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題 名 | 生質材料在熱分解過程中揮發物質散出的數值分析 |
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作 者 | 林正亮; 洪大有; 艾群; | 書刊名 | 農業工程學報 |
卷 期 | 41:3 1995.09[民84.09] |
頁 次 | 頁98-105+97 |
分類號 | 341.364 |
關鍵詞 | 模式; 熱傳遞; 質傳遞; Model; Heat transfer; Mass transfer; |
語 文 | 中文(Chinese) |
中文摘要 | 農業廢棄物受熱後,揮發物質散出的模式,可考慮熱傳遞、質傳遞、和化學分解反應等因素,分析推導而得。其中,化學分解為大量獨立平行的一階反應,並假設反應參數中的頻率因素為常數,而活化能為常態分佈;熱傳遞則包含了顆粒內的熱傳導、顆粒表面的熱對流與熱輻射;質傳遞則為顆粒內揮發物質的擴散和顆粒表面的質量對流。熱傳遞分析結果顯示,顆粒的溫升大部份是由於熱輻射的效應;此外,本模式的分析結果亦可描述,生質顆粒在熱分解過程中,揮發物質散出的現象,且能明確區分在三個不同顆粒大小範圍內,影響揮發物質散出的控制因素。當顆粒粒徑小於30 μm時,化學反應為主要控制因素,熱傳遞為次要控制因素;當顆粒粒徑介於30-3000 μm時,熱傳遞為主要控制因素;當顆粒粒徑大於3000 μm時,揮發物質散出主要是受限於揮發物質擴散的快慢,其次才是熱傳遞。 |
英文摘要 | A volatile release model of agricultural waste during heating period was developed by considering factors of heat transfer, mass transfer, and kinetics of decomposition. The kinetics of decomposition was assumed to be a large number of independent, parallel first-order reactions in which frequency factor to be a constant and activation energy to be large enough to be expressed as a normal distribution function. Heat conduction in particle and heat convection as well as radiation on particle surface were included in the heat transfer. Mass transfer was based on volatile diffusion in particle and mass convection on surface. Results of thermal analyses indicated that temperature rise of particle to be partially due to radiation. Solutions of the model were derived to describe the volatile release behavior of biomass. In addition, the present analyses identify control mechanism of volatile release for three diameter ranges. As particle diameter smaller than 30 μm, chemical kinetics was the limiting step with heat transfer to be a minor factor. Between 30-3000 μm, the controlling factor was heat transfer. Above 3000 μm, volatile release was limited largely by mass transfer and partially by heat transfer. |
本系統中英文摘要資訊取自各篇刊載內容。