Reduction Effects of Suspended Particulate Matters in Air by Thermal Moisture Swing Method

2011 ◽  
Author(s):  
Nagisa Onoda ◽  
Shota Ishiguchi ◽  
Osamu Nakabeppu
Keyword(s):  
Particle Size ◽  
Energy Consumption ◽  
Simple Model ◽  
Experimental Result ◽  
Particulate Matters ◽  
Removal Mechanism ◽  
Air Cleaning ◽  
Suspended Particulate ◽  
Suction Flow ◽  
Suspended Particulate Matters

We are studying the effects of thermal moisture swing air-cleaning method on removal of suspended particulate matter, SPM. This method continuously humidifies sample air with heating and dehumidifies it by cooling, in a channel. It was experimentally demonstrated that the thermal moisture swing method reduces SPM suspended in sample air. The experimental result showed reduction of SPM above 10 nm in particle size, and the removal ratio increased with intensifying the thermal moisture swing. The SPM removal mechanism of this method was theoretically estimated. The estimation suggests that the reasons for the SPM reduction are suction flow accompanying condensation and thermophoresis. These phenomena would transport SPM to cooling wall of the dehumidifier. Also, diffusional deposition and gravitational sedimentation would transport SPM to the wall of the channel. And, the transported particles are separated from the air with adhering on the wall. We estimated the effects of these phenomena on SPM removal using simple model and energy consumption. The estimation qualitatively agreed with the experimental result.

Variation in Size Distribution of Suspended Particulate Matters in Air With Humidity Swing Operation

2010 ◽  
Author(s):  
Nagisa Onoda ◽  
Osamu Nakabeppu
Keyword(s):  
Particulate Matters ◽  
Nuclear Condensation ◽  
Cleaning Method ◽  
Air Cleaning ◽  
Submicron Size ◽  
Suspended Particulate ◽  
Spm Concentration ◽  
Suction Flow ◽  
Nano Size ◽  
Suspended Particulate Matters

The aim of this study is to develop a new air cleaning method being applicable to suspended particulate matters (SPM) of wide sizes. We experimentally studied about the effects of a humidity swing operation where sample air is continuously humidified with heating and dehumidified with cooling. The total of SPM concentration of sample air decreased with the humidity swing operation; however, the concentration of SPM from 0.3 to 1 μm markedly increased. Suction flow accompanying condensation, cohesion and thermophoresis were considered as the SPM reduction effects. It would appear that the nano-size SPM grew to submicron size by nuclear condensation and submicron size SPM increased. The experimental results showed that the SPM concentration of 0.3 μm or less decreased by 89% and the total of that decreased by 80%. The applicability of the humidity swing operation to removal of SPM including nano size SPM was shown by the results. Also, exponential reduction of the SPM concentration was demonstrated with applying the repeated humidity swing operation in a circulation air-cleaning apparatus. This method is expected to become effective air cleaning method applicable to wide size range of SPM.

Air Cleaning Method With Humidity Swing Operation for Reducing Suspended Particulate Matters

2011 ◽  
Author(s):  
Nagisa Onoda ◽  
Osamu Nakabeppu
Keyword(s):  
Experimental Result ◽  
Particulate Matters ◽  
Nuclear Condensation ◽  
Removal Mechanisms ◽  
Suspended Particulate ◽  
Mechanical Pump ◽  
Spm Concentration ◽  
Micrometer Size ◽  
Suction Flow ◽  
Suspended Particulate Matters

SPM (suspended particulate matters) removal effects of a humidity swing operation where sample air is continuously humidified with heating and dehumidified with cooling were experimentally studied. The experimental results showed that the humidity swing operation reduced SPM ranging from nanometer to micrometer sizes due to multiple phenomena such as suction flow accompanying condensation and thermophoresis, and the total SPM concentration decreased by 80% under the maximum humidity swing condition. The removal mechanisms were theoretically estimated. It was estimated that contributions of the suction and thermophoresis are significant, gravitational sedimentation works above 5 μm size, and the effect of inertial collision is insignificant. Nuclear condensation that markedly changes the SPM size distribution would not be an effective SPM removal effect. The sum of the theoretical estimations is smaller than the experimental result, and study for clarifying the removal mechanisms is necessary. It was also experimentally confirmed that the SPM reduction effects have no dependence on the concentration. The SPM removal experiment in a circulating system was also conducted. With repeatedly applying the humidity swing operation, the SPM concentration for whole size ranges exponentially decreased and converged at certain value. SPM generation by a mechanical pump might occur. With improving the apparatus, this method is expected to become an effective SPM removal method applicable for the SPM from nanometer to micrometer size.

Removal Mechanisms of Suspended Particulate Matter in Humidity Swing Air Cleaning Method

2013 ◽  
Author(s):  
Nagisa Onoda ◽  
Osamu Nakabeppu
Keyword(s):  
Mass Transfer ◽  
Absolute Humidity ◽  
Survival Ratio ◽  
Removal Mechanism ◽  
Moist Air ◽  
Nuclear Condensation ◽  
Air Cleaning ◽  
Suspended Particulate ◽  
Spm Concentration ◽  
Suction Flow

We are studying the removal of the SPM by a humidity swing method, in which sample air is consecutively humidified with heating and dehumidified with cooling. First, the removal effect of this method was experimentally demonstrated. The sample air was humidified to saturated moist air up to 66°C and then cooled to 13°C. The results showed the decrease of the SPM concentration. The SPM survival ratio is plotted against the drop of absolute humidity through the dehumidification; and the survival ratio exponentially decreased to ∼0.2. Also, the dependence of removal characteristic on SPM concentration was not shown for 10 ∼ 10000 particles/cc. Also, growth of SPM due to nuclear condensation was observed in the experiments. However, the number of SPM grown to several micrometers where SPM significantly decreases with gravity was very small. Therefore gravitational sedimentation would not be enhanced. Next, SPM transfer in the dehumidifier was calculated. The heat and mass transfer through the dehumidifier was calculated; and then, variation of SPM concentration by suction flow and themophpresis were obtained. The analysis of SPM transfer showed that the dominant phenomenon for SPM transport in the dehumidifier is suction flow. However, the calculation considering thermophoresis and suction flow predicted the removal effects several times lower than the experiments. Thus, the removal mechanism of the humidity swing method should be explained by unidentified phenomena.

Inorganic and organic chemical characteristics and sources of suspended particulate matters in Ulaanbaatar, Mongolia

2020 ◽  
Vol 54 (4) ◽  
pp. 267-276
Author(s):  
Koshi Yamamoto ◽  
Yuta Suzuki ◽  
Gochoobazar Oyunjargal ◽  
Hiroyuki Fukuda ◽  
Munkhtsetseg Oidov ◽  
...  
Keyword(s):  
Organic Chemical ◽  
Chemical Characteristics ◽  
Particulate Matters ◽  
Suspended Particulate ◽  
Suspended Particulate Matters ◽  
Inorganic And Organic
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