2007-08-012024-05-17https://scholars.lib.ntu.edu.tw/handle/123456789/680323摘要：當氣膠粒子周圍之氣體溫度分布不均勻時，氣膠粒子會由高溫處往低溫處移動，此種現象稱為熱泳運動。熱泳效應可藉由氣體動力論加以解釋，由於氣體分子在高溫處比低溫處有較高的動能與粒子碰撞，因此促使粒子由高溫處向低溫處運動。由氣膠粒子熱泳運動產生的沉積現象，在工業上有許多應用。藉由熱泳運動可有效地移除或收集氣體中的粒子，而使空氣淨化或做為氣膠粒子的取樣之用。熱泳現象也可用於探討致使熱交換器之熱傳係數降低的成因機構。藉由化學氣相沉積程序製造光纖時，熱泳現象是氣膠粒子沉積於管壁的主要機構。在電子晶片的製造程序上，無塵室中的污染微粒因熱泳而附著於晶片表面上，是造成產率損失的主要原因。對於核能安全，熱泳原理可用於計算輻射性氣膠粒子的外洩速率。而在過去，關於氣膠粒子熱泳運動的理論研究，幾乎皆僅針對球形粒子。 然而，大部分的氣膠粒子並非球形，因此很有必要對於非球形氣膠粒子之熱泳運動進行探討。非球形粒子之熱泳與球形粒子的差異，主要在於必須考慮粒子與外加溫度梯度的相對方向，亦即通常非球形氣膠粒子之熱泳可動度不再具有等方向性，且熱泳速度與溫度梯度不再同向。最近，一表面不具有內外溫度躍差與摩擦滑移等效應之橢球形氣膠粒子的熱泳速度，已被分析求得。可是，完整包括粒子表面之內外溫度躍差、熱滑移、與摩擦滑移等效應的非球形氣膠粒子之熱泳運動則尚未能有學者進行解析探討。 本計畫為一個二年期的計畫，將嘗試對於非球形氣膠粒子於一均勻外加溫度梯度中之熱泳運動進行綜合性的理論分析。所考慮的粒子形狀包括近球形、狹長形、橢球形等，而粒子表面之內外溫度躍差、熱滑移、與摩擦滑移等效應皆可被允許。本計畫主要目的是為求得這些非球形氣膠粒子的熱泳速度，並比較其與球形粒子相關結果的差異。<br> Abstract: Thermophoresis refers to the motion of aerosol particles in response to a temperature gradient. The thermophoretic effect can be explained in part by appealing to the kinetic theory of gases. The higher energy molecules in the hot regions of the gas impinge on the particle with greater momenta than molecules coming from the cold regions, thus resulting in the migration of the particle in the direction of decreasing temperature. Being a mechanism for the capture of aerosol particles on cool surfaces, thermophoresis is of considerable importance in many practical applications, such as sampling of aerosol particles, cleaning of air, scale formation on surfaces of heat exchangers, modified chemical vapor deposition, manufacturing of microelectronics, nuclear reactor safety, and removal of soot aerosol particles for combustion exhaust gas systems. Most aerosol particles are not spherical and it is therefore of considerable interest to examine the effect of particle shape on thermophoresis. The thermophoretic theories of non-spherical particles differ from those of spheres in that there is an orientational problem. In general, the thermophoretic mobility of a non-spherical particle is anisotropic and the velocity of the particle is no longer collinear with the prescribed temperature gradient. Recently, the thermophoresis of a spheroidal particle in an arbitrary orientation without temperature jump and frictional slip at its surface was analyzed. However, the problem of thermophoresis of non-spherical particles with all the effects of temperature jump, thermal slip, and frictional slip at the particle surface has not been solved yet. In the present two-year-long research project we attempt a general analytical study for the thermophoresis of a non-spherical particle, such as a rigid particle with a slightly deformed spherical shape, a slender-body particle, etc., immersed in a gaseous medium with a prescribed uniform temperature gradient, and the temperature jump, thermal slip, and frictional slip conditions prevail at the particle surface. The object is to obtain a correction to the thermophoretic velocity of a spherical particle.熱泳非球形氣膠粒子近球形粒子狹長形粒子熱滑移與摩擦滑移ThermophoresisNon-spherical aerosol particlesSlightly deformed sphereSlender particleThermal and frictional slip