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Sources of Air Pollution
Published in Subhash Verma, Varinder S. Kanwar, Siby John, Environmental Engineering, 2022
Subhash Verma, Varinder S. Kanwar, Siby John
North–South flow also occurs by a number of processes in both the troposphere and the stratosphere, and thus leads to air exchange between hemispheres. Most of the heat in the troposphere is received from the ground rather than directly from the sun. The troposphere, which is roughly 12 km in depth, contains about 85% of the mass of the atmosphere. As most living things exist in this sphere, it is of greatest importance as regards air pollution and control. The density of air, which is about 1.23 kg/m3 at sea level, decreases significantly with an increase in altitude. In fact, above the troposphere, there is not enough oxygen to support life.
Fluid Flow
Published in Daniel H. Nichols, Physics for Technology, 2019
The drag coefficient is a measure of how streamlined an object is, and has no unit. The drag force is a function of the density of the fluid. Air is considered a fluid of low viscosity. The density of air varies with temperature, humidity, and pressure. At 20°C and 101.3 kPa, dry air has a density of 1.2041 kg/m3. At 70°F and 14.696 psi, dry air has a density of 0.075 lb/ft3. The drag coefficients of cars include the total frontal area of a car including the area facing forward including mirrors, luggage rack, etc. (Table 9.1).
Air Blast Effects
Published in Per-Anders Persson, Roger Holmberg, Jaimin Lee, Rock Blasting and Explosives Engineering, 2018
Per-Anders Persson, Roger Holmberg, Jaimin Lee
The velocity of sound in air at standard temperature and pressure (STP) is 340 m/s (331 m/s at O°C). The density of air at STP is 1.29 kg/m3. In air or other gases, the velocity of sound increases proportionally with the square root of the absolute temperature; the velocity increase is approximately 2% for each 10° C temperature increase.
An Experimental Study on Performance Assessment of Solar Updraft Tower Power Plant with Guide Vanes
Published in Heat Transfer Engineering, 2022
Pritam Das, V. P. Chandramohan
The increased concerns over climate change, global warming, and energy security lead to paying more and more effort toward the development of various technologies to utilize renewable energy sources. Solar updraft tower (SUT) or solar chimney power plant is one of such viable technology for utilizing solar energy for power generation applications. The buoyancy principle and greenhouse effect are the basic working principle behind the concept [1, 2]. The SUT plant consists of a collector cover, absorber plate, solar tower or chimney and a turbine. The collector cover and absorber plate harness the solar energy and result in increasing the air temperature. The density of air decreases and moves upward due to the increase in its temperature. The kinetic energy of upward moving air is converted to electricity through the turbine coupled with a generator which is placed at the base of the tower. Apart from power generation applications, SUT can be useful for other applications such as desalination of water [3], agricultural food drying [4, 5], building ventilation [6] and air pollution mitigation [7]. The SUT plants have enormous advantages such as simple design, higher operational reliability, and long service life with zero emission. However, the thermal efficiency of the system was very low due to being constrained by environmental parameters such as ambient temperature and solar flux. The first prototype was developed at Manzanares city of Spain in the 1980s [1]. A 50-kW capacity plant was built with the chimney height (Hch), diameter (Dch) and collector diameter (Dap) of 194.6 m, 10.16 m, and 244 m, respectively. The plant operated successfully for 7 years and produced 36 kW power. The maximum velocities achieved were 15 m/s and 9 m/s under no-load and load conditions, respectively [2]. However, the Manzanares plant was collapsed due to a windstorm. After that, many researchers put interests in the area of the SUT plant and studied its thermo-fluidic behavior and thermal performance enhancement through various experimental, analytical, and numerical studies.
Assessment of wind energy potential: a case study
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
Abdullah Düzcan, Yusuf Ali Kara
Wind rose is subdivided into 12 equal sections to attain main wind direction. Twelve consecutive CFD simulations are performed. The speed above ABL is set to 10 m/s to avoid convergence problems (Fallo 2007). The density of air is fixed as 1.225 kg/m3.
Analysis of communication tower with different heights subjected to wind loads using TIA-222-G and TIA-222-H standards
Published in Journal of Asian Architecture and Building Engineering, 2023
Ali Murtaza Rasool, Yasser E. Ibrahim, Mohsin Usman Qureshi, Zafar Mahmood
Except the methods used in the paper, some of the most representative computational intelligence algorithms can be used to solve the problems, like monarch butterfly optimization (MBO) (Feng et al. 2021), earthworm optimization algorithm (EWA) (Pasupuleti and Balaswamy 2021), elephant herding optimization (EHO) (Wang, Deb, and Coelho 2015), moth search (MS) algorithm (Wang 2018), Slime mould algorithm (SMA) (Li et al. 2020), hunger games search (HGS) (Yang et al. 2021), Runge Kutta optimizer (RUN) (Ahmadianfar et al. 2021), colony predation algorithm (CPA) (Tu et al. 2021), and Harris hawks optimization (HHO) (Heidari et al. 2019). This study gives a comparative analysis of two ANSI/TIA standards (222-G & H) that are commonly used for the analysis and design of communication towers, poles, antennas, and supporting structures for antennas and small wind turbines. The procedure presented in the paper about the design calculations of wind load is a useful guide for structural engineers involved in the analysis and design of communication towers. The analysis results showed that the member axial forces increased by a percentage of 37% when analyzed for a wind speed of 125 & 225 kph (Risk Category-I) and 22% when analyzed for Risk Category-II, which can assist the practitioner in more optimized design.The wind speed in TIA-222-H is significantly higher than in TIA-222-G. This is due to the change from using nominal wind speeds to ultimate wind speeds, which essentially have load factors and importance factors already built-in.Ground elevation factor (Ke) is also an important factor. The density of air decreases as its distance from ground level increases. This means that at the same wind speed air produces more pressure on an object at sea level than it does at a higher elevation. TIA-222-H establishes a ground elevation factor (Ke) to take advantage of this, whereas, TIA-222-G conservatively calculated the wind pressure by assuming the site was located at sea level.The ice thicknesses in TIA-222-H generally appear twice as big as in TIA-222-G. This is because a factor of two (02) was moved from the design ice thickness equation in TIA-222-G to the values in the ice thickness map in TIA-222-H. Essentially, a 1-inch thickness on the TIA-222-G map is equivalent to a 2-inch thickness on the TIA-222-H map. Incorporating the load factors into the mapped values makes the ice maps more consistent with the wind and seismic maps.The latest TIA-222-H standard has some additional features including seismic analysis requirements for all risk categories (except Category-I), limit states for analysis of mounting systems, enhanced climber safety requirements, construction-related loading, etc.