scholarly journals Analysis of the Thermal Behavior of a New Structure of Protected Agriculture Established in a Region of Tropical Climate Conditions

Fluids ◽  
2021 ◽  
Vol 6 (6) ◽  
pp. 223
Author(s):  
Edwin Villagrán ◽  
Andrea Rodriguez
Keyword(s):  
Thermal Behavior ◽  
Management Strategies ◽  
Decision Makers ◽  
Cultural Work ◽  
Cfd Model ◽  
Climate Conditions ◽  
Average Temperature ◽  
Agricultural Structure ◽  
The Hours ◽  
Computational Fluid Dynamics Cfd

Determining airflow patterns and their effect on the distribution of microclimate variables such as temperature is one of the most important activities in naturally ventilated protected agricultural structures. In tropical countries, this information is used by farmers and decision makers when defining climate management strategies and for crop-specific cultural work. The objective of this research was to implement a validated Computational Fluid Dynamics (CFD) model in 3D to determine the aerodynamic and thermal behavior of a new protected agricultural structure established in a warm climate region in the Dominican Republic. The numerical evaluation of the structure was carried out for the hours of the daytime period (6–17 h), the results found allowed to define that the CFD model generates satisfactory predictions of the variables evaluated. Additionally, it was found that airflow patterns are strongly affected by the presence of porous insect screens, which generate moderate velocity flows (<0.73 m s−1) inside the structure. It was also identified that the value of the average temperature inside the structure is directly related to the air flows, the level of radiation and the temperature of the outside environment.

Thermal Analysis of a Fluid Immersed Brushless DC Motor for Aerospace Applications

2013 ◽  
Vol 416-417 ◽  
pp. 1126-1131
Author(s):  
Wei Chen ◽  
Xiao Yan Huang ◽  
Jien Ma ◽  
You Tong Fang
Keyword(s):  
Thermal Behavior ◽  
High Speed ◽  
Dc Motor ◽  
Brushless Dc Motor ◽  
Cfd Model ◽  
Brushless Dc ◽  
Aerospace Applications ◽  
Actuation System ◽  
Computational Fluid Dynamics Cfd ◽  
Permanent Magnet Brushless Dc

In this paper, the thermal behavior of a 12kW, 12000rpm, wet-type Permanent Magnet Brushless DC motor (BLDC) with skydrol oil inside designed for electro-hydraulic actuation system (EHA) was analyzed. A 3-D computational fluid dynamics (CFD) model has been built. The influence of skydrol hydraulic oil in thermal behavior at both low-speed and high-speed conditions was discussed. The results confirm that the skydrol oil passing through the motor has different impact on the thermal performance in different conditions.

Optimization of a Combined Photovoltaic/Thermal Unit Using Computational Fluid Dynamics

2014 ◽  
Author(s):  
Andrew Roberts ◽  
Ming-Chia Lai ◽  
Chi-Yang Cheng
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Theoretical Model ◽  
Cfd Model ◽  
Ansys Fluent ◽  
Climate Conditions ◽  
Flow Energy ◽  
Computational Fluid Dynamics Cfd ◽  
Heat Transfer System ◽  
D Model

The goal of this project was to develop a model for a Combined Photovoltaic/Thermal (PV/T) unit to ease in the assessment of potential changes to the unit before fabrication of actual parts. This process reduces the time to assess changes in the system; once the initial model is created changes are relatively simple. It also reduces cost incurred for actual testing by certified labs and can simulate output variations in different climate conditions, site locations and times of year. A commercially available PV/T unit was chosen for analysis, which utilizes two water channels under the photovoltaic assembly instead of the conventional sheet-and-tube design to actively cool the solar cells while also collecting thermal energy that can be used for heating water or air via a heat transfer system. The project described in this paper modeled the PV/T unit in two ways: (1) as a one-dimensional theoretical model and (2) modeling the system in ANSYS FLUENT and simulating the fluid flow, energy and radiation models using computational fluid dynamics (CFD). The baseline CFD model was correlated to published Solar Rating and Certification Corporation (SRCC) test data for pressure drop and thermal performance to gage accuracy of the model. Through a literature search of past work on similar modules and systems, several potential improvements to the unit were identified and a detailed analysis was conducted by individually adding each to the theoretical model, then comparing them to the output of the baseline model. Combinations of improvements were evaluated as well and assessed based on output improvement, technical feasibility and expected cost. The accuracy of the 1-D model was compared to the CFD model to assess the benefits gained from the added complexity of using computational fluid dynamics.

scholarly journals Potential Global Distribution of Daktulosphaira vitifoliae under Climate Change Based on MaxEnt

Insects ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 347
Author(s):  
Wei Ji ◽  
Gary Gao ◽  
Jiufeng Wei
Keyword(s):  
Management Strategies ◽  
Climatic Conditions ◽  
Decision Makers ◽  
Invasive Pest ◽  
Distribution Area ◽  
Daktulosphaira Vitifoliae ◽  
Climate Conditions ◽  
Eastern Usa ◽  
Major Factors ◽  
Control And Management

Grape phylloxera, Daktulosphaira vitifoliae, is a small, invasive, sap-sucking pest that is widely present in most viticulture regions all over the world. It is originally from North America and feeds on grapevine roots and leaves. In the current study, the potential distribution area of the leaf-feeding population was investigated with MaxEnt based on population occurrence data under different environmental variables. Results suggested that under current climatic conditions, Europe, East and North China, Japan, the Eastern USA, Uruguay, and the Southeast of South America are highly suitable areas for the occurrence of phylloxera leaf populations. The results showed that isothermality and precipitation of coldest quarter were major factors which contribute more than 60% of the model under current climate conditions. Our results provide important information for governmental decision makers and famers to develop control and management strategies against D. vitifoliae, and can also be used as a reference for studies on other invasive pest.

Reduction of Pollutants Emissions From Domestic Boilers: CFD Study

2008 ◽  
Author(s):  
Gasser Hassan ◽  
Mohamed Pourkashanian ◽  
Derek Ingham ◽  
Lin Ma ◽  
Stephen Taylor
Keyword(s):  
Combustion Chamber ◽  
Combustion Process ◽  
Pollutant Emissions ◽  
Combustion Model ◽  
Cfd Model ◽  
Inlet Velocity ◽  
Average Temperature ◽  
Partially Premixed Combustion ◽  
Boiler Efficiency ◽  
Computational Fluid Dynamics Cfd

This study is concerned with building a computational fluid dynamics (CFD) model to simulate the combustion process occurring in the combustion chamber of some domestic boilers. The burner used in this boiler is a conventional cylindrical premix burner with small inlet holes on its surface. A two-dimensional (2D) CFD model is built to simulate the combustion chamber domain and the partially premixed combustion model with a postprocessor for NOx calculations is used to simulate the combustion process inside the combustion chamber. A complete description of the formation characteristics of NOx produced from the boiler is discussed in detail. A comparison between the CFD numerical results and the experimental measurements at different boiler loads is performed in order to validate the numerical model and investigate the accuracy of the CFD model. The validated CFD model is used to investigate the effect of different boundaries temperatures and the mixture inlet velocity on the flue gas average temperature, residence time and hence the CO and NOx concentrations produced from the combustion chamber. The concept of changing the mixture inlet velocity is found to be an effective method to improve the design of the burner in order to reduce the pollutant emissions produced from the boiler with no effect on the boiler efficiency.

Effects of Over Fire Air on the Combustion and NOx Emission Characteristics of a 600 MW Opposed Swirling Fired Boiler

2012 ◽  
Vol 512-515 ◽  
pp. 2135-2142 ◽  
Author(s):  
Yu Peng Wu ◽  
Zhi Yong Wen ◽  
Yue Liang Shen ◽  
Qing Yan Fang ◽  
Cheng Zhang ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Empirical Method ◽  
Nox Emission ◽  
Emission Characteristics ◽  
Cfd Model ◽  
Nitrogen Release ◽  
Computational Fluid Dynamics Cfd ◽  
Low Nox Emission

A computational fluid dynamics (CFD) model of a 600 MW opposed swirling coal-fired utility boiler has been established. The chemical percolation devolatilization (CPD) model, instead of an empirical method, has been adapted to predict the nitrogen release during the devolatilization. The current CFD model has been validated by comparing the simulated results with the experimental data obtained from the boiler for case study. The validated CFD model is then applied to study the effects of ratio of over fire air (OFA) on the combustion and nitrogen oxides (NOx) emission characteristics. It is found that, with increasing the ratio of OFA, the carbon content in fly ash increases linearly, and the NOx emission reduces largely. The OFA ratio of 30% is optimal for both high burnout of pulverized coal and low NOx emission. The present study provides helpful information for understanding and optimizing the combustion of the studied boiler

scholarly journals Morphometric analysis and prioritization of upper Benue River watershed, Northern Nigeria

2021 ◽  
Vol 11 (2) ◽  
Author(s):  
Caleb Akoji Odiji ◽  
Olaide Monsor Aderoju ◽  
Joseph Bisong Eta ◽  
Idris Shehu ◽  
Adama Mai-Bukar ◽  
...  
Keyword(s):  
Management Strategies ◽  
Decision Makers ◽  
Order System ◽  
Hydrological Process ◽  
Drainage Pattern ◽  
River Watershed ◽  
Digital Elevation ◽  
Hypsometric Integral ◽  
Cumulative Length ◽  
Elevation Model

AbstractThe upper Benue River watershed is undergoing remarkable modifications due to man-made and natural phenomena. Hence, an evaluation is required to understand the hydrological process of the watershed for planning and management strategies. This study aimed to assess the morphometric characteristics and prioritize the upper Benue River watershed. The boundary of the watershed and sub-watersheds, as well as stream networks, was extracted from the digital elevation model (DEM) coupled with hydrological and topographic maps. Twenty-eight morphometric parameters under three categories, i.e. linear, areal, and relief aspects were computed and mapped. Findings from the study revealed that the watershed is a seventh stream order system characterized by a dendritic drainage pattern. The result also showed that 4821 streams were extracted with a cumulative length of 30,232.84 km. The hypsometric integral of the watershed was estimated to be 0.22, indicating that it is in the old stage. In the prioritization of the watershed, the morphometric variables were utilized to calculate and classify the compound factor. The result showed that sub-watersheds 12, 16, 18, 24, 26, and 27 were ranked as very high priority for which conservation measures are required to mitigate the risk of flood and erosion. The outcome of this study can be used by decision-makers for sustainable watershed management and planning.

scholarly journals Land Degradation Vulnerability Mapping in a Newly-Reclaimed Desert Oasis in a Hyper-Arid Agro-Ecosystem Using AHP and Geospatial Techniques

Agronomy ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1426
Author(s):  
Ahmed S. Abuzaid ◽  
Mohamed A. E. AbdelRahman ◽  
Mohamed E. Fadl ◽  
Antonio Scopa
Keyword(s):  
Remote Sensing ◽  
Soil Quality ◽  
Land Degradation ◽  
Quality Index ◽  
Management Strategies ◽  
Remote Sensing Data ◽  
Western Desert ◽  
Soil Quality Index ◽  
Climate Conditions ◽  
Sensing Data

Modelling land degradation vulnerability (LDV) in the newly-reclaimed desert oases is a key factor for sustainable agricultural production. In the present work, a trial for usingremote sensing data, GIS tools, and Analytic Hierarchy Process (AHP) was conducted for modeling and evaluating LDV. The model was then applied within 144,566 ha in Farafra, an inland hyper-arid Western Desert Oases in Egypt. Data collected from climate conditions, geological maps, remote sensing imageries, field observations, and laboratory analyses were conducted and subjected to AHP to develop six indices. They included geology index (GI), topographic quality index (TQI), physical soil quality index (PSQI), chemical soil quality index (CSQI), wind erosion quality index (WEQI), and vegetation quality index (VQI). Weights derived from the AHP showed that the effective drivers of LDV in the studied area were as follows: CSQI (0.30) > PSQI (0.29) > VQI (0.17) > TQI (0.12) > GI (0.07) > WEQI (0.05). The LDV map indicated that nearly 85% of the total area was prone to moderate degradation risks, 11% was prone to high risks, while less than 1% was prone to low risks. The consistency ratio (CR) for all studied parameters and indices were less than 0.1, demonstrating the high accuracy of the AHP. The results of the cross-validation demonstrated that the performance of ordinary kriging models (spherical, exponential, and Gaussian) was suitable and reliable for predicting and mapping soil properties. Integrated use of remote sensing data, GIS, and AHP would provide an effective methodology for predicting LDV in desert oases, by which proper management strategies could be adopted to achieve sustainable food security.

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