Capturing Particles By A Rotating Disk In A Kitchen Exhaust Hood

Cooking can produce large amount of fume particles,especially for the Chinese cooking due to its particular cooking method,and it is the main factor that indoor particulate matter(PM2.5 and PM10)is higher than the outdoor environment.The exposure to the high concentration cooking fumes threatens the health of kitchen staff,and becomes the main cause of cancer in indoor non-smoking people.Hitherto,the trendy range hood in the market lacks efficient way to filter and purify the smoke,resulting in smoke escape to the outdoor atmosphere.These organic aerosols accumulate in the limited environment of the urban atmosphere and become one of the important emission sources of atmospheric haze.So,the filtration equipment in the range hood is of great necessity to collect and dispose smoke fumes.Former research mainly focuses on the ultrafine particles(PM0.1)and fine particles(PM2.5)since PM2.5 constitutes more than 90%of the concentration of particulate matter produced during cooking.However,the pollution and blockage of smoke pipes problem caused by coarse particles should also be paid enough attention.Thus,this research mainly focuses on the disposal of particles with the diameter between 3 to 20 microns.At present,some research has been done on the internal filter of range hood for capturing lampblack particles,mainly on the static filter.However,such device has great limitation in practical use because it cannot automatically drain the collected grease.This project proposes one rotating filter which can dispose the collected grease automatically to pretreat the oil.combined the simulation method based on the moving mesh technology and Lagrangian arithmetic with the experiments conducted in the wind tunnel,this paper detects the capability of the particle capture in different conditions and analyze several factors that affect the performance of the device.The experimental results can verify the simulation outcomes to some extent,and the reason of the deviation between the two are analyzed as well.Based on the verified simulation model,we propose two ways to improve the capture capability of this rotating filter.The major conclusions are listed as follows:the capture efficiency of this rotating filter increases with the diameter of the particles.it can hardly capture the particle smaller than 1 micron,but almost complete capture can be achieved for particles of 20microns.The capture efficiency increased with disk rotation speed but decreased with exhaust airflow rate.The lower layer of the wires has higher capture ability than the upper layer of the wires and the supporting bar.Making wires in the middle region and outer region denser or employing double disks system can significantly enhance the capture efficiency.Besides,two disks rotating in opposite direction has a higher improvement compared with rotating in the same direction.In the actual use process,it is recommended to use the improved rotating disk with denser underlayer to work at the rated speed of 2050r/m,and keep the air flow as small as possible(such as 300m~3/h),so that the capture efficiency of 10 micron particles can reach 81.7%.