Search

During their rapid economic development and industrialization, megacities in the developing nations with high populations (especially in the east and south Asia) are plagued by severe air pollution problems (e.g., heavy haze), which impose a threat not only to public health but also to the sustainable development of society and the economy. To relieve the burden of air pollution for the general public, this article reviewed several geoengineering measures based on solar chimneys, which have the large-scale elimination ability on pollutants in the air, particularly for particulate matter. These geoengineering measures include driving the polluted air penetrate the planetary boundary layer into the troposphere to avoid the dramatic growth of concentrations of particulate matter, spraying water on the top of the solar chimney into the air to scavenge pollution, and intercepting fine particles in the air driven by the solar energy with large filters. Compared with traditional methods (e.g., giant spray trucks), those solar chimney geoengineering measures have the following advantages: 1) they can be operated 24 h a day, thus keeping the pollution removal function stable and continuous; 2) they are environment-friendly and can generate clean electricity to compensate for energy consumption; 3) they are also robust and operational with very low maintenance for a long period. Given the advantages of the solar chimney geoengineering measures and the economic and human health losses caused by air pollution, those geoengineering approaches deserve to be studied further and implemented in those countries that are suffering from heavy air pollution problems. [ABSTRACT FROM AUTHOR]

The acceleration of urbanization process, which triggered a series of environmental issues, has become increasingly prominent. Air pollution, especially atmospheric fine particulate matter (PM 2.5 ), is one of the most severe pollutions affecting the human health and living standard. In this article, a novel solar chimney with an inverted U-type cooling tower and a water spraying system (SCIUCTWSS) was proposed to mitigate the urban air pollution. In this system, an inverted U-type cooling tower was used to take place of the traditional chimney erected in the center of the collector; a water spraying system was installed at the turning point of the inverted U-type cooling tower to enhance the driving force; a filtration screen is placed near the entrance of the collector to filter out PM 2.5 and large particulate matter from the airflow. The clean air out of the system’s outlet can immediately improve the air quality in the spectrum of human activity. A mathematical model to describe the fluid flow, heat transfer of the system was further developed. Influence of injected water from the water spraying system on the pressure, velocity, temperature, and air density distributions were analyzed. The numerical simulation results indicated that water injection is efficient that can strengthen the natural convection and has a positive influence on the heat transfer process within the system. This proposed SCIUCTWSS in this article is able to process atmospheric air at a volume flow rate of 810 m 3 /s, corresponding to the volume of 69,984,000 m 3 of air to be cleaned in one day. However, in view of the economic and human comfort, the amount of injected water should be taken into comprehensive consideration. [ABSTRACT FROM AUTHOR]