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Title: | 應用垂直式光徑煙流分佈技術推估儲槽排放率:電腦模擬研究 Applying Vertical Radial Plume Mapping Technique to Estimate Emission Rate of Storage Tanks:a simulation study |
Authors: | Jia-Yau Wu 吳嘉曜 |
Advisor: | 吳章甫(Chang-Fu Wu) |
Keyword: | 排放率,通量,垂直式光徑煙流分佈,模擬研究,光學遙測, emission rate,flux,Vertical Radial Plume Mapping,simulation study,optical remote sensing, |
Publication Year : | 2013 |
Degree: | 碩士 |
Abstract: | 工業區中有許多儲槽,儲槽所排放的揮發性有機化合物有可能會對廠區內的員工與附近居民的身體健康造成不良的健康危害。垂直式光徑煙流分佈(Vertical Radial Plume Mapping, VRPM)為美國環保署用來預測下風處垂直面的濃度分佈並計算其排放率(emission rate)的方法,但是VRPM技術的假設為煙流擴散模式為高斯分佈,實際環境中煙流擴散模式受到其他因素影響是否依然為一個完整的高斯分佈還有待驗證。為了證實VRPM高斯分佈的假設適用於回推排放率,本研究使用美國氣象協會�美國環保署管制模式(American Meteorological Society Environmental Protection Agency Regulatory Model, AERMOD)模擬的下風處濃度分佈與排放率,來比較與VRPM預測的結果有無顯著的差異性。所模擬的時間為一年,儲槽的數量設定為1個與6個,考量到建築物下沖(building downwash)作用的影響,VRPM垂直面與儲槽的距離設定為16公尺與86公尺。由於風向不一定與VRPM垂直面垂直,因此使用多項式迴歸線來做通量(flux)的校正,迴歸線冪次的次數分別選取一次、二次與三次。結果顯示即使地形平坦且沒有其他建築物的影響,只有儲槽這項因子對於校正後的通量就會低估,而且VRPM垂直面與儲槽的距離愈遠時低估的情形愈嚴重,大部分通量校正後與真值的關係為:真值>校正後AERMOD通量>校正後VRPM通量,校正後VRPM通量低估校正後AERMOD通量的百分比為8.5%至31.6%。未來在實際應用中,如果監測的風向與風速資料平均分佈,可以參考本研究排放率低估的百分比。 In industrial complexes, there are many storage tanks. The volatile organic compounds (VOCs) they emit may cause adverse health effects to employees working in factories and people living in nearby communities. The Vertical Radial Plume Mapping (VRPM) technique is a method for predicting downwind concentration distribution and estimating emission rates of the storage tanks. In the VRPM technique, the plume is modeled with a Gaussian distribution. Nevertheless, plume dispersion could be influenced by many factors in the field. Therefore, it is necessary to verify whether the assumption of Gaussian distribution in the VRPM is applicable to reconstruct the emission rates. In order to verify this assumption, we used AERMOD (American Meteorological Society Environmental Protection Agency Regulatory Model) to simulate the distribution of downwind concentration and the emission rate. The results of the AERMOD estimates were compared with the results of applying the VRPM technique. In this simulation study, there were three assumptions. First, the simulation period is one year. Second, the number of tanks was 1 or 6. Third, to concern the building downwash effect, the distances between the VRPM configurations and storage tanks were set at 16 meters or 86 meters. Since the wind directions were not always perpendicular to the VRPM plane, we utilized linear polynomial, quadratic polynomial, and cubic polynomial to adjust the flux values. In the results, without any presence of other buildings, we found that the adjusted flux values were underestimated when the storage tank was the only factor concerned. Moreover, the farther of the distances between the VRPM configuration and the storage tanks, the more underestimation were found in the adjusted flux. The general trend among the true and estimated flux was: True value > adjusted AERMOD flux > adjusted VRPM flux. Compared to the adjusted AERMOD flux, the adjusted VRPM flux was underestimated in the range of 8.5% to 31.6%. While applying the VRPM technique in future field measurements, researchers could refer to this study if wind directions and wind speeds are distributed evenly. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/58860 |
Fulltext Rights: | 有償授權 |
Appears in Collections: | 環境衛生研究所 |
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ntu-102-1.pdf Restricted Access | 1.54 MB | Adobe PDF |
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