering six different locations of axial fans inside the greenhouse. Additional elements such as a false ceiling and front and back internal walls were included in some configurations to analyze their contribution in improving the air distribution. Numerical simulations were focused on dynamic fluid models in order to select the best configuration to achieve homogeneous air distribution and velocity among the six proposals. Then, the temperature distribution was analyzed considering the contribution of solar energy in the best-selected greenhouse configuration. Additionally, the Discrete Ordinate (DO) model was used to simulate the mechanism of heat transfer from solar radiation to the greenhouse. The results showed that installing an air recirculation system (including: axial fan, false ceiling, back and front walls), into the greenhouse can increase the air velocity in the drying chamber from 0.71 m/s to 1.5 m/s and the temperature from 315 K to 360 K , which represent an increase of approximately 111.26% y 11.11%, respectively, compared with the greenhouse without an air recirculation system. This improvement could result in the reduction of drying time and a homogeneous moisture content in dry products. • New application air recirculation system was studied. • Differences in fan positioning influence the air flow distribution and air velocity. • The internal walls added to the dryer influence the air flow distribution and air velocity. • The false ceiling and additional internal walls allow to increase the air temperature inside the drying chamber. • The greenhouse drying with the new air recirculation system is suitable for food drying. [ABSTRACT FROM AUTHOR]

This study employed a self-developed viscous numerical wave tank based on the piston type wave maker and user-defined functions of Fluent software to explore the wave shadowing effect of the transmission of waves near the underwater object and the reef. In the study, various factors such as the permeability of the reef, changes in topography, and objects motion were considered, and detailed simulation analyses were conducted for five scenarios: a solitary reef, a fixed underwater object, a forced moving underwater object, and a free moving underwater object. The results showed that this method can effectively simulate the complex flow field changes around the underwater object and the reef under different conditions, while also fully considering the strong nonlinearity and fluid viscosity effects between the wave surface and the object. Furthermore, it was found that between the free-moving object and the reef, there would be significant swirls and streamline distortion. This indicates that a portion of the incident wave energy is transformed into kinetic energy of swirls, resulting in a smoother and more uniform flow field and reducing wave forces. • A numerical wave tank considering viscous problems under the finite water depth based on CFD. • Application of FLUENT UDF to add piston-type wave maker into the N–S equation. • Real-time motion of an object using the MEL method, Newton's second law, and dynamic grid. • Applied to the problem of wave interaction between underwater object and the permeable reef. [ABSTRACT FROM AUTHOR]

Walnut shell media plays an important role in polymer flooding and alkaline-surfactant-polymer oil recovery wastewater treatment, but the regeneration of walnut shell has always been a difficult problem. To solve this problem, axial dynamic backwashing technology has shown good regenerative effects in practice, and investigation on the hydrodynamic characteristics and backwashing efficiency of axial turbine filtration used for the filtration are necessary. In this study, three types of turbines (flatness, twisted, and airfoil loading) were experimentally studied and compared in terms of their backwashing performances. The cascade efficiency was calculated and it was concluded that airfoil loading was the key to improve cascade efficiency. The flow field distributions of three kinds of the turbine were analyzed, and the results showed that the flatness and twisted characteristics determined the flow field distribution forms. The vortex energy loss efficiency was calculated and the results showed that the flow field distribution determined the vortex energy loss. The G value of three kinds of turbine backwashing showed that the G value of axial dynamic backwashing technology was larger and more controllable than that of gas--water backwashing. The local backwashing G value could reach 35~45 times of the G value of gas--water backwashing at the optimal rotational speed of 1,420~1,810 rpm. The relationship between three geometric characteristics and backwashing efficiency was finally established- the head can be increased by loading airfoil, and the backwashing G value can be increased by changing the degree of blade distortion. This research not only provides technical support for the lower cost operation of axial dynamic backwashing technology but also will contribute to providing an important reference for other backwashing technologies by pump washing. [ABSTRACT FROM AUTHOR]

• A comprehensive CFD model of OVAR using ANSYS-FLUENT has been proposed. • ANSYS-FLUENT decouples heat transfer between absorbers and return air. • Temperature mapping and flux splitting methodologies used to couple heat transfer. • Circumferential (Joule) heating of absorbers can mimic laboratory solar simulators. Open volumetric air receiver (OVAR) has great potential as a source of process heat for metals processing operations. The two major components of OVAR are the porous absorbers and the return air flow chamber (RAFC). Heat exchange between the "cooler" return air and the hot curved absorber surface in RAFC is critical as it prevents overheating of absorbers. Unfortunately, modeling of air flow in the RAFC is conspicuous by its absence. Calculations were performed in ANSYS-FLUENT using the local thermal non-equilibrium model for heat transfer in the porous absorber. Three dimensional flow and heat transfer simulations were carried out in the RAFC. Unfortunately, ANSYS decoupled heat exchange between the absorbers and return air by splitting the curved absorber surface into real and imaginary surfaces. Decoupling also meant that heat flux had to be specified separately on the absorber and the RAFC, which was a challenge since only the total input solar flux is known. Hence the major contribution of this paper has been to incorporate two innovations in the simulation methodology. One, to couple the absorber and RAFC thermally by mapping the temperature of the real surface to the imaginary surface. Two, the flux used for heating air in the absorber was calculated iteratively. Limited simulations suggest that in laboratory experiments, relatively inexpensive circumferential (Joule) heating of absorbers can reasonably mimic heating of absorbers by concentrated solar radiation. [ABSTRACT FROM AUTHOR]

• Two coupled parallel frameworks for shell and tube heat exchangers are proposed. • Fully three-dimensional parallel computation on both sides of the heat exchanger is realized. • One-to-one method achieves 85% parallel efficiency in 14 cores computation. • One-to-many method improves computational efficiency by about 20 times over serial in 28 cores computation. Shell and tube heat exchanger is widely used as a common type of heat exchanger. When the size and the number of heat exchanger tubes are enormous, it is difficult to use the direct modeling method for numerical simulation of heat exchangers. The simplified modeling method based on porous media utilizing user-defined function (UDF) has been widely applied. However, when the three-dimensional (3D) modeling is required on the tube side, the parallelization problem still restricts the computational efficiency of numerical simulation. In this paper, a one-to-one parallel method was first developed to solve the problem of coupled parameter transfer between the primary and secondary sides in the parallel framework, which was tested to achieve a parallel efficiency of 85% under 14 cores. However, the method acquires complicated data transfer between nodes, large memory occupation, and the modeling of the tube side is different from the actual structure under certain circumstances. To solve the problems, a one-to-many parallel method is proposed, and the computational efficiency is tested to be enhanced by about 20 times under 28 cores compared with single core, with a parallel efficiency of 70%. The two methods proposed in this paper are of great significance to the parallel transformation of the future 3D full-size code for shell and tube heat exchangers development and the calculation efficiency improvement. [ABSTRACT FROM AUTHOR]

The advancement of nuclear research reactors hinges on precise thermal-hydraulic analyses, especially when reactors undergo potential design modifications or power uprates. This study uses the computational fluid dynamics (CFD) tool, FLUENT, to analyze thermal-hydraulic behavior in the Replacement Research Reactor (RRR) and the Missouri University of Science and Technology Reactor (MSTR). The RRR model operates at 20 MW (MW) with flat plate fuel assemblies, while the MSTR explores a hypothetical power uprate from 0.2 to 2 MW using curved plate assemblies. Two CFD methods—realistic and porous media modeling—are applied for thermal-hydraulic analysis in RRR and MSTR. For RRR, realistic simulations at 5.08 m/s led to a 245 kPa pressure drop. In MSTR, simulations across 0.25–1.25 m/s velocities yielded maximum fuel and fluid temperatures of 323 K and 303 K, respectively, at 0.25 m/s and 2 MW power. The determined inertia resistance factors are 9.81 m−1 (RRR), 12.35 m−1 (MSTR), and viscous resistance factors are 1.98 × 107 m−2 (RRR), 683,060 m−2 (MSTR). This study validates porous media modeling as a computationally efficient approach for thermal-hydraulic analysis in nuclear reactors, effectively complementing realistic simulations for in-depth assessments. • Realistic and porous media models are developed for RRR and MSTR. • 2 MW power uprate of MSTR is investigated and CFD models are prepared, • Inertia resistance factors are 9.81 m−1 (RRR), 12.35 m−1 (MSTR) and viscous resistance factors are 1.98 × 107 m−2 (RRR), 683,060 m−2 (MSTR). • Peak temperature shifts radially outwards in curved fuel plates. • Porous media models showed faster convergence and can be used for thermal hydraulics analysis of research reactors. [ABSTRACT FROM AUTHOR]

This paper presents a novel 2D numerical and experimental approach which can be used to assess the thermal performances of a polymer solar collector as a part of the design process. Numerical simulations are performed using software package FLUENT. To simulate radiative heat transfer, different radiation models that are available within FLUENT are applied including the discrete ordinates (DO) and surface-to-surface (S2S) model. Solar incident radiation is taken into account as an energy source computed analytically or via ray tracing software or as an external beam which is a part of boundary condition in semi-transparent DO model. Different combinations of longwave and shortwave radiation modeling are tested, first on a segment of a typical flat plate collector. In the second step, these models are applied to the test box at different boundary conditions and materials. Numerical models are then applied to the geometry of polymer solar collector prototype to assess its thermal efficiency. Combination of longwave radiation computed with DO and S2S sub-model and solar incident radiation modeled analytically or via ray tracing software yields sufficiently accurate results on the all tested computational domains, thus any of them can be used to compute thermal efficiency of a polymer solar collector. On the other hand, when applying semi-transparent DO model with the solar incident radiation modeled by the external beam, the obtained results are unphysical. Present approach is a part of the research aimed at the development of a thermally efficient low-cost polymer solar collector running in a drain back system. The prototype will be then experimentally tested. • A novel 2D numerical and experimental approach is described and discussed. • Numerical simulations are performed with software package FLUENT. • Radiative heat transfer is considered with DO and S2S. • Both models provide sufficiently accurate results. • Thermal efficiency and materials temperatures of a polymer solar collector are computed. [ABSTRACT FROM AUTHOR]

• A theoretical method was developed to evaluate response time of I.C. quantitatively. • Increasing the size of both inlet and outlet pipe is an effective way to decrease response time of an I.C. • Different species of carrier gas also result in different response time of an I.C. Response time of ionization chambers for tritium measurements in dynamic mode is very important to indicate the change of tritium concentration in line. CFD software ANSYS FLUENT is firstly introduced to evaluated the response time of ionization chambers quantitatively, and effects of parameters including chamber size, gas flow velocity, size of inlet/outlet pipe, et al., have been calculated. Results show that both chamber size and shape have significant influence on response time of an ionization chamber. Chambers with small volume or larger diameter/length ratio at given volume help greatly to reduce response time. For a given chamber, increasing the size of both inlet and outlet pipe connected to the chamber is also an effective way to improve response time. Comparing with helium, air and methane as carrier gas, argon gives the fastest response time at the same condition. Besides, a decrease in tritium concentration in inlet carrier gas will take longer time to be indicated by an ionization chamber than the time for increased tritium concentration. [ABSTRACT FROM AUTHOR]

Air pollution in urban areas constitutes a global environmental problem, with shipping being one major contributor to hazardous pollutants in harbour areas. This work concerns the application of a method using CFD modelling to study how ships affect the air quality of port areas at a microscale level. A steady RANS-CFD approach was applied to simulate the dispersion of shipping-emitted pollutants, and a spatial sensitivity analysis of the CFD modelling results was conducted. The port of Marseille was used as a case study, and the CFD predictions were compared with on-site observations from two monitoring stations for CO 2 , CO, NO x , SO 2 and PM concentrations. Representative modelled and measured concentrations were considered at the location of the monitoring stations to facilitate one-by-one comparisons for all pollutants in three different test cases of departing vessels. The modelling predictions presented an 8.2% (95% CI: -9.3%, 25.7%) average deviation from the measurements. Validation metrics were included to conduct a statistical comparison between predicted and measured concentrations, with almost all metric values indicating acceptable agreement between the CFD model and measurements. From a technical perspective, this study demonstrates the reliability of the applied CFD modelling method in estimating shipping plume dispersion, while from a societal perspective, this model can serve as an advisory tool for port authorities and policy makers to reduce the impact of shipping emissions on urban air quality. • Harbour-scale steady RANS-CFD modelling for plume dispersion of pollutants emitted from ships. • CFD assesses ship plume dispersion in ports and cities down to 2.5 m resolution. • Predicted pollutant concentrations deviate 8.2% from observed levels at the 80th percentile, 250 m downwind of the vessel. • Steady-state solution proposed to reliably capture ship pollution incidents while reducing computational cost. • Tool suitable to assess the effectiveness of reduction measures for exposure to ship pollution. [ABSTRACT FROM AUTHOR]

Abstract The lead based reactor concept is considered to be the most promising reactor option for the Accelerator Driven Subcritical (ADS) system. Lead based reactor engineering validation facility CLEAR-S is a large scale integrated non-nuclear pool type facility which has been built to provide a unique experimental platform for full-scale prototype components test of lead based reactors. In this article, three-dimensional steady state analysis of flow in the hot and cold pools of CLEAR-S was carried out by using computational fluid dynamics (CFD) code FLUENT during forced and natural circulation conditions. The results showed that the simulation had a good agreement with the design parameters of CLEAR-S and the temperature profile was uniform in the whole domain of the hot and cold pools without considering any conduction through the coupled walls. The temperature distribution in the hot and cold pools became non-uniform with the coupled wall conduction and thermal stratification was observed in the cold and hot pools near the bottom wall of the hot pool. This non-uniform distribution of temperature could cause thermal stresses on equipment, which is dangerous for the integrity of the system. During natural circulation conditions, the coupled wall conduction enhanced the natural circulation and kept the hot pool at a relatively low temperature because the cold pool cooled the hot pool through heat transfer between the walls of the hot and cold pools. Therefore, wall conduction has some advantages and disadvantages as it enhances the natural circulation on one hand but disturbs temperature uniformity on the other hand. Highlights • Steady state analysis of CLEAR-S was carried out by using FLUENT 15 during forced and natural circulation. • During FC coupled wall conduction made temperature profile non-uniform within the LBE pool. • During NC coupled wall conduction kept the hot pool at relatively low temperature. [ABSTRACT FROM AUTHOR]

Highlights • Three-dimensional FLUENT simulations of a thermoplate conical heat exchanger. • Experimental data of heat transfer in a compact hybrid solar-thermal collector. • Numerical model validation using experimental data. • Modeling the performance of a small scale cavity receiver. Abstract A three-dimensional ANSYS-FLUENT Computational Fluid Dynamics (CFD) model of the central receiver in a compact hybrid solar-thermal collector is presented. The small scale cavity receiver is conical in shape, laser welded from Inconel 625 with a 38 mm entrance aperture, and uses pressurized water as the Heat Transfer Fluid (HTF) within a thermoplate serpentine flowpath. The coupled thermofluidic CFD model examines a simplified unrolled version of this dimpleplate heat exchanger, representing the laminar flow within 10 × 1 mm expanded flowpath serpentine channels complete with intrachannel spot welds and non-uniform concentrated solar irradiance heating. The computational model is validated against experimental results with the receiver at the focus of a 2.7 m 2 parabolic dish, two-axis tracking rooftop solar collector. For steady state conditions with the outlet HTF reaching temperatures in excess of 200 ° C, the HTF temperature rise predicted by the computational model is in agreement with the experimental data. In order to accurately capture the heat losses from the heat exchanger to its surrounding, we present an additional three-dimensional CFD model including the heat exchanger and surrounding thermal insulation. Contours of temperature and velocity at the midplane of the dimpleplate receiver heat exchanger are presented. [ABSTRACT FROM AUTHOR]

Abstract In this study, a three-dimensional (3D) computational fluid dynamics (CFD) analysis is performed to investigate the heat transfer performance and fluid flow characteristics using a helical screw tape insert in pipe flow. An inserted tube geometry was improved using a helical coil i.e., wire-wrapped with 1.92 twist ratio. Single-phase, horizontal, and a laminar flow (200 < Re <2300) through an annular channel is considered. A flow domain is created first, and then discretized, later all boundary conditions are applied and finally, simulated it using ANSYS FLUENT. The results are analyzed and processed further to check for mesh sensitivity and experimental validation. The simulated results showed that the heat transfer rate in terms of Nusselt number increased 1.34-2.6 times, whereas, the friction factor also increased 3.5-8 times for wire-wrapped-tube i.e., the tube with helical screw tape insert in comparison to the plain tube. The thermal performance factor was evaluated and the maximum value is found 3.79 at a constant pumping power. The pressure drop was estimated which was increased due to the increased flow restriction by inserted coils. [ABSTRACT FROM AUTHOR]

Abstract A three-dimensional computational conjugate heat and mass transfer study has been carried out using computational fluid dynamics (CFD) software package ANSYS FLUENT to investigate the effect of insert's twist ratio on the heat transfer and fluid flow performance. Investigation was carried out for air flow at 300 Kelvin and Reynolds number ranging from 3642 to 21857 through a tube with constant wall heat flux of 8000 W/m2. Validating against Gneilski and Petukhob models, the current model has been used to investigate the effect of insert with twist ratio 3.46 and 7.6 on Nusselt number, friction factor and thermal performance factor of the tube. Results show that for twist ratio of 3.46, Nusselt numbers and friction factors are increased by 20% to 62% and 185% to 245% respectively, and thermal performance factor ranged between 0.9 and 1.2. Those were observed to be increased by 10% to 30%, 128% to 183% and ranged between 0.95 to 1.05 respectively for twist ratio of 7.6. It is concluded that twisted tapes provide better heat transfer enhancement at relatively lower Reynolds number and twist ratio. [ABSTRACT FROM AUTHOR]

Abstract Regenerative thermoelectric generators (RTEGs) are used to recover waste heat from car engines. Compared to conventional thermoelectric generators (CTEGs), RTEGs can help significantly reduce the negative effects of engine transients on the performance of thermoelectric generators. In this study, a new type of RTEG, based on the CTEG, was designed. Numerical simulations of both the CTEG and the RTEG were performed using Fluent under dynamic temperature conditions based on the New European Driving Cycle (NEDC). The results show that the fluctuations in the hot-side temperature and output voltage decreased by 86.46-87.71% and 86.45-89.16%, respectively, with the use of different types of RTEGs compared to the CTEG. Moreover, the RTEG helped avoid the inversion problem of the electromotive force direction for a short time when the temperature of the heat source suddenly decreases. [ABSTRACT FROM AUTHOR]

Highlights • Flow blockage in an assembly in JRR-3M reactor is simulated combining RELAP5/MOD3.4 and FLUENT codes. • It is necessary for the analysis of the assembly blockage to consider the power distribution in space. • Accident consequence depends heavily on the blockage ratio. Abstract The main purpose of the paper is to execute the thermal-hydraulic analysis of flow blockage in a single fuel assembly in the JRR-3M research reactor (Upgraded Japan Research Reactor No. 3). Using the one-dimensional system analysis code RELAP5/MOD3.4, flow region in a standard fuel assembly (SFA) is lumped into a coolant channel. 5 similar coolant channels representing 5 independent assemblies are modeled to consider the interaction between blocked channel and adjacent channels. The rest of the core is lumped into 1 average channel and 1 bypass channel. The coolant system is also modeled in detail. Meanwhile, a three-dimensional model of heated part in the assembly is built using the computational fluid dynamics (CFD) code FLUENT. Results calculated by RELAP5/MOD3.4 are used as the boundary conditions of the 3D model. The user-defined function (UDF) is adopted to describe phase change and the power distribution in axial and radial direction in the assembly. Results indicate that it is necessary for assembly blockage to consider the influence of power distribution on accident consequence. When the blockage ratio is 64%, coolant in the hottest subchannel is still supercooled while coolant temperature at outlet is close to saturation temperature. It is the critical blockage ratio to ensure the reactor safety. When the blockage ratio is 70%, departure from nucleate boiling (DNB) will occur. According to the FLUENT code, the process of bubble generation and growth is discussed. It can be found that if the bubbles largely generate, there will be obvious impacts on heat transfer of fuel plate and coolant flow. Fuel plates may damage locally. [ABSTRACT FROM AUTHOR]

We present three-dimensional numerical simulations to quantify the design specifications of a directed thermoplate expanded channel heat exchanger, also called dimpleplate. Parametric thermofluidic simulations were performed independently varying the number of spot welds, the diameter of the spot welds, and the thickness of the fluid channel within the laminar flow regime. Results from computational fluid dynamics simulations show an improvement in heat transfer is achieved under a variety of conditions: when the thermoplate has a relatively large cross-sectional area normal to the flow, a ratio of spot weld spacing to channel length of 0.2, and a ratio of the spot weld diameter with respect to channel width of 0.3. Experimental results performed to validate the model are also presented. [ABSTRACT FROM AUTHOR]

In recent years, phase change materials have played an important role in the field of energy storage because of their flexibility and high efficiency in energy storage and release. However, most phase change processes are unsteady and highly nonlinear. The ways to obtain exact solutions are urgently needed. This study first summarizes the principles and characteristics of different methods to solve the phase transition process, including analytic methods, numerical methods, and CFD numerical methods. After that, the advantages of employing CFD software to simulate the phase change process are discussed, and the solidification and melting models in FLUENT are introduced. In particular, the influences and weights of natural convection and nanoparticles on the solidification/melting processes are revealed and enumerated in detail. Finally, the challenges and future developments in the solution methods, theoretical models, and numerical simulation applications of phase change materials are prospected. This review shows that most of the phase change heat transfer problems are solved by numerical methods. FLUENT is high-precision software commonly used in CFD software, its solidification and melting model is convenient to simulate the phase change process. Both natural convection and nanoparticles can shorten the melting time of phase change materials. [Display omitted] • The classifications and patterns of phase change materials are reorganized. • Solution methods of analytic, numerical, and CFD are summarized and compared. • Modeling approaches for most of the solution methods are generalized. • Superiorities and governing equations of CFD software are explored and discussed. • Influences of natural convection and nanoparticles are enumerated. [ABSTRACT FROM AUTHOR]

Prior to equipment maintenance and "baking" operation, the Experimental Advanced Superconducting Tokamak (EAST) carries out a "blow-out" operation. Utilizing a manifold structure, pressurized nitrogen gas is driven into the Plasma Facing Components (PFCs)' cooling channels to eject residual cooling water. The "outcome" of the blow-out operation, the final steady-distribution of the gas-liquid two-phase in the manifold, significantly influences the efficiency, the time and energy cost of the subsequent drying process and indirectly shapes the quality of the vacuum environment required for plasma operation. In this context, this paper presents a theoretical analysis and simulation of the outcome of blow-out operation of EAST manifold. The analysis discusses three kinds of steady distribution state within a manifold branch: "Stagnant", "Two-phase flow", and "Near-dry flow". It is observed that stable "Two-phase flow" cannot be maintained when multiple branches flow concurrently due to the unstability of parallel flows. Thus, in such scenarios, the branch primarily exhibits only "Stagnant" and "Near-Dry" states. Furthermore, the total gas flow rate plays a significant role in determining the number of "Near-Dry" branches. Simulation provides specific quantities prediction of "Near-Dry" branches under varying gas volume flow rates. Finally, the theoretical analysis and simulation results is validated through experimental data. This study offers valuable insights for optimizing future blow-out operations of the EAST manifold. [ABSTRACT FROM AUTHOR]

This paper presents the method to simulate groundwater flow and heat transfer in complex hydrogeological conditions for standing column well (SCW) system, pumping and injecting groundwater in single borehole among ground source heat pump (GSHP) systems. The borehole is modeled to 1D discrete elements, aquifers are modeled to 3D elements by FEFLOW to simulate pumping, injecting and bleeding of SCW. In this paper, we analyzed effect of roughness of borehole and conductivity of dip tube for SCW by using FLUENT, and focused on groundwater flow and heat transfer in complex geological and hydrogeological conditions rather than turbulent flow inside borehole or heat conduction through dip tube. The results show that the model developed in this paper is consistent with experimental results. The geothermal heating and cooling system for a field problem was developed based on simulation results of SCW. [ABSTRACT FROM AUTHOR]

The velocity distribution and turbulence characteristics in circular open channel flows are investigated numerically using the commercial CFD software Fluent. The Reynolds stress model, which has been widely used in open channel flow simulation since a dissipation rate formula for the surface boundary condition was proposed by Naot and Rodi, is employed herein to model the turbulence anisotropy. To reflect the surface damping effect and the sidewall retardation effect, a reduction factor is introduced to the surface correction term in the Reynolds transport equation, and a new constant is taken in the dissipation rate formula for the surface boundary condition. The proposed model is demonstrated to be able to reproduce the secondary currents, predict the dip phenomenon well and give right level of turbulence quantities. It is found that the pattern of secondary currents is affected by both the cross-section shape and the filling ratio. The secondary motion contributes to the dip phenomenon, which occurs when the filling ratio is greater than 50%. Turbulence intensities behave differently from those in rectangular channels when the water depth is over the radius while the eddy viscosity shows a parabolic distribution approximately irrespective of the filling ratio. [ABSTRACT FROM AUTHOR]

Many important engineering applications involve the interaction of free-moving objects with dispersed multi-phase flows, however due to the challenge and complexity of modelling these systems, modelling approaches remain very limited and very few studies have been reported. This work presents a new method capable of addressing these problems. It integrates a dynamic meshing approach, used to explicitly capture the flow induced by free-moving large object(s), with a conventional CFD-DEM method to capture the behaviour of small particles in particle-fluid flow. The force and torque acting on the large object due to the fluid flow are explicitly calculated by integrating pressure and viscous stress acting on the object's surface and the forces due to collisions with both the smaller particles and other structures are calculated using a soft-sphere DEM approach. The developed model has been fully implemented on the ANSYS/Fluent platform due to its efficient handling of dynamic meshing and complex and/or free-moving boundaries, thus it can be applied to a wide range of industrial applications. Validation tests have been carried out for two typical gas-solid fluidization cases, they show good qualitative and quantitative agreement with reported experimental literature data. The developed model was then successfully applied to gas fluidization with a large immersed tube which was either fixed or free-moving. The predicted interacting dynamics of the gas, particle and tube were highly complex and highlighted the value of fully resolving the flow around the large object. The results demonstrated that the capability of a conventional CFD-DEM approach could be enhanced to address free-body fluid-structure interaction problems encountered in particle-fluid systems. [ABSTRACT FROM AUTHOR]

A new scene analysis method of reactor thermal explosion accident based on process simulation and CFD method is proposed. The thermal runaway of batch reactor with methanol and acetic anhydride is simulated by Aspen Plus. The molecular weight and component concentration of steam after explosion overpressure are studied. The vapor cloud explosion is simulated by Fluent. The propagation law of vapor cloud explosion pressure wave and flame front is analyzed based on the simulation results. [ABSTRACT FROM AUTHOR]

Kitefoil boards are a novel, emerging and disrupting class of sailing crafts, with major economical implications for the tourism sector due to their capability to enable kitesurfing in light wind areas. This paper investigates the hydrodynamics of the underwater appendage of a state-of-the-art kitefoil with a potential flow panel method implemented in the open source code Apame and with the Navier-Stokes solver ANSYS Fluent. The first objective has been to establish a valid range for the potential flow method predictions. It has been found that the potential flow panel method renders similar forces than those obtained using CFD, in the typical cruise range. Moreover, in leeway incidence conditions, additional drag originating from the fuselage, where potential assumptions are not applicable, represents less than 10% of the overall drag. These results enable potential flow panel methods to be used as design tools for this kind of devices, in particular the open source solver used in this study, whose large computational efficiency is a major advantage considering the number of headings that have to be considered to feed velocity-prediction-programs. The second objective has been to investigate the system of forces and moments in the appendage during navigation. The way the various elements of the craft interact (main and rear foil, mast, kite and rider) under different sailing conditions is explained based on the hydrodynamic forces obtained with the numerical methods used. [ABSTRACT FROM AUTHOR]

The correlation for heat transfer and flow friction characteristics of fins is the basis for the optimization of heat exchangers, and it is of great importance to develop generally accurate formulas. To study the hydrodynamics and heat transfer characteristics of offset strip fins, Fluent is adopted to conduct the numerical simulation. Based on the calculation results of empirical correlations, the fluid constitutive model under different Reynolds numbers is determined in order to ensure the prediction efficiency and accuracy of offset strip fins. Good agreements are obtained between the numerical simulation and the Manglik & Bergles correlation, which verifies the validity and reliability of the numerical simulation method. Due to the fact that the traditional empirical formula is not able to cover the general specifications of Chinese domestic offset strip fins, the correlation of flow and heat transfer characteristics is improved based on the numerical simulation results and the industrial standard (Aluminum plate-fin heat exchanger NB/T 47006-2009). By coupling the Manglik & Bergles equation with the ALEX equation, a new relational expression of offset strip fins is proposed. [ABSTRACT FROM AUTHOR]

This paper presents a new type of semi circular heat absorbing plate structure of solar air collector, the establishment of the physical model and mathematical model, using Fluent simulation software, the air heat exchange heat transfer numerical simulation in different shapes of the absorb plate. The results show that the semi circular heat absorbing plate has a large heat absorbing area, which is favorable for increasing the heat exchange between the air and the heat absorbing plate, so as to increase the outlet temperature and improve the efficiency of the air collector. [ABSTRACT FROM AUTHOR]

Floor heating has become more and more popular due to its comfort and energy efficiency nowadays. However, there is no specific testing device and evaluation system for the wood floor materials. In order to fill the gap, we proposed a method of wood materials used for floor heating. First, the preheated wood samples from Betula platyphylla, Fraxinus mandshurica, B.alnoides and Quercus mongolica, which could be used for floor heating, were set at the middle of the bottom of the testing cylindrical cavity, as heat source. After setting up the initial values and boundary conditions of the model, the temperature distributions at different periods were analyzed by FLUENT. The results of temperature distribution were compared and evaluated. The results show that, the method can accurately demonstrate the temperature distribution for different wood samples, and be used to evaluate the heat storage performance of different wood floor materials, which is of great significance to standardize the products and market for wood floor industry in our country. [ABSTRACT FROM AUTHOR]

This paper introduced a methodology to calculate the heat transfer coefficient between two adjacent air conditioning zones via a virtual wall aims to improve the independent zonal temperature control for a VAV system. The selected room was divided into two subzones with each controlled by 2 square ceiling diffusers mounted on the up-ceiling level. A virtual wall was artificially identified and split into the fluid domain in Fluent. The heat transfer coefficient (HTC) across the virtual wall was derived from the discrete energy equations and obtained by implementing UDFs in the Fluent solver, both the heat transfer due to air mass flows and the heat exchange due to turbulence were considered in the model. A 2-separate VAV control platform was established in TRNSYS and the HTC was fed to the control platform to evaluate the impact of HTC on the temperature control system. The simulation results shown it has an insignificant impact on the controllers, but the temperature on both sides were controlled precisely within the expected range compared with CFD simulation results. [ABSTRACT FROM AUTHOR]

Unprecedented opportunities for the development of pure electric vehicle industry have been brought by constantly growing issues of energy crisis and environmental pollution. The performance of electric vehicles is decisively influenced by the battery pack, which is the only power source of pure electric vehicles. However, the efficiency of battery drops under the conditions of ultra-high, ultra-low, and uneven temperature distribution inside the battery pack. To improve the performance, reliability and safety of the lithium-ion battery pack, the negative effect of non-uniform heat dissipation should be alleviated. In this paper, the thermal model of the lithium-ion battery is described. A 3D battery pack model is built. Several structural factors that affect the heat dissipation, including the selection of the location and quantity of the battery pack outlet, the arrangement mode of cells, and the distance between cells and wall, are simulated by utilizing the finite element analysis (FEA) and discussed. According to the simulation result, the factors influencing the battery temperature field and the influence law is summarized. [ABSTRACT FROM AUTHOR]

A vast evolution to renewable energy resources such as solar energy is the best option for alleviating poverty in developing countries where the majority of people do not have access to modern forms of energy. Renewable energy resources, due to their inherent decentralized nature can largely contribute to resolve the energetic problems. Among these techniques and technologies for the exploitation of this solar energy, the Photovoltaic conversion is known to produce electricity; and thermal collectors that provide heating energies. The two systems are independent and different, but there are not compatible, that can be completed using a hybrid design that allows using both techniques, thermal and electrical, in the process called (PV/T). The hybrid solar photovoltaic thermal (PV/T) offers an interesting option now because the absorbed solar radiation is converted into electric energy and heat (the conversion can be done simultaneously or separately). In this paper, the mathematical model is presented; the studied system consists of a photovoltaic panel for the production of electricity, with a thermal system for water heating. It is constituted by a sheet and tube placed below the surface on which the solar cells are assembled to extract heat from the photovoltaic module, in order to cool the cells and to increasing their electric efficiency. This phenomenon is due to the unobserved part by cells. This model is based on the equations of the energy balances written for the various nodes of the system, and the coupled differential equations obtained are solved by using the finite difference method. The temperatures of the various layers of solar PV/T Collector and the coolant temperature are predicted. The objective of this work is to study theoretically and experimentally the hybrid (PV/T) Collector. The fluid flow and heat transfer in the module are studied using the ANSYS14 Software. The heat transfer phenomenon conjugate between the photovoltaic cells and the coolant is modeled using the FLUENT Software. The transfer of heat by the solar radiation is not modeled; however, the effects of radiation are taken into consideration when calculating the conditions for heat flux limit for the Collector layers. The geometric model and fluid domain for the CFD analysis is generated using ANSYS software Design Modeler, mesh geometry is carried out by ANSYS Meshing Software. [ABSTRACT FROM AUTHOR]

Beetles demonstrate excellent flight performance, and their various flight skills predominantly depend on the ingenious structure of the wing membrane. The wings of insects have been optimized in structure, function and material through millions of years of evolution. The hindwings of most beetles are thin and fragile; when at rest, they are held over the back of the beetle. From drawings, it is clear that the biological wing structure of beetles could be exploited for the efficient flight of Micro Air Vehicles (MAVs). This paper strives to reveal the hydraulic mechanism at work during the hindwing unfolding process through the use of the finite element method in FLUENT. The inlet pressure was set to be similar to the folded point pressure, and the flow pattern was treated as similar to a one-way flow. We anticipate that our work will serve as the basis of further sophisticated research on the folding/unfolding mechanisms of beetle hindwings, which may provide design insights for portable MAVs with morphing wings and guide the development of bioinspired deployable systems. [ABSTRACT FROM AUTHOR]

PDEC towers with spray systems are known to achieve substantial energy savings. Various parameters such as the wet-bulb depression, the tower height, and the wind speed have been known to be key factors affecting the performance of the system. To date, the significance of these parameters and other important factors have not been adequately treated in the literature. There also has been a lack of models that can successfully investigate potential benefits of the system under various conditions where this particular system could be applicable. To address these critical issues, this study performed a parametric analysis by using a FLUENT model validated against experimental data. It demonstrated the significance of individual parameters including water droplet sizes. As a result, practical design guidelines for important system parameters were presented. A statistical analysis was then used to formulate analytic models that account for all of the relationships found in this study between the parameters and the supply air conditions of the system. Two regression equations were formulated for predicting supply air temperature and velocity. [ABSTRACT FROM AUTHOR]

AP1000 nuclear plant is an advanced pressurized reactor developed by Westinghouse Electric Company (WEC), with several passive systems applied to the plant to increase its safety. One of the main passive systems is the passive containment cooling system (PCCS), which aims to ensure the integrity of the containment and remove decay heat from the containment during postulated accidents. Film evaporation outside the steel vessel wall plays an important role for the heat removal process in the PCCS. In this study, the Eulerian Wall Film model in ANSYS FLUENT is applied to study falling film evaporation and natural convection outside the PCCS of AP1000. The thermal–hydraulic phenomena of both liquid film and gas mixture in the outside air flow path of the PCCS are analyzed. The Eulerian Wall Film model shows promising performance in modeling falling film behavior and mass transfer between liquid film and gas phase. [ABSTRACT FROM AUTHOR]

• Thermal and hydrodynamic characteristics of staggered drop-shaped tubes were studied. • The effect of the number of tube rows N R on the performance was investigated. • The effect of increasing Reynolds number Re on the performance was analyzed. • The investigation covered 1.78 × 103 ≤ Re ≤ 18.72 × 103 and 1 ≤ N R ≤ 20. • New correlations for N u ¯ , f , and ε considering N R were developed. In this paper, for the first time, air-side correlations were developed and introduced to describe the average Nusselt number N u ¯ , friction factor f , and thermal − hydraulic performance ε of compact heat exchanger employing drop-shaped tubes considering the number of tube rows (N R). Drop-shaped tubes were arranged in a staggered formation and placed in 1 to 20 consecutive rows in the flow direction, each consisting of 7 tubes in the transverse direction. The Reynolds number (Re) varied from 1.78 × 103 to 18.72 × 103. The calculations were carried out using Ansys Fluent software package. Tube row and Reynolds number effects on the thermal and hydrodynamic characteristics of the studied heat exchangers were analyzed. The simulation results were in a good agreement with the available literature. The results showed that N u ¯ and ε increase, while f decreases as Re increases. Moreover, an increase in N R leads to an increase of f and a decrease of ε. The maximum values of N u ¯ were obtained for N R = 2, which were higher by 3.95–6.69% and 19.91–24.62% than those for N R = 1, and N R = 20, respectively. Heat transfer was stabilized only from the 19-row onwards. In addition, a 1-row heat exchanger had better thermal − hydraulic performance compared to that with a larger N R (ε for N R = 1 was about 22.32–27.24 times higher than those for N R = 20). The maximum deviation between the numerical results and the obtained correlations developed from them was ± 8.87%, which provides a useful reference for future studies and designs of heat exchangers with different row numbers of drop-shaped tubes. [ABSTRACT FROM AUTHOR]

Numerical and experimental analyses of open channel natural convection heat transfer of a finned plate were carried out. By varying the fin spacing, the heat transfer rates were calculated using FLUENT 6.3.26 for Prandtl numbers in the range 0.7 ≤ Pr ≤ 2000. Mass transfer experiments were carried out to verify the simulated data, exploiting the analogy between heat and mass transfer. The optimal fin spacing increased as the Prandtl number decreased. The calculated velocity and temperature profiles revealed the interaction between the thermal boundary layers on adjacent fins as a function of the Prandtl number. The observations of the overlap of the thermal boundary layers that develops at the corners of the fins, led the derivation of a simple heat transfer correlation that can be used to predict the heat transfer rate of a finned plate, based on an existing heat transfer correlation for a planar surface. [ABSTRACT FROM AUTHOR]

A three-dimensional mathematical model is developed describing arc plasma behavior in double-wire gas metal arc welding (DW-GMAW). The distribution of some physical quantities are completely investigated including arc temperature, arc pressure, velocity, current density, heat flux, magnetic flux density and electromagnetic force by solving conservation equations of mass, momentum, and energy, as well as part of Maxwell's equations. Meanwhile, a comparison study of arc plasma behavior between single-wire gas metal arc welding (SW-GMAW) and DW-GMAW is studied. It is found that due to the inter-attraction of double arcs, the arc plasma deflects to the middle of double welding wires, the maximum arc pressure decreases and the occurrence of welding defects such as undercut and humping is less in DW-GMAW than that in SW-GMAW. In addition, the effect of welding current on inclined angle, maximum temperature of arc plasma and heat flux on workpiece is investigated. The numerical results show good agreement with experimental ones and published literature, which proves that our model has relatively high reliability. The paper lays a foundation for true three-dimensional comprehensive modeling of DW-GMAW including arc plasma, metal transfer and weld pool. [ABSTRACT FROM AUTHOR]

A numerical investigation of laminar natural convective heat transfer inside cavity filled with air having left heated wall and cold left wall. The top and bottom walls of the cavity are kept to be adiabatic. The finite volume approach for the Prandlt Number pr=0.7, 3,6,10 and Ra 10 4 are used to solve the governing equations, in which buoyancy is modeled via the Boussinesq approximation in FLUENT. The visualization of flow patterns and temperature fields are shown by means of streamlines and isotherms, respectively. The influence of Prandlt numbers on the hot wall of the cavity are analyzed. Variations of the maximum value of the dimensionless stream function and Nusselt Number were also presented. The computed result indicated that Nusselt number increases along the length of the hot wall and then gradually decreases near the end of the wall. Also as Prandlt number increases heat transfer rate decreases. [ABSTRACT FROM AUTHOR]

The vortex formation at pump intake is a common problem encountered by practicing engineers of pumps. The vortex formation due to low submergence and high intake velocity leads to mechanical damage to impeller and loss of pump performance. In order to meet the flow requirement, sometimes multiple pumping systems are used where suction pipes are located nearby. Because of this arrangement, the performance of the pumps gets influenced. The objective of the present work is to investigate the mechanism of flow structure developing around a suction pipe of a pump. Work has been executed using ANSYS Fluent. The flow patterns of double pipe pump intake system is examined and discussed under various flow conditions. The suction effect on approaching flow near the bell mouth is examined using numerical modeling. The swirl angle in pump intake system is used to evaluate its performance. The results indicate that the pump becomes less efficient with decrease in submergence depth. [ABSTRACT FROM AUTHOR]

Based on the known geometric model of classrooms using hybrid ventilation with solar chimney, the solar radiation intensity of the solar chimney's effect on indoor air temperature and velocity is simulated and analyzed based on the Fluent software. Combined with the numerical simulation analysis, it can be seen that ventilation quantity increases with the increase of solar radiation and the variation of average temperature with a series of room heights under different solar radiation can be available. Study and Research on the solar chimney can provide the theoretical evidence for the ventilation effect of classrooms, however, a more accurate conclusion will be required for further study on the numerical simulation and experimental verification. [ABSTRACT FROM AUTHOR]

Numerical analysis of thermal enhancement for a single Proton Exchange Membrane Fuel Cell (PEMFC) cooling plate is presented in this paper. A low concentration of Al2O3 in Water - Ethylene Glycol mixtures was used as coolant in 220 mm x 300 mm cooling plate with 22 parallel mini channels of 1 x 5 x 100 mm. This cooling plate mimicked conventional PEMFC cooling plate as it was made of carbon graphite. Large header was added to have an even velocity distribution across all Re number studied. The cooling plate was subjected to a constant heat flux of 100W that represented the artificial heat load of a single cell. Al 2 O 3 nano particle volume % concentration of 0.1 and 0.5 vol was dispersed in 50:50 (water: Ethylene Glycol) mixtures. The effect of different flow rates to heat transfer enhancement and fluid flow in Re range of 30 to 150 were observed. The result showed that thermal performance has improved by 7.3 and 4.6% for 0.5 and 0.1 vol % Al 2 O 3 consecutively in 50:50 (water:EG) as compared to base fluid of 50:50 (water:EG). It is shown that the higher vol % concentration of Al 2 O 3 the better the heat transfer enhancement but at the expense of higher pumping power required as much as 0.04W due to increase in pressure drop. The positive thermal results implied that Al 2 O 3 nanofluid is a potential candidate for future applications in PEM fuel cell thermal management [ABSTRACT FROM AUTHOR]

In recent years, Computational Fluid Dynamics (CFD) methodology has been widely used for solving multi-dimensional thermal-hydraulics problems in nuclear science and engineering. As for the neutronics analysis, it mostly depends on the deterministic or probabilistic method codes which are independent of the thermal-hydraulic ones. Usually an extra interface program needs to be developed for the data exchange between the two kinds of codes in the coupled calculation. In this paper, a Temporal And Spatial Neutronics Analysis Module (TASNAM) in commercial CFD package FLUENT was developed based on the User Defined Function (UDF) and User Define Scalar (UDS) to solve the neutronics problems. Neutron diffusion equations and delayed neutron precursors balance equations are discretized by finite volume method (FVM) and can be solved with CFD conservation equations simultaneously. In order to demonstrate the feasibility and accuracy of TASNAM in FLUENT, three neutronics benchmark problems, the 2D-IAEA, 2D-TWIGL, and 2D-LRA benchmark problem are analyzed. The calculation results in the present paper have a good agreement with the reference values, which demonstrates that the TASNAM in FLUENT can solve neutronics problems accurately. [ABSTRACT FROM AUTHOR]