scholarly journals CFD Simulations – Efficient Tool for Designers of Industrial HVAC Applications

2019 ◽  
Vol 63 (3) ◽  
pp. 201-206
Author(s):  
Zuzana Straková ◽  
Jozef Vojtaššák ◽  
Peter Beňovský ◽  
Daniela Koudelková
Keyword(s):  
Natural Ventilation ◽  
Inlet Temperature ◽  
Cfd Modelling ◽  
Cfd Simulations ◽  
Air Inlet ◽  
Industrial Ventilation ◽  
Adiabatic Cooling ◽  
The Stability ◽  
The Many ◽  
Aluminium Plant

The aim of this study is to design industrial ventilation in the production hall. With respect to the many parameters which influence the appropriate proposal of industrial ventilation that need to be considered, there is a good chance for miscalculations when design the industrial ventilation. Especially when the heat loads from technology threaten the stability of construction of the building. There are two different ways of solution of aeration in the aluminium plant. There is only a natural ventilation using outside air in case of melting of aluminium and an adiabatic cooling for air inlet combined with natural ventilation. The results and practice has shown, that to use only an outside air is not sufficient and the temperature in the hall is really very high. Adiabatic cooling decreases the air inlet temperature in the production hall and improves the working conditions. A thermovision mapping of the technology was used prior to start the CFD modelling. The simulation emphasize the important effect of design and location of different elements on the functionality of ventilation proposal.

scholarly journals Microencapsulation ofβ-Carotene by Spray Drying: Effect of Wall Material Concentration and Drying Inlet Temperature

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Luiz C. Corrêa-Filho ◽  
Maria M. Lourenço ◽  
Margarida Moldão-Martins ◽  
Vítor D. Alves
Keyword(s):  
Antioxidant Activity ◽  
Spray Drying ◽  
Encapsulation Efficiency ◽  
Fruits And Vegetables ◽  
Wall Material ◽  
Inlet Temperature ◽  
Carotene Content ◽  
Arabic Gum ◽  
Air Inlet ◽  
Adverse Environmental Conditions

Carotenoids are a class of natural pigments found mainly in fruits and vegetables. Among them,β-carotene is regarded the most potent precursor of vitamin A. However, it is susceptible to oxidation upon exposure to oxygen, light, and heat, which can result in loss of colour, antioxidant activity, and vitamin activity. Thus, the objective of this work was to study the microencapsulation process ofβ-carotene by spray drying, using arabic gum as wall material, to protect it against adverse environmental conditions. This was carried out using the response surface methodology coupled to a central composite rotatable design, evaluating simultaneously the effect of drying air inlet temperature (110-200°C) and the wall material concentration (5-35%) on the drying yield, encapsulation efficiency, loading capacity, and antioxidant activity. In addition, morphology and particles size distribution were evaluated. Scanning electron microscopy images have shown that the particles were microcapsules with a smooth surface when produced at the higher drying temperatures tested, most of them having a diameter lower than 10μm. The conditions that enabled obtaining simultaneously arabic gum microparticles with higherβ-carotene content, higher encapsulation efficiency, and higher drying yield were a wall material concentration of 11.9% and a drying inlet temperature of 173°C. The systematic approach used for the study ofβ-carotene microencapsulation process by spray drying using arabic gum may be easily applied for other core and wall materials.

scholarly journals Using CFD to Evaluate Natural Ventilation through a 3D Parametric Modeling Approach

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2197
Author(s):  
Nayara Rodrigues Marques Sakiyama ◽  
Jurgen Frick ◽  
Timea Bejat ◽  
Harald Garrecht
Keyword(s):  
Natural Ventilation ◽  
Parametric Modeling ◽  
Cfd Simulations ◽  
3D Design ◽  
Post Process ◽  
Test House ◽  
Model Set ◽  
Computational Fluid Dynamics Cfd ◽  
Set Up ◽  
Passive Strategy

Predicting building air change rates is a challenge for designers seeking to deal with natural ventilation, a more and more popular passive strategy. Among the methods available for this task, computational fluid dynamics (CFD) appears the most compelling, in ascending use. However, CFD simulations require a range of settings and skills that inhibit its wide application. With the primary goal of providing a pragmatic CFD application to promote wind-driven ventilation assessments at the design phase, this paper presents a study that investigates natural ventilation integrating 3D parametric modeling and CFD. From pre- to post-processing, the workflow addresses all simulation steps: geometry and weather definition, including incident wind directions, a model set up, control, results’ edition, and visualization. Both indoor air velocities and air change rates (ACH) were calculated within the procedure, which used a test house and air measurements as a reference. The study explores alternatives in the 3D design platform’s frame to display and compute ACH and parametrically generate surfaces where air velocities are computed. The paper also discusses the effectiveness of the reference building’s natural ventilation by analyzing the CFD outputs. The proposed approach assists the practical use of CFD by designers, providing detailed information about the numerical model, as well as enabling the means to generate the cases, visualize, and post-process the results.

Rough Air-Soft Elastohydrodynamic Lubrication

2013 ◽  
Vol 420 ◽  
pp. 30-35
Author(s):  
Khanittha Wongseedakaew ◽  
Jesda Panichakorn
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Modulus Of Elasticity ◽  
Contact Region ◽  
Elastohydrodynamic Lubrication ◽  
Multilevel Methods ◽  
Inlet Temperature ◽  
Film Pressure ◽  
Air Inlet ◽  
Air Film

This paper presents the effects of rough surface air-soft elastohydrodynamic lubrication (EHL) of rollers for soft material under the effect of air molecular slip. The time independent modified Reynolds equation and elasticity equation were solved numerically using finite different method, Newton-Raphson method and multigrid multilevel methods were used to obtain the film pressure profiles and film thickness in the contact region. The effects of amplitude of surface roughness, modulus of elasticity and air inlet temperature are examined. The simulation results showed surface roughness has effect on film thickness but it little effect to air film pressure. When the amplitude of surface roughness and modulus of elasticity increased, the air film thickness decreased but air film pressure increased. However, the air inlet temperature increased when the air film thickness increased.

Consumer Behavior Changes Post Pandemic Covid-19

2020 ◽  
Vol 2 (2) ◽  
pp. 84-89
Author(s):  
Tati Maryati
Keyword(s):  
Consumer Behavior ◽  
Eating Habits ◽  
Supply And Demand ◽  
Health Economy ◽  
Behavior Changes ◽  
The World ◽  
The Stability ◽  
The Many ◽  
New Consumer ◽  
At Home

The Corona virus or Covid-19 which is unexpected will come to us, has an impact on health, economy and also humanity throughout the world and is able to fundamentally change the world. Supplements are disrupted because production is stopped, retail stores close, causing consumers to change their behavior, which had previously gone offline shopping. Not just shopping, when a pandemic, the way of thinking becomes different. Consumers around the world are looking for products and brands through new ways and new habits are formed. Online transactions focus more on basic products to make ends meet. The fact that Covid-19's anti-virus has not been found raises concerns about disrupted health and the Government's regulation to work and stay at home also raises concerns about disrupted businesses. Differences from habits and interests or preferences that are different for each person, provide different responses to the problems faced and solutions for the future. The habit of shopping offline has a tendency to continue for complementary products while food products are more directed towards offline. The rest eating habits at home can be continued because it provides more hygiene guarantees. The new habit of holding online meetings with distant relatives or colleagues will be increasingly considered given the many more positive things that can be obtained. Likewise with work problems, working from home is more interesting to consider because it is more efficient and effective and the results can be more productive. This new consumer behavior is adjusted to provide satisfaction for many parties, with the assistance of institutions or governments that oversee the security of supply and demand and maintain the stability of both. 

scholarly journals Characteristics of a Non-Premixed Rotating Detonation Combustor Using Natural Gas-Hydrogen Blend at Elevated Air-Preheat Temperature and Backpressure

2018 ◽  
Author(s):  
Arnab Roy ◽  
Donald Ferguson ◽  
Todd Sidwell ◽  
Peter Strakey
Keyword(s):  
Experimental Study ◽  
Natural Gas ◽  
Detonation Wave ◽  
Inlet Temperature ◽  
Operational Mode ◽  
Atmospheric Conditions ◽  
Theoretical Understanding ◽  
Air Inlet ◽  
Continuous Detonation ◽  
Rotating Detonation

Operational characteristics of an air breathing Rotating Detonation Combustor (RDC) fueled by natural gas-hydrogen blends are discussed in this paper. Experiments were performed on a 152 mm diameter uncooled RDC with a combustor to inlet area ratio of 0.2 at elevated inlet temperature and combustor pressure while varying the fuel split between natural gas and hydrogen over a range of equivalence ratios. Experimental data from short-duration (∼6sec) tests are presented with an emphasis on identifying detonability limits and exploring detonation stability with the addition of natural gas. Although the nominal combustor used in this experiment was not specifically designed for natural gas-air mixtures, significant advances in understanding conditions necessary for sustaining a stable, continuous detonation wave in a natural gas-hydrogen blended fuel were achieved. Data from the experimental study suggests that at elevated combustor pressures (2–3bar), only a small amount of natural gas added to the hydrogen is needed to alter the detonation wave operational mode. Additional observations indicate that an increase in air inlet temperature (up to 204°C) at atmospheric conditions significantly affects RDC performance by increasing deflagration losses through an increase in the number of combustion (detonation/Deflagration) regions present in the combustor. At higher backpressure levels the RDC exhibited the ability to achieve stable detonation with increasing concentrations of natural gas (with natural gas / hydrogen-air blend). However, losses tend to increase at intermediate air preheat levels (∼120°C). It was observed that combustor pressure had a first order influence on RDC stability in the presence of natural gas. Combining the results from this limited experimental study with our theoretical understanding of detonation wave fundamentals provides a pathway for developing an advanced combustor capable of replacing conventional constant pressure combustors typical of most power generation processes with one that produces a pressure gain.

Effect of Temperature Nonuniformity on Heat Transfer in an Unshrouded Transonic HP Turbine: An Experimental and Computational Investigation

2010 ◽  
Author(s):  
Imran Qureshi ◽  
Andy D. Smith ◽  
Kam S. Chana ◽  
Thomas Povey
Keyword(s):  
Heat Transfer ◽  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
Test Facility ◽  
Effect Of Temperature ◽  
Inlet Temperature ◽  
Experimental Measurements ◽  
Turbine Stage ◽  
Cfd Simulations ◽  
Turbine Inlet

Detailed experimental measurements have been performed to understand the effects of turbine inlet temperature distortion (hot-streaks) on the heat transfer and aerodynamic characteristics of a full-scale unshrouded high pressure turbine stage at flow conditions that are representative of those found in a modern gas turbine engine. To investigate hot-streak migration, the experimental measurements are complemented by three-dimensional steady and unsteady CFD simulations of the turbine stage. This paper presents the time-averaged measurements and computational predictions of rotor blade surface and rotor casing heat transfer. Experimental measurements obtained with and without inlet temperature distortion are compared. Time-mean experimental measurements of rotor casing static pressure are also presented. CFD simulations have been conducted using the Rolls-Royce code Hydra, and are compared to the experimental results. The test turbine was the unshrouded MT1 turbine, installed in the Turbine Test Facility (previously called Isentropic Light Piston Facility) at QinetiQ, Farnborough UK. This is a short duration transonic facility, which simulates engine representative M, Re, Tu, N/T and Tg /Tw at the turbine inlet. The facility has recently been upgraded to incorporate an advanced second-generation temperature distortion generator, capable of simulating well-defined, aggressive temperature distortion both in the radial and circumferential directions, at the turbine inlet.

Coating of Particles in Spouted Bed: Flow Regime and Stability

2010 ◽  
Vol 660-661 ◽  
pp. 573-579
Author(s):  
J.L. Vieira Neto ◽  
J.E. Borges ◽  
Claudio Roberto Duarte ◽  
Marcos A.S. Barrozo
Keyword(s):  
Power Spectrum ◽  
Pressure Fluctuations ◽  
Flow Regimes ◽  
Main Flow ◽  
Agricultural Products ◽  
Soybean Seeds ◽  
Spouted Bed ◽  
Cyclical Motion ◽  
The Stability ◽  
The Many

The coating and encapsulating of particles presents many applications in the chemical, pharmaceutical, food and agricultural products industries. Among the many applications of seeds coating, the enlargement of small seeds is included in order to facilitate the planting, the addition of herbicides, fungicides, fertilizers, micronutrients and inoculation. The spouted bed has often been used in studies related to the coating of particles, due to the cyclical motion of the material, which promotes a fast axial mixture of particles and an excellent gas-particle contact. In this work, the coating of soybean seeds with inoculum and micronutrients in spouted bed has been studied. The different flow regimes were investigated using the pressure fluctuations and power spectrum. The results of the present work showed that it was possible to identify the main flow regimes and to analyze the influence of the coating in the stability of those regimes.

Optimization for Powder Yield of Spray-Dried Garlic Extract Powder Using Box-Behnken Experimental Design

2020 ◽  
Vol 859 ◽  
pp. 301-306
Author(s):  
Nattakanwadee Khumpirapang ◽  
Supreeya Srituptim ◽  
Worawut Kriangkrai
Keyword(s):  
Experimental Design ◽  
Spray Drying ◽  
Flow Rate ◽  
Interactive Effect ◽  
Garlic Extract ◽  
Process Conditions ◽  
Inlet Temperature ◽  
Feed Flow Rate ◽  
Air Inlet ◽  
Liquid Feed

Garlic exerts its pharmacological activities; antihyperglycemic, antihyperlipidemia, antihypercholesterolemic, and antihypertensive activity. Therefore, the aim of this study was to determine and optimize the influence of the individual and interactive effect of process conditions variables on the yield of garlic extract powders by three factors and three level-Box-Behnken design under response surface methodology. Spray drying processes the transformation of a garlic juice extract into a dried powder, where usually maltodextrin (MD) as a drying agent is used. According to experimental design, the mixing of garlic juice extract (85 – 95 %w/w) and MD (5 – 15 %w/w) were dried at an air inlet temperature 110°C - 150°C and liquid feed flow rate 5 – 35 rpm. The optimum spray-drying process conditions which maximized the yield of garlic extract powder (31%w/w) were found as follows: air inlet temperature of 150°C, the liquid feed flow rate of 16 rpm, and 5 %w/w MD. The experimental values slightly closed to the corresponding predicted values. Hence, the developed model was adequate and possible to use.

scholarly journals NECESSITY TO IMPROVE THE MATHEMATICAL MODEL OF FREIGHT CARS TO STUDY CASES OF ITS DERAILMENTS

2020 ◽  
pp. 442-451
Author(s):  
А.V. Batig ◽  
A. Ya. Kuzyshyn
Keyword(s):  
Mathematical Model ◽  
Mathematical Models ◽  
Computer Experiment ◽  
Rolling Stock ◽  
Software Systems ◽  
Freight Car ◽  
The Stability ◽  
The Many ◽  
The Impact ◽  
The Mathematical Model

One of the most important problems that pose a serious threat to the functioning of railways is the problem of freight cars derailment. However, according to statistics, the number of cases of the derailments of freight cars in trains annually grows. Тo prevent such cases, the necessary preventive measures are developed, and to study the causes of their occurrence, a significant number of mathematical models, programs and software systems created by leading domestic and foreign scientists. Studies of such mathematical models by the authors of this work have led to the conclusion that they are not sufficiently detailed to the extent that it is necessary for analyze the reasons of its derailment. At the same time, an analysis of the causes of the rolling stock derailments on the railways of Ukraine over the past five years showed that in about 20 % of cases they are obvious, and in 7 % of cases they are not obvious and implicitly expressed. The study of such cases of rolling stock derailment during an official investigation by the railway and during forensic railway transport expertises requires the use of an improved mathematical model of a freight car, which would allow a quantitative assessment of the impact of its parameters and rail track on the conditions of railway accidents. Therefore, taking into account the main reasons that caused the occurrence of such railroad accidents over the last five years on the railways of Ukraine, the article selected the main directions for improving the mathematical model of a freight car, allowing to cover all the many factors (explicit and hidden) and identify the most significant ones regarding the circumstances of the derailment rolling stock off the track, established on the basis of a computer experiment. It is proposed in the mathematical model of a freight car to take into account the guiding force, the value of which is one of the main indicators of the stability of the rolling stock. The authors of the article noted that not taking into account the influence of the guiding forces on the dynamics of the freight car can lead to an erroneous determination of the reasons for the rolling stock derailment or even to the impossibility of establishing them.

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