Scientists are researching whether pumping super-cold gas into Beijing's atmosphere can help reduce air pollution in the capital.
He Hui, a researcher at the government's Beijing Weather Modification Office, said liquid nitrogen, an industrial coolant nearly three times as cold as dry ice, was promising as an anti-smog agent though it was in the early stages of development.
The government-funded research involves pumping the gas from large tanks into the air as a fine mist at least 10 metres above ground.
Crystals form on the small particles of dust and other pollutants, which then fall to the ground. The belt of cooler air, less than 20 metres thick, also stops polluted air above reaching street level. The researchers said that during colder weather the belt, rich in vaporised liquid nitrogen, could remain hanging in the atmosphere for several hours.
http://www.scmp.com/news/china/arti...en-may-help-clean-beijing-smog-scientists-say
He's team was given 250,000 yuan (HK$317,000) by the National Natural Science Foundation last year to carry out computer simulations of how various chemical agents might help clean the air. Other agencies, which He declined to name, funded the liquid nitrogen experiments. This had proved the most promising research, he said.
"Our experiments showed that in an environment with temperatures below freezing point, liquid nitrogen outperformed all other agents, but in summer or autumn its effect was less obvious,'' He said. Other scientists have questioned whether this can be done safely.
He Hui, a researcher at the government's Beijing Weather Modification Office, said liquid nitrogen, an industrial coolant nearly three times as cold as dry ice, was promising as an anti-smog agent though it was in the early stages of development.
The government-funded research involves pumping the gas from large tanks into the air as a fine mist at least 10 metres above ground.
Crystals form on the small particles of dust and other pollutants, which then fall to the ground. The belt of cooler air, less than 20 metres thick, also stops polluted air above reaching street level. The researchers said that during colder weather the belt, rich in vaporised liquid nitrogen, could remain hanging in the atmosphere for several hours.
http://www.scmp.com/news/china/arti...en-may-help-clean-beijing-smog-scientists-say
He's team was given 250,000 yuan (HK$317,000) by the National Natural Science Foundation last year to carry out computer simulations of how various chemical agents might help clean the air. Other agencies, which He declined to name, funded the liquid nitrogen experiments. This had proved the most promising research, he said.
"Our experiments showed that in an environment with temperatures below freezing point, liquid nitrogen outperformed all other agents, but in summer or autumn its effect was less obvious,'' He said. Other scientists have questioned whether this can be done safely.
