Numerical study of the optimum width of 2a diurnal double air-channel solar chimney

Energy ◽  
2018 ◽  
Vol 147 ◽  
pp. 403-417 ◽  
Author(s):  
I. Zavala-Guillén ◽  
J. Xamán ◽  
I. Hernández-Pérez ◽  
I. Hernández-Lopéz ◽  
M. Gijón-Rivera ◽  
...  
Keyword(s):  
Numerical Study ◽  
Solar Chimney ◽  
Air Channel ◽  
Optimum Width

The Comparison of CFD Flow Field between Slope Solar Energy Power Plant and Traditional Solar Chimney Power Generating Equipment

2013 ◽  
Vol 561 ◽  
pp. 614-619 ◽  
Author(s):  
Qing Ling Li ◽  
Xiao Qing Xie ◽  
Jun Chao ◽  
Xuan Xin ◽  
Yan Zhou
Keyword(s):  
Power Plant ◽  
Velocity Field ◽  
Solar Energy ◽  
Numerical Study ◽  
Solar Chimney ◽  
Heat Collector ◽  
Fluent Software ◽  
Generating Equipment ◽  
The Cost ◽  
Power Generating Equipment

A numerical study with FLUENT software has been carried out as to air performance in the slope solar energy power plant. The velocity field, temperature and pressure fields in the solar chimney, and the simulated result were compared with the simulated result of traditional solar chimney power generating equipment. The simulation results show that distribution of the temperature field and the velocity field in slope solar energy power plant and traditional solar chimney power generating equipment. In the case of the same height, the velocity of traditional is slightly larger than the slope style's, but there is little difference. In order to achieve the same power generation effect, the overall height of slope style is more than the traditional style, but the vertical chimney height of traditional style is greater than the slope style. The cost of construction of vertical chimney is expensive, and many problems have been considered, like radix saposhnikoviae and earthquake prevention, the heat collector also need to be cleaned on time. The slope style can take full advantage of land, the height of vertical chimney will be reduced, so the construction of the chimney will be relatively easy. Rainwater can clean the heat collector when it runs down from it. All things considered. The slope solar energy power plant has more development prospects.

The Effect of Injection and Suction on the Interfacial Mass Transport Resistance in a Proton Exchange Membrane Fuel Cell Air Channel

2014 ◽  
Author(s):  
Mustafa Koz ◽  
Satish G. Kandlikar
Keyword(s):  
Proton Exchange Membrane ◽  
Numerical Study ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Channel Cross Section ◽  
Flow Through ◽  
Air Channel ◽  
Air Channels ◽  
Exchange Membrane

Proton exchange membrane fuel cells are efficient and environmentally friendly electrochemical engines. The present work focuses on air channels that bring the oxidant air into the cell. Characterization of the oxygen concentration drop from the channel to the gas diffusion layer (GDL)-channel interface is a need in the modeling community. This concentration drop is expressed with the non-dimensional Sherwood number (Sh). At the aforementioned interface, the air can have a non-zero velocity normal to the interface: injection of air to the channel and suction of air from the channel. A water droplet in the channel can constrict the channel cross section and lead to a flow through the GDL. In this numerical study, a rectangular air channel, GDL, and a stationary droplet on the GDL-channel interface are simulated to investigate the Sh under droplet induced injection/suction conditions. The simulations are conducted with a commercially available software package, COMSOL Multiphysics.

Computational fluid dynamics for modeling the turbulent natural convection in a double air-channel solar chimney system

2016 ◽  
Vol 27 (08) ◽  
pp. 1650095 ◽  
Author(s):  
I. Zavala-Guillén ◽  
J. Xamán ◽  
G. Álvarez ◽  
J. Arce ◽  
I. Hernández-Pérez ◽  
...  
Keyword(s):  
Natural Convection ◽  
Mexico City ◽  
Mass Flow ◽  
Solar Chimney ◽  
Turbulent Natural Convection ◽  
Air Turbulence ◽  
Warm Summer ◽  
Air Channel ◽  
Arid Desert ◽  
Volume Method

This study reports the modeling of the turbulent natural convection in a double air-channel solar chimney (SC-DC) and its comparison with a single air-channel solar chimney (SC-C). Prediction of the mass flow and the thermal behavior of the SC-DC were obtained under three different climates of Mexico during one summer day. The climates correspond to: tropical savannah (Mérida), arid desert (Hermosillo) and temperate with warm summer (Mexico City). A code based on the Finite Volume Method was developed and a [Formula: see text] turbulence model has been used to model air turbulence in the solar chimney (SC). The code was validated against experimental data. The results indicate that during the day the SC-DC extracts about 50% more mass flow than the SC-C. When the SC-DC is located in Mérida, Hermosillo and Mexico City, the air-changes extracted along the day were 60, 63 and 52, respectively. The air temperature at the outlet of the chimney increased up to 33%, 38% and 61% with respect to the temperature it has at the inlet for Mérida, Hermosillo and Mexico City, respectively.

Effects of wall proximity on the airflow in a vertical solar chimney for natural ventilation of dwellings

2020 ◽  
Vol 44 (3) ◽  
pp. 225-250
Author(s):  
Y Quoc Nguyen ◽  
John Craig Wells
Keyword(s):  
Heat Source ◽  
Natural Ventilation ◽  
Vertical Wall ◽  
Air Gap ◽  
Horizontal Plate ◽  
Solar Chimney ◽  
Horizontal Wall ◽  
Induced Flow ◽  
Air Channel ◽  
Wall Proximity

This study investigates performance of a vertical solar chimney, which absorbs solar energy and induces airflow for natural ventilation and cooling of dwellings, under effects of walls neighboring to its air channel. A computational fluid dynamics model was developed to predict induced flow rate and thermal efficiency of a vertical solar chimney with four types of nearby walls: a vertical wall to which the solar chimney was attached, a horizontal plate above the outlet of the air channel, a horizontal plate, and a horizontal wall below the inlet of the air channel. Examined factors included the heat flux in the air channel, the chimney height, the air gap, the distance of the walls, and the location of the heat source in the air channel. The results showed that effects of the wall proximity were modulated by the location of the heat source and the ratio G/ H between the air gap and the chimney height. Particularly, performance of the chimney was enhanced when the heat source was on the opposite side of the vertical wall and when G/ H was large.

Applying CFD for Studying the Dynamic and Thermal Behavior of Solar Chimney Drying System with Reversed Absorber

2017 ◽  
Vol 13 (11) ◽  
Author(s):  
Souheyla Khaldi ◽  
A. Nabil Korti ◽  
Said Abboudi
Keyword(s):  
Thermal Behavior ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Numerical Study ◽  
Packed Bed ◽  
Maximum Temperature ◽  
Storage Material ◽  
Solar Chimney ◽  
Solar Dryer

AbstractThis article provides numerical study of the solar chimney (SC) assembled with a reversed absorber and packed bed for the indirect-mode solar dryer. The present study was designed to determine the effects of using the SC in three configuration and physical proprieties of the packed (thickness and porosity) on the dynamic and thermal behavior of airflow. The results reveal that (1) using SC without storage material can increase the maximum mass flow rate up to 5%. However, integrating a storage material in the SC can improve the mass flow rate up to 32% during nighttime; (2) the use of a packed bed can decrease the crops temperature fluctuation until about 76% and increase the operating time of the solar dryer up to 12.5 hours rather than 10 hours in the case without packed bed; (3) increasing the porosity from 0.1 to 0.8 can increase the maximum temperature by about 10°C.

Virtual Height Aided Solar Chimney: A New Design

2011 ◽  
Author(s):  
Khaled I. E. Ahmed ◽  
Ali K. Abdel-Rahman ◽  
Mahmoud Ahmed ◽  
Wael M. Khairaldien
Keyword(s):  
Electric Power ◽  
Co2 Emissions ◽  
Conversion Efficiency ◽  
Numerical Study ◽  
Air Flow ◽  
Flow Speed ◽  
Numerical Results ◽  
Solar Chimney ◽  
Virtual Height ◽  
Wide Range

Renewable energy source deployment is growing rapidly as it reduces CO2 emissions and increases diversity and security of supply. Solar chimney (SC) is a promising large-scale power technology, which absorbs solar radiation and converts parts of solar energy into electric power free of CO2 emissions. A major problem of Solar Chimney Power Plant (SCPP) is its low conversion efficiency as determined by the thermal performance of the system. However, the conversion efficiency of SCPP significantly increases with the SC height increase. The current paper proposes a new design of a virtual height aided solar chimney. In this new system the solar chimney is aided with a passive cooling system at the top of the chimney and a passive solar heater at its base to virtually mimic larger heights of the chimney. The new design has been simulated numerically for development and optimization. The numerical study is done in two stages to examine this concept. In the first stage, numerical results are obtained for the effect of the chimney height on the inside air flow speed. Then, in the second stage, the effect of decreasing the temperature at the chimney exit and the effect of increasing the temperature at the chimney base on the air flow speed are examined separately for small chimney heights. Then the combined effect of the two actions is investigated at a wide range of chimney heights. The numerical results have shown that the localized base heating and exit cooling have significantly enhanced the chimney performance for chimney heights up to 500m. A chimney with height of 300m gains an increase in the air velocity more than 25% due to the heating and cooling actions. Virtual height aided Chimney with original height of 300m acts similarly to a conventional chimney with height of 500m due to the effect of base heating and exit cooling actions. This air flow velocity increase reflects 100% increase in the expected generated electric power. Further detailed results are presented and discussed.

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