İS (SİYAH KARBON) TOPAKLANMALARINDA YAPISAL DURUMLARIN IŞINIM ÖZELLİKLERİNE ETKİLERİ

Yanma ürünü olan is (siyah karbon) parçacıkları topaklanarak atmosfere yayılırlar. Kanserojene yol açan (PAH) molekül içermeleri nedeniyle toksikolojik etkilere sahiptirler ve ışınım özelliklerinin artması nedeniyle global ısınmaya güçlü etkilerinin olduğu bilinmektedir. Bu çalışmada, siyah karbon topaklanmalarının ışınım özelliklerine topaklanma yapısının ve büyüklüğünün etkileri, Discrete Dipole Approximation (DDA) yöntemi ile analiz edilmiştir. N = 200 parçacıktan oluşan iki ayrı yapıdaki topaklanma örneği 0.532 ve 1.064 μm dalga boylarında ışınım saçılımı açısından incelenmiştir. Her iki topaklanma yapısı, üç farklı yapısal durumda yani parçacıklar nokta temaslı, iç içe geçmiş ve topaklanmanın hacimsel büyütülmüş durumları için topaklanmaların ışınım özellikleri hesaplanmıştır. Yapılan analizlerden, is topaklanmalarının ışınım özelliklerinin topaklanma hacim eşdeğer yarıçapları ve incelenen dalga boyundan oldukça etkilendiği görülmüştür. Parçacık temaslı topaklanma genişlemesi ile parçacıkları iç içe geçen topaklanmaların ışınım özelliklerinin aynı değerlere sahip olduğu saptanmıştır.

Anahtar Kelimeler:

ışınım özellikleri, siyah karbon, is topaklanmaları, polarizasyon, DDA

Effects of Morphology on the Radiative Properties of Fractal Soot Aggregates

The soot (black carbon) particles which are produced by combustion emits into atmosphere in forms of aggregates. The aggregates contain of PAH molecules that are causing carcinogens have toxicological effects. It is well known that soot aggregates which are enlarged of radiative properties effect on global warming. In this study, the impact of morphology on the radiative properties of fractal soot aggregates was investigated using the discrete dipole approximation (DDA). The radiative properties of aggregates of N = 200 primary particles were numerically evaluated at 0.532 and 1.064 μm wavelength. The radiative properties of three different cases, formed by point-touching, overlapping and aggregate expansion for soot aggregates were calculated. The effects of radiative properties of soot aggregates vary strongly with the volume equivalent radius aeff and wavelength. It was found that the expansion of aggregates has the same effect on radiative properties as overlapping.

Keywords:

Radiative properties, black carbon, fractal soot aggregates, polarization, DDA,

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