Application of the TheRmophoretic Annular Precipitator (TRAP) for the study of soot aggregates morphological influence on their thermophoretic behaviour

A study about the influence of soot particles morphological parameters on their thermophoretic behaviour is presented in this paper. Soot particles with variable morphological parameters were produced using a miniCAST (Combustion Aerosol Standard) JING5120 type C. Ex-situ (TEM) and online (CPMA) techniques were used in order to characterize the generated particles. The TheRmophoretic Annular Precipitator (TRAP) developed in our previous study (Ait Ali Yahia, Gehin, & Sagot, 2017) was used to evaluate the soot particles thermophoretic diffusion coefficient Kth. The TRAP is a device where a thermal gradient is created in the 1 mm annular space between two concentric 0.5 m length tubes, the inner tube is cooled and the outer one heated. Particles flowing through the annular space will migrate and deposit by thermophoresis on the cold tube external wall. The thermal gradient was fixed at 46,000 K m−1 and a laminar aerosol flow was applied (Re = 380). The new experimental results obtained in this work confirmed and completed the results presented by Brugière (Brugière, Gensdarmes, Ouf, Yon, & Coppalle, 2014). These results provide also new indications about the influence of the particles size, the primary particles diameter and the presence of organic compound on the soot particles thermophoretic behaviour.