scholarly journals Comparison between the experimental and numerical study of (air-oil) flow patterns in vertical pipe

2019 ◽  
Vol 14 ◽  
pp. 100424
Author(s):  
S.A. Abood ◽  
M.A. Abdulwahid ◽  
M.A. Almudhaffar
2018 ◽  
Vol 26 (04) ◽  
pp. 1850034 ◽  
Author(s):  
Sabreen A. Abood ◽  
Mohammed A. Abdulwahid ◽  
Mujtaba A. Al-Mudhafar

This paper provides the results of experimental stream flow patterns (water–oil) investigated in vertical and horizontal pipes with an elbow. The pipes are made from Perspex; the inner diameter is 0.024[Formula: see text]m, and the lengths of the vertical and horizontal pipes are 6 and 3[Formula: see text]m, respectively. The values of pressure at the four locations where [Formula: see text], 138, 248, and 304 are measured in various cases. The superficial velocities of the water range from 0.1 to 0.4[Formula: see text]m/s and of the oil from 0.1 to 0.9[Formula: see text]m/s. The pressure decreases with an increase in the height and the speed. Droplet/elongated/churn and annular streams are observed in a vertical pipe. The flow patterns are the stratified wavy stream with droplets at the interface, scattering (dispersion) of oil in water with a water layer, and annular flow in the horizontal pipe. These results of flow patterns are determined by a digital camera.


2021 ◽  
Vol 13 (9) ◽  
pp. 4748
Author(s):  
Edwin Villagran ◽  
Carlos Bojacá ◽  
Mohammad Akrami

The use of covered structures is an alternative increasingly used by farmers to increase crop yields per unit area compared to open field production. In Latin American countries such as Colombia, productive areas are located in with predominantly hillside soil conditions. In the last two decades, farmers have introduced cover structures adapted to these soil conditions, structures for which the behavior of factors that directly affect plant growth and development, such as microclimate, are still unknown. Therefore, in this research work, a CFD-3D model successfully validated with experimental data of temperature and air velocity was implemented. The numerical model was used to determine the behavior of air flow patterns and temperature distribution inside a Colombian passive greenhouse during daytime hours. The results showed that the slope of the terrain affects the behavior of the air flow patterns, generating thermal gradients inside the greenhouse with values between 1.26 and 16.93 °C for the hours evaluated. It was also found that the highest indoor temperature values at the same time were located in the highest region of the terrain. Based on the results of this study, future researches on how to optimize the microclimatic conditions of this type of sustainable productive system can be carried out.


Author(s):  
Faraz Afshari ◽  
Bayram Sahin ◽  
Barbara Marchetti ◽  
Fabio Polonara ◽  
Francesco Corvaro ◽  
...  

2015 ◽  
Vol 26 (12) ◽  
pp. 1550140 ◽  
Author(s):  
Amin Ebrahimi ◽  
Ehsan Roohi

Flow patterns and heat transfer inside mini twisted oval tubes (TOTs) heated by constant-temperature walls are numerically investigated. Different configurations of tubes are simulated using water as the working fluid with temperature-dependent thermo-physical properties at Reynolds numbers ranging between 500 and 1100. After validating the numerical method with the published correlations and available experimental results, the performance of TOTs is compared to a smooth circular tube. The overall performance of TOTs is evaluated by investigating the thermal-hydraulic performance and the results are analyzed in terms of the field synergy principle and entropy generation. Enhanced heat transfer performance for TOTs is observed at the expense of a higher pressure drop. Additionally, the secondary flow generated by the tube-wall twist is concluded to play a critical role in the augmentation of convective heat transfer, and consequently, better heat transfer performance. It is also observed that the improvement of synergy between velocity and temperature gradient and lower irreversibility cause heat transfer enhancement for TOTs.


Author(s):  
Tony Herbert Freire de Andrade ◽  
Kelen Cristina Oliveira Crivelaro ◽  
Severino Rodrigues de Farias Neto ◽  
Antonio Gilson Barbosa de Lima

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