According to Xinhua News Agency, Beijing, December 20, Hong Kong media said that scientists are studying whether injecting ultra-cold gas into Beijing's atmosphere can help reduce air pollution in the capital. He Hui, a researcher at the Office of Weather Modification in Beijing, said that industrial refrigerant liquid nitrogen, which has almost twice the capacity of dry ice, is expected to be an anti-fog agent, although the research is still in its infancy.
According to the South China Morning Post website reported on December 18th, the government-funded research project is to pump liquid nitrogen from a huge container into the air to form a mist at least 10 meters above the ground. These liquid nitrogen will crystallize on the fine particles of dust and other contaminants and then fall to the ground. This cooling gas belt, which is less than 20 meters thick, also prevents contaminated air from falling onto the street. According to the researchers, this strip of water containing a large amount of hazy liquid nitrogen can remain in the atmosphere for hours in colder weather conditions.
Lin Keqing, deputy mayor of Beijing, said this week that the city is studying the use of this technology to fight smog, but he did not provide details.
Conventional methods of controlling haze include spraying chemicals into the clouds for artificial rainfall or snowfall to remove contaminants from the air. Artificial rain was used on the eve of the 2008 Beijing Olympics. But spraying a lot of chemicals over the capital with an airplane can be costly, and the effect of this method will be discounted in the winter. The frequency of haze weather in the winter in the north is higher.
According to the report, He Hui’s research team received a research grant of RMB 250,000 from the National Natural Science Foundation last year to conduct a computer simulation of the air cleaning effects that various chemical agents may have. The liquid nitrogen experiment was funded by other departments, but He Hui refused to disclose the names of these departments. He said that the use of liquid nitrogen has proven to be the most promising. He said: "Our experiments have shown that liquid nitrogen outperforms other preparations in temperatures below freezing, but in summer or autumn, the effect is less pronounced." Other scientists are safe about this method. Sexuality raised doubts.
Wang Xinfeng, who is engaged in atmospheric chemistry research at Shandong University, said that the use of liquid nitrogen to control air pollution is an unprecedented innovation and is supported by basic science, but the operation of this technology must be very careful. “It’s theoretically possible to use artificial nitrogen to create a barrier against air pollutants,†he said. “It’s theoretically possible, because the temperature of liquid nitrogen is extremely low, even if we’re experimenting. Be very careful when working in the room."
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