scholarly journals Off-Design Exergy Analysis of Convective Drying Using a Two-Phase Multispecies Model

Energies ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 223
Author(s):  
Andrea Aquino ◽  
Pietro Poesio
Keyword(s):  
Energy Use ◽  
Convective Drying ◽  
Reference Scenario ◽  
Two Phase ◽  
Initial Product ◽  
Energy Needs ◽  
Wide Range ◽  
Different Seasons ◽  
Euler Model ◽  
Stable Performance

The design of a convective drying cycle could be challenging because its thermodynamic performance depends on a wide range of operating parameters. Further, the initial product properties and environmental conditions fluctuate during the production, affecting the final product quality, environmental impact, and energy usage. An off-design analysis distinguishes the effects of different parameters defining the setup with the best and more stable performance. This study analyzes a reference scenario configured as an existing system and three system upgrades to recover the supplied energy and avoid heat and air dumping in the atmosphere. We calculate their performance for different seasons, initial product moisture, input/output rate, and two products. The analysis comprises 16 simulation cases, the solutions of a two-phase multispecies Euler–Euler model that simulates the thermodynamic equilibrium in all components. Results discuss the combination of parameters that maximizes the evaporation rate and produces the highest benefits on global performance up to doubling the reference levels. The advantages of heat recovery vary by the amount of wasted energy, increasing the exergy efficiency by a maximum of 17%. Energy needs for air recirculation cut the performance at least by 50%. Concluding remarks present the technical guidelines to reduce energy use and optimize production.

Time Domain Simulation of the Vibration of a Steam Generator Tube Subjected to Fluidelastic Forces Induced by Two-Phase Cross-Flow

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Téguewindé Sawadogo ◽  
Njuki Mureithi
Keyword(s):  
Steam Generator ◽  
Two Phase Flow ◽  
Work Rate ◽  
Fretting Wear ◽  
Phase Flow ◽  
Reference Case ◽  
Two Phase ◽  
Steam Generator Tube ◽  
Wide Range ◽  
Instability Regime

Having previously verified the quasi-steady model under two-phase flow laboratory conditions, the present work investigates the feasibility of practical application of the model to a prototypical steam generator (SG) tube subjected to a nonuniform two-phase flow. The SG tube vibration response and normal work-rate induced by tube-support interaction are computed for a range of flow conditions. Similar computations are performed using the Connors model as a reference case. In the quasi-steady model, the fluid forces are expressed in terms of the quasi-static drag and lift force coefficients and their derivatives. These forces have been measured in two-phase flow over a wide range of void fractions making it possible to model the effect of void fraction variation along the tube span. A full steam generator tube subjected to a nonuniform two-phase flow was considered in the simulations. The nonuniform flow distribution corresponds to that along a prototypical steam-generator tube based on thermal-hydraulic computations. Computation results show significant and important differences between the Connors model and the two-phase flow based quasi-steady model. While both models predict the occurrence of fluidelastic instability, the predicted pre-instability and post instability behavior is very different in the two models. The Connors model underestimates the flow-induced negative damping in the pre-instability regime and vastly overestimates it in the post instability velocity range. As a result the Connors model is found to underestimate the work-rate used in the fretting wear assessment at normal operating velocities, rendering the model potentially nonconservative under these practically important conditions. Above the critical velocity, this model largely overestimates the work-rate. The quasi-steady model on the other hand predicts a more moderately increasing work-rate with the flow velocity. The work-rates predicted by the model are found to be within the range of experimental results, giving further confidence to the predictive ability of the model. Finally, the two-phase flow based quasi-steady model shows that fluidelastic forces may reduce the effective tube damping in the pre-instability regime, leading to higher than expected work-rates at prototypical operating velocities.

scholarly journals Energy implications of the millennium drought on urban water cycles in Southeast Australian cities

2017 ◽  
Vol 18 (1) ◽  
pp. 214-221
Author(s):  
K. L. Lam ◽  
P. A. Lant ◽  
S. J. Kenway
Keyword(s):  
Water Supply ◽  
Water Conservation ◽  
Energy Use ◽  
Water Supply Systems ◽  
Urban Water ◽  
Demand Side ◽  
Related Energy ◽  
Millennium Drought ◽  
Wide Range ◽  
Supply Systems

Abstract During the Millennium Drought in Australia, a wide range of supply-side and demand-side water management strategies were adopted in major southeast Australian cities. This study undertakes a time-series quantification (2001–2014) and comparative analysis of the energy use of the urban water supply systems and sewage systems in Melbourne and Sydney before, during and after the drought, and evaluates the energy implications of the drought and the implemented strategies. In addition, the energy implications of residential water use in Melbourne are estimated. The research highlights that large-scale adoption of water conservation strategies can have different impacts on energy use in different parts of the urban water cycle. In Melbourne, the per capita water-related energy use reduction in households related to showering and clothes-washing alone (46% reduction, 580 kWhth/p/yr) was far more substantial than that in the water supply system (32% reduction, 18 kWhth/p/yr). This historical case also demonstrates the importance of balancing supply- and demand-side strategies in managing long-term water security and related energy use. The significant energy saving in water supply systems and households from water conservation can offset the additional energy use from operating energy-intensive supply options such as inter-basin water transfers and seawater desalination during dry years.

Closed-Form Correlation of Buildings Energy Use With Key Design Parameters Calibrated Using a Genetic Algorithm

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Raed I. Bourisli ◽  
Adnan A. AlAnzi
Keyword(s):  
Genetic Algorithm ◽  
Closed Form ◽  
Energy Use ◽  
Building Design ◽  
Office Buildings ◽  
Design Parameters ◽  
Wide Range ◽  
Variable Function ◽  
Real Coded Genetic Algorithm ◽  
The Difference

This work aims at developing a closed-form correlation between key building design variables and its energy use. The results can be utilized during the initial design stages to assess the different building shapes and designs according to their expected energy use. Prototypical, 20-floor office buildings were used. The relative compactness, footprint area, projection factor, and window-to-wall ratio were changed and the resulting buildings performances were simulated. In total, 729 different office buildings were developed and simulated in order to provide the training cases for optimizing the correlation’s coefficients. Simulations were done using the VisualDOE TM software with a Typical Meteorological Year data file, Kuwait City, Kuwait. A real-coded genetic algorithm (GA) was used to optimize the coefficients of a proposed function that relates the energy use of a building to its four key parameters. The figure of merit was the difference in the ratio of the annual energy use of a building normalized by that of a reference building. The objective was to minimize the difference between the simulated results and the four-variable function trying to predict them. Results show that the real-coded GA was able to come up with a function that estimates the thermal performance of a proposed design with an accuracy of around 96%, based on the number of buildings tested. The goodness of fit, roughly represented by R2, ranged from 0.950 to 0.994. In terms of the effects of the various parameters, the area was found to have the smallest role among the design parameters. It was also found that the accuracy of the function suffers the most when high window-to-wall ratios are combined with low projection factors. In such cases, the energy use develops a potential optimum compactness. The proposed function (and methodology) will be a great tool for designers to inexpensively explore a wide range of alternatives and assess them in terms of their energy use efficiency. It will also be of great use to municipality officials and building codes authors.

The control of the qualitative and quantitative composi-tion of vitamins and tocopherols of various types of vegetable oils

2021 ◽  
pp. 92-95
Author(s):  
Александр Николаевич Остриков ◽  
Наталья Леонидовна Клейменова ◽  
Инэсса Николаевна Болгова ◽  
Максим Васильевич Копылов ◽  
Екатерина Юрьевна Желтоухова
Keyword(s):  
Vegetable Oils ◽  
The Body ◽  
Quantitative Composition ◽  
Vitamin B ◽  
Silybum Marianum ◽  
Qualitative And Quantitative ◽  
Energy Needs ◽  
Wide Range ◽  
Cold Pressed ◽  
Vitamin Activity

Использование растительных масел в рационе человека необходимо для удовлетворения энергетической потребности организма и регулирования биологических процессов. В настоящей работе представлен качественный и количественный состав витаминов и токоферолов различных видов растительных масел, полученных холодным отжимом из выращенных в нашей стране расторопши, горчицы, подсолнечника, рыжика, рапса. Проведен сравнительный анализ литературных источников о наличии витаминов и токоферолов в различных растительных маслах. Количественный и качественный витаминный состав для одного и того же вида масла, по данным разных авторов, варьируется в достаточно широком диапазоне. В ходе исследования изучен витаминный состав пяти растительных масел. Результаты свидетельствуют, что наибольшей витаминной активностью обладают масла рыжиковое, расторопши и горчичное. Установлено наличие витамина А в маслах: рыжиковом (27,15±0,002 мкг%), расторопши (19,07±0,02 мкг%), горчичном (24,77±0,02 мкг%). Витамины В и В присутствуют в маслах горчичном, рыжиковом и расторопши; витамин В определен в горчичном и рыжиковом, В - в рыжиковом и расторопши. В маслах горчичном и расторопши присутствует витамин В. Наиболее богаты витамином Е масла рыжиковое (52,8±0,02 мг%), подсолнечное (48,3±0,02 мг%), расторопши (47,12±0,02 мг%). Витамин К и токоферолы определены во всех растительных маслах. Присутствие b-каротина обнаружено в рыжиковом (1,237±0,004 мг%), расторопши (0,812±0,002 мг%), подсолнечном (0,22±0,02 мг%) и горчичном (0,148±0,002 мг%) маслах. Анализируемые масла холодного отжима можно рассматривать как ценный источник при проектировании новых многоцелевых продуктов или побочных продуктов для промышленного, косметического и фармацевтического использования. The use of vegetable oils in the human diet is necessary to meet the energy needs of the body and regulate biological processes. This work presents the qualitative and quantitative composition of vitamins and tocopherols of various types of vegetable oils obtained by cold pressing from silybum marianum, mustard, sunflower, camelina, rapeseed grown in our country. A comparative analysis of the literature on the presence of vitamins and tocopherols in various vegetable oils has been carried out. The quantitative and qualitative vitamin composition for the same type of oil, according to different authors, varies in a wide range. During the study, the vitamin composition of five vegetable oils was studied. The results indicate that the following oils have the highest vitamin activity: camelina, silybum marianum and mustard. The presence of vitamin A was found in oils: camelina (27.15±0.002 μg%), silybum marianum (19.07±0.02 μg%), mustard (24.77±0.02 μg%). Vitamins B and B are present in mustard, camelina and silybum marianum oils; vitamin B is found in mustard and camelina; B in camelina and silybum marianum. Mustard and silybum marianum oils contain vitamin B. The richest in vitamin E are camelina (52.8±0.02 mg%), sunflower (48.3±0.02 mg%), silybum marianum (47.12±0.02 mg%). Vitamin K and tocopherols are found in all vegetable oils. The presence of b-carotene was found in camelina (1.237±0.004 mg%), silybum marianum (0.812±0.002 mg%), sunflower (0.22±0.02 mg%) and mustard (0.148±0.002 mg%) oils. The analyzed cold-pressed oils can be considered as a valuable resource when designing new multipurpose products or by-products for industrial, cosmetic and pharmaceutical applications.

Prediction of High Viscosity Liquid/Gas Two-Phase Slug Length in Horizontal and Slightly Inclined Pipelines

2021 ◽  
Author(s):  
Omar Shaaban ◽  
Eissa Al-Safran
Keyword(s):  
Numerical Optimization ◽  
Flow Behavior ◽  
Mechanistic Model ◽  
High Viscosity ◽  
Oil Well ◽  
Liquid Slug ◽  
Two Phase ◽  
Proposed Model ◽  
Wide Range ◽  
Flow Closure

Abstract The production and transportation of high viscosity liquid/gas two-phase along petroleum production system is a challenging operation due to the lack of understanding the flow behavior and characteristics. In particular, accurate prediction of two-phase slug length in pipes is crucial to efficiently operate and safely design oil well and separation facilities. The objective of this study is to develop a mechanistic model to predict high viscosity liquid slug length in pipelines and to optimize the proper set of closure relationships required to ensure high accuracy prediction. A large high viscosity liquid slug length database is collected and presented in this study, against which the proposed model is validated and compared with other models. A mechanistic slug length model is derived based on the first principles of mass and momentum balances over a two-phase slug unit, which requires a set of closure relationships of other slug characteristics. To select the proper set of closure relationships, a numerical optimization is carried out using a large slug length dataset to minimize the prediction error. Thousands of combinations of various slug flow closure relationships were evaluated to identify the most appropriate relationships for the proposed slug length model under high viscosity slug length condition. Results show that the proposed slug length mechanistic model is applicable for a wide range of liquid viscosities and is sensitive to the selected closure relationships. Results revealed that the optimum closure relationships combination is Archibong-Eso et al. (2018) for slug frequency, Malnes (1983) for slug liquid holdup, Jeyachandra et al. (2012) for drift velocity, and Nicklin et al. (1962) for the distribution coefficient. Using the above set of closure relationships, model validation yields 37.8% absolute average percent error, outperforming all existing slug length models.

Activity coefficients, densities, dipole moments, and surface tensions of the system triethylamine–methylethylketone–water

1981 ◽  
Vol 59 (1) ◽  
pp. 127-131 ◽  
Author(s):  
Alan N. Campbell
Keyword(s):  
Surface Layer ◽  
Dipole Moments ◽  
Phase System ◽  
Constant Composition ◽  
Two Phase ◽  
Three Phase ◽  
Wide Range ◽  
Isothermal System ◽  
Total Composition ◽  
Two Phases

The properties named in the title have been determined by standard methods. Viscosity, molar volume, and orientation polarisation all indicate abnormalities of the nature of association between the components.The most interesting result is that of surface tension which indicates that, in the case of the binary system triethylamine–water, a surface layer of constant composition is formed over a wide range of total composition. When, by a rise in temperature of two or three degrees, this layer becomes unstable, it splits into two phases of different composition. The surface layer may then be instantaneously reformed and so on. A mechanism for the generation of a two-phase system is thus established. The data for the three-phase, isothermal, system are not so convincing, for reasons that are suggested.

scholarly journals Two-phase equilibrium in binary and ternary systems II. The system methane-ethylene III. The system methane-ethane-ethylene

1940 ◽  
Vol 176 (964) ◽  
pp. 140-152 ◽  
Keyword(s):  
Phase Equilibrium ◽  
Ternary System ◽  
Binary Systems ◽  
Ternary Systems ◽  
Two Phase ◽  
Composition Diagram ◽  
Wide Range ◽  
Binary And Ternary Systems

The liquid-vapour equilibrium of the system methane-ethylene has been determined at 0, -42 , -78, -88 and -104° C over a wide range of pressures and the results are shown on a pressure-composition-temperature diagram and by a series of pressure-composition curves. The liquid-vapour equilibrium of the ternary system methane-ethane-ethylene has been determined at -104, -78 and 0° C. Values for the two binary systems methane-ethane and methane-ethylene and for the ternary system methane-ethane-ethylene are shown on a composite pressure-composition diagram.

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