垃圾乾燥過程之數值計算

Abstract

本文利用一維數值方法模擬乾燥垃圾過程，欲將垃圾本身的物理性質模擬為多孔性物質。由熱風作用於多孔性物質表面達到乾燥，分析垃圾水分蒸發速率。研究探討重要參數，如：對流熱傳係數、對流質傳係數、外界熱風溫度高低、空氣濕度高低、翻轉影響。又以二維數值模擬方法，探討裝在液態薄膜上的多孔性凸塊經由噴射衝擊流衝擊後所產生的蒸發擴散現象，探討的影響參數，如：孔隙率、顆粒球徑比、雷諾數等。雖然多孔性介質會增大氣體蒸發擴散的阻抗，對於液態薄膜蒸發擴散是一項缺點，但是利用多孔性介質的大散熱面積、高熱傳遞係數效率及水膜蒸發時所需帶走大量蒸發潛熱的優點，促使增強高溫面的熱傳效率。

In this study is simulated to dry garbage by using the method of one dimension numerical, and physical properties of the garbage is simulated porous media. The porous media is dried through the hot air is acted on surface, and water evaporation rate of garbage is analyzed. The important parameters, such as, heat transfer coefficient, mass transfer coefficient, temperature of hot air, moisture of air and effect of turn is studied. And by using the method of two dimension numerical, it is investigated the phenomenon of evaporation to add the porous block which is impinged by impinging jet. The important parameters, such as, porosity, the diameter of sphere making of the media and Reynolds number is studied. Although it is a fault to add obstruction of air evaporation for aqueous film evaporation, porous media can provide larger heat exchange surface, larger heat transfer coefficient, aqueous film evaporation is advantage of carrying larger latent heat of evaporation, and increases heat transfer rate on high surface.